GB2034943A - Well logging system and method - Google Patents

Abstract

A well logging system and technique is provided for correlating historically derived measurements with new measurements being derived at correlative depths as the well is logged. A logging sonde generates and delivers to the surface digital logging data in realtime as a function of preselected depth intervals. This data is merged with compatible digital data which is historical in character and derived at correlative depths. The realtime and historical measurements derived at the same borehole elevations are correlatively matched for realtime recording, display and processing of the matched data. A converging technique is provided for accomplishing the initial merger independent of the direction of logging, the relative starting elevation of the sonde and historical data, and whether the realtime logging has begun prior to the merging process. Provision is made for transmitting from one or more remote observation and control sites the historical data employed in the merger, for transmitting the merged data to a remote location, and for transmitting from the remote location to the well site control signals in response to the merged data received by the remote site.

Description

SPECIFICATION Well logging system and method This invention relates to novel methods and apparatus for providing a plurality of functionally integrated subsurface well logging measurements and more particularly relates to improved logging methods and apparatus for correlatively merging historical logging measurements with similar or other different measurements being derived on a realtime basis.

It is well known that oil and gas is found in subsurface earth formations, and that wells are drilled into these formations to recover such substances. What is not generally known is that, for various reasons, the contents of most such formations do not automatically discharge into the well bore upon being penetrated. Furthermore, it is usually necessary to survey or "log" the entire length of the borehole to locate those formations of interest, before the well can be completed to produce the oil or gas.

There is no single well logging technique or device which can provide a direct indication of oil or gas in a particular formation of interest.

Instead, the logging techniques which are most commonly used are those which measure a plurality of different characteristics or parameters of the earth substances adjacent the borehole, whereby such measurements can thereafter be interpreted according to selected functional relationships for identifying those formations of possible interest.

Since no one earth parameter, or even any one combination of such parameters, can of itself provide a definitive and conclusive indication of the presence of oil and gas in commercial quantities, there has been a continuing need to perform as many different types of logging measurements as possible.

The cost of making a well log is quite expensive, however, and is directly dependent on the time required to traverse the borehole with the sonde or logging tool, and measurements taken during different trips through the hole are extremely difficult to correlate with respect to depth, magnitude, etc. Accordingly, there has been an increasing need to provide methods and apparatus for making a plurality of different but correlated measurements during the same trip through the borehole.

However, it is often difficult to generate in one pass through the borehole all measurements required to reliably evaluate a formation of interest. One reason for this is that certain logging instruments are not compatible for simultaneous operation. Furthermore, the increased weight and length of the sonde required to house the various instruments, which are conventionally arranged in tandem, frequently complicate the traversal of the sonde through deviated as well as straight boreholes. Still further, limitations on band width, high signal density recovery equipment, and channel availability of communication links between the borehole and the surface equipment often necessitate multiple passes of the sonde through the borehole.In addition, it is often desirable to combine or otherwise correlatively integrate measurements taken at some earlier time and, perhaps, for a different purpose, with new measurements being derived from current logging operations. In this respect, however, those measurements which are derived at the surface during passage of the logging sonde through the borehole are commonly known as "realtime" measurements or logs, in contrast with a measurement taken at any earlier time, and which is known as "historical" measurements regardless of when they are made.

It will be readily apparent that when it is sought to correlate or otherwise combine different sets of logging measurements taken at different times, such correlation will be meaningful only when all such measurements are derived at correlatively identical depths within the borehole. Thus, the problem becomes one of matching or "merging" measurements from one set of logging data with the measurements taken at correlative depths from another set of data.

Even when all the required measurements are generated during the same trip in the borehole, it is nevertheless still frequently necessary to solve the problem of merging the data thereby generated with data derived at a different time. This may be due to a desire to check the integrity and validity of the data with a previous log. It may also be desirable to even correlate measurements derived from one borehole with that of yet another borehole, also necessitating the merger of two data sets.

One attempted solution to the problem of merging sets of logging data has been to first generate visible representations of the data in the form of films from conventional film recorder cameras well known in the art. These films are then positioned adjacent one another on a light table, and then manually shifted with respect to each other, so that correlative measurements may be visibly compared. Because this method requires production of films, comparisons may not be made in realtime. Yet another disadvantage is that the aligning process is manual and highly subjective, requiring visual judgment. Furthermore, the resultant merged data is not in a form suitable for further processing, such as the digital recording of the present invention.

Yet another attempted solution has been to generate separate tape recordings of each set of measurement data which is to be merged.

Any two such tapes are thereafter replayed, whereby correlative measurements are automatically selected from each tape and thereafter recorded onto a third tape. While this method may eliminate the hereinbefore noted manual steps of the light table method, neither technique provides for merger in realtime of historical logging data with other logging data as it is being produced in realtime. This, in turn, means that the integrity and validity of the realtime data cannot be checked and compared with previously derived data until the logging operation is completed, which may necessitate an expensive and time consuming re-log of the borehole if the data is defective. Moreover, this technique is extremely time consuming in the case of logs having numerous sample intervals, as it requires that the tape of the realtime log must be re-run in order to produce a "merged" tape.Thus, it is also not possible with this technique to perform realtime processing of historical and realtime data which have been merged in realtime, which may be desired, for example, in order to control the realtime logging operation in response to the processed data. Still further, this technique requires simultaneous capability and attendant equipment to read data from two sources such as tape decks and thereafter record the merged results at yet a third tape deck or other location. These extra steps of recording and reading the reaitime data in order to effect a merger further contributes to unreliability of the technique necessitated by the additional runs of tape decks or the like.Still further, because the realtime data is not being generated in correlation with historical data points, thus providing opportunity to dynamically adjust, either visibly or automatically, the depth of future realtime data acquisition in relation to the historical data, the resulting sets of data points frequently are not correlative to identical borehole depths and require additional processing time in attempts to so correlate them by interpolation techniques and the like.

In addition to the problems of the prior art, an additional problem has arisen due to the advent of offshore drilling operations, whereby a need has arisen to provide for observation and control of logging operations and data at locations remote to the well site, and also to provide technology for not only comparing logging data with correlative logging data obtained at different times, but also to provide a technique whereby such stored data may be correlatively recovered and merged with new logging data as it is being derived from a downhole sonde.Finally, and perhaps more critical, it has become increasingly desirable if not essential that such "realtime" and "historical" logging data be generated in a form such that it can be conveniently correlated to provide information not easily obtained by mere comparative inspection of data obtained by conventional techniques, and whereby functional conclusions may be derived in a more accurate manner for judging whether to complete the well at a particular depth.

These and other disadvantages are overcome with the preferred embodiment of the present invention, however, wherein improved well logging methods and apparatus are provided to generate more accurate measurements of a plurality of different lithological parameters. Improved means and methods are provided for correlatively merging historical logging data with data being obtained on a realtime basis, whereby both the historical and the realtime data may be employed in a conventional computer, and whereby such logging operations may be conveniently controlled, monitored, and even recorded at one or more locations remote to the well site.

There is depicted and described in our U.S.

patent application S/N 949,592, filed October 10, 1978, an integrated digital well logging system and apparatus, wherein a plurality of realtime logging measurements may be generated and merged with correlative historical logging measurements derived at corresponding borehole depths. In particular, techniques and apparatus are depicted therein for generating logging measurements downhole at preselected depth intervals so as to insure that realtime measurements to be generated will be generated at depths correlative to the historical measurements they are to be correl actively merged or "matched" and recorded with. Reference may be had to the aforesaid U.S. patent application for details of the digital logging apparatus and the disclosure of said patent is considered incorporated herein for all intents and purposes.

The merger circuitry of the aforementioned patent application is specifically illustrated in Fig. 2, and is described in detail therein as to mode of operation and construction. The essential features of the therein described merger circuitry comprise primary storage 56 for storing and retrieving realtime logging data generated by the logging system, and a secondary storage 57 for storing and retrieving historical logging data. The merger circuitry further comprises a master controller 40, which selectively retrieves historical and realtime logging samples from storage 56 and 57 derived at correlative borehole depths for realtime display on cathode ray tube 52 or for recording on film recorder 50, plotters 54 and 65, or the like.

Use of the merger circuitry of the aforesaid patent application has revealed that it will merge realtime and historical data with reasonable effectiveness, and that it thus possesses significant advantages over conventional non realtime merger techniques heretofore discussed.

On the other hand, it will be readily apparent from a consideration of the teachings hereinafter set forth that merger circuitry is provided with improved capability over that depicted in the prior application. Basically, the herein disclosed merger circuitry is of identical construction as described in our prior patent application. However, the merger circuitry of the present invention provides for improved methods and apparatus for initiating the merger function, whereby the starting depth of historical data is periodically compared with that of the sonde in a convergent process until a realtime and historical sample correlative to identical borehole depths are matched. The improved merger circuitry will accomplish this function regardless of sonde movement, the reading of historical data prior to merger, or both.

In a preferred embodiment of the invention, a well logging system is provided which, in its overall concept includes a sonde which generates electrical representations of a selected plurality of lithological characteristics, a logging cable for suspending and passing the sonde through the borehole past the formations of interest, and appropriate circuitry at the surface for processing and recording data provided by the sonde. More particularly, the sonde will preferably include a circuit whereby one or more of these measurements are converted or formed into "frames" of digital representations which, in turn, are transmitted through the logging cable to the surface in response to a depth-dependent command signal.

At the surface, all data signals are stored for sequential sampling and processing, before being recorded and displayed. As will hereinafter be explained, it is a particular feature of the invention to coordinate different logging measurements to provide more information.

The surface equipment includes both a "primary" storage, whereby realtime data signals from the sonde are stored also in response to the depth-dependent command signal prior to processing. In addition, however, a "secondary" magnetic tape storage is provided whereby these realtime signals, which are all in digital form, may also be stored for later reproduction and re-use.

The surface equipment comprises sampling circuitry, whereby the data in the primary storage may be sampled on a time-dependent basis in accordance with a predetermined sequence. In addition, the sampling circuit not only cycles through the realtime data in the primary storage, but may also cycle out historical logging data previously passed into the secondary storage, as may be deemed appropriate.

It is a particular feature of the preferred embodiment of the present invention to provide for correlatively merging realtime data with historical data as a function of borehole depth. In this respect, the different data may be separately, although correlatively, included in a common display or record, or a function of such logging data may be appropriately derived on a realtime basis and included with the individual logging signals being displayed and recorded. In this respect, novel circuitry and techniques are provided for more effectively correlating historical data with realtime data, in order to enhance the informative aspects of this data.In addition, it is a significant aspect of this invention to provide for visual observation and monitoring of the logging signals and other data on a realtime basis, together with the historical data being merged therewith Many of the foregoing features may be effectively incorporated and used either separately or as a part of a generally conventional well logging system. For example, the aforementioned merger capability may be effectively used to combine two or more historical measurements separate and apart from any realtime data signals wherein each such measurement was generated or sampled at preselected depths in response to a depth dependent command signal.It is a particular feature of the integrated logging system, however, to provide for visual display and recording of both the realtime and historical data at one or more observations sites which are remote to the well site, and also to provide for partial or complete control of the operation at such remote observation site. The realtime data may be merged in realtime at the well site with historical data which may have been transmitted to the well site in realtime from a remote location. Alternatively, the realty me data may be transmitted to a remote site and merged in realtime at the remote site with historical data present at the remote site.

In a preferred embodiment of the invention, as the sonde traverses the borehole, it will sequentially generate and transmit to the surface measurements at preselected increments along the borehole. Appropriate merger circuitry will periodically compare the current depth of the sonde and the depth at which the first of a plurality of historical measurements to be merged was derived, also sequentially generated and stored. These historical measurements are preferably also derived from identical preselected increments as the realtime measurements. As the sonde progresses up the borehole, realtime measurements thus produced will be recorded. When the depth at which the next measurement to be made by the sonde reaches the depth at which the first historical measurements were made, the merger circuitry detects this state, causing the merger process to begin.The merger circuitry will thereafter alternately cause to be recorded in a storage device, data samples generated by the sonde and correlative historical data samples retrieved from another storage wherein the sonde and historical samples were generated at the same depths. This correlative matching and recording in succession of a realtime sample and a historical sample derived at a correlative depth, fol lowed by a next realtime sample and historical sample both derived at a next different preselected and discrete borehole elevation will continue throughout the course of the log.If the historical data samples begin at a deeper elevation within the borehole than the sonde, they will be selectively read from storage and recorded in another storage device until the merger circuitry detects that the next historical data sample to be read was derived at the current sonde depth at which the next realtime measurement is to be made. The merger process will then begin, whereby, also in alternate fashion, selected realtime data samples from the sonde will be recorded, followed by historical data samples retrieved from storage which were derived at correlative subsurface depths.By periodic interrogation of the current sonde depth prior to "merger" or the correlative realtime recording in the same storage of both realtime and historical data derived at identical depths, the start of the merger process is made independent of sonde movement as well as the relative starting location of the sonde and the depth at which initial historical data was derived.

Provision is made for realtime processing of this historical and realtime data which is being merged in realtime whereby the logging operation may be dynamically controlled in response to the merged data. A realtime display of the merged data is further provided, wherein realtime and historical data derived over preselected identical increments of borehole are displayed side-by-side, so as to permit comparison of the realtime samples with correlative historical samples, in order to check validity of the respective data. The merger circuitry provides for transmitting in realtime the merged data to a remote location, and for transmitting from the remote location to the well site in realtime control signals in response to the merged data received by the remote site.

A further different feature of a preferred embodiment of the invention includes a technique for investigating the lithological characteristics of subsurface earth materials traversed by a borehole, comprising deriving a first digital measurement of a selected characteristic of said materials, electrically displaying a visual representation of said first digital measurement on a realtime basis and in functional correlation with borehole depth, deriving a second digital measurement of a selected characteristic of said materials on a historical basis, and electrically displaying a visual representation of said second digital measurement in functional correlation with said visual representation of said first digital measurement.

Apparatus is described for investigating the lithological characteristics of subsurface earth materials traversed by a borehole, comprising first conversion means for deriving a first digital measurement in realtime of a selected characteristic of said materials, second conversion means for deriving a second digital measurement of a selected characteristic of said materials on a historical basis, display means for electrically displaying a visual representation of said first and second digital measurements on a realtime basis and in functional correlation with borehole depth, and display means for electrically displaying a visual representation of said second digital measurement in functional correlation with said visual representation of said first digital measurement.

A well logging system is described including a sonde and the like for generating electrical measurement signals in a borehole, a logging cable coupled therewith for transmitting said measurement signals to the surface, and surface apparatus connected to said cable for deriving lithological information from said measurement signals, wherein said system further includes the improvement in combination therewith comprising receiving means for deriving from said measurement signals a correlative data signal functionally related to the depth of said sonde in said borehole, first signal processing means responsive to selected discrete portions of said data signal for deriving a first information signal representative of the lithological character of earth materials traversed by said borehole, second signal processing means responsive to different selected discrete portions of said data signal for deriving a second information signal representative of the lithological character of earth materials traversed by said borehole, and recording means for correlatively recording said first and second information signals as a function of the depth of said sonde in said borehole.

The invention will be better understood from the following description of a preferred embodiment thereof, given by way of example only, reference being had to the accompanying drawings, wherein: Figure 1 is a simplified functional representation of an embodiment of the present invention.

Figure 2 is another functional representation of the present invention, including a more detailed representation of the master controller portion of the apparatus depicted in Fig. 1.

Figures 3A and 3B are flow diagrams depicting the functional operation of the apparatus depicted in Figs. 1, 2, 4A and 4B.

Figures 4A and 4B are more detailed functional representations of one embodiment of the present invention.

As hereinbefore explained, the present invention is directed to an improved well logging system of the type depicted in our prior U.S. patent application S/N 949,592, and reference may be had thereto for details of the system. Thus, the disclosure of the prior appli cation is considered to be incorporated herein for all intents and purposes and with reference to a full understanding of the improvement of the present invention. It should be apparent that Fig. 1 of the accompanying drawings parallels Fig. 2 of the prior application. The operation of the improved merger circuitry of the present invention and its environment are thus identical with that of the prior application, except as hereinafter set forth.The prior application should therefore be referred to for a complete understanding of the overall digital well logging system operation and for the location and coaction of the improved merger circuitry disclosed herein.

Referring now to Fig. 1, there may be seen a simplified functional diagram of one embodiment of the present invention, and wherein there is more particularly shown the logging sonde 2 which may suitably include such portions as a radioactivity logging section 2A, an induction logging section 2B, an acoustic logging section 2C, and a pulse code modulation section 2D, all arranged to provide appropriate measurements of the lithology surrounding a subsurface borehole (not depicted). Measurements from these sections may be conveniently transferred from the borehole to the surface by way of a conventional logging cable 3 which is arranged to rotate a sheave wheel 4, or the like, to provide a correlative indication of the borehole depth at which such measurements are taken.More particularly, the sheave wheel 4 may also be conveniently coupled to suitable depth encoder circuitry 6, by a drive shaft 5 or the like, whereby the depth encoder circuitry 6 will deliver a functionally correlative depth measurement signal 7 to the surface portion of the well site system, in conjunction with the measurements provided by the logging cable 3.

As previously stated, it is a feature of the well site system depicted functionally in Fig. 1 to transmit fully correlated logging measurements to a suitable base observation and control station such as that referred to in copending U.S. Patent Application S/N 949,592, filed October 10, 1978, and which, in turn, may be suitably located at a position remote from the location of the well site system. Accordingly, and as will hereinafter be explained in detail, the well site system will appropriately encode and condition these measurements to provide correlative indications to the remote base station, at the time such measurements are received from the logging cable 3, through a suitable communications link 1 5 which may be a conventional telephone line, radio communication satellite, or the like.Furthermore, like signals may also be provided to the customer or user at his respective user station (not depicted) which, in turn, may be located remotely from both the well site system and the operator's base station (not depicted). These indications, may also be conveniently transferred to the user station by a similar communications link 1 6 interconnecting the well site system with the user station, and thereafter relayed to base station by means of another different communications link (not depicted), or they may be relayed from the base station to the user station on such communications link.It should be noted that the well site system suggested by Fig. 1 may be operated directly by the base station, and therefore the communications link 1 5 may also include provision for delivering suitable control signals from the base station to the well site system by way of the communications link 1 5. Similarly, the communications link may be used to provide control signals from the base station to the user station, or in some circumstances, to provide control signals from the user station to the well site system or base station, by way of the communications link 1 6.

Referring again to Fig. 1, there may be seen a simplified functional diagram of the uphole circuits comprising the apparatus located at or composing the well site system. As will hereinafter be explained in detail, the sections of the logging sonde 2 are preferably adapted to deliver their respective measurements to the conductors composing the logging cable in a manner whereby all of the measurements are delivered to the surface together. It should be noted that information may also be desirably transferred from surface circuitry to the borehole for reasons to be hereinafter explained in greater detail. For example, it may be desirable to control various transmitters and receivers contained in acoustic logging section 2C from the surface.

Accordingly, it may be seen from Fig. 1 that at appropriate times and in response to a command signal 44 from a well site master controller 20, transmitter firing circuitry 23 may be caused to generate transmitter firing signals 23A for purposes of controlling the various circuitry in the acoustic logging section 2C of the sonde 2. This transmitter firing signal 23A may preferably be delivered to a conventional line control circuit 24 which couples the signal 23A to the appropriate conductor within the logging cable 3.

As indicated in Fig. 1, when measurement signals are received from sonde 2, the output of the logging cable 3 is preferably also delivered to a line control circuit 24 which, in turn, passes the signals as its output 24A to a suitable arrangement of signal conditioning circuits 25 for filtering, gain adjustment, and other suitable processing. The conditioned logging signals 26, which are provided by the signal conditioning circuits 25, may then be delivered through a suitable switching circuit 27 to either a PCM buffer/receiver circuit 29, or to a binary gain amplifier 28, or in a further alternative, to a low speed/high speed analog-to-digital converter 31 and suitable ra dioactivity pulse counters 30, by way of sig nals 27a, 27b, or 27c, respectively.

It is well known that the outputs from a conventional sonde 2 will be in either analog form, or in the case of radiological measure ments, will be composed of pulses which occur in a random manner. As will hereinafter become apparent, however, it is particularly desirable for the purposes of the instant invention, that these signals be presented to the surface circuitry in digital form. Accordingly, and as more particularly depicted in Fig. 1, the sonde 2 will preferably include a pulse code modulation or "PCM" circuit 20 for encoding such signals in digital form before delivery to the PCM buffer/receiver circuit 29 shown in Fig. 1.If the signals are not so encoded, however, then they may be conveniently applied to a suitable analog/digital converter 31 or the like, before being processed and recorded Alternatively, pulses deriving from radiological measurements may conveniently be applied to appropriate counters 30 and the like, which will then suitably deliver their outputs in digital form.

Referring again to Fig. 1, it will be seen that the signals being generated by the radioactivity section 2A of the sonde 2, will accordingly originate as a train of electrical pulses indicating the occurrence of radiations emanating from the borehole materials surrounding the sonde 2, and will therefore be suitably delivered to the pulse counters 30 which, alternatively, produce a suitable digitized representation of this data as output signal 30A. On the other hand, the output signals from the induction logging section 2B and the acoustic logging section 2C of the sonde 2 will, conventionally, be delivered to the surface in the form of analog measurements representative of lithological characteristics of the borehole material adjacent the sonde 2.Accordingly, such outputs from switching circuit 27 which compose signal 27c will, in turn, be converted to digital representations of the data sought to be obtained. These representations, which are indicated as output 31A, will accordingly be conducted by a suitable lead 32A and the like to an input of the logging signal recovery controller 32.

It will be noted that the analog-to-digital converter 31 receives input signals 27c and 28a from both the switching circuit 27 and the binary gain amplifier 28. The reason for this is that, in some cases, the signals generated from the induction logging section 2B and the acoustic logging section 2C of the sonde 2 are sufficient in amplitude to be applied directly to the analog-to-digital converter 31. On the other hand, such signals are often of such a magnitude, or, alternatively, attenuated by the logging cable 3 to an extent that they exceed the dynamic range of converter 31 and must accordingly be attenuated or amplified, respectively, before they can be properly handled by the converter 31. Accord ingly, the switching circuit 27 will respond to route such signals to the binary gain amplifier 28 prior to conversion of the analog signal into digital form at converter 31.

More particularly, the well site master control 20 is adapted to generate another command signal 33 to the switching circuit 27 to route its output either in the form of a digital signal 27a to the PCM buffer/receiver circuit 29, or in the form of an analog signal 27c which is delivered to the converter 31 or to the pulse counters 30. If, as herein before stated, the signal 27c is of an insufficient amplitude to be properly handled by the converter 31, or if the amplitude is too great for the dynamic range of the converter 31, then the master controller 20 will, according to program, generate a command signal 22 to cause the switching circuit 27 to deliver its output signal 27b (instead of signal 27c) to the binary gain amplifier 28.It will be noted that binary gain amplifier 28 may be provided with a suitable gain control signal 34 which serves the purpose of continuously adjusting the gain of binary gain amplifier 28 in response to command signal 33 delivered to recovery controller 32 from master controller 20. It will be seen that because the input to analog-to-digital converter 31 may be periodically interrogated by master controller 20 in a manner to be described hereinafter, master controller 20 may cause gain control signal 34 to appropriately adjust gain of binary gain amplifier 28 so as to insure that input signal 28a is maintained within the dynamic range of analog-to-digital converter 31. Accordingly, the amplified signal 28 , which is produced by the binary gain amplifier 28, is then delivered to the converter 31 in lieu of the output signal 27c.

Referring again to Fig. 1, it may, for the purposes of illustration, be assumed that the sonde 2 is composed of a plurality of sensing elements such as the radioactivity logging section 2A, the induction logging section 2B, and the acoustic logging section 2C, and that all of these sensors are continually and simultaneously delivering meaningful data signals to the logging cable 3. It is preferable that the well site system sort and handle these signals in a manner to distinguish one from another, as well as to handle such signals in correlation with appropriate indication of the depth at which such signals originated. Accordingly, the analog-to-digital converter 31, the pulse counters 30, and PCM buffer/receiver circuit 29, will all include appropriate buffer circuitry, whereby these signals may be stored until the well site master controller 20 generates its command signal 33 to cause the recovery controller 32 to interrogate the components selected. Upon such interrogation, which is indicated in Fig. 1 by the interrogation signal 32c, the recovery controller 32 will cause the appropriate or selected component to transfer one of outputs 29A, 30A or 31A to the recovery controller 32 which, in turn, conducts such information to the master controller 20 in the form of output 32b. Upon receiving output 32b, the master controller 20 conducts such output to either the primary storage facility 35, or the secondary storage facility 36 by means of the input signals 37.

As hereinbefore stated, the measurements provided by the logging sonde 2 must be correlated with an indication of the depth at which such measurements are taken. Accordingly, it should be noted that when the master controller 20 generates its command signal 33, it also generates an appropriate depth data/control signal 21 to cause the depth controller 1 2 to deliver the information it has previously taken from the output 11 of depth logic 10. Thus, this data, which also passes to the controller 20 by way of the depth data/control signal 21, will be correlated effectively with the logging data signals provided by the recovery controller 32 in the form of output 32b.It will be noted that in order for depth logic 10 to provide appropriate information to depth controller 12, information from depth encoder circuitry 6 may conveniently be transmitted to receiver 8 by means of depth measurement signal 7, and from receiver 8 to depth logic 10 on receiver output 9.

There may further be seen in Fig. 1 visual display and recording devices which may preferably include analog film recorder 39, visual display 40, and a suitable large scale plotter 41 and small scale plotter 42. Information which is desired to be displayed or recorded may be transferred to these various display or recording apparatus from master control 20 through logging data information signal 43.

More particularly, information signal 43 may be desirably routed to a film recorder controller 45 which will provide necessary interfacing between master controller 20 and digital-toanalog converter 46, and thereafter communicated from controller 45 to converter 46 on output line 45A. After conversion of the digital information on line 45A by converter 46 to analog information, this analog information may be conveniently coupled by output line 46A to analog film recorder 39. It should be noted that recorder 39 may preferably be a conventional galvanometer type recorder well known in the well logging industry which is particularly suited for recording graphical data and the like associated with well logging operations.

In like manner, data from master controller 20 carried on information signal 43 may also preferably be communicated to continuous display controller 47 which may process these signals to provide output signals 47A, 47B and 47C which are communicated to visual display 40. More particularly, and as will be hereinafter be explained in detail, continuous display controller 47 may preferably process information signal 43 so as to generate a visual picture of desired well logging information over a preselected borehole depth interval which has been traversed by sonde 2.

Still further, it may be seen from Fig. 1 that the information signal 43 may be conveyed to a plotter controller 48 for processing the desired information signal 43, in a manner to be hereinafter described in greater detail, prior to being delivered as input 48A to a suitable plotter interface 49. The function of the interface 49 is to further adapt these information signals 43 for delivery as output 49A to suitable processing circuitry such as a digitalto-analog converter 50, wherein they are converted to an appropriate analog output 50A for recording on film within the large scale plotter 41. In like manner, it may be desirable to display various information signals 43 associated with the well logging operation on a smaller scale than that employed in large scale plotter recorder 41.Accordingly information signals 43 may be introduced into plotter controller 51 which may suitably process and transfer these signals as output 51A to plotter interface 52 which, after additional signal processing, will communicate these signals as output 52A to suitable circuitry such as a digital-to-analog converter 53 wherein they may be converted to an appropriate analog output 53A to small scale plotter 42.

It will be noted that information signals 43 which are provided to analog film recorder 39, large and small scale plotters 41 and 42, respectively, as well as those provided to visual display 40, may be desirably under the control of master controller 20. Accordingly, controller 20 may desirably provide information signals 43 so as to cause display and recording of well logging information in a variety of formats and from a variety of sources. These may include, for example, primary storage 35 and secondary storage 36, which may transfer information stored therein to master controller 20 as storage output 38 and in response to input signal 37.

It will be readily apparent that for purposes of testing the operation of the integrated well logging system herein described, or for purposes of personnel training or the like, it may be desirable to simulate the various signals associated with sonde 2 without the necessity of actually providing the sections of well logging circuitry normally contained therein, and further without the necessity of subjecting the sonde 2 to an actual borehole environment.

Accordingly, in Fig. 1 there may be seen a signal simulator 54 which, in response to appropriate simulator command signals 55A, may generate various test signals 56 as herein before mentioned which, for example, may include signals similar to those which might be expected to be present on logging cable 3 from sonde 2. It will further be noted that these test signals 56 may appropriately be delivered to line control circuit 24, thus simulating similar signals on logging cable 3 which may also be delivered to the input of line control circuit 24. While the present invention contemplates automatic performance of the various well logging tasks under control of master controller 20, it may be appreciated that it is often desirable to include provisions for human interaction with the integrated well logging system of the present invention.For example, it may be desirable for a logging engineer to override various functions performed by master controller 20, to adjust the format or scaling of information provided to the various peripheral display devices, or to communicate directly with base station or user station. Conversely, it may further be desirable for master controller 20 to have the capability of outputting information to a human operator. Accordingly, a suitable well site teleprinter 57 may be provided for such communication between master controller 20 and a human operator having an interrogate/respond channel 58 for interrogating or instructing controller 20 in a conventional manner, and also for receiving appropriate information therefrom.

As hereinbefore stated, it is a feature of the present invention to provide for observation and control of well site logging operations from a remote base station or user station.

Referring now to Fig. 1, there may be seen a communications modulator-demodulator or "modem" 59 which may transmit information signal 43 to base station and user station on communication links 1 5 and 16, respectively, under control of a data/control signal 60 from controller 20. It will furthermore be noted that modulator-demodulator 59 may conveniently be adapted to receive information and control signals from base station and user station on communication links 15 and 16, respectively, which are further communicated to controller 20 as indicated by data/control signals 60.

Referring now to Fig. 2, there will be seen a general functional representation of the manner in which the data merging of the present invention is accomplished in a preferred embodiment. A primary storage 35, such as a conventional tape drive, may be provided for storing electrical data signals composed of digital representations of well logging measurements derived correlative to a sequence of preselected depths within a borehole. Any desired number of such representations may be retrieved from the primary storage 35 in response to an input signal 37 from a merger controller circuit 63, so as to cause such representations to be delivered out of the primary storage 35 on primary storage output 38 to a suitable merge memory 1, 66, or a merge memory 2, 67, on their respective merge memory inputs 38b or 38c.The merge memories 66 and 67 preferably each provide a memory output 78 delivered to the merge circuit 63, for instructing the merge circuit 63 as to when a particular merge memory 66 or 67 has had all logging measurements removed therefrom, in which case the particular merge memory will be available to receive further representations from the primary storage 38 in a manner previously described.

It will be noted that the merge memories 66 and 67 may further be provided with correlative merge controller outputs 75 and 74. In response to each controller output 75 and 74 from the merge controller 63, the respective merge memories 66 or 67 will successively deliver on their respective memory outputs 80 and 81 digital representations of logging measurements derived at successive depths stored in the memories 66 and 67 to a suitable merge storage 62. More particularly, logging measurements in the primary storage 38 are preferably stored therein in the order in which they were derived at successively deeper or shallower preselected depth intervals.The order of these measurements will preferably be retained throughout all transfers through memories 66 and 67, merge storage 62, memories 64 and 75, and eventually secondary storage 36, as will all realtime or historical measurements transferred through the input memory 61, storage 62, merge memories 64 and 65, and to secondary storage 36.

It will be noted that the merge controller 63, in response to the memory output 78 from the memories 66 and 67, may be designed so as to generate a controller output 74 or 75 so as to cause only one merge memory, 66 or 67, to generate memory outputs 80 or 81, while the other merge memory receives a next number of digital representations on merge memory input 38b or 38c from the primary storage 35. This technique may be recognized as "double-buffering", a technique well known in the art whereby measurements may be selectively retrieved from or stored in one memory while a second memory is being filled with or "reading out" blocks of data to input or output devices.

When all of the data is thus sequentially retrieved from the first memory, data will thereafter be sequentially retrieved from the second filled memory while the depleted first memory is thus being again filled with data blocks.

Referring again to Fig. 2, it will further be seen that the well site controller 20 preferably will include an input memory 61 for storing digital representations of well logging measurements derived by the sonde 2 in a manner previously described. It will be recalled that the recovery controller 32 may deliver each such representation, which has been derived on a depth-dependent basis, on the controller output 32b to the well site controller 20 or, more particularly with respect to Fig. 2, to the input memory 61. It will further be recalled that a depth controller 1 2 will preferably be provided for generating a sequence of pulses derived from rotation of the sheave wheel, which is in turn correlative to movement of the sonde 2 within the borehole, indicative of and related to different selected depths along a portion of the borehole.These pulses may be delivered as depth/data control signal 21 to the merge controller 63 of the well site controller 20. As each pulse is delivered on control signal 21, a measurement derived in response thereto at a correlative depth will accordingly be present in the input memory 61. The merge controller 63 will, in response to the control signal 21, generate a merger controller output 69, causing a transfer of the sample presently stored in the input memory 61 to the merge storage 62 on the memory output 68. As previously noted, the merge controller 63 is preferably provided with controller outputs 74 and 75 for commanding the correlative merge memory 67 or 66 to deliver a correlative data sample derived at a particular depth from the respective merge memory 67 or 66 to the merge storage 62.Each controller output 74 and 75 will preferably be generated by the merge controller 63 in functional response to receipt by the merge controller 63 of a pulse from the control signal 21 correlative to a particular depth at which a measurement derived by the sonde 2 which is stored in the input memory 61 was derived. Accordingly, it will be appreciated that in response to such a pulse on control signal 21, a next data sample from the input memory 61 and a next data sample from either the merge memory 66 or 67 will accordingly be caused to be transferred and stored in the merge storage 62, and each such pair of next samples will have been derived at correlative depths.

Still referring to Fig. 2, there will also be seen a merge memory 64, and a merge memory 65, each having correlative storage outputs 72 and 71. It will also be noted that a merge controller output 70, generated by the merge controller 63 in response to a pulse from control signal 21, may be delivered to the merge storage 62. The purpose of this controller output 70 is to cause the merge storage 62 to deliver in response thereto the data samples stored in the merge storage 62 on the storage output 71 or 72 to their correlative merge memories 65 or 64 in a manner to be described. In like manner to the merge memories 66 and 67, there will be seen in Fig. 2 a memory output 79 delivered from the merge memories 64 and 65 to the merge controller 63.Also, in like manner, there will be seen merge controller outputs 76 and 77 delivered from the merge controller 63 to the correlative merge memories 65 and 64, these controller outputs being correlative to those of controller outputs 74 and 75 for the merge memories 67 and 66. It may thus be appreciated that the merge memories 64 and 65 are preferably arranged in a "doublebuffering" mode, similar to that of the merge memories 66 and 67. Information carried on the memory output 79 may instruct the merge controller 63 as to the relative status of the merge memories 64 and 65. More particularly, the merge controller 63 will thus detect when a particular merge memory 64 or 65 has been filled with a full "block" of data, such as samples derived over a ten foot depth increment.When this occurs, a merge controller output 76 or 77 will command the particular memory 65 or 64 to deliver its respective stored contents on merge memory 37d or 37c to the hereinbefore noted secondary storage 36 by means of the input signal 37, or to a suitable continuous display control 47 by means of the log data information signal 43.

While data samples are thus being "read out" from a particular merge memory, the merge controller 63 is, by means of the merge controller output 70, able to command the merge storage 62 to begin filling the remaining one of merge memories 64 or 65 by causing the merge storage 62 to deliver successive paired data samples stored in the merged storage 62 to the particular merge memory 64 or 65 by means of selecting the appropriate storage output 71 or 72 on which these data samples will be delivered.

Referring now to Figs. 3a and 3b, there will be seen a decisional flow diagram functionally representative of the operation of the apparatus depicted in Figs. 4a and 4b, which is one particular embodiment of merger apparatus typical of the present invention. In the present example it will be assumed that a sequence of measurements from one data set, either realtime or historically generated, is presented to the merge storage 62 on output 68 wherein each successive measurement was derived at a progressively shallower depth within the borehole and at a preselected depth from the preceeding measurement. In like manner, it will be assumed that another sequence of measurements from another data set, again either realtime or historical, is presented to the merge storage 62 on memory output 80 or 81.Each of these measurements also preferably was derived at the same progressively shallower depths as correlative measurements from the first set. To achieve the correlative recording or "matching" of samples from two or more sets of data derived at predetermined depths, it will be appreciated that it is preferable to insure that the first sample from each set to be correlatively rec orded was generated at a correlative depth. In this manner, if each successive sample from the first set is recorded with the successive sample from the second set derived at a correlative depth, merger may thus be achieved. Thus, it may be desirable to provide means for detecting when the first two such sample of a merger operation from each data set is available for commencing the recording and the operation of merger.In a typical logging operation, wherein it is desired to merge two or more sets of logging data, it will be noted that two possible situations may arise. First, the starting depths at which the first samples from each set of data were derived may be equal, in which case the correlative matching of further such samples may commence immediately. On the other hand, the starting depth at which initial samples from one set of data were derived may be alternatively either derived from deeper or shallower within the borehole than the first such samples derived from the other set of data. In the latter case, it should be obvious that a means may be provided for determining when two samples from respective data sets have been located which were derived at the desired starting depth of the merge.

More particularly, for purposes of illustration, in a typical application of the merge feature of the present invention, a historical tape of logging data derived at predetermined increments of depth within a borehole has been generated, and such historically derived data points are to be correlatively recorded with realtime measurements to be generated by the logging sonde 2, which will also preferably be derived at predetermined depth increments as the sonde 2 traverses the borehole. In such a case, it will be noted that the sonde 2 may have been pre-positioned prior to the merger operation at a depth correlative to the depth at which a first sample stored on the historical tape was also derived.Conversely, it will also be appreciated that the sonde 2 may be positioned at an elevation within the borehole wherein its beginning measurements will commence at a depth either shallower or deeper than that of the first sample from the historical tape to be merged.

Thus, it may be desirable to provide means for detecting the relative position of the sonde 2 and the depth at which the first such measurement from the historical tape were derived. It may thus be necessary to first move the sonde 2 upward until it reaches the elevation of the first sample of the historical tape, or conversely, if the sonde 2 is positioned shallower than the elevation at which the initial samples on the historical tape were derived, it may be necessary to advance the historical tape to the sample derived at the depth at which the sonde 2 is beginning derivation of realtime measurements.

Referring more particularly now to Fig. 3a, the path from block 1 93 to block 205 represents the functions performed by the apparatus depicted in Fig. 2 when the sonde 2 is in the hereinabove noted position relative to the depth at which the first sample was derived on the historical tape, wherein the anticipated merge depth "DP" or current sonde depth minus 1 is equal or greater than the depth of this first measurement. As depicted in block 1 93 of Fig. 3a, the controller 20 of Fig. 2 preferably will first load the merge memories 66 and 67 of Fig. 2 with data samples stored on the historical tape in the primary storage 35 which were derived at sequentially shallower increments within the borehole.This may be accomplished by the merger controller 63 generating an input signal 37 instructing the primary storage 38 to deliver a first sequence of such measurements on merge memory input 38b to the merge memory 66 and a next such sequence of measurements on the merge memory input 38c to the merge memory 67. It is preferable that the historical data samples be stored in the primary storage 35 and delivered to the merge memories 66 and 67 in the form of "blocks" of logging samples, although this is not necessary. Thus, a typical block would preferably consist of, for example, 36 logging measurements derived sequentially in onefourth foot increments over a nine foot increment of borehole depth.Thus, for example, after the merge memory load of block 1 93 is accomplished, the merge memory 66 may typically contain, for example, 36 logging measurements derived at quarter foot intervals from 1 ,000 feet up to 9,991 feet within the borehole, and the merge memory 67 may contain a next block of 36 logging measurements derived at quarter foot intervals from 9,991 feet up to 9,982 feet within the borehole. Referring now to block 1 95 of Fig. 3a, it will be seen that the next function to be performed by the apparatus of Fig. 2 is to determine the starting depth of the first sample in the first block of data contained in the base or historical tape.It will be noted that the historical tape stored in the primary storage 35 will preferably contain at the beginning or "header" of the tape such a starting depth of the first block of data contained therein. Accordingly, the merge controller 63 will preferably generate another input signal 37 so as to cause the primary storage 35 to deliver such starting depth information to the merge controller 63 on the merge controller input 38a. Referring next to block 1 97 of Fig.

3a, now that the starting depth of the first historical sample is stored in the merge controller 63, to determine the relative position of the sample to the sonde 2, it is only necessary to determine the current sonde 2 depth.

It will be recalled that a function of the depth controller 1 2 of Fig. 2 is to deliver such information on control signal 21 to the well site controller 20 or, more specifically, to the merge controller 63 in functional relation to the generation of depth pulses from the depth encoder 6. It will be assumed in the present discussion, for purposes of illustration, that the logging operation will proceed in a generally upward direction, as is typical. The reason for calculating the current sonde.depth minus 1, or the "anticipated" merge depth, as depicted in block 197, will be hereinafter described.Once the merge controller 63 has thus obtained the historical or base tape first sample starting depth and the current sonde depth from which an integer 1 may be subtracted by the merge controller 63, the merge controller 63 may then perform the comparison depicted in the block 1 99 to determine if the anticipated merge depth is greater or equal to the first sample starting depth. Assuming for the moment that this is the case, the merge controller 63 may then generate a merge controller output 74 or 75 to the respective merge memory 67 or 66 which contains the sample generated at the starting depth. This output 74 or 75 will, in turn, cause the particular merge memory to deliver this first sample to the merge storage 62 on merge memory output 80 or 81.The merge controller 63 will also set an internal register (not shown) in the condition depicted in block 203, signifying that the anticipated merge depth is equal to or greater than the starting historical tape depth first space. The merge controller 63 will thereafter determine whether the anticipated merge depth is equal to the current sonde depth as depicted in block 214. If not, the anticipated merge depth must accordingly be deeper than the starting tape depth, in which case the merge controller 63 will generate a controller output 69, causing a sample derived and stored in the input memory 61 as previously described to be transferred to the merge storage 62, as depicted in blocks 207 and 209.The merge controller 63 will thereafter generate a controller output 70 instructing the merge storage 62 to deliver the previously stored first historical sample and the sample from the input memory 61, as storage outputs 71 or 72, to the correlative merge memories 65 or 64. It will be recalled that due to the memory output 78 from the merge memories 64 and 65, the merge controller 63 will generate the appropriate controller output 70 to deliver the contents of the merge storage 62 to the appropriate merge memories 64 or 65 in a manner consistent with the hereinabove described double buffering technique. As depicted in Fig. 3a, the sequence just described will be repeated as the apparatus of Fig. 2 circulates through the functions depicted between the paths 212 and 283 until the anticipated merge depth equals the tape starting depth, as depicted in block 214.It will be noted that as the sonde 2 progresses up the borehole generating measurements, until it generates a measurement at the depth of the first historical sample, the same historical sample may continue to be stored in the merge storage 62 with each corresponding next sample from the input memory 61, and thereafter stored in the merge memory 3 or 4 along with the successively generated measurements delivered from the input memory 61.

Referring now to path 21 5 from block 214, it will be seen that this represents the condition wherein the sonde 2, as it has traversed up the borehole, is now in a position wherein the anticipated merge depth equals the starting depth of the tape. Accordingly, the merge controller 63 may detect this condition, in that the sonde depth is continually fed to the merge controller 63 on the control signal 21, and thus causes the previously noted internal register (not shown) to be set "on", indicating that the condition for merger has been achieved.Therefore, as depicted in block 219, each time a next sample is derived at a next depth and received by the input memory 61, it will be transferred to the merge storage 62 together with a measurement derived at a correlative depth from either merge memory 66 or 67, and these paired measurements thereafter transferred to either merge memory 65 or 65. It will be recalled that, in accordance with the previously described double buffering technique, when a particular merge memory 64 or 65 has received a complete block of samples described below, which may be conveniently sensed by the memory output 79, the merge controller 63 will generate an appropriate merge controller output 76 or 77, causing that memory to deliver its block of data to a suitable secondary storage 36 and display control 47 for display on a CRT 40 or the like.While this is occurring and until the remaining merge memory has thus been filled in like manner, paired samples will be directed to and begin filling the remaining merge memory 64 or 65. From the foregoing, it will be appreciated that the merge storage 62 will preferably receive one or more samples derived at a particular depth from one source, such as the sonde 2, on memory output 68 and a correlative one or more samples derived at a functionally related depth from either the merge memory 66 or 67. These samples, in turn, were preferably derived from another source of logging measurements such as the primary storage 35, wherein there may be stored data obtained from a previous logging of the same borehole, for example.Each time sets of one or more samples from the two sources derived at functionally related depths are present on the merge storage 62, they will be thereafter transferred to the merge memory 64 or 65 to build a block of such sets of samples. More particularly, the sets of samples stored in the merge storage 62 will be directed to the same merge memory either 64 or 65 in sequence until the particular merge memory contains samples, in present illustration, derived over a particular predetermined increment of bore hole depth.For example, 36 sets of samples derived at quarter foot intervals over a nine foot borehole depth from the primary storage 35 may be sequentially and correlatively stored in merge memory 64 with 36 samples derived from the sonde, or other source, wherein these samples were, in like manner, derived over quarter foot intervals over a nine foot increment of borehole depth. When a block of such samples is thus completed, the entire block, wherein samples from the two sources have been correlatively matched, will thus be available for output to the secondary storage 36 and the continuous display control 47.

Referring again to Fig. 3a, and more particularly to the block 199, it will be noted that the merge controller 63 may, in response to interrogation of the first historical sample starting depth and the anticipated merge depth, determine that the first historical sample was derived at an elevation deeper within the borehole than the anticipated merge depth. This, of course, corresponds to the fact that there are initial samples contained on the historical tape derived at a deeper elevation than the elevation at which further such samples are to be merged or matched with samples derived by the sonde 2 at correlative depths. Thus, it will be noted that it may be necessary to index through such initial samples until the sample is located which is correlative to the depth at which the next sonde 2 measurement is to be derived.Rather than to begin storage of historical samples from the primary storage 35 commencing with those historical samples derived at depths correlative to samples derived from the sonde 2, it may be preferable to first record on the secondary storage 36 or display on the display control 47, those historical samples which may exist derived at elevations within the borehole deeper than the depth at which the correlative merging of samples from the two cources, the sonde 2 and the primary storage 35, are to begin. It will accordingly be appreciated that it may be necessary to first determine how many such historical samples may be so recorded or displayed until the first one is reached which correlates in depth with the next sample to be derived from the sonde 2, at which time the correlative recording or merging of the samples from the two sources will begin.Moreover, it will further be noted that if the starting depth of the first historical sample contained in the primary storage 35 is sufficiently deeper than the anticipated merge depth, one or more blocks of historical data, comprising integer multiples of 36 samples derived at quarter foot intervals over nine foot increments of borehole depth may desirably be retrieved from the primary storage 35 and passed through the merge storage 62 before the particular historical sample stored in the primary storage 35 derived at a depth correlative to the next such sample to be derived by the sonde 2 is matched with the correlative sample from input memory 61.Referring again to Fig. 3a, the paths from path 220 through 228, 232 and 230 will be seen which represent the functions to be performed by the apparatus of Fig. 2 so as to retrieve such blocks of historical data from the primary storage 35 and transfer them through merge storage 62. For purposes of illustration, it will again be presumed that 36 sets of one or more samples derived at quarter foot intervals over a nine foot increment of borehole depth constitute a "block" of data. Moreover, it will be assumed, for like purposes, that the first such historical sample stored in the primary storage 35 was derived at a 10,000 foot depth within the borehole, and that the current depth of the sonde 2 is 9,976 feet within the borehole, in which case the anticipated merge depth is 9,975 feet.Thus, it will be seen that two blocks of data samples may be retrieved from the primary storage 35 and transferred through merge storage 62 before a historical sample will be reached which was derived at a depth correlative to the anticipated merge depth of 9,975 feet. More particularly, a first block will be thus retrieved and stored having samples derived from 10,000 up to 9,991 feet, and a second block will thereafter be thus retrieved and stored which was derived from an elevation of 9,991 feet up to 9,982 feet. Still further, it will be noted that the number of complete blocks which may be read from the primary storage 35 and transferred through merge storage 62 may be determined by taking the integer value of the difference between the first historical sample starting depth minus the anticipated merge depth divided by the increment of feet of data per block.Thus, in the present example, the integer value of (10,000 - 9,975)/9 = 2, the number of blocks to be read from the primary storage 35. It will be recalled that the merge controller 63 has previously been instructed as to the anticipated merge depth and starting depth of the first block of data contained in the base or historical tape of the primary storage 35 prior to branching to the block 221 on the path 220. The primary controller 63 may also preferably be instructed as to the feet per block on the controller input 38a at the time that the starting depth is delivered to the merge controller 63. Accordingly, as depicted in the block 227, the merge controller 63 may thereafter calculate the number of blocks to read from the primary storage 35, and through merge storage 62 as previously indicated. The merge controller 63 will thereafter begin generating a series of controller outputs 70, 74, 75, 69 and input signals 37 so as to cause the samples contained in the two previously calculated blocks to be sequentially re trieved from the primary storage 35, delivered to the merge memories 66 and 67, transferred to the merge storage 62 with the same sample each time present in input memory 61 and thereafter to the merge memories 64 and 65.More particularly, the merge controller 63 will preferably contain a decrementing counter and comparator which continuously count the number of controller outputs 70 such that each time a block or 36 sets of correlative samples from the input memory 61 and the primary storage 35 have thus been transferred to the merge memories 64 or 65, the memory output 79 will instruct the merge memory 64 or 65 to deliver a block of data to the secondary storage 36 and display control 47.

Each time one such block has thus been transferred the counter/decrementer in the merge controller 63 will decrement by 1 until it reaches zero, thus indicating to the merge controller 63 that all such blocks of data have been removed from the primary storage 35, delivered through the merge memories 66 and 67, through the merge storage 62, through the merge memories 64 and 65 and out to the secondary storage 36. Functionally, this series of events performed by the apparatus of Fig. 2 is illustrated in the blocks 229, 233, and 235 of Fig. 3a.When the counter/decrementer has thus determined that the integer number of blocks to read previously calculated has thus reached zero, the merge controller 63 must thereafter determine the number of historical samples within the next or "current" block to move from the merge memory 66 or 67 to the merge storage 62 and thereafter to the merge memory 64 or 65 such that the next such historical sample will have been derived at a depth correlative to the sample derived from the sonde 2 which is present in the input memory 61.As illustrated in block 236, in order to perform this function, the merge controller 63 preferably will first set a counter within the merge controller 63, whose purpose will hereinafter be described, to zero, and will thereafter, also for purposes to be described, initialize a flip-flop contained in the merge controller 63 (not depicted) to the "off" position, prior to deter mining whether there are more historical samples to move through merge storage 62 to attain the merger condition wherein subsequent samples received by the input memory 61 will correlatively be matched and stored in the merge storage 62 with correlative samples from the merge memories 66 and 67 derived at the same depths. This setting of the counter and flip-flop may be seen illustrated in block 236 of Fig. 3a and block 238 of Fig.

3b.

Continuing the present example, if two complete blocks of samples have been retrieved from the primary storage 35 and stored in the secondary storage 36, each having a nine foot increment of logging data and block starting depths of 10,000 and 9,991 feet, respectively, the depth of the first sample in the next block will thus be 9,982 feet. As previously noted, the anticipated merge depth is 9,975 feet.Accordingly, seven more feet of logging data, or 28 samples if the sample interval is one quarter foot, must be transferred from the current block having a starting depth of 9,982 and contained in the merge memory 66 or 67 to the merge storage 62 and thereafter to the merge memory 64 or 65 in order that the next sample, derived at a depth of 9,975 feet, may be correlatively matched with the sample next to be derived at the correlative anticipated merge depth, which will be stored in the input memory 61. Referring to block 246, it will be seen that this block represents the calculation which the merge controller 63 must perform to determine the number of historical samples with the current block starting at 9,982 feet which must be moved prior to merger.It will further be seen that this number of samples to move will equal 4 times the difference between the current block depth and the anticipated merge depth minus the count of the number of samples previously moved (CT), which was previously set to zero, or Y = (9,982 - 9,975)X 4 - 0 = 28.

It will be recalled that the current block starting depth of 9,982 feet contains historical samples derived at the depth of 9,975 feet and has been previously derived by the merge controller 63, as well as the anticipated merge depth of 9,975 feet also derived by the merge controller 63. Because there are preferably 4 samples per foot being derived in the present example, it will be apparent that the first 28 samples from the block of samples derived from the 9,982-9,975 foot depth increment, must be transferred through the merge storage 62 prior to the merger condition, wherein subsequent measurements derived at quarter foot intervals at successively shallower depths from 9,975 feet, stored in the primary storage 35, are successively matched with correlative measurements being sequentially derived by the sonde 2 and stored in the input memory 61.It will be noted in the block 246 of Fig. 3B that the number of samples in the current block to move includes an adjustment for the number of samples previously moved, "CT". As will be more apparent from the hereinbelow discussion, if a number of samples has previously been moved within a particular block, this number must be preferably subtracted in determining the present number of samples in the current block to be moved to reach the sample corresponding to the anticipated merged depth. Referring now to block 248, it will now be seen that the merge controller 63 will preferably be adapted so as to sense if the number of samples in the current block to move to reach the anticipated merge depth is greater than zero.Still further, it will be seen from the path 253 that if this is not the case, this corresponds to the fact that the conditions for merger may now presently exist wherein the anticipated merge depth is equal to the depth at which the next historical sample to be transferred through merge storage 62 was derived. During the time in which the calculations have been made to determine whether this condition is met, it will be appreciated that the anticipated merge depth may have changed due to movement of the sonde 2.

This factor is represented by the block 262 of Fig. 3B. If the anticipated merge depth has not changed, as depicted in the path 264, the conditions for merger have thus been achieved, as shown in block 265, in which case the merge controller 63 will branch by the path 266 to the previously described condition, wherein subsequently derived measurements in the input memory 61 will be correlatively matched with historical samples from the merge memory 66 or 67 to be transferred to the merge storage 62 and thereafter correlatively recorded, as previously described, in the secondary storage 36.Referring again to the block 248, alternatively, the merge controller 63 may detect that there are samples in the current block starting at those derived at 9,982 feet to be moved to the merge memories 64 and 65 prior to arriving at the condition of merger, wherein the sample is derived at 9,975 feet stored in merge memory 66 or 67 is correlatively matched in the merge storage 62 with a measurement derived at the same depth stored in the input memory 61. As depicted in the block 250 of Fig. 3B, the merge controller 63 will next determine whether the number of samples previously moved (CT) plus the number of samples in the current block (Y), which were just calculated and are to be moved, are greater than 36.This corresponds to a determination of whether all of the samples may be moved from the current block without requiring additional samples from the next block of data derived at depths from 9,973 to 9,964 feet. For example, in the present illustration, if 28 samples had been previously moved from the 9,982 foot block (CT = 28) and the number of samples in the current block to move, just calculated, equals 20 (Y = 20), it will be seen that because there are 36 samples per block, 28 + 20 - 36 = 1 2 samples from the block having a first sample derived at 9,973 feet must be moved, or, in other words, all of the samples of the 9,982 block will have been "used" or transferred, and we will have "crossed" the 9,973 foot block barrier which is required to retrieve the additional 1 2 samples needed.It will further be noted that, due to the quarter foot sampling intervals of the present invention, the thirteenth sample will have been derived at 9,970 feet. Continuing with the present illustration, as depicted in the block 254 of Fig. 3B, in the case where 28 samples from the block 9,982 are to be moved, and further, wherein Y + CT is not greater than 36, as shown by the path 252, the merge controller 63 will first update a counter (not shown) with the number of samples to move plus the number of samples previously moved, or with Y + CT for purposes to be described hereinbelow in determining when a block "boundary" has been crossed.The merge controller 63 will thereafter generate merge controller outputs 74 or 75 so as to cause these Y = 28 samples to be moved from the merge memory 66 or 67 through the merge storage 62 to the merge memory 64 or 65 with the correlative same sample stored in the input memory 61, as previously described. From the block 258, it will be noted that the merge controller 63 will detect during this movement of samples whether the current block commencing with samples derived at 9,982 feet has had all such samples within the block transferred. If not, as illustrated by the path 260, once such transfer has occurred, the conditions for merger may thus exist and consequently the merge controller 63 will again determine whether the anticipated merge depth has changed as shown by the block 262.If not, the hereinbefore noted merge flip-flop is set to the "on" condition and the correlative storage of merged samples thereafter proceeds, in the manner previously described. However, if the merge controller 63 has detected that the anticipated merge depth has changed, corresponding to the fact that the sonde 2 has changed elevation subsequent to the prior pass through the block 262, as depicted in the block 267, the merge controller 63 will, in response to the control signal 21 from the depth controller 12, update the prior anticipated merge depth stored therein, for use in subsequent calculations. Still further, as depicted in the path 239, the merge control 63 will also initialize the hereinbefore noted more samples to move" flip-flop to the "on" position as depicted in block 238. Referring again now to the block 250 of Fig. 3B, it will be recalled that the merge controller 63 deter mines at this point whether the number of samples in the current block to move, due to the previous number moved, will necessitate moving additional samples from the next block commencing at 9,973 feet in order to achieve the merge condition. If this is the case, as depicted in block 268, and further in accordance with the present illustration wherein 28 samples from the 9,982 block were previously moved and it is desired to move an additional 20 samples wherein the anticipated merge depth will now be 9,970 feet, the merge controller 63 will set a register (not shown) equal to the number of samples moved in the current block to reach the end of the block, or Y = 36 - 28 = 8.As shown in the block 270, the merge controller 63 will thereafter set the "more samples to move flip-flop to the "on" condition, and thereafter update the internal counter, as depicted in the block 254, to equal the number of samples previously moved, or Y + CT = 8 + 28 = 36.

As shown in the block 256, the eight remaining samples from the 9,982 foot block, will then be moved from the merge memory 66 or 67 through the merge storage 62 to the merge memory 64 or 65 in response to the correlative controller outputs 78 and 70, as previously described. As depicted in the block 250, the merge controller 63 will thereafter determine that the current 9,982 block of samples has been used up, and in accordance with the path 259, and as depicted in the block 272, the merge controller 63 will accordingly, after generating the appropriate merge controller output 76 or 77, cause the block of 36 samples contained in the 9,982 foot block thus transferred to the merge memory 64 or 65 to be thereafter transferred to the secondary storage 36.The merge controller 63 will thereafter reset the internal counter which records the number of samples previously moved (CT), as depicted in the block 274, to zero, will thereafter update the current block depth to 9,973 feet, depicted by the block 276, due to the moving of the entire previous 9,982 foot block as hereinbefore described, and the merge controller 63 will thereafter detect whether there are still more samples to move to the merge memory 64 or 65 prior to achieving the merger condition, as depicted in the block 278 in Fig. 38.

It will be recalled in the previous illustration that the more samples to move flag was previously set in the "on" condition at block 270, corresponding to the fact that the number of samples to move Y = 20 plus the number of samples previously moved CT = 28 were greater than 36, in turn, corresponding to the fact that the entire block of samples from the 9,982 foot block was to be moved and an additional twelve samples in the 9,973 block in order to reach the merger condition wherein the anticipated merge depth was 9,968 feet.Accordingly, the merger controller 63, as depicted in the block 278, will detect that the additional twelve samples from the 9,973 foot block must be moved, in which case, as depicted in the path 240, the merge controller will again set its internal more samples to move flag to the "off" condition, and will continue the sequential operation as depicted in the steps of Fig.

3B subsequent to the path 241. However, in the case in which samples from an entire block have been transferred to the merge memory 64 or 65, but the more samples to move flag is not in the on condition, this corresponds to the fact that the conditions for merger have been achieved at a block boundary, in which case the anticipated merge depth at which historical samples will be correlatively merged with subsequent samples derived and stored in the input memory 61 were both derived at the beginning of a next block. As illustrated in Fig. 3B, the merge controller 63 in accordance with the path 261, will preferably thereafter only have to detect whether the anticipated merge depth, or consequently the sonde 2 depth has changed subsequent to the arrival in this condition, as depicted in the block 262.The merge controller 63, after determining whether the anticipated merge depth has changed, will recycle in accordance with the path 264 or 263, in the manner previously described.

Referring now to Figs. 4A and 4B, there will be seen depicted therein a more detailed diagram of the apparatus of the present invention, including a more detailed depiction of the apparatus included in the well site controller 20. In the discussion which follows hereinafter, reference should be made to the figs.

3A and 3B and the foregoing accompanying description for understanding of the sequence of operation of the apparatus depicted in Figs.

4A and 4B. Referring first to the function of initial loading of the merge memories 66 and 67, it will first be seen that the merge controller circuit 63 may first generate a controller output 102 instructing the primary storage 35 to generate a storage output 100 which contains, preferably, digital representations of historical logging measurements derived at sequential quarter foot intervals throughout a borehole. These samples will be preferably delivered through the switch 282 in sequence as they were derived on the switch output 91 or 92 to the correlative merge memory 66 or 67 until the respective merge memory is filled. An appropriate double buffer control 280 may be provided which will continually sense whether either merge memory 66 or 67 has been filled to capacity by monitoring the merge memory output 96 from each merge memory 66 and 67.When the double buffer control 280 has thus determined that a particular merge memory 66 or 67 has been filled, an appropriate switch output 98 from the double buffer control 280 will cause subsequent historical samples from the primary storage 35 to be delivered to the alternate merge memory which has not yet been filled.

When the merge memory 66 and 67 have thus been filled, the merge controller 63, as depicted in block 1 95 of Fig. 3A, will then preferably generate a controller output 102, causing the primary storage 35 to deliver the starting depth of the first sample contained in the base or historical tape stored in the primary storage 35, on the storage output 103 to an appropriate storage 104. Also as depicted in the block 197, the merge controller circuit 63 will also preferably store the anticipated merge depth, or current sonde 2 depth minus 1 in a suitable storage 1 08. It will be recalled that the depth control 1 2 preferably will continuously deliver on control output 105 an information signal correlative to the current depth of the sonde 2.This depth number, after having the integer 1 subtracted from it by a conventional subtracter 106 will be delivered on the subtracter output 107 to the hereinbefore noted storage 108. Thus, it will be noted that the storage 108, at all times, will contain a digital representation of the anticipated merge depth, and, accord ingly, in response to the controller output 1 61 from the merge controller 63, this anticipated merge depth value will be delivered on the storage signal 110 to a conventional comparator 111 well known in the art. It will be seen from Fig. 4A that the starting depth of the first historical sample contained in the primary storage 35, in addition to being delivered to the storage 104, will also be delivered to the comparator 111.This comparator 111 will preferably be designed so as to compare the magnitude of the anticipated merge depth and the starting depth of the base tape. If the anticipated merge depth is equal to or greater than the starting depth of the base tape first block, the comparator 111 will preferably generate a comparator signal 11 2 setting a merge flip-flop 11 6 in the off condition. It will further be noted that the comparator signal 11 2 will also trigger a transfer command generator 281. The command generator 281 will generate a transfer command 99 which, in turn, will be delivered on the switch output 91 or 92 to the correlative merge memory 66 or 67, dependent upon the state in which the switch 282 has been set in accordance with the switch output 98.As previously noted, the buffer control 280 will determine the setting of the switch 98 so as to cause the command generator outputs 99 to be directed to the appropriate merge memory 66 or 67.

These outputs 99 so as cause the appropriate one of merge memories 66 or 67 to sequentially deliver in response to each command generator output 99 the historical sample derived at the deepest elevation within the sonde progressing to the shallowest most on the merge memory output 95 to the merge storage 62.

For example, in response to each command generator output 99, the merge memory 66 may be caused to deliver the sequentially derived samples stored therein at one quarter foot intervals from the elevation of 10,000 feet up to 9,991 feet on the merge memory output 95 until all such samples may have been delivered. The buffer control 280 will sense delivery of all samples, causing the switch 282 to deliver subsequent transfer command generator outputs 99 to the merge memory 67 on the switch output 92 so as to cause subsequent quarter foot samples from the depth intervals 9,991 up to 9,982 to be delivered on the merge memory output 95 to the merge storage 62.

Referring now to Fig. 3a, it will be seen that the apparatus of Figs. 4a and 4b is now presently in the state wherein the merge controller 63 determines whether the merge flipflop has been set in the "on" condition, as depicted in block 205 of Fig. 3a. Thus, themerge controller 63 will generate an appropriate interrogation command 114. If the merge flip-flop 11 6 has not previously been set in the "on" condition, an appropriate flip-flop output 11 5 will thus be generated, which, in turn, will cause the storage 104 and 108 to deliver to the comparator 111 to deliver the present anticipated merge depth and starting depth of the first historical sample on comparator inputs 11 7 and 11 8 to a conventional comparator 119.The comparator 119, will, accordingly, preferably determine the relative magnitudes of the anticipated merge depth and the starting depth of the base tape first block, as depicted in block 214 of Fig. 3a. If the two values are equal, the correlative comparator output 1 25 will thus instruct the merge controller 63 of this event as well as to set the merge flip-flop 11 6 on the on condition.Thereafter, every time the merge controller 63 interrogates the merge flip-flop 11 6 as to its status on interrogation command 114, the merge flip-flop 11 6 will thus generate a flip-flop output 1 26 corresponding to the fact that the merge condition has been met, wherein the present elevation of the sonde 2 is such that the anticipated merge depth equals the starting depth of the first sample of the historical tape first block.It will be seen from Fig. 4b that this flip-flop output 1 26 will enable the transfer command generator 281, such that samples from the recovery controller 32 will thereafter be correlatively matched with samples from the merge memory 66 or 67 derived at correlative depths and both such samples will be stored in the merge storage 62 for later storage on the secondary storage 36 as will be hereinafter described.

More particularly, after the transfer command generator 281 receives such a flip-flop output 126, each time the recovery controller 32 receives a new sample from the sonde 2 derived at subsequently shallower one-quarter foot intervals, each such sample will be delivered to the input memory 61 on the recovery controller output 1 20. This recovery controller output 1 20 is also transferred to the command generator 281 causing it to generate a correlative command generator output 99 for each such new sample received by the recovery controller 32. Thus, it will be seen that for every new sample delivered on the recovery controller output 1 20 to the input memory 61 and thereafter to the merge storage 62 on the input memory output 121, a correlative sample from the merge memory 66 or 67, in response to the command generator output 99 will be delivered on the merge memory output 95 to the merge storage 62. Assuming, as depicted in path 283 of Fig. 3a, that the anticipated merge depth is greater than the starting depth of the first sample of the historical tape, the comparator 11 9 will accordingly generate a correlative comparator output 124, instructing the merge controller 63 of this state.It will further be seen that the comparator output 1 24 will also be delivered to the input memory 61, the merge storage 62 and storage 279 on the respective memory input 122, merge storage input 123, and storage input 1 28. It will be noted that the storage 279 receives the outputs from the merge memory 66 and 67 as does the merge storage 62. When the first output is delivered from the merge memory 66 or 67, this value is stored in the storage 279. Thereafter, this value is delivered on the storage output 1 29 to the merge storage 62 each time a newly derived measurement from the sonde 2 is also transferred to the merge storage 62 from the input memory 61.It will be noted that the command generator 281 receives an indication on recovery controller output 1 20 of every such newly derived sample, such that the command generator output 99 may cause the storage 279 to deliver such a stored sample to the merge storage 62 with each newly arrived sample from the recovery controller 32.

Referring now to block 1 99 of Fig. 3a, it will be noted that the starting depth of the first historical sample of the base tape may be greater than the anticipated merge depth, in which case the apparatus of Figs. 4a and 4b will then operate in a manner consistent with the path depicted commencing with path 220 of Fig. 3a.More particularly, it will be seen from block 227 that this path represents the case in which historical samples present in the primary storage 35 were derived at a depth deeper than that of the anticipated merge depth, in which case such samples must be moved from the primary storage 35 through the merge memories 66 and 67 and through the merge storage 62, prior to the condition of merger wherein subsequent historical samples may be correlatively matched and recorded in the merge storage 62 with samples derived from the sonde 2 and delivered from the input memory 61 which were derived at correlative depths. Accordingly, again referring to block 227, it is apparent that the number of such blocks of historical data which must be read from the primary storage and cycled through the merge storage 62 must be calculated.It will be seen that in response to a determination from the comparator 111 that the starting depth of the base tape is greater than that of the anticipated merge depth, a comparator output 131 will thus be generated and transmitted to storage 130, 104, 108. These storages will, in response thereto, generate their correlative storage outputs 132, 1 34 and 133, which, in turn, will be delivered to a subtracter circuit 1 35 in the case of storage output 1 32 and 134, and a conventional divider circuit 1 37 in the case of storage output 1 33.It will be seen from Fig. 4b that the subtracter circuit 1 35 will accordingly provide a difference signal 1 36 equal to the difference between the starting depth of the base tape block and the anticipated merge depth, and this difference signal 1 36 will be conveniently delivered to a divider circuit 1 37 which will divide this difference by the number of feet of data per block, stored in the storage 1 30. The resulting quotient will then be delivered on the divider circuit output 1 38 to an integer storage 1 39 which will store the integer value of this quotient.It will thus be appreciated that this integer value corresponds to the number of complete blocks of historical data to be read from the merge memories 66 and 67 and circulated through the merge storage 62 prior to the condition of merger. The integer output 141 will then be delivered to a conventional comparator 142 which, as depicted in block 229 of Fig. 3a, will determine whether this integer value is equal to zero. If not, an appropriate comparator output 149 will be generated. As can be seen from Fig.

4b, this comparator output 1 49 will first cause the integer value stored in the integer storage 139, which is delivered to the decrementer 151 on integer storage output 150 to be decremented by 1 as the decrementer 151 responds to the input from the comparator output 149. It will also be seen that the comparator output 149 is further delivered to a transfer command generator 143, storage 145, and to the transfer command generator 281. Each time the comparator 142 generates an output 149, the transfer command generator 1 43 is thus instructed to transfer a block of data from the merge memory 85 or 86 to the secondary storage 36 in a manner to be described which is similar to the transfer of a block of data from the primary storage 35 to the merge memory 66 or 67.Each such comparator output 149 will also cause the command generator 281 to generate a series of transfer commands on command generator output 99 so as to cause a block of samples stored in the merge memory 66 or 67 to be transferred to the merge storage 62 and thereafter to the merge memory 85 or 86. When the decrementer output 1 52 which is delivered to the comparator 142 eventually equals zero, corresponding to the fact that all complete blocks of data samples have thus been read from the primary storage 35 and transferred through the merge storage 62, the comparator 142 will thereafter detect this condition generating a comparator output 153, corresponding to the path 231 of Fig.

3a. As depicted in Fig. 4b, this comparator output 1 53 will preferably first set a register 1 54 which will contain the number of samples within a block previously moved to the value zero, as shown in the block 236 of Fig. 3a. The comparator output 1 53 will also set a flip-flop 155, depicted in block 238 of Fig. 3a to the "on" condition. The apparatus of Figs. 4a and 4b must then determine the number of samples within the current block which must be moved prior to the merger condition existing. Accordingly, the previously described calculation in which the number samples in the current block to move must be calculated, as depicted in block 246 of Fig.

3a. Accordingly, the merge controller circuit 63 will generate first a merge controller output 156, which causes the integer storage 1 39 to deliver the previously stored integer on integer storage output 1 57 to a multiplier 1 57a. It will further be noted that the feet per block has also been delivered to the multiplier 1 57 on the storage output 1 33. The resulting product will thereafter be delivered on the multiplier output 1 57b to an appropriate substracter circuit 1 60. It will further be noted that the subtracter circuit 1 60 is accordingly provided with the storage output 1 59 corresponding to the starting depth of the historical samples.The resulting difference signal 1 63 is preferably delivered to another subtracter circuit 1 64 as well as the anticipated merge depth which is present on the storage output 162. The resulting difference signal 165, after being multiplied by 4 in a conventional multiplier circuit 1 66 is delivered as multiplier output 1 69 to another subtracter circuit 1 70.

It will be seen from Fig. 4b that the subtracter circuit 1 70 is also provided with a register output 1 68 from the register 154, corresponding to the number of samples previously moved which, due to the prior setting of the register 154, equals zero. The resulting output Y, which is the result of the calculation performed in block 246 of Fig. 3b, may thereafter be delivered as difference signal 1 71 to a conventional storage 1 76 and comparator 172. The difference signal 171 is delivered to the storage 1 76 in order to store the number of samples in the current block to move previously calculated for purposes to be hereinafter described.As depicted in block 248 of Fig. 3b, the comparator 1 72 will thereafter determine whether the number of samples in the current block to move is greater than zero. If not, the comparator will generate a comparator output 1 73 which will interrogate the storage 108 to determine whether the anticipated merge depth has changed. If not, the merge flip-flop 11 6 will, in response to the storage output 1 75 be set in the "on" position and the apparatus of Figs 4a and 4b will proceed as depicted in path 266 of Fig. 3b as hereinbefore described.

However, referring to the block 262, if the anticipated merge depth has changed, as shown by the path 263 of Fig. 3b, the storage output 1 74 will thus be generated.

This storage output 1 74 will set the more samples to move flip-flop 1 55 to the "on" position, and will cause the present anticipated merge depth, starting depth of the base tape, and feet per block values to be delivered to the subtracter circuit 1 35 and divider circuit 137, as previously described so that the number of samples in the current block to be moved, represented by the block 246, may thus be calculated in the manner previously described.

Referring again to the block 248, it will be noted that the apparatus of the present invention, in particular the comparator 172, may have determined that the number of samples in the current block to move is greater than zero, in which case the comparator output 1 77 will be generated.Accordingly, the comparator output 1 77 will cause the register 1 54 to deliver the number of samples previously moved (CT) on register output 1 78 to the adder circuit 1 79. Comparator output 1 77 will also preferably cause the number of samples in the current block to be moved, previously stored in the storage 176, to be delivered on the storage output 1 28 to the adder 1 79. The resulting adder output 182 thereafter may be conveniently stored in a conventional storage 184 and delivered to a comparator 1 80.It will be appreciated that the comparator 1 82 will then determine whether the number of samples in the current block to move plus the number of samples previously moved or Y + CT is greater than 36, indicating that samples from a next block of data must also be moved if this is the case.

If the sum is not greater than 36, as indicated in the path 252 and block 254 of the Fig. 3b, the comparator 1 80 will generate a comparator output 1 80a which will cause the storage 184 to deliver a storage output 1 27 thus updating the register 1 54 with the adder output 1 82 which equals the number of samples in the current block to move plus the number of samples previously moved. The comparator output 180a, which also may be delivered to the storage 1 76 will cause the storage 1 76 to generate a storage output 1 83. From Fig. 4b, it will be seen that this storage output 183, which contains the number of samples in the current block to move, will be delivered to the command generator 281 and the buffer control 280 so as to cause this number of samples to move through the merge storage 62 and to the merge memory 64 or 65. As previously described, the buffer control 280 is continually monitoring the status of the merge memories 66 and 67.Accordingly, as depicted in the block 258 of Fig. 3b, when the buffer control 280 determines, after the command generator 281 has thus transferred the number of samples in the current block which are to be moved in response to the storage output 183, that the current block has not been used up, the buffer control 280 will generate an appropriate buffer control output 185 to interrogate the storage 108 in order to determine whether the anticipated merge depth has changed. In response to this interrogation, the storage 108 will generate the appropriate signal so as to cause the apparatus of Figs. 4a and 4b to follow either the operations following the path 264 or 263 of Fig. 3b as hereinbefore described.

Referring again to the block 250 of Fig. 3b, it will be noted that the number of samples in the current block to move may be so large so as to cross a block boundary, wherein additional samples from the next block must be moved. This is depicted in the path 251 of Fig. 3b, and corresponds to a correlative comparator output 186 which will preferably be delivered to a conventional storage 112. It will be seen from Fig. 4b that the storage 11 2 may then deliver a storage output 187, which, in turn, will cause the register 1 54 to deliver the previous number of samples moved on the register output 1 88 to a subtracter circuit 1 89.It will further be seen that the storage output 1 87 may preferably be delivered directly to the subtracting circuit 1 89 so as to cause the register output 1 88 to be subtracted from the number stored in the storage 11 2 and delivered on the storage output 1 87. In the present example, this number will equal the number of samples per block, or 36. Referring now to the output of the subtracter 189, it will be seen that the output 200, which will be the newly calculated number of samples in the current block to move, or Y = 36 - CT, will then be delivered to the storage 1 76 so as to update this Y value.Still further, it will be seen that the comparator output 1 86 will also be delivered to the more samples to move flip-flop 1 55 so as to set this flip-flop in the "on" condition.

The latter two operations, it may be seen, will correspond to the blocks depicted in block 268 and 270 of Fig. 3b. After the comparator output 1 86 has updated the register 1 54 with the new value of the number of samples which will have been previously moved after the samples are moved, or Y + CT, the comparator output 186, which is also delivered to the storage 176, will cause these Y samples to be moved from the merge memory 1 or 2 to the merge memory 3 or 4 in the manner previously described, and in response to the storage output 183.

Referring now to the path 259 of Fig. 3b, it will be seen that the buffer control 280 may determine in response to the storage output 1 83 that the number of samples remaining in the current block will be moved or "used up" in response to this output 183, in which case the buffer control 280 will generate a buffer control 1 90. This buffer control output 1 90 will, in turn, be delivered to the command generator 143 so as to cause a next complete block of samples to be transferred to the secondary storage 36.The buffer control output 1 90 will also preferably be delivered to the register 1 54 so as to reset the number of samples previously moved to zero, will be delivered to the subtracter 1 64 to update the current block depth, be delivered to the flipflop 1 55. The buffer control output 190, will act as an interrogation command to the flipflop 155, so as to interrogate the flip-flop 1 55 to determine whether there are more samples to move or not. The flip-flop 1 55 may, therefore, deliver an output 1 92 correlative to the path 261 of Fig. 3b, indicating that there are no more samples to move.Thus, the storage 104 will be interrogated in response thereto, to determine whether the anticipated merge depth has changed or not. The operation of the apparatus of Fig. 4a and 4b will then proceed as hereinbefore described following either the path 264 or 263 of Fig. 3b.

However, if the "more samples to move" flipflop was in the "on" position, a flip-flop output 191 will accordingly be generated. The flip-flop 1 91 will reset the flip-flop 1 55 to the "on" condition, and will again trigger the storage 104, 108, and the register 1 54 to deliver their correlative stored starting depth, anticipated merge depth, and number of samples previously moved, to cause the subtracter 1 70 to again calculate the number of samples in the current block to move, as previously described and depicted in the block 246 of the Figure 3b. Referring to Fig. 4b, it will be appreciated that a double buffer arrangement has been provided similar to that depicted in Fig. 4a.More particularly, the double buffer control 82 is preferably provided with a merge memory output 88 from the merge memory 64 and 65. In response thereto, the buffer control 82 will generate a buffer control output 87 delivered to a switch 144 and the command generator 143. Thus, when a particular merge memory 64 or 65 has been filled, as detected by the buffer control 82, the buffer control output 87 will direct command generator output 83 through the switch 1 44 so as to cause the command generator output 1 83 to be delivered to the particular full memory 64 or 65 so that samples from that memory may be delivered on the merge memory output 89 to the secondary storage 36 and on the merge memory output 90 to the display control 47. In like manner, the buffer control 82 will detect which merge memory 64 or 65 is not full and thus available to receive additional sequential samples from the merge storage output 84.

Accordingly, the buffer control output 87 will set the switch 144 so as to deliver these additional samples from the merge storage output 84 on the switch output 85 or 86 to appropriate merge memory 64 or 65 which is available to receiving such samples. It will be apparent that the realtime data to be merged need not have been generated in response to the hereinbefore noted depth command pulse.

Rather, it is within the scope of the present invention that the realtime data may have been generated on a time-dependent basis but sampled on a depth-dependent basis prior to merger with the historical data. Moreover, it should also be apparent that rather than realtime data from the sonde 2 being merged, historical data derived on a depth-dependent basis may be substituted for this data and stored by conventional methods. Each such historical sample may then be selectively retrieved from the storage and merged in the manner previously described with samples from the other set of historical data. Thus, it will be noted that merger may thus be achieved two historical sets of data derived on a depth command basis and the present invention accordingly is not limited to merger of only realtime with historical data.

It will thus be appreciated that in accordance with the present invention a "merged" tape may thus be produced on the secondary storage 36 during a logging operation. The tape will contain digital representations of logging measurements just generated at preselected depths within the borehole together with correlatively recorded digital representations of logging measurements contained on the historical tape in the primary storage 35 generated at correlative depths. More importantly, it will be noted that the correlative matching and recording of such realtime and historical data occurred during the logging operation, so as to result in a merged tape available immediately at the end of the logging run for further processing.Thus, the disadvantages of the prior art are obviated wherein a tape of the realtime data is made and this tape is thereafter merged with the historical tape data, taking additional time.

Still further, it will be noted that any merged data contained in the secondary storage 36 may be retrieved by the master controller 20 for processing in realtime during the logging operation, and the results therefrom used to dynamically control the realtime logging operation. It is also contemplated that the merged data, in addition to being delivered to the secondary storage 36, may be delivered to the modem 59 for transmission to a remote location. Moreover, the historical data to be merged may first have been transmitted from a remote location through the modem 59 and stored in the primary storage 35 prior to the merger operation.

Many modifications and variations besides those specifically mentioned may be made in the techniques and structures described herein and depicted in the accompanying drawings without departing substantially from the concept of the present invention. Accordingly, it should be clearly understood that the forms of the invention described and illustrated herein are exemplary only, and are not intended as limitations on the scope of the present invention.

The above described embodiment of the invention provides a well logging system for investigating earth parameters and the like in a borehole, comprising first signalling means for deriving a first electrical signal representative of a first earth parameter, second signalling means for deriving a second electrical signal representative of a second earth parameter, third signalling means for deriving from said first signal a third electrical signal functionally representative of the magnitude of said first earth parameter at preselected depths in said borehole, and recording means for receiving and correlating said second and third electrical signal as a function of depth.It also provides a well logging method for investigating earth parameters and the like in a borehole, comprising deriving a first electrical signal representative of a first earth parameter, deriving a second electrical signal representative of a second earth parameter, deriving from said first signal a third electrical signal functionally representative of the magnitude of said first earth parameter at preselected depths in said borehole, and receiving and correlating said second and third electrical signals as a function of depth.

The preferred embodiment provides for realtime processing of logging data samples derived in realtime with historically derived logging data samples derived at correlative depths within earth formations. It provides for realtime control of a logging operation in response to a functional relation between realtime logging data samples and historically derived logging data samples derived at correlative depths within earth formations. It also provides for verifying logging measurements as they are derived by realtime digital processing of the measurements with previously derived correlative measurements. Visual comparison of realtime logging samples with logging samples historically derived at correlative depths within earth formations is possible.

Further, it is possible to produce, during a logging operation, a digital record comprising a first plurality of realtime logging measurements, each derived during the logging operation at different borehole depths, and a second plurality of historical logging measurements, each derived prior to said logging operation and at a borehole depth correlative to a different one of said first plurality of logging measurements, wherein each of said second plurality is recqrded in functional relation to said first plurality. Two or more logging measurements derived at different times can be merged with increased reliability and reduced data storage requirements. One or more well logging measurements, taken at an earlier date, may be reproduced and functionally merged with other later measurements as they are derived. Historical and realtime measurements can be systematically merged according to preselected lithological relationships. One or more well logging measurements, taken at an earlier date, may be reproduced and functionally merged with other later measurements as they are derived. Realtime well logging measurements taken at different depths in the borehole can be correlated.

Claims (55)

1. A well logging system for investigating earth parameters and the like in a borehole, comprising: first signalling means for deriving a first electrical signal representative of at least one of said earth parameters; second signalling means for deriving a second electrical signal representative of at least one of said earth parameters; third signalling means for deriving from said first signal a third electrical signal functionally representative of the magnitude of said first signal in relationship to preselected depths in said borehole; and recording means for receiving and correlating said second and third electrical signals as a function of depth.

2. The apparatus of claim 1 wherein said first and second electrical signals are representative of the same earth parameter.

3. The apparatus of claim 1, further including fourth signalling means for deriving from said second signal a fourth electrical signal functionally representative of the magnitude of said second signal in relationship to said preselected depths in said borehole.

4. The apparatus of claim 3, wherein said recording means receives and correlates said third and fourth electrical signals as a function of said preselected depths.

5. The apparatus of claim 1, further including: fourth signalling means for deriving from said first signalling means a fourth electrical signal functionally representative of the magnitude of said at least one of said earth parameters at said preselected depth in said borehole after said recording means receives and correlates said second and third signals.

6. The apparatus of claim 5, further including visual display means for generating a visual image of said second and third electrical signals.

7. The apparatus of claim 6, wherein said second signalling means is located at a first position, and wherein said first and third signalling means and said recording means are located at a second position remote to said first position.

8. The apparatus of claim 1, wherein said recording means further includes means for receiving and correlating said second and third electrical signals in functional response to said third electrical signal.

9. The apparatus of claim 7, further in cluding transmitting means for transmitting said second electrical signal from said first position to said second position.

10. The apparatus of claim 9 wherein said transmitting means further includes means for transmitting said second electrical signal from said first position to said second position prior to said receiving and correlating by said rec ording means.

11. The apparatus of claim 5 further in cluding processing means for deriving a func tional relationship between said second and third signals prior to said derivation of said fourth electrical signal.

1 2. A well logging system for investigat ing earth parameters and the like, comprising: first measuring means for deriving a first electrical measurement of a selected earth parameter at preselected depths in a borehole; second measuring means for deriving a second electrical measurement of a selected earth parameter at said preselected depths in a borehole; and recording means for correlatively recording said first measurement with said second mea surement in functional relationship to said preselected borehole depths.

1 3. The system described in claim 12, further comprising command means intercon nected with said first measuring means for selecting said borehole depths.

14. The system described in claim 1 3 wherein said command means is intercon nected with said recording means for syn chronizing said first measurement with said second measurement.

1 5. The apparatus of claim 1 2 further comprising: first storage means for storing said first measurement as a function of depth; second storage means for storing said sec ond measurement as a function of depth; and retrieval means for delivering said first and second measurements from respective first and second storage means to said recording means for correlatively recording said mea surements.

16. The apparatus of claim 1 2 further comprising timing means for recording in said recording means a first sample from said first measurement derived at a first said prese lected borehole depth with a correlative first sample from said second measurement de rived at said first said preselected borehole depth prior to deriving a next sample from said first measurement.

1 7. A well logging system for investigat ing earth parameters and the like, comprising: first signalling means for deriving an electri cal command signal as a function of depth; second signalling means for deriving an electrical measurement of a selected earth parameter in response to said command signal; third signalling means for deriving an electrical measurement of a selected earth parameter; and recording means responsive to said command signal for correlatively recording said measurements.

18. The apparatus of claim 17, wherein said recording means further comprises: means for correlatively recording a first electrical measurement from said second signalling means together with a first electrical measurements from said third signalling means prior to generating a next electrical measurement from said second signalling means.

19. The apparatus of claim 18 wherein said third signalling means further includes means for deriving an electrical measurement in response to said command signal.

20. The apparatus of claim 17, wherein said third signalling means further comprises means for said sampling said electrical measurement as a function of depth.

21. Apparatus for investigating the subsurface materials traversed by a borehole, comprising: a well logging tool suspended in and movable through said borehole at the end of an electrical cable; command means for generating and transmitting a command signal through said cable to said tool and functionally indicative of the depth of said tool in said borehole; a first sensor responsive to said command signal for generating a first electrical data signal functionally indicative of a first selected characteristic of said earth materials adjacent said logging tool; sampling means for transmitting said first signal through said cable and to the surface; a second sensor for generating a second data signal prior to said command signal and functionally indicative of a second different selected characteristic of said earth materials adjacent said logging tool;; a first storage means for recording said second signal; and, a second storage means for retrieving said second signal from said first storage means and correlatively recording said first and second signals in response to said command signal.

22. Apparatus for investigating the subsurface earth materials traversed by a borehole, comprising: command means for generating an electrical command signal functionally indicative of a selected depth in said borehole; first sensing means for generating a first electrical measurement of the lithological characteristic of said earth materials at said borehole depth in response to said command signal; sampling means for transmitting said first measurement from said borehole to the surface of the earth in response to said command signal; receiving means for electrically receiving said first transmitted measurement at the surface; second sensing means for generating a second electrical measurement of another different characteristic of said earth materials at said borehole depth prior to said command signal; surface storage means for storing said second measurement at the surface;; selection means for selecting said transmitted first measurement and said second measurement according to a predetermined sequence; and, processing means for processing from said selection means said first and second measurements at the surface in response to said command signal.

23. The apparatus described in claim 22, further including: generating means for deriving a historical electrical representation functionally related to said second measurement; and, signal mixer means for combining said first measurement and said historically derived measurement in response to said command signal.

24. The apparatus described in claim 23, including recording means for electrically recording said combined measurements.

25. The apparatus described in claim 24, including visual display means for displaying measurements.

26. The apparatus described in claim 25, wherein said visual display means is located at a position remote to the well site.

27. Apparatus for investigating lithological characteristics of subsurface earth materials traversed by a borehole, comprising: first conversion means for deriving a first digital measurement in realtime of a selected characteristic of said materials; second conversion means for deriving a second digital measurement of a selected characteristic of said materials on a historical basis; and display means for electrically displaying a visual representation of said first and second digital measurements on a realtime basis and in functional correlation with borehole depth.

28. Apparatus described in claim 27, including: sampling means for activating first conversion means progresively along the length of said borehole; generator means for generating a visual representation of a correlative fixed increment of the length of said borehole; and coupling means for coupling said generator means and said first and second conversion means to said display means.

29. A well logging method for investigating earth parameters and the like in a borehole, comprising: deriving a first electrical signal representative of at least one of said earth parameters; deriving a second electrical signal representative of at least one of said earth parameters; deriving from said first signal a third electrical signal functionally representative of the magnitude of said at least one of said earth parameter at preselected depths in said borehole; and, receiving and correlating said second and third electrical signals as a function of depth.

30. The method of claim 29, wherein said first and second signals are representative of identical said earth parameters.

31. The method of claim 29, further including deriving from said second signal a fourth electrical signal functionally representative of the magnitude of said at least one of said earth parameters at said preselected depth in said borehole.

32. The method of claim 31, further comprising receiving and correlating said third and fourth electrical signals as a function of depth.

33. The method of claim 29, further including deriving from said first signal means after said receiving and correlating of said second and third signals a fourth electrical signal functionally representative of the magnitude of said at least one of said earth parameters at said preselected depth in said borehole.

34. The method of claim 33, further comprising generating a visual image of said second and third electrical signals.

35. The method of claim 34, further including deriving said first and second electrical signals in functional relation to parameters representative of at least two different boreholes.

36. The method of claim 35, further comprising receiving and correlating said second and third electrical signals in functional response to said third electrical signal.

37. The method of claim 36, further including transmitting said second electrical signal from a location remote to said borehole to a location adjacent said borehole.

38. The method of claim 37, wherein said transmitting step further includes transmitting said second electrical signal prior to said receiving and correlating.

39. The method of claim 38, further comprising deriving a functional relationship between said second and third signals prior to said derivation of said fourth electrical signal.

40. A method of investigating the earth materials traversed by a borehole, comprising: generating an electrical command signal functionally indicative of a selected depth in said borehole; generating an electrical data signal functionally representative of a selected lithological characteristic of said materials in response to said command signal; deriving from said data signal a digital representation of said characteristic of the earth materials at said selected borehole depth in response to said command signal; generating a compatible electrical representation of an historically derived data signal functionally representative of a selected characteristic of the earth materials adjacent said borehole; and combining in realtime said compatible representation and at least one of said digital representations derived on the basis of realtime.

41. The method described in claim 40, further including combining said compatible representation and said at least one of said realtime digital representations in functional response to said command signal.

42. The method described in claim 41, further including recording said combination of said compatible representation and said at least one of said realtime digital representations in correlation with said command signal.

43. The method described in claim 42, further including visually displaying said combination of said compatible representations and said at least one of said realtime digital representations on the basis of realtime.

44. A method of investigating the lithological characteristics of subsurface earth materials traversed by a borehole, comprising: deriving a first digital measurement of a selected characteristic of said materials; electrically displaying a digital representation of said first digital measurement on a realtime basis and in functional correlation with borehole depth; deriving a second digital measurement of a selected characteristic of said materials on an historical basis; and electrically displaying a visual representation of said second digital measurement in correlation with said visual representation of said first digital measurement.

45. The method described in claim 44 further comprising correlatively recording said first and second digital measurements as a function of borehole depth.

46. The method described in claim 45 wherein the step of correlative recording further comprises recording said first and second digital measurements in realtime.

47. The method of claim 46 wherein the step of deriving said first digital measurement further comprises generating a first measurement of a selected characteristic of said materials in realtime.

48. The method of claim 47 wherein said first and second digital measurements are derived as a function of a plurality of identical preselected depths within said borehole.

49. A method of investigating the character of subsurface earth materials and the like traversed by a borehole, comprising: deriving an electrical command signal as a function of depth in said borehole; deriving a first electrical measurement of said earth materials in response to said command signal; deriving a second electrical measurement of said earth materials having a first sample derived at a predetermined depth; and correlatively displaying said first and second measurement signals at a function of depth in said borehole.

50. The method of claim 49, further comprising: deriving a different signal functionally related to said predetermined depth and said command signal; recording a first portion of said second measurement functionally relates to said difference signal; generating a third electrical measurement of said earth materials in response to said command signal; and, thereafter correlatively recording said third electrical measurement and a next portion of said second electrical measurement different from said first portion of said second electrical measurement.

51. A method of surveying subsurface earth materials and the like traversed by a borehole, comprising: progressively measuring a selected characteristic of said earth materials along a portion of the length of said borehole; generating an electrical command signal composed of a sequence of pulses functionally indicative of and related to different selected depths in and along said portion of said borehole; generating in response to said command signal pulses a first electrical data signal composed of digital representations of said measured characteristics of said earth materials at correlative ones of said different selected depths in said portion of said borehole;; generating in functional relationship to said command signal pulses a second electrical data signal composed of digital representations of a measured characteristic of said earth materials at a sequence of functionally correlative depths in said borehole; generating an electrical indication of the depth in said borehole to which said representations composing said first data signal are related; and, correlatively recording said first and second data signals in functional relationship with said command signal.

52. A well logging system, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

53. Apparatus for investigating the subsurface materials traversed by a borehole, substantially as herein before described with reference to and as shown in the accompanying drawings.

54. A well logging method, substantially as hereinbefore described with reference to the accompanying drawings.

55. A method of investigating the earth materials traversed by a borehole, substantially as hereinbefore described with reference to the accompanying drawings.