CA1147825A - Well logging system and method - Google Patents

Abstract

IMPROVED WELL LOGGING SYSTEM AND METHOD
ABSTRACT OF THE DISCLOSURE
An improved well logging system and technique is pro-vided for correlating historically derived measurements with new measurements being derived at correlative depths as the well is logged. A logging sonde generates and de-livers 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 record-ing, display and processing of the matched data. A con-verging 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

rr 1~7825 This invention relates to novel methods and apparatus for providing a plurality of functionally integrated sub-surface 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 know that oil and gas is found in subsur-face earth formations, and that wells are drilled into these formations to recover such substances. What is not gener-ally known is that, for various reasons, the contents of most such ormations 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 indica~ion 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 para-meters of the earth substances adjacent the borehole, whereby such measurements can thereafter be interpreted ~7~3Z5 .2.
according to selected functional relationships for iden-tifying those formations of possible interest.
Since no one earth parameter, or even any one combi-nation of such parameters, can of itself provide a defini-tive and conclusive indication of the presence of oil andgas in commercial quantities, there has been a continuing need to perform as many different types of logging measure-ments 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 in-struments, 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 neces-sitate 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 mea-surements 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" mea-surements 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.

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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 bore-hole. Thus, the problem becomes one of matching or "merging"
measurements from one set of logging data with the measure-ments 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 neces-sitating the mergerof two data sets.
One attempted solution to the problem of merging sets of logging data has been to first generate visible repre-sentations of the data in the form of films from conven-tional 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, compari-son8 may not be made in realtime. Yet another disadvantage i8 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 thepresent 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 tech-nique provides for merger in realtime of historical logging data with other logging data as it is being produced in ~1~7~5 .4.
realtime. This, in turn, means that the integrity and validity of the realtime data cannot be checked and com-pared 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 in-tervals, 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 realtime data in order to effect a merger further contributes to unreliability of the technique neces-sitated 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 acqui-sition in relation to the historical data, the resulting sets of data points fre~uently are not correlative to iden-tical 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 corre-lative 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 ~14'7825 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 noteasily 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 present invention, however, wherein improved well logging methods and apparatus are provided to generate more accurate measurements of a plurality of different lithological para-meters. Improved means and methods are provided for correlatively merging historical logging data with data being obtained on a realtlme 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.
In an integrated digital well logging system and apparatus, 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 ensure that realtime measurements to be generated will be generated at depths correlative to ;~ the historical measurements they are to be correlatively merged or "matched" and recorded with.
tm/~ 5-~1~78Z5 The meryer circuitry of the aforementioned patent application is specifically illustrated in Fi~ure 2, and is described in detail therein as to mode of operation and tm/, -5a-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.

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~147825 One aspect of the present invention resides in a well logging system for investigating earth parameters and the like, the system having first measuring means for deriving in real-time a first electrical measurement of a selected earth parameter at preselected depths in a borehole. Second measuring means are used for deriving in historical time a second electrical measurement of a selected earth parameter at the preselected depths in a bore hole. Recording means is provided for correlatively recording in real-time the first measurement with the second measurement in functional relationship to the preselected borehole depths.
According to another aspect of the invention there is provided a method of investigating the earth materials traversed by a borehole, the method including the steps of generating an electrical command single functionally indicative of a selected depth in the borehole and generating an electrical data signal functionally representative of a selected lethological characteristic of the materials in response to the command signal. A digital representation of the characteristics of the earth materials at the selected borehole depth in response to the command signal is derived from the data signal. A compatible electrical representation of an historically derived data signal functionally representative of a selected characteristic of the earth materials adjacent the borehole is generated. There is then combined in real-time the compatible representation in at least one of the digital representations derived on the basis of real-time.
According to yet another aspect of the presen-t invention there is provided an apparatus for investigating 7 _ ~ '~ pc/ ~, ~.r ' ~78;~5 lithological characteristics of subsurface earth materials traversed by borehole, the apparatus including first conversion means for deriving a first digital measurement in real-time of a selected characteristic of the materials, second conversion means for deriving a second digital measure-ment of a selected characteristic of the materials on any historical basis and dlsplay means for electrically displaying a visual representation of the first and second digital measurements on a real-time basis and in functional relationship with borehole depth. According to yet another aspect of the invention there is provided a method of investigating the lithological characteristics of subsurface earth materials traversed by borehole but includes the steps of deriving a first digital measurement of a selected characteristic of the materials, electrically displaying a digital representation of the first digital member on a real-time basis and in functional correlation with borehole depth, deriving a second digital measurement of a selected characteristic of the materials on an historical basis and electrically displaying a visual representation of the second digital measurement in correlation with the visual representation of the first digital measurement.
In a specific 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 pc/;,~

provided by the sonde. More particularly, the sonde will preferably include a circuit whereby one or more of these measurements are converted or formea 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 béing 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 real-time 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 real-time signals, which are all in digital form, may also be fftored 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 real-time 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 present invention to provide for correlatively merging reai-time data with historical data as a function of borehole depth. In this respect, the different data may be separately, although ~ ~ r~ _ 9 _ ~, pC/~

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~147825 correslatively, included in a common display or xecord, or a function of such logging data may be appropriately derived on a real-time 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 real-time data, in order to enhance the informative aspects of this data. In addition, it is a feature of this invention to provide for visual observation and monitoring of the logging signals and other data on a real-time 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 real-time 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 real-time 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 real-time data may be merged in real-time at the well site with historical data which may have been transmitted to the well site in real-time from a remote location.
Alternatively, the real-time data may be transmitted to a remote site and merged in real-time at the remote site with pc/ ~

~7~25 historical data present at the remote site.
In a specific embodiment of the invention, as the sonde traverses the borehole, it will sequentially generate and transmit to the surface measurements at preselected in-crements 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 real-time measurements. As the sonde progresses up the borehole, real-time 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 measure-ments 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 real-time sample and a historical sample derived at a correlative depth, followed by a next real-time 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 pc/ r~

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detects that the next historical data sample to be read was derived at the current sonde depth at which the next real-time measurement is to be made. The merger process will then begin, whereby, also in alternate fashion, selected real-time 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 real-time recording in the same storage of both real-time 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 real-time data which is being merged in real-time whereby the logging operation may be dynamically controlled in response to the merged data.
A real-time display of the merged data is further provided, wherein real-time and historical data derived over preselected identical increments of borehole are displayed side-by-side, so as to permit comparision of the real-time samples with correlative historical samples, in order to check validity of the respective data. The merger circuitry provides for transmitting in real-time the merged data to a remote location/ and for transmitting from the remote location to the well site in real-time control signals in response to the merged data received by the remote site.

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~ ~5 These and other features and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.
In the Drawings 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 Figure 1.
Figures 3A and 3B are flow diagrams depicting the functional operation of the apparatus depicted in Figures 1, 2, 4A and 4B.

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~47825 Figures 4A and 4B are more detailed functional representations of one embodiment of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring now to Figure 1, there may be seen a simpli-fied 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 lo~ging cable 3 which is arran~ed 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 ,~/ t - -14-- . .

~78ZS

provided ~y the log~ing cable 3.
As previously stated, it is a feature of the well site system depicted functionally in Figure 1 to transmit fully correlated logging measurements to a suitable base observation and control station, and which, in turn, ma~ be suitably located at a pc-sition remote ~rom 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 Xemote base station, at the time such measurements are re-ceivea ~ro~ t~e logging cable 3, thxough a suitable communi-cations lin~ lS which may be a c~nventional telephone line, xaaio communi~cation satellite, or the like~ Furthermore, like signals-may also be provided to the customer or user at ~is respective user station (not depicted) which, in turn, ~a~ be located remotely from both the well site system and the operator's base station ~not depicted). These indications, m~y also be conveniently transferred to the user station by a similar communications link 16 interconnecting the well slte system with the user station, and thereafter relayed to base station by means of another different communications link ~ot depicted~, or they may be relayed from the base station to the user ~tation on such communications link. It shou}d ~e noted t~at the well site system suggested by Figure 1 may be o~erated directly by the base station, and thexefore the co~munications link 15 may also include provision for deliver-ing suitable control signals from the base station to the well site syste~ by way of the communications link 15. Similarly, the communications link may be used to provide control signals ~rom the base station to the user station, or in some circum-~tances, to provide control signals ~rom the user station to the well site system or hase station, by way of the communi-cations link 16.
Re~erring again to ~iguxe 1, there may be seen a simp~ified ~unctional diagram ~f the uphole cixcuits comprising the appax~tus located a~ or composing the well site system. ~s will hereinafter be explained in detail, .., ,. ~.

3~47~3~5 .16.
t~e 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 trans-mitterS and receivers contained in acoustic logging section 2C from the surface. Accordin~ly, it may be seen from Figure 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 Figure 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 conditionaing circuits 25 for filtering, gain adjustment, and other suitable pro-cessing. 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 suit-able rad.ioactivity pulse counters 30, by way of signals 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 measurements, will be composed of pulses which occur in a random manner. As will hereinafter be-come apparentl however, it is particularly desirable for the purposes of the instant invention, that these signals 1~7~25 .17.
be presented to ~he surface circuitry in digital form.
Accordingly, and as more particularly depicted in Figure 1, the sonde 2 will preferably include a pulse code modu-lation or "PCM" circuit 20 for encoding such signals in digital form before delivery to the PCM buffer/receiver circuit 29 shown in Figure 1. If the signals are not so encoded, howe~er, then they may be conveniently applied to a suitable analog/digital converter 31 or the like, ~efore being processed and recorded. Alternatively, pulses deriying 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 Figure 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 radia-tions emanating from the borehole materials surrounding the sonde 2, and will therefore be suitably delivered to the pulse counters 30 which, alternatively, produce a suit-able digitized representation of this data as output signal 30A. On the other hand, the output signals from the in-duction logging section 2B and the acoustic logging sec-tion 2C of the sonde 2 will, conventionally, be delivered to the surface in the form of analog measurements repre-sentative 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 log-ging signal recovery controller 32.
It will be noted that the analog-to-digital converter 31 receives input signals 27c and 28a from both the switch-ing circuit 27 and the binary gain amplifier 28. The rea-son 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 am-plitude to be applied directly to the analog-to-digital , ~7~ZS
.18 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. Accordingly, the switching circuit 27 will respond to route such signals to the binary gain am-plifier 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 switch-ing 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 ~Grm of an analog signal 27c which is delivered to lS the converter 31 or to the pulse counters 30. If, as here-inbefore 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 con-verter 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 8ignal 27c~ to the binary gain amplifier 28. It will be noted that binary gain amplifier 28 may be provided with a auitable 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 con-troller 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 con-verter 31. Accordingly, the amplified signal 28a, 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 Figure 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 ~7~325 .19 .
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 appro-priate 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, w~ll all include appropriate buffer circuitry, whereby these signals may be stored until the well site master con-troller 20 generates its command signal 33 to cause the recovery controller 32 to interrogate the components se-lected. Upon such interrogation, which is indicated in Figure 1 by the interrogation signal 32c, the recovery controller 32 will cause the appropriate or selected com-ponent to transfer one of outputs 29A, 30A or 31A to the recoYery controller 32 which, in turn, conducts such in-formation 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 indica-tion of the depth at which such measurements are taken!
Accordingly, it should be noted that when the master con-troller 20 generates its command signal 33, it also generates an appropriate depth data/control signal 21 to cause the depth controller 12 to deliver the informatin it has previously taken from the output 11 of depth logic 10. Thus, this data, which also passes to the controller 2a by way of the depth data/control signal 21, will be correlated effectively with the logging data signals pro-vided 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 .20.
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 Figure 1 visual display and recording dev~ces which may preferably include analog film recorder 39, visual display 40, and a suitable large scale plotter 41 and small scale plotter 42. Information ~hich is desired to be displayed or recorded may be trans-ferred 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 control-ler 20 and digital-to-analog converter 46, and thereafter communicated from controller 45 to converter 46 on output line 45A. After ConYerSiOn 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.
~oreparticularly, and as will 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 pre-selected borehole depth interval which has been traversed by sonde 2.
Still further, it may be seen from Figure 1 that the information signal 43 may be conveyed to a plotter con-troller 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 -.

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7~25 .21.
plotter interface 49. The function of the interface 49 i5 to further adapt these information signals 43 for delivery as output 49A to suitable processing circuitry such as a digital-to-analog converter 50, wherein they are converted to an appropriate analog output 50A for recording on film ~ithin the large scale plotter 41. In like manner, it may be desirable to display various information signals 43 associated ~ith 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 int~rface 52 which, after additional signal processing, will com-municate 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 sig-nals 43 wh.ich 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 de-sirably under the control of master controller 20. Ac-cordingly, controller 20 may desirably provide information signals 43 so as to cause display and recording of well log~ing information in a variety of formats and from a ~ar~ety of sources. These may include, for example, pri-mary storage 35 and secondary storage 36, which may trans-fer 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 te.sting 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 neces-- sity 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 bore-hole environme.nt. Accordingly, in Figure 1 there may be seen a signal simulator 54 which, in response to appro-priate simulator command signals 55A, may generate various ~78;~S
.22.
test signals 56 as hereinbefore mentioned which, for ex-ample, may include signals similar to those which might be expected to he present ~n 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 con-trol 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 inYention. For example, it may be desirable for a logging engineer to override various functions performed ~y 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 communi-cation 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.
~a 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 Figure 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 15 and 16, respectively, under control of a data/control signal 60 from controller 20. It will furthermore be noted that modulator-demodu-lator 59 may conYeniently 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.
."

~1478Z5 .23.
Referring now to Figure 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, m~y be provided for storing electrical data signals composed of digital representa-tions of well logging measurements derived correlative to ~ 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 ~rom a merger controller circuit 63, so as to cause ~uch 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 re-spective merge memory inputs 38b or 38c. The merge mem-ories 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 avail-able 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 represen-tations 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 ~torage 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 ,....

~' ~'78ZS
.24.
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 S 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 10 as ~double-buffering", a technique well known in the art ~hereby measurements may be selectively retrieved from or stored in one memory while a second memory is being filled ~ith or "reading out" blocks of data to input or output devices. When all of the data is thus sequentially re-15 trieved 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 Figure 2, it will further be seen 20 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 representa-25 tion, which ha~ been derived on a depth-dependent basis, on the controller output 32b to the well site controller 20 or, more particularly with respect to Figure 2, to the input memory 61. It will further be recalled that a depth controller 12 will preferably be provided for 30 generating a sequence of pulses derived from rotation of the sheave wheel, which is in turn correlative to move-ment 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/
35 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 înput memory 61. The merge controller 63 will, in - . .
. - .

~ ' ' .

~7~2S
.~5.
response to the control signal 21, generate a merger con-troller output 69, causing a transfer of the sample pres-ently 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 de-rived 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 accord-ingly 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 Figure 2, there will also be seen a merge memory 64, and a merge memory 65, each having cor-relative 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 Figure 2 a memory output 79 de-livered 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 ~4~8Z5 .26.
and 66. It may thus be appreciated that the merge memo-ries 64 and 65 are preferably arranged in a "double-buffering" 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 remain-ing 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 out-put 71 or 72 on which these data samples will be delivered.
Referring now to Figures 3a and 3b, there will be seen a deci~ional flow diagram functionally representative of the operation of the apparatus depicted in Figure 4a and 4b, which is one particular embodiment of merger appa-ratus typical of the present invention. In the present 3q example it will be assumed that a sequence of measurements from one data set, either realtime or historically gener-ated, is presented to the merge storage 62 on output 68 wherein each successive measurement was derived at a pro-gressively 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 ~782S
.27.
preferably was derived at the same progressively shal-lower 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 pre-determined depths, it will be appreciated that it is preferable to insure that the first sample from each set to be correlatively recorded was generated at a correla-tive depth. In this manner, if each successive sample from the fîrst 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 avail-able 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.
~irst, the starting depths at which the first samples fxom 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 3amples 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 start-ing 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 ~1~7825 .28.
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 r it will also be appreciated that the sonde 2 may be positioned S at an elevation within the borehole ~herein its beginning measurements will commence at a depth either shallower or deeper than that of the first sample from the histoxical 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 neces-sary 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 position shallower than the elevation at wh~ch the initial samples on the historical tape were derived, it may be necessary to advance the hlstorical tape to the sample derived at the depth at which the sonde 2 is beginning derivation of realtime measurements~
Referring more particularly now to Figure 3a, the path from block 1~3 to block 205 represents the functions pe~formed by the apparatus depicted in Figure 2 when the sonde 2 i8 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 thiC first measurement. As depicted in block 193 of Figure 3a, the controller 20 of Figure 2 pre~erably will first load the merge memories 66 and 67 Of Figure 2 with data samples stored on the historical tape in the primary storage 35 which were derived at se-quentially 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 71~ZS
.29.
delivered to the merge memories 66 and 67 in the form ~f:
"blocks" of logging samples, although this is not neces-sary. Thus, a typical block would preferably consist of, for example, 36 logging measurements derived sequentially in one-fourth foot increments over a nine foot increment of ~oYehole depth. Thus, for example, after the merge memory load o~ block 193 is accomplished, the merge memory 66 may typically contain, for example, 36 logging measure-ments derived at quarter foot intervals from 1,000 feet 1~ up to 9,9~1 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,~82 feet within the borehole. Referring now to block 195 of Figure 3a, it will be seen that the next function to be performed by the apparatus of Figure 2 is to deter-mine 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 begin-ning 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 8tarting depth information to the merge controller 63 on the merge controller input 38a. Referring next to block 197 of Figure 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 12 of Figure 2 is to deliver such infor-mation 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 di-rection, as is typical. The reason for calculating the current sonde depth minus 1, or the "anticipated" merge ;7~3Z~
.30.
depth, as depicted in block 197, will be hereinafter de-scribed. 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 con-troller 63 may then perform the comparison depicted in the block 199 to determine if the anticipated merge depth is greater or equal to the first sample startin~ depth.
Assuming for the moment that this is the case, the merge controller 53 may then generate a merge controller out-put 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 stoxage 62 on merge memory putput 80 or 81. The merge controller 63 will also set an internal register (not shoun~ 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 2~7 and 209. The merge controller 63 will there-after 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 con-troller 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 Figure 3a, the ~1~782S
.31~
sequence just described will be repeated as the appa-ratus of Figure 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 pro-gresses up the borehole generating measurements, until it generates a measurement at the depth of the first his-torical ~ample, the same historical sample may continue to be stored in the merge storage 62 with each correspond-ing next sample from the input memory 61, and thereafter stored in the merge memory 3 or 4 along with the succes-sively generated measurements delivered from the input memory 61.
Referring now to path 215 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 con-troller 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", indi-cating that the condition for merger has b~en achieved.
Therefore, as depicted in block 219, each time a next 25 sample is derived at a nextdepth::an~:.r~e~vedl~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 mea-surements 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 oc-curring and until the remaining merge memory has thus been ~7~Z5 .32.
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 re-lated depths are present on the merge storage 62, they will be thereafter transferred to the merge memory 64 or 65 to ~uild a block of such sets of samples. More par-ticularly, 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 particu-lar predetermined increment of borehole depth. For example, 36 sets of samples derived at quarter foot in-texvals 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 in-crement 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 Figure 3a, and more particularly to the block l99, it will be noted that the merge con-troller 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 de-rived at an elevation deeper within the borehole than the anticipated merge depth. This, of course, corresponds 3~ ~25 .33.
to the fact that there are initial samples contained on the histoxical 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 de-rived at elevations within ths borehole deeper than the depth at which the correlative merging of samples from the two sources, 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 irst 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 ~urther 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 Figure 3a, the paths from path 220 through 228, 232 and 230 will be seen which repre-sent the functions to be performed by the apparatus of Figure 2 so as to retrieve such blocks of historical data 1~L7~2S
.34.
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 de-rived at quarter foot intervals over a nine foot incre-ment of borehole depth constitute a "block" of data. More-over, it will be assumed, for like purposes, that the first such historical sample stored in the primary stor-age 35 was derived at a 10,000 foot depth within the borehole, and that the current depth of the sonde 2 is ~,976 feet within the borehole, in which case the antici-pated merge depth is 9,975 feet. Thus, it will be seen that t~o 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 ~ill be thus retrieved and stored having samples derived from 10,000 up to 9,991 feet, and a second block will thexeafter 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 ~hich 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 antici-pated merge depth divided by the increment of feet of data per blo¢k. Thus, in the present example, the integer value of (10,000 - 9,975~/9 = 2, the number of blocks to be xead from the primary storage 35. It will be recalled that the merge controller 63 has previously been in-structed 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 con-troiler 63. Accordingly, as depicted in the block 227, the merge controller 63 may thereafter calculate the ` - -~47~3ZS
,35.
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 con-tain a decrementing counter and comparator which con-tinuously 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. Function-ally, this series of events performed by the apparatus of Figure 2 is illustrated in the blocks 229, 233, and 235 of Figure 3a. When the counter/decrementer has thus determined that the integer number of blocks to read pre-viously calculated has thus reached zero, the merge con-troller 63 must thereafter determine the number of his-torical 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 L7~25 .36.
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 ~lip-flop con-tained in the merge controller 63 (not depicted~ to the "off" position, prior to determining whether there are more historical samples to move through merge storage 62 to attain the merger condition wherein subsequent samples xeceived by the input memory 61 will correlatively be matched and stored in the merge storage 62 with correla-tive samples from the merge memories 66 and 67 derived at the same depths. This setting of the counter and ~lip-flop may be seen illustrated in block 236 of Figure 3a and block 238 of Figure 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 8taxting 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 ~1~7825 .37.
(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 ~,~82 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 con-troller 63. Because there are preferably 4 samples per foot being derived in the present example, it will be ap-parent that the first 28 samples from the block of samples der~ved 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,~75 feet, stored in the primarv storage 35, are æuccessively matched with correlative measurements being sequentially deriyed by the sonde 2 and stored in the in-put memory 61. It will be noted in the block 246 of Figure 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. Reerring 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 aurrent 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 c~rresponds 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 deriyed 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

3~47~3ZS
.38.
may have changed due to movement of the sonde 2. This factor is represented by the block 262 of Figure 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 pre-viously described condition, wherein subsequently de-rived measurements in the input memory 61 will be correlati~ely matched with historical samples from the merge memory 66 or 67 to be transferred to the merge storage 62 and thereafter correlatively recorded, as preyiously described, in the secondary storage 36. Re-ferring again to the block 248, alternatively, the merge controller 63 may detect that there are samples in the curxent 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 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 de-picted in the block 250 of Figure 3B, the merge controller 63 ~ill next determine whether the number of samples previousl~ moved (CT) plus the number of samples in the current block (~1, which were just calculated and are to be mo~ed, 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 illus-tration, 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 (~ = 20), it will be seen that because there are 36 samples per block, 28 + 20 - 36 = 12 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 12 samples needed.

~1~7~Z5 .39.
It will further be noted that, due to the quarter foot sampling intervals of the present invention, the thir-teenth sample will have been derived at 9,970 feet. Con-tinuing with the present illustration, as depicted in the block 254 of F~gure 3B, in the case where 28 samples from the block ~,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 1~ of samples pxeviously 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 de-scxibed. 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 con-troller 63 will again determine whether the anticipated mexge 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 de-scribed. However, if the merge controller 63 has de-tected that the anticipated merge depth has changed, cor-responding 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 ~ill, 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 8~S
.40.
"more samples to move" flip-flop to the "on" position as depicted in block 238. Referring a~ain now to the block 250 of Figure 3B, it will be recalled that the merge con-troller 63 determines 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 ~ere 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 up-date the internal counter, as depicted in the block 254, to e~ual the number of samples previously moved, or CT = 8 + 28 = 36. As shown in the block 256, the eight rema;ning samples from the 9,982 foot block, will then be moYed 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 pre-viously 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 ~ccordance 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 .

7~325 .41.
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 achieYing the mer~er condition, as de-picted in the bloc~ 278 of Figure 3B. 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. Ac-cordingly, the merger controller 63, as depicted in the block 278, will detect that the additional twelve samples ~rom 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 opera-tion as depicted in the steps of Figure 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 con-ditions for merger have been achieved at a block boundary, in which case the anticipated merge depth at which his-torical samples will be correlatively merged with subse-quent samples derived and stored in the input memory 61 were both derived at the beginning of a next block. As illustrated in Figure 3B, the merge controller 63 in ac-cordance 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 re-cycle in accordance with the path 264 or 263, in the manner previously described.

11~825 Referring now to Fi~ures 4A and 4B, there will be seen depicted therein a more detailed diagram of the apparatus of the present invention, including a more de-tailed depiction of the apparatus included in the well site controller 2Q. In the discussion which follows hereinafter, reference should be made to the Figures 3A
and 3B and the fore~oing accompanying description for understanding of the sequence of operation of the appara-tus depicted in Figures 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 lQ2 instructing the primary storage 35 to generate a storage output 100 which contains, preferably, digital represen-tations 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 ~1 or 92 to the correlative merge memory 66 or 67 until the respective merge memory is filled. An appro-priate double buffer control 280 may be provided which ~ill 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 con-trol 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 195 of Figure 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 lQ3 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 ~7~'5 ~43, sonde 2 depth minus 1 in a suitable storage 108. It will be recalled that the depth control 12 preferably will con-tinuously deliver on control output 105 an information signal correlative to the current depth of the sonde 20 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, accordingly, in response to the controller output 161 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 Figure 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 antici-pated 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 com-parator 111 will preferably generate a comparator signal 112 setting a merge fllp-flop 116 in the off condition.
It will further be noted that the comparator signal 112 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 buf~er control 280 will determine the setting of the switch 98 so as to cause the command generator out-puts 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 re-sponse 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 ~5 .44.
output 95 to the mexge 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 S 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 28~ will sense delivery of all samples, causing the switch 282 to deliver subsequent transfer command generator out-puts 99 to the merge memory 67 on the switch output 92 so as to cause subsequent quarter foot samples from the depth intervals 5~91 up to 9~82 to be delivered on the merge memory output 95 to the mer~e storage 62.
Referring now to Figure 3a, it will be seen that the apparatus of Figure 4a and 4b is now presently in the state wherein the merge controller 63 determines whether the merge flip-flop has been set in the "on" condition, as depicted in block 205 of Figure 3a. Thus, the merge controller 63 will generate an appropriate interrogation 2~ command 114. If the merge flip-flop 116 has not previously been set in the "on"condition, an appropriate flip-flop ~utput 115 will thus be ~ ated, which, in turn, will cause the storage 104 and 108 to deliver to the comparator 111 to deliver the present anticipated merge depth and gtarting depth of the first historical sample on compara-tor inputs 117 and 118 to a conventional comparator 119.
The comparator 119, will, accordingly, preferably deter-mine the relative magnitudes of the anticipated merge depth and the starting depth of the base tape first block, as depicted in block 214 of Figure 3a. If the two values are equal, the correlative comparator output 125 will thus instruct the merge controller 63 of this event as well as to set the merge flip-flop 116 on the on condition.
Thereafter, every time the merge controller 63 interro-gates the merge flip-flop 116 as to its status on interro-gation command 114, the merge flip-flop 116 will thus generate a flip-flop output 126 corresponding to the fact that the merge condition has been met, wherein the present elevation of the sonde 2 is such that the anticipated 7~25 .45 merge depth equals the starting depth o~ the first sample of the hi~torical tape first block. It will be seen from Figure 4b that this flip-flop output 126 will enable the transfer command generator 281, such that samples from the recovery controller 32 will thereafter be correla-tively 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 de-5cxibed. 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 de-livered to the input memory 61 on the recovery controller output 120. This recovery controller output 120 is also txansferred 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 de-livered on the recovery controller output 120 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 gene-rator output 99 will be delivered on the merge memory out-put 95 to the merge storage 62. Assuming, as depicted in path 283 of Figure 3a, that the anticipated merge depth is greater than the starting depth of the first sample of the historical tape, the comparator 119 will accordingly generate a correlative comparator output 124, instructing the merge controller 63 of this state. It will further ~e seen that the comparator output 124 will also be de-livered 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 128. 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.

.46.
Thereafter, this value is delivered on the storage output 129 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 indica-tion on recovery controller output 120 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 199 of Figure 3a, it will be noted that the starting depth of the first historical sample of the base tape may be greater than the antici-pated merge depth, in which case the apparatus of Figures 4a and 4b will then operate in a manner consistent with the path depicted commencing with path 220 of Figure 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 thxou~h the merge memories 66 and 67 and through the merge ctorage 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 xeferring to block 227, it is apparent that the number of such blocks of historical data which must be xead 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, and 1~8. These storages will, in response thereto, generate their correlative storage outputs 132, 134 and 133, which, in turn, will be delivered to a subtracter circuit 135 in the case of storage output 132 and 134, and .47.
a conventional divider circuit 137 in the case of storage output 133. It will be seen from Figure 4b that the sub-tracter circuit 135 will accordingly provide a difference signal 136 equal to the difference between the starting depth of the base tape block and the anticipated merge depth, and this difference signal 136 will be conveniently delivered to a divider circuit 137 which will divide this difference by the number of feet of data per block, stored in the storage 130. The resulting quotient will then be delivered on the divider circuit output 138 to an integer storage 139 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 his-torical 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 de-picted in block 229 o~ Figure 3a, will determine whether this integer value is equal to zero. If not, an appro-priate comparator output 149 will be generated. As can be seen from Figure 4b, this comparator output 149 will first cause the integer value stored in the integer stor-age 139, which is delivered to the decrementer 151 on in-teger storage output lS0 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 ls 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 143 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 .48.
and thereafter to the merge memory 85 or 86. When the decrementer output 152 which is delivered to the compara-tor 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 Figure 3a. As depicted in Figure 4b, this comparator output 153 will preferably la first set a register 154 which will contain the number of samples within a block previously moved to the value zero, as shown in the block 236 of Figure 3a. The comparator output 153 will also set a flip-flop 155, depicted in bloc~ 238 of Figure 3a to the "on" condition. The ap-paratus of Figures 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 Figure 3a. Accordingly, the mer~e controller circuit 63 will generate first a merge controller output 156, which causes the integer storage 139 to deliver the previously stored integer on integer storage output 157 to a multiplier 157a. It will further be noted that the feet per block has also been delivered to the multiplier 157 on the storage output 133. The re-sulting product will thereafter be delivered on the mul-tiplier output 157b ~o an appropriate subtracter circuit 160. It will further be noted that the subtracter cir-cuit 160 is accordingly provided with the storage output 159 corresponding to the starting depth of the historical samples. The resulting difference signal 163 is pre-ferably delivered to another subtracter circuit 164 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 mul-tiplier circuit 166 is delivered as multiplier output 169 to another subtracter circuit 170. It will be seen from Figure 4b that the subtracter circuit 170 is also provided ~1~78Z~
,4~, with a register output 168 from the registex 154, corres-ponding to the num~er of samples previousl~ moved which, due to the prior setting of the register 154, equals zero.
The resulting output Y, which is the result of the calcu-lation per~ormed in block 246 of Figure 3b, ma~ thereafter ~e delivered as difference signal 171 to a conventional storage 176 and comparator 172~ The difference signal 171 is delivered to the storage 176 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 Figure 3b, the comparator 172 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 173 which will interrogate the storage 108 to determine whether the anticipated merge depth has changed. If not, the merge flip-flop 116 will, in response to the storage output 175 be set in the "on" position and the apparatus of Figure 4a and 4b will proceed as depicted in path 266 Of Figure 3b as hereinbefore described. However, re-ferring to the block 262, if the anticipated merge depth has changed, as shown by the path 263 of Figure 3b, the storage output 174 will thus be generated. This storage output 174 will set the more samples to move flip-flop 155 to the "on" position, and will cause the present an-ticipated merge depth, starting depth of the base tape, and feet per block values to be delivered to the sub-tract~r circuit 135 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 177 will be generated.
Accordingly, the comparator output 177 will cause the re~ister 154 to deliver the number of samples previously moved (CT~ on register output 178 to the adder circuit 179.

~ 7825 .50.
Comparator output 177 will also preferably cause the num-ber of samples in the current block to be moved, previously stored in the storage 176, to be delivered on the storage output 1~8 to the adder 179~ The resulting adder output 182 thereafter may be conveniently stored in a conventional storage 184 and delivered to a comparator 180. It will be appreciated that the comparator 182 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 1~ greater than 36, indicating that samples from a next block Qf 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 Figure 3b, the comparator 180 will generate a comparator output 180a which will cause the storage 184 to deliver a storage output 127 thus updating the register 154 with the adder output 182 which equals the number of samples in the current block to move plus the number of samples previously moved. The compara~or output 180a, which also may be delivered to the storage 176 will cause the storage 176 to generate a storage out-put 183. From Figure 4b, it will be seen that this stor-age output 183, which contains the number of samples in the current block to move, will be delivered to the com-mand 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 pre-viously 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 Figure 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 ap-propriate buffer control output 185 to interrogate the storage 108 in order to determine whether the anticipated merge depth has changed. In response to this interroga-tion, the storage 108 will generate the appropriate signal so as to cause the apparatus of Figure 4a and 4b to follow 71~2S
.51.
either the operations following the path 264 or 263 of Figure 3b as hereinbefore described.
Referring again to the block 250 of Figure 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 Figure 3b, and corresponds to a correlative comparator output 186 which will preferably be delivered to a con-ventional storage 112. It will be seen from Figure 4b that the storage 112 may then deliver a storage output 187, wbich, in turn, will cause the register 154 to deliver the previous number of samples moved on the register out-put 188 to a subtracter circuit 189. It will further be seen that the storage output 187 may preferably be de-livered directly to the subtracting circuit 189 so as to cause the register output 188 to be subtracted from the number stored in the storage 112 and delivered on the storage output 187. In the present example, this number will equal the number of samples per block, or 36. Re-ferring now to the output of the subtract.~r 189, it will be seen that the output 200, which will be the newly cal-culated number of samples in the current block to move, or Y = 36 - CT, will then be delivered to the storage 176 so as to update this Y value. Still further, it will be seen that the comparator output 186 will also be delivered to the more samples to move flip-flop 155 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 Figure 3b. After the comparator out-put 186 has updated the register 154 with the new value of the number of samples which will have been previously moved after the samples are moved, or Y ~ CT, the com-parator output 186, which is also delivered to the stor-age 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.

~1~71325 .52.
Referring now to the path 259 of Figure 3b, it will be seen that the buffer control 280 may determine in re-sponse to the storage output 183 that the number of samples remaining in the current block will be moved or "used up"
in response to this output 1837 in which case the buffer control 280 will generate a buffer control 190. This buffer control output 190 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 stor-age 36~ The ~uffer control output 190 will also prefer-ably be delivered to the register 154 so as to reset the number of samples previously moved to zero, will be de-livered to the subtracter 164 to update the current block depth, be delivered to the flip-flop 155. The buffer con-trol output 190, will act as an interrogation command to the flip-flop 155, so as to interrogate the flip-flop 155 to determine whether there are more samples to move or not. The flip-flop 155 may, therefore, deliver an output 192 correlative to the path 261 of Figure 3b, indicating that there are no more samples to move. Thus, the storage 104 will be interrogated in response thereto, to determine ~hether the anticipated merge depth has changed or not.
The operation of the apparatus of Figure 4a and 4b will then proceed as hereinbefore described following either the path 264 or 263 ~f Figure 3b. However, if the "more samples to move" flip-flop was in the "on" position, a flip-flop output 191 will accordingly be generated. The flip-flop 191 will reset the flip-flop 155 to the "on"
condition, and will again trigger the storage 104, 108, and the register 154 to deliver their correlative stored starting depth, anticipated merge depth, and number of samples previously moved, to cause the subtracter 170 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 Figure 4b, it will be appreciated that a double buffer arrangement has been pro-vided similar to that depicted in Figure 4a. More parti-cularly, the double buffer control 82 is preferably pro-vided with a merge memory output 88 from the merge memory -- ~14782S
.53.
~4 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 de-tected by the buffer control 82, the buffer control out-put 87 will direct command generator output 83 through the switch144 so as to cause the command generator output 183 to be delivered to the particular full memory 64 or 65 50 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 out-put 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 ox 65 which is available for receiving such samples.
It ~ill be apparent that the realtime data to be merged need not have been generated in response to the hexeinbefore noted depth command pulse. Rather, it is within the scope of the present invention that the real-time 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-depen-dent 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 between 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 - ~478~5 .54.
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 ~ith corxelatively 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 o such real-time and historical data occurred during the logging opera-tion, so as to result in a merged tape available immed-iately at the end of the logging run for further proces-sing. 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 atorage 36 may ~e retrieved by the master controller 20 for proces5ing in realtime during the logging operation, and the results therefrom used to dynamically control the xealtime logging operation. It is also contemplated that the merged data, in addition to being delivered to the secondaxy storage 36, may be delivered to the modem 59 for transmission to a remote location. Moreover, the hi~torical data to be merged may first have been trans-mitted 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 accompany-ing drawings without departing substantially from the con-cept of the present invention. Accordingly, it should be clearly understood that the forms of the invention de-scribed and illustrated herein are exemplary only, and are not intended as limitations on the scope of the present invention,

Claims (20)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A well logging system for investigating earth parameters and the like, comprising: first measuring means for deriving in real-time a first electrical measurement of a selected earth parameter at preselected depths in a borehole, second measuring means for deriving in historical time a second electrical measurement of a selected earth parameter at said preselected depths in a borehole, and recording means for correlatively recording in real-time said first measure-ment with said second measurement in functional relationship to said preselected borehole depths.

2. The system described in claim 1, further com-prising command means interconnected with said first measuring means for selecting said borehole depths.

3. The system described in claim 2 wherein said command means is interconnected with said recording means for synchronizing said first measurement with said second measurement.

4. The apparatus of claim 1 further comprising:
first storage means for storing said first measurement as a function of depth; second storage means for storing said second 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 measurements.

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

6. The system of claim 1 further including converging means for recording in said recording means a portion of said real-time measurements without a correlative portion of said historical-time measurement when said real-time portion is derived at borehole depths exceeding borehole depths at which said historical-time measurements were derived.

7. The system of claim 6 wherein said converging means further includes means for recording a portion of said historical-time measurements without a correlative portion of said real-time measurements when said historical-time portion is derived at borehole depths exceeding borehole depths at which said real-time measurements were derived.

8. The system of claim 7 wherein said converging means further includes means for initiating said correlative recording in real-time of said first and second measurements only when the borehole depths at which first portions of each of said first and second measurements were derived are substan-tially equal.

9. Apparatus for investigating lithological characteristics of subsurface earth materials traversed by a borehole, comprising: first conversion means for deriving a first digital measurement in real-time of a selected character-istic 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 real-time basis and in functional correlation with borehole depth.

10. Apparatus described in claim 9, including:
sampling means for activating said 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.

11. 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 charac-teristic 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 real-time said compatible representation and at least one of said digital representations derived on the basis of real-time.

12. The method described in claim 11, further including combining said compatible representation and said at least one of said real-time digital representations in functional response to said command signal.

13. The method described in claim 12, further including recording said combination of said compatible representation and said at least one of said real-time digital representations in correlation with said command signal.

14. The method described in claim 13, further including visually displaying said combination of said com-patible representations and said at least one of said real-time digital representations on the basis of real-time.

15. The system of claim 11, further including comparing the borehole depths at which a portion of said compatible and said digital representations were derived, and recording portions of only one of said compatible and said digital representations prior to said combining said compatible and said digital representations when said depths are unequal.

16. 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 real-time 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 correlation with said visual representation of said first digital measurement.

17. The method described in claim 16, further comprising correlatively recording said first and second digital measurements as a function of borehole depth.

18. The method described in claim 17 wherein the step of correlative recording further comprises recording said first and second digital measurements in real-time.

19. The method of claim 18 wherein the step of deriving said first digital measurement further comprises generating a first measurement of a selected characteristic of said materials in real-time.

20. The method of claim 19 wherein said first and second digital measurements are derived as a function of a plurality of identical preselected depths within said borehole.