NL7907404A - METHOD AND APPARATUS FOR PUTLOGGING CORRELATION. - Google Patents

Description

DRESSER INDUSTRIES, INC., Dallas, Texas, United States of America.

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Method and apparatus for well logging correlation.

The invention relates to methods and apparatus for providing a number of functionally integrated underground logging measurements. The invention particularly relates to techniques for providing a number of logging measurements, each of which is integrated based on well depth.

When searching for underground oil and gas-containing earth formations, it is often necessary to investigate or "log" the formations by passing a logging probe through a wellbore, which probe measures various parameters at different depths in the wellbore. This information is then processed, analyzed and compared with similar data produced at grain depths in accordance with known functional ratios to determine whether the formation is of commercial interest.

A serious problem with this data comparison is that often only a comparison or "matching" of data points produced at the same well depth or time, or produced at a preselected granular different depth or time, will give meaningful results, However, because measurements are often taken over two or more runs through the well, it is often difficult to ensure that measurements of each run selected for comparison were made at the same relative depths or times.

One reason for this is that depth indications, where measurements are made, histories are unreliable since they depend on several factors, which include differences in well structures, well fluids and logging cables to name just a few.

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In addition, the conventional depth measurement method for measuring the movement of the logging cable across a measuring wheel introduces further variations in recorded depth measurements. For example, dimensional variations of the measuring wheel due to temperature and wear, as well as vibrations of the measuring wheel due to a varying cable tension contribute to variations in the depth measurement. Furthermore, slippage of the logging cable across the gauge wheel and strain in the logging cable due to temperature and humidity effects, the weight of the cable and logging tool, and stress due to well constrictions further aggravate the problem of obtaining accurate depth indications.

When a parameter or logging curve produced during a logging operation is to be compared with an identical parameter previously measured within the same wellbore, difficulties arise due to the above-mentioned problems, which match data points obtained at the same depths extremely difficult. However, the correlation of data points becomes more difficult when the identical parameters are not compared, due to the dissimilarity of the logging curve appearances and values. Furthermore, it is sometimes necessary to compare measurements produced at granular depths within different wells, and even when the measurements relate to identical parameters, this comparison is often again made extremely difficult. Even though measurements can be obtained as a function of depth as a result of a depth dependent command signal sent into the well as described in U.S. patent application no. 749,592, the above factors may still contribute to apparent discrepancies in depth where measurements of two or more logs are made.

Several techniques have been used in the past to granulate two or more sets of well logging data points. One technique involves the juxtaposed visual comparison of conventional film-recorded logging-35 records of two or more parameters, where logging curve can be slid onto 790 7 4 04 * * + "" 3 a film relative to the curves on the other film, and granular measurements are then read and recorded from the film, this attempted solution has numerous drawbacks, such as the inability to perform this granulation in real time when log to be granulated is produced, the need for conventional film logging and the fact that the final product of this granulation is not a form suitable for further conventional processing.

In other attempts to solve the problem of providing correlated logging measurements, it has been storing each set of logging data by an appropriate device, such as digital tape recordings, and then selectively reading associated data pairs obtained at similar depths for further operation. An apparent problem associated with this method 15 is that, as with the use of graphic light tables, all data to be granulated is first produced and recorded. Thus, the possibility of real-time processing of correlated data as it is produced and the real-time registration of this correlated data is excluded.

Yet another problem with this approach is that often no sample from the second set of data is available, which was obtained at the same well depth as the sample from the first data set. Thus, it may be necessary to interpolate between data points of the second set to estimate a sample value, which will grain with a sample of the first set with respect to the depth at which they are obtained.

Thus, it will be appreciated that it is desirable to provide a method and apparatus by which logging parameters of interest can be measured at granular well depths 30 during successive passes of the probe through the same wells or different wells for their usefulness for data accuracy and increase reliability controls, for combining these measurements obtained at granular well depths to determine functional ratios and the like. It will therefore be highly desirable to adjust the depth where future logging 790 74 04. ·· *

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4 t measurements are produced or sampled as a result of a visual or automatic analysis of the samples now produced, either alone or in comparison to other histories. In addition, it will be desirable to sample or select samples obtained on a depth basis for a granular fit to depth with samples from other data sets by visual or automatic comparison of other sample points from each set of data. These and other features are provided by the present invention, which also solves the above-mentioned serious problems associated with the prior art, and provides new techniques and apparatus for granulating two or more sets of logging data in a manner to be described below.

In a preferred embodiment of the invention, measurements of at least one well logging parameter are produced at pre-selected heights within the wellbore and recorded as a function of depth. A probe is used to make these measurements, where the probe will produce the measurements and send them to the surface as a result of a depth dependent command signal sent to the probe. A graphical visual representation of the measurements is then made by playing the recorded samples in sequence in spatial relation to the depth indications; where they were done in the order in which they were produced. A subsequent logging operation is started simultaneously with the visual image, which also produces logging measurements as a function of the depth command and at the same or granularly preselected heights within the wellbore as measured in accordance with the probe measuring depth. Each logging measurement is then displayed granularly as it is produced, with the granular measurement of the previous logging data set 30 produced in accordance with the probe depth measuring device at the identical or granular well depth and in spatial relationship thereto. Several measurements of both data sets produced over a wellbore increment are compared, and any discrepancies between apparent depths where samples from each imaged 790 74 04 * * - * S 'data set were obtained are noted.

For example, the spontaneous potential or natural gamma ray log parameters are measured and recorded during the movement of the probe through wellbore, along with other parameters that may be of interest. All parameters are produced or sampled as a function of identical or related pre-selected depth intervals. During a subsequent pass through the same or different well, the same spontaneous potential or gamma ray log is preferably produced or sampled, as are other parameters, which may include all or part of the pre-measured parameters or yet another set of parameters. All measurements are again preferably performed at depths that are granular with those of the first pass. When the next pass measurements are thus performed, the parameter measurement common to both passes is preferably graphically offset side by side, with those of the previous or "historical" log being selectively and sequentially read and displayed from the record in the order in which they. were produced. All measurements are preferably tilted in a rolling manner, as shown and described in U.S. Patent Application Serial No. 030,058, filed April 13, 1979 in the United States of America, the vertical axis corresponding to the wellbore depth and the horizontal axis corresponding to the value of the parameter.

By comparing similar distinctive curve perturbations or shapes in size between parts of the two logs, which preferably include the past produced as well as the newly produced logs, discrepancies or depth shifts can be detected, allowing measurements between the two courses at different depths seem to have been done. As a result of this comparison and in functional relationship to said discrepancies, the depth orders are adjusted to produce subsequently obtained true time samples of the probe at greater or smaller depth intervals, which will be more granular in depth with their historical counterparts. These 35 real-time samples subsequently obtained are thereafter also visually cut off, granular 790 74 04 * 6

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with historical data set samples obtained at a granular depth within the wellbore, as indicated by the depth indicating device, and again the depth discrepancies are noted, after which the depth command is further adjusted in accordance therewith. By the same parameter in subsequent probe runs .....

to granulate, all other parameters of each pass will be granulated, since they are also produced as a function of the adjusted depth command.

In a preferred embodiment of the present invention, the probe depth detection device comprises a pulse generator, which produces pulses as a function of the angular rotation of the pulley wheel over which the logging cable moves. A pulse counter is used, whereby after setting a preselected number of pulses (Y) produced by the pulse generator, a depth command is produced in order to have the probe measure another measurement.

The counter can be preset after each depth command production to subtract or add a preselected variable number (Y) of pulses from the incoming pulses, until the produced preselected number (Y) of pulses 20 is reached and the following input command is produced. In this way, the depth command will cause the production of the next sample in real time in a depth interval that is larger and smaller, respectively, than the previous interval by a factor of plus or minus X / Y. An apparatus is used to repeatedly produce this adjusted input command as a function of the difference in depth between the apparent depths where samples from the two data sets were produced, which can be seen visually by the above image, or automatically.

Thus, the depth shift will gradually adjust or become "smoothed", causing the device to resume measurements at the depth intervals correlated with the historical data as each (Y) pulse occurs.

Thus, a feature of the invention is to provide a number of functionally integrated underground logging measurements. Another feature of the invention is to provide 790 74 04 * 7 new methods and apparatus for producing or sampling real-time logging measurements at depths within the well, granular with depths where historical logging measurements were made.

Another feature of the invention is to provide methods and apparatus for selecting from historical logging data of samples produced at depths that are granular with that of another different set of historical logging data.

A further feature of the invention is to provide methods and apparatus for smoothly correcting depth errors that occur between logging data samples of at least two sets of samples over a pre-selected well depth increment.

A further feature of the invention is to significantly improve the obtaining of functional relationships between measurements of two or more logging parameter data sets obtained as a function of depth, including their accuracy and reliability.

Another particular feature of the invention is to provide a method and apparatus for examining the character of underground earth materials and the like traversed through a wellbore, comprising obtaining an electrical command signal as a function of depth in the well, obtaining a first electrical measurement of the earth materials as a result of the command signal, obtaining a second electrical measurement of the earth materials, and incrementally adjusting the command signal to record the first measurement signal in correlation with the second measuring signal and depth indication.

The invention is further elucidated in the following description with reference to the drawings.

Fig. 1 is a functional representation of an embodiment of the invention.

Fig. 2 is another functional representation of the embodiment of the invention of FIG. 1, showing a more detailed view of the master controller of FIG. 1 790 74 04 * 4 \ δ.

Pig. 3 is a more detailed functional representation of the depth logic of the embodiment of the present invention shown in FIG.

FIG. 4 is another functional representation of an alternative embodiment of the depth logic shown in FIG.

As noted, the invention is directed to an improved well logging system of the type described in U.S. Patent Application 949,592, and reference is made there for details of the system. Thus, description of this US application is considered to be incorporated herein by reference to an understanding of the improvement of the invention. Figure 1 of this description is the same as figure 2 of the mentioned application. Thus, the operation of the improved synthesis circuit of the invention and its environment are identical to those of the aforementioned application except as will be explained hereinafter.

Therefore, for a complete understanding of the overall digital well logging system operation and for the location and cooperation of the improved aggregation circuit described herein, reference is made to the aforementioned US application.

Fig. 1 shows a simplified functional diagram of one embodiment of the present invention, showing the logging probe 2, which may include a radioactivity logging section 2A, an induction logging section 2B, an acoustic logging section 2C, and a pulse code modulation section 2D, providing appropriate measurements of the lithology around an underground well (not shown). Measurements from these sections can be sent from the wellbore to the surface by a conventional logging cable 3, which will rotate a pulley 4 or the like to provide a correlative indication of the wellbore where these measurements are made. The pulley wheel 4 may also be coupled to an appropriate depth coding circuit 6 through a drive shaft 5 or the like, whereby the depth coding circuit 6 will provide a functional granular depth 35 signal 7 to the surface portion of the well 790 7 4 04 £ 9 plate system, together with the measurements provided by the logging cable 3.

As noted above, it is a feature of the well plate system functionally shown in Figure 1 to transmit fully correlated logging measurements to an appropriate base observation and control station, such as that described in U.S. Patent Application 949,592, which may in turn be located in a position remote from the well system location. Thus, as will be explained in detail below, the well plate system will appropriately encode and condition these measurements to provide granular indications to the remote base station at the time when these measurements are received from the logging cable 3 via an appropriate communication link 15, which conventional telephone line, radio communication satellite or the like.

Furthermore, the same signals can also be provided to the customer or user in his respective user station (not shown), which in turn may also be remote from both the well plate system and the user station (not shown). These indicia can also be sent to the user station by a similar communication link 16, which connects the well plate system to the user station, and then relayed to the base station by yet another communication link (not shown) or they can pass through the base station be relayed to the user station via this communication link.

It is noted that the well plate system suggested by Figure 1 can be operated directly by the base station, and therefore the communication link 15 may also include a facility for supplying appropriate control signals from the base station to the well plate system by means of the communication link 15. Similarly In a manner, the communication link may be used to cause control signals from the base station to be supplied to the user station, or in some cases to provide control signals from the user station to the well plate system or base station by means of the communication link 16.

Figure 1 shows a simplified functional diagram 790 74 04 «ί“ * 10 of the above-ground circuits, which comprise the device constituting the well plate system. As will be explained hereinafter, the sections of the logging probe 2 are preferably arranged to supply their respective measurements to the conductors making up the logging cable in such a way that all measurements are provided jointly to the surface. It is noted that information can also be transferred from the surface circuit to the wellbore. reasons, which will be explained below. For example, it may be desirable to control several transmitters and receivers in the acoustic logging section 2C from the surface. Thus, in Figure 2, it can be seen that at appropriate times and as a result of a command signal 44 from a pit site master controller 20, the transmitter ignition circuit 23 can produce transmitter ignition signals 23A to detect the various circuits in the acoustic logging section 2C 15 of the probe 2. arrange for. This ignition signal 23A can preferably be supplied to a conventional line control circuit 24, which supplies the signal 23A to the relevant conductor within the logging cable 3.

As indicated in Figure 1, when measuring signals 20 are received from the probe 2, the output of the logging cable 3 is preferably also supplied to a line control circuit 24, which in turn supplies the signals as its output 24A to an appropriate arrangement of signal conditioning circuits 25 for filtering, gain control, and other operations. The conditioned logging signals 26, which are supplied by the signal conditioning circuits 25, can then be supplied via an appropriate switching circuit 27 to a PMC buffer / receiver circuit 29, or to a binary amplifier 28, or in another alternative to a low speed / high speed A / D converter 31 and radioactivity pulse counters 30 by means of the 30 signals 27a, 27b or 27c, respectively.

It is known that the outputs of a conventional probe 2 will be in analog form, or in the case of radiological measurements will consist of pulses, which occur randomly. As will become apparent hereinafter, however, it is particularly desirable for the purpose of the present invention that these signals be supplied to the surface circuit in digital form 790 74 04 * 11. The probe 2 will therefore (Figure 1) "preferably contain a pulse code modulation or" PCM "circuit 20 for encoding these signals in digital form by supplying them to the PCM buffer / receiver 29. However, if the signals are not encoded in this way, they can be supplied to an A / D converter 31 or the like before they are processed and recorded. Also, pulses from the radiological measurements can be supplied to counters 30 and the like, which will then output their outputs in digital form.

The signals produced by the radioactivity section 2A of the probe 2 will appear as a series of electrical pulses indicating the occurrence of radiation from the wellbore materials of the probe 2, and they will be supplied to the pulse counters 30, which produce a digitized representation of this data as an output signal 30A. On the other hand, the output signals of the induction logging section 2B and the acoustic logging section 2C of the probe 2 will be conventionally supplied to the surface in the form of analog measurements, which are representative are for lithological properties of the wellbore material adjacent to the probe 2. These 20 outputs of the switching circuit 27, which form the signal 27c, will in turn be converted into digital representations of the searched data. These representations designated as output 31A will be passed through an appropriate conductor 32A and the like to an input of the logging signal recovery controller 32.

It is noted that the A / D converter 31 receives input signals 27c and 28a from both the switching circuit 27 and the binary amplifier 28. The reason for this is that in some cases the induction logging section 2B and the acoustic logging section 2C of the probe 2 signals have an amplitude sufficient to be directly supplied to the analog-to-digital converter 31. On the other hand, these signals often have such value or are attenuated by the logging cable 3 that they exceed the dynamic range of the converter 31 and are attenuated accordingly, respectively. must be amplified before they can be properly processed by the converter. Thus, the switching circuit 27 will respond to pass these signals to the binary amplifier 28 before the conversion of the analog signal to digital form in the converter 31 takes place.

The pit site master controller 20 may supply another command-5 signal 33 to the switching circuit 27 to route its output in the form of a digital signal 27a to the PCM buffer / receiver circuit 29, or in the form of an analog signal 27c, which is supplied to the converter 31 or to the pulse counters 30. When, as mentioned above, the signal 27c has an insufficient amplitude to be properly processed by the converter 31, or when the amplitude is too large for the dynamic range of the converter 31, the master controller 20 will produce a command signal 22 in accordance with the program to cause the switching circuit 27 to supply its output signal 27b (instead of the signal 27c) to the binary amplifier 28. It is noted that the binary amplifier 28 may be provided with an appropriate gain control signal 34 which serves to continuously adjust the gain of the binary amplifier 28 as a result of the command signal 33 supplied from the master controller 20 to the recovery controller 32. Since the input to the A / D converter 31 may be interrogated periodically by the master controller 20 in a manner to be described below, the master controller 20 may suitably adjust the gain of the binary amplifier 28 through the gain control signal 34 to ensure, that the input signal 28a remains within the dynamic range 25 of the analog-to-digital converter 31. Thus, the amplified signal 28a produced by the binary amplifier 28 is supplied to the converter 31 instead of the output signal 27c.

For illustrative purposes, it can be assumed in Figure 1 that the probe 2 consists of a number of sensor elements, such as the radioactivity logging section 2A, the induction logging section 2B, and the acoustic logging section 2C, and that all these sensors continuously and simultaneously provide meaningful data signals to the logging cable. 3. Preferably, the well plate system handles and sorts these signals in a way to distinguish them from each other, and uses these 35 signals in correlation with an appropriate indication of depth, where 790 74 04 ♦ * »* 13 these signals originated . Thus, the analog / digital converter 31, the pulse counters 30, and the PMC buffer / receiver circuit 29 will all include an appropriate buffer circuit, allowing these signals to be stored until the well site master controller 20 produces its command signal 33 to be selected components by the recovery controller 32. to question. After this interrogation indicated in Figure 1 by the interrogation signal 32c, the recovery controller 32 will control the relevant or selected component to transmit one of the outputs 29A, 30A or 31A to the recovery controller 32, which in turn provides this information. to the master controller 20 in the form of the output 32b. After receiving the output 32b, the master controller 20 directs this output to the primary storage facility 35, or to the secondary storage facility 36 through the input signals 37.

As mentioned, the measurements produced by the logging probe 2 must be correlated with an indication of the depth at which these measurements are made. Thus, when the master controller 20 produces its command signal 33, it must also produce an appropriate depth data / control signal 21 to causing the depth controller 20 to provide the information 20 it has previously taken from the output 11 of the depth logic 10. Thus, this data, which also goes to the controller 20 via the depth data / control signal 21, will be correlated with the logging data signals provided by the recovery controller 32 in the form of the output 32b. It is noted that in order for depth logic 10 to provide appropriate information to the depth controller 12, information from the depth encoding circuit 6 may be sent to the receiver 8 by the depth measurement signal 7, and from the receiver 8 to the depth logic 10 at the receiver output. 9.

In Figure 1, further visual imaging and recording devices can be seen, which preferably include an analog film camera 39, a visual imaging device 40, and an appropriate large-scale plotter 41 and small-scale plotter 42. Information to be displayed or recorded can be fed to these different imaging or recording devices from the master controller 20 through the logging data information signal 43. The information signal 790 74 04 * 14 information signal 43 can be fed to a movie camera controller 45, which will form the necessary interface between the master controller 20 and the digital / analog converter 46, and the signal then passes from the controller 45 to the converter 46 on the output line 45A. After converting the digital information on the line 45A by the converter 46 into analog information, this analog information can be passed through the output line 46A to the analog film recording device 39. It is noted that the recording device 39 is a recording device of may be the galvanometer type, which is known in the logging industry and which is particularly suitable for recording graphic data and the like associated with well logging operations.

Similarly, data from the master controller 20 on the information signal 43 can also preferably be fed to the continuous mapping controller 47, which can process these signals to produce output signals 47A, 47B and 47C, which are fed to the visual imaging device 40 The continuous mapping controller 47 may preferably process the information signal 43 to produce a visual image of desirable well logging information about a preselected wellbore depth interval traversed by the probe 2.

The information signal 43 may be fed to a plotter controller 48 to process the desired information signal 43 in a manner to be described below before it is supplied as an input 48A 25 to an appropriate plotter interface 49. The function of the interface 49 is to further these information signals 43 adaptable for delivery as output 49A to an editing circuit, such as a digital / analog converter 50, into which they are converted into an appropriate analog output 50A for recording on film in the large-scale plotter 41. Similarly, it may be desirable to have different information signals 43 associated with the well logging operation to be displayed on a smaller scale than that used in the large-scale plotter recorder 41. The information signals 43 can be introduced into the plotter controller 35 51, which processes these signals and transfers them as output 51A to the 790 7 4 04 15 ν 15 plotter interface 52, which after diff A signal processing will feed these signals as output 52A to an appropriate circuit, such as a digital / analog converter 53, in which they are converted into an appropriate analog output 53A to the smallest-scale plotter 42, 5. It is noted that the information signals 43, which are supplied to the analog film recording device 39, large and small scale plotters 41 and 42, respectively, as well as those supplied to the visual display device 40, are under the control of the master controller 20. The controller 20 can provide the information signals 43 such that the mapping and recording of the well logging information takes place in various formats and from various sources. For example, the sources may include the primary storage 35 and the secondary storage 36, which may transfer information stored therein to the master controller 20 as storage output 38 and as a result of the input signal 37.

It will be appreciated that for testing for the operation of the well logging system described herein, or for personnel training or the like, it may be desirable to simulate the various signals associated with probe 2 without the need for the normally present sections of the well logging circuit. and without the need to expose probe 2 to a trip through a well. Therefore, in Figure 1, a signal simulator 45 is shown, which can produce several test signals 56 as mentioned above due to simulator command signals 55A, which may include, for example, signals similar to those expected on the logging cable 3 from the probe 2 It is further noted that these test signals 56 can be supplied to the line control circuit 24, thus simulating similar signals on the logging cable 3, which can also be supplied to the input of the line control circuit 24. Although the present invention has focused on automatically performing various well logging tasks under the control of the master controller 20, it is noted that it is often desirable to make arrangements for human intervention in the integrated well logging system of the invention. For example, it may be desirable for a logging engineer to skip several functions performed by the master controller 20, or to adjust the format or scaling of information provided to the various peripheral imaging devices, or directly to the base station or communicate the user-5 station. It may further be desirable for the master-controller 20 to have the ability to supply information to a human operator. A well plate teleprinter 57 can be used for such communication between the master controller 20 and a human operator, the teleprinter having an interrogation / response channel 10 58 for interrogating or instructing the controller 20 in a conventional manner, and also for receiving it therefrom. appropriate information.

A feature of the invention is also to provide observation and control of well location logging operations from a remote base station or user station. In Fig. 1, a communication modulator demudulator or "modem" 59 can be seen, which can send the information signal 43 to the base station and user station via communication links 15 and 16 respectively, under the control of a data / control signal 60 from the controller 20. It is further noted that the modem 59 can receive information and control signals from the base station and user station on the communication links 15 and 16, respectively, which further communicate with the controller 20 as indicated by the data / control signals 60.

Figure 2 is a general functional representation of the manner in which the data merging according to the present invention takes place in a preferred embodiment. A primary storage means 35 such as a conventional tape recorder can be used to store electrical data signals consisting of digital representations of well logging measurements produced granularly with a range of preselected depths within a wellbore. Any desired number of these representations may be extracted from the primary storage device 35 as a result of an input signal 37 from a synthesis controller circuit 63, to supply these representations from the primary storage device 35 on a primary storage output 38 to an appropriate synthesis memory 1.66 , or a merge memory 790 7 404 17 gene. 2.67, on their respective aggregation memory inputs 38b or 38c.

The merge memories 66 and 67 preferably each provide a memory output 78 which is supplied to the merge circuit 63 to instruct the merge circuit 63 as to the time at which all logging measurements have been removed from a given merge memory 66 or 67, in which case the particular merge memory will be available to receive further representations from the primary storage device 38 in a manner described above.

It is noted that the merge memory 66 and 67 may further be provided for granular merge controller outputs 75 and 74. As a result of each controller output 75 and 74 of the merge controller 63, the respective merge memories 66 and 67 will successively be on their respective memory outputs 80 and 81 provide digital representations of logging measurements produced at successive depths to an appropriate aggregation storage device 62. Logging measurements in the primary storage device 38 are preferably stored therein in the order in which they were produced at successively deeper or shallower preselected depth-20 intervals. . The order of these measurements will preferably be maintained in all transfers through the memories 66 and 67, the merge storage 62, the memories 64 and 75, and ultimately the secondary storage 36, as well as any real-time or historical measurements transferred through the input memory 61, the storage device 62, the merging memories 64 and 65, and to the secondary storage device 36.

It is noted that due to the memory output 78 from the memories 66 and 67, the merge controller 63 may generate a controller output 74 or 75 so as to produce memory outputs 80 and 81 only by one merge memory 66 or 67, while the other merge memory produces a receive the next number of digital representations on the aggregation memory input 38b or 38c from the primary storage device 35. This technique can be recognized as "double buffering", a well known technique in which measurements are selectively extracted or stored in one memory, while 790 74 04 * »18 a second memory is filled with data blocks or" reads out "to input or output devices. So when all data is taken from the first memory in sequence, data will then be taken from the second filled memory in sequence, while the data is 5 first memory is then again filled with data blocks.

The well location controller 20 (Figure 2) will further preferably include an input memory 61 for storing digital representations of well logging measurements produced by the probe 2.

It is recalled that the recovery controller 32 can supply any representation produced on a depth-dependent basis on the controller output 32b to the well location controller 20, or (Figure 2) to the input memory 61. Furthermore, remembered that a depth adjuster 12 will preferably be used to produce a series of pulses due to a rotation of the pulley wheel, which rotation is in turn correlative with the movement of the probe 2 within the wellbore, indicative of and related to different selected depths along a portion of the well. These pulses can be supplied as a depth / data control signal 21 to the aggregation controller 63 of the well location controller 20.

Since each pulse is applied to the control signal 21, a measurement produced as a result of it at a granular depth will not correspondingly be present in the input memory 61. The aggregation controller 63 will produce a controller output 69 as a result of the control signal, thereby transferring the now sample stored in the input memory 25 61 is caused to the synthesis storage device 62 on the memory output 68. The synthesis controller 63 is preferably provided with controller outputs 74 and 75 for controlling the granular synthesis memory 67 or 66 to produce a granular data sample which is produced at a given depth, from the respective aggregation memory 67 or. 66 to the merge storage device 62. Each controller output 74 and 75 will be produced by the merge controller 63 in functional response to the reception by the merge controller 63 of a pulse of the control signal 21, which is granular by a certain depth at which a the probe 2 produced measurement stored in the input memory 790 7 4 04 19 61r was produced. As a result of this pulse on the control signal 21, a subsequent data sample from the input memory 61 and a subsequent data sample from the merging memory 66 or 67 will be transferred to and stored in the merging storage device 62, and each pair of subsequent samples will be produced at granular depths .

Figure 2 also shows a pooling memory 64 and a pooling memory 65, each of which has granular storage outputs 72 and 71. A merge controller output 70, 10 produced by the merge controller 63 as a result of a pulse of the control signal 21 can be supplied to the storage memory 62. The purpose of this controller output 70 is the merge storage device 62 as a result of the data sample stored in the merge storage device 62 on the provide storage output 71 or 72 to their granular aggregation memories 65 or 64 in a manner to be described below. In the same manner as the merging memories 66 and 67, in Fig. 2 a memory output 79 is provided, which is supplied by the merging memories 64 and 75 to the merging controller 63. Also, merging controller-20 outputs 76 and 77 supplied by the merging controller 63 are shown. to the granular merge memories 65 and 64, which controller outputs are correlative to those of the controller outputs 74 and 75 for the merge memories 67 and 66. Thus, the merge memories 64 and 65 are preferably arranged in a "double-buffering" mode, similar to that of the merge memories 66 and 67. Information on the memory output 79 may instruct the merge controller 63 as to the relative status of the merge memories 64 and 65. Thus, the merge controller 63 will detect when a particular merge memory 64 or 65 is filled with a full " data block ", such as the samples produced over a depth-in crement of 10 feet. When this happens, a merge controller output 76 or 77 will command the determined memory 65 or 64 to deliver its respective stored contents of the merge memory 37d or 37c to the above-mentioned secondary storage 36 by the input signal 37, or 790 74 04 20 to an appropriate continuous mapping control 47 by means of the log data information signal 43. While data samples are thus "read out" from a particular merge memory, the merge controller 63 through the merge controller output 70 is able to command the merge storage device 62 to start with filling the remaining memory of the merge memories 64 or 65 by supplying successive paired data samples stored in the merge storage device 62 through the merge surface member 62 to the determined merge memory 64 or 65 by selecting the regarding storage output 71 or 72, w on which these data samples will be delivered.

Fig. 3 shows a simplified and more detailed functional diagram of an embodiment of the depth logic 10 of Fig. 1. In a typical well logging operation, it is often desirable to obtain information at a given time or at pre-selected depth intervals that relates to the depth of the probe 2 in the wellbore, as well as the speed and direction in which the probe 2 moves within the wellbore. Since the system produces logging measurement on a depth-dependent basis, it is desirable to produce appropriate depth measurement signals to communicate to master controller 20 when probe 2 is at pre-selected depth in the wellbore. In order to accurately perform above this logging depth, speed and direction measurements within reasonable limits, it may be necessary to correct inherent inaccuracies known in the logging technique. These inaccuracies arise, for example, from dimensional variations of the pulley wheel 4, elongation and slippage of the logging cable 3, and vibrations of the pulley wheel 4, which are known as "yo-yo" and which result from varying stresses in the logging cable 3. The purpose of the depth 30 logic 10 is thus to provide information necessary in the logging operation regarding logging speed, depth, direction and the like, as well as supplying the master controller 20 with the appropriate depth dependent command signals at pre-selected depth intervals. instruct master controller 20 when various components of the system are to be interrogated through the recovery 790 74 04 21 recovery controller 32. Another purpose of the depth logic 10 is to compensate this information for accuracies, such as the inaccuracies described above and to be pre-selected provide adjustments of this information to allow the aggregation of two e or more sets of logging data measured, for example, at different times, and to correct depth shifts as described above.

In Figure 1 it can be seen that a depth encoder 6 is used to produce a series of depth pulses which are functionally related to the angular movement of the drive shaft 5 and the pulley wheel 4. Note that these depth pulses may also be related to the movement of the probe 2 within the wellbore due to the fact that this movement rotates the pulley 4. After the encoder 6 has produced these depth-related pulses 15, they are fed as a signal 7 to a receiver 8. This receiver 8 supplies the necessary signal conditioning before these depth pulses on the output 9 are fed to the depth logic 10 of Figure 1. .

In Figure 1, it can be seen that the depth logic 10 will process the pulse information related to the depth of the probe 2 and is present at the receiver output 9, and will process input data from other sources in a manner to be described below, in order to the depth controller 12 on the output 11 provide all depth and logging speed information necessary for proper operation of the well plate system.

For illustrative purposes, it is believed that no corrections to the depth pulse output 9 of the receiver 8 are necessary, and therefore each pulse accurately relates to a preselected incremental movement of the probe 2 within the wellbore. Thus, the pulseoutput well 9 will pass through the adder subtractor 199 on the pulse 190e to the adder 103 through the output 199b. From the adder 203, the pulses, which originated from the pulse output 190b, will be output on the output 203a to a conventional multiplexer 205, and from the multiplexer 205 to a depth counter 240 through the output 205a.

790 7 4 04 • ► 22

Assuming that the lagging operation has started in a generally downward direction at a height of 0 feet, it will be appreciated that if the depth counter accumulates or counts 240 pulses coming from the adder 203, the pulse count contains the depth of the probe 2 within the wellbore, because each pulse on the output 203a corresponds to a known movement of the pulley 4, which in turn corresponds to a known movement of the logging cable 3 and thus a known movement of the probe 2. This accumulated count of depth pulses in the counter 240, output 240a can be supplied to a conventional visual image 80, which is used, for example, for monitoring the depth of the probe 2. In figure 3 it can be seen that the depth information contained in the counter 240 is also shown on the output 11 can be supplied to the controller 20 via the depth controller 12 as a result of inter-15 interrogation signals from the controller 20, which may be sent to the controller 12 g Be supplied on the data / control signal 21. It should be noted that it may be desirable to preset the depth indication in the depth counter 20 to a preselected depth level. This may be useful, for example, when a certain logging operation has begun at a preselected depth within the wellbore, and the historical data obtained in advance is known that the current depth indication in Figure 80 does not correlate with depth. indications of this historical data. A suitable bias logic 206 may be used for this which will produce a bias logic output 206a from a master bias signal 20a through output 12 on output 11, or as a result of a manual bias signal 217a from a manual bias circuit 217b. , which will preset the depth counter 240 and the corresponding image 80 to the desired preselected depth. Since an up or down lying operation 30 can take place in the wellbore, provision must be made for instructing depth adjuster 12 with respect to the direction of movement of probe 2 within the wellbore. It is necessary to have the depth counter 240 detect whether the pulses are to be counted and accumulated, which are received at the multiplexer output 205a corresponding to 790 7 4 04 23 with the movement of the probe 2 downward within the wellbore, or to decrement an existing count in the depth counter 240 due to the depth pulses at the multiplexer output 205a corresponding to the movement of the probe 2 in an upward direction. Thus, in Figure 3, it can be seen that a direction flip-flop 191 is used to detect the phase information of the direction of movement of the probe 2 contained in the pulse output 190b. The direction information will be fed on the flip-flop output 191a through the multiplexer 205 to the depth counter 240 on the multiplexer output 205a, thus instructing the depth counter 240 whether to add the pulse output information received on the multiplexer output 205a or subtract.

In addition to the information about the depth where logging data has been produced, in logging operations it is often necessary to obtain an appropriate indication of the rate at which the logging operation is being performed, or the rate at which the probe 2 is moving within the wellbore. The depth pulse output information present on the multiplexer output 205a can be supplied to an appropriate log rate counter 81, which will count the arrival rate of these pulses per unit time, and then on output 81a the resulting log rate for observation in Figure 82. It is also recalled that it is a feature of the invention to perform lithological measurements and the like as a result of a control signal, which may be functionally related to the depth of the probe 2, and thus it is necessary to produce a control signal at pre-selected depth intervals. In Figure 3, it can be seen that a depth interrupt generator 219 is used to receive the depth pulses present on the multiplexer output 205a. This depth interrupt generator generator 219 will produce an output 21'9a as a result of receiving a preselected number of depth pulses at the multiplexer output 205a. This control signal output 219a is fed at the output 11 to the depth controller 12, and can then be fed to the master controller 20 and the probe 2 for purposes to be described below.

It is noted that the control signal output 219a of the depth interrupt generator 790 74 04 24 generator 219 can be set to produce a control signal output 219a at preselected depth intervals. This can be achieved, for example, by causing the depth controller 12 to produce a depth / data control signal 21 as a result of instructions from the master controller 20 ', also on the signal 21. It is further noted that due to interrogation commands from the master controller 20, supplied to the depth controller 12 on the depth / data control signal 21, the depth controller 12 can interrogate and receive appropriate information on the output 11 of the log rate counters 81, the depth 10 counter 240, and the depth interrupt generator 219.

For further illustration purposes, it is now believed that it is desirable to change the number of depth pulses on the pulse line 190e before they are supplied on the multiplexer output 205a to the log rate counter 81, the depth counter 240, and the depth interrupt generator 219. Assumed becomes desirable to add further pulses to or subtract existing pulses from the depth pulses present on the pulse line 190e in a continuous manner during the time these pulses are present at the receiver output 9. As mentioned, there are numerous reasons for making this feature desirable. For example, it may be known that the circumference of the pulley wheel 4 has been reduced by a predetermined value due to frictional wear against the logging cable 3, so that the functional relationship between the distance between depth pulses produced by the pulley wheel 4 on the receiver output 190a and the movement of the logging cable 3 over the pulley wheel 4 has changed and it is therefore desirable to compensate for this wear. It may also be desirable, for example, to subtract a preselected number of pulses from the depth pulses produced by the pulley wheel 4 to compensate for the fact that, due to stretching of the logging cable 3 while the probe 2 is being pulled out of the well, depth pulses produced by the pulley wheel 4, which corresponds to the movement of the logging cable 3 over the pulley wheel 4, do not correlate with the movement of the probe 2 within the wellbore. The depth logic 10 may thus comprise a continuous correction circuit 196, which will produce a number of 790 7 4 04 25 depth correction pulses on the output 195a for a predetermined number of depth pulses produced by the pulley 4 which are present at the receiver output 9. For example, when one pulse at the receiver output 9 corresponds to a movement from a foot of the probe 2, it may be desirable to subtract a pulse from every thousand pulses produced, corresponding to a 1 foot cable rack per one thousand feet logging cable 3.

It is further noted that these correction pulses 196a 10 will be supplied to a conventional pulse for a circuit 200 and then be output on the output 200a to an adder subtractor 199. Logic control 198 may also be provided, which due to a correction switch 193 will produce logic control output 198a, which in turn will cause the adder subtractor 199 to not correct the depth pulses present on the pulse line 190e, or the adder subtractor 199 to add or subtract correction pulses from the pulse shaper output 200a to or from the depth pulses on the pulse line 190e. After the appropriate addition or subtraction of pulses in the adder subtractor 199, the resulting depth pulse information, now corrected, will be sent on output 199b for any mapping on mappers 80 and 82, and the like, or fed on the adder subtractor output 199a to a yo-yo detector 202, which will be explained in detail below. It is noted that in order for the continuous correction circuit 196 to produce a preselected number of correction pulses relative to another preselected number of depth pulses produced by the pulley wheel 4, it is necessary to provide the circuit 196 with information related to the number of depth pulses produced and the number of desired correction pulses. Thus, in Figure 3, it can be seen that information regarding the number of desired correction pulses can be supplied to the continuous correction circuit 196 through an appropriate output 194a of a depth correction switch set to the desired number of correction pulses. Similarly, information about the number of depth pulses produced by the 790 7404 26 pulley wheel 4 is fed to the continuous correction circuit 196 at the input 196b. It is noted that the instant yo-yo correction circuit 195, such as the continuous correction circuit 196, produces correction pulses that are added to or subtracted from the depth pulse information on the pulse line 190e in a manner to be described below in order to avoid the yo-yo phenomenon. correct as mentioned above. It is also noted that these correction pulses produced by correction circuits 195 and 196 should not interfere with each other because they will change the same pulse information present on pulse line 190e. Thus, the continuous correction circuit 196 obtains its necessary information relating to the production of depth pulses on the input 196b of the correction circuit 195 in order to avoid producing correction pulses at the same time. However, the correction circuit 196 still receives depth pulse information from the receiver output 9, in that this information is fed on the instantaneous correction input 190d to the correction circuit 195 and then on the input 196b to the continuous correction circuit 196.

Instead of adjusting the output 11 for a continuous 20 and fixed amount of cable rack compensation, dimensional variations of the pulley 4 and the like as mentioned above, it may also be desirable to adjust the output 11 on an instant dynamic basis at any point during a logging operation to compensate, for example, the above-mentioned yo-yo phenomenon. Another example of the desirability of providing this instantaneous compensation may occur during the merging of two or more sets of logging data measured at different times, with an erroneous depth shift being observed in the graphical image of these two data sets. Referring first to the desirable feature whereby a preselected number of correction pulses can be added to or subtracted from another preselected number of depth pulses at any desired time due to a manually operated input, it can be seen in Figure 3 that the depth logic 10 may be provided of a correction switch 790 7 4 04 27 193, which has a number of manually operated depth deductions and depth addition settings. As a functional response to these settings, correction switch 193 will produce one output 193a, causing instant yo-yo correction circuit 195 to produce a granularly pre-selected 5 number of correction pulses on output 195b for each pre-selected number of depth pulses received by correction circuit 195 on the correction input 190d. It can be seen that the correction circuit 195 includes a reset counter 197.

The purpose of the counter 197 is to count the number of correction pulses produced by the correction circuit 195, which are fed on the output 195b to the reset counter 197. When the preselected number of the correction pulses are produced, the reset counter 197 will output 197b, whereby the correction switch 193 will respond again to its addition or subtraction setting when further depth correction pulses are desired. Using the previous example, during a logging operation from a graphical image of logging data received, it can be determined that depth indication of the data is erroneous and thus shifted 5 feet from its proper height. It may therefore be desirable to divide this correction of 5 feet over an increment of 1QQ0 fiet future logging data to be received, and it will therefore be desirable to produce five additional depth correction pulses which are added to the next 1000 depth pulses produced by the pulley 4. . Thus, due to a depth addition input setting of the correction switch 193 and the correlative correction switch output 193a, the instant yo-yo correction circuit 195 will begin monitoring the depth pulses at the correction circuit input 190d, and a depth correction pulse at its output 195b and 195a will for every 200 depth pulses, 30 are received on the correction circuit input 190d. When five depth correction pulses have been produced and counted by the reset counter 197, the output 197b will again release the correction switch 193, thus indicating that the 5 foot depth shift has been corrected and the depth correction circuit is available for 35 further corrections. It can be seen that the depth correction pulses present on output 195b are supplied to a pulse former circuit 200 and then fed as output 200a to adder subtractor 199. It is further noted that depth add and subtract settings also provide an information signal (not shown) to the logic controller 198, so that the logic controller output 198a will instruct the adder subtractor 199 to add or subtract the pulses present on the pulse shaper output 200a due to whether a depth addition or depth subtraction setting was present on the switch 193. It is also noted that the depth logic 10 may be arranged such that when a down logging operation takes place in the wellbore, the depth pulses produced are accumulated while when a logging operation in upward from a preselected depth, the depth pulses produced will be subtracted from one preselected number.

Thus, it will be appreciated that the adder subtractor 199 must receive one indication of the direction of movement of the probe 2, indicating that depth correction pulses produced by the correction circuit 195-196 present at the pulse shaper output 200a must be added to or subtracted. of the depth pulses present on the pulse line 190e 20. The logic controller 198 is thus provided with a direct input 205c which receives information from the direction flip-flop 191 on the flip-flop output 191a, indicating the direction of movement of the probe 2. Logic controller 198, as a result of this information, will produce the appropriate output 198a, which instructs adder-subtractor 199 to add or subtract the pulse present on the pulse shaper output 200a from the depth pulses on the pulse line 190e.

Referring now to the correction of depth pulses for the yo-yo phenomenon described above, it will first be noted for illustrative purposes that an oscillation type that can be moved in a logging operation is one in which as the probe 2 is pulled up from the wellbore. there. moments where the probe 2 will change direction and move in a downward direction over a short depth interval before resuming its upward movement. Since the depth encoder 6 receives pulses 790 7 4 04 29 from the pulley wheel 4 which are functionally related to the movement of the probe 2 independent of the direction of its movement, it is noted that it may be desirable to provide a circuit for detecting the point where the probe 52 has changed direction to avoid incorrectly adding depth pulses produced during the movement of the probe 2 in the undesired direction.

In addition, it will further be desirable to provide a circuit for resuming the correct incrementing or decrementing 10 of the depth counter 240, depending on the desired general direction of movement of the probe 2, after the probe 2 resumes its movement in the desired direction exactly to the point where it started moving in the undesired direction. Thus, the depth logic 10 includes a direction change detector 201, which, due to the flip-flop output 191a of the direction flip-flop 191, which is fed to the input 205b of the direction change detector 201, will produce a detector output 201a, which is fed to the yo-yo detector 202. The yo-yo detector 202 may produce an output 202b due to an indication on the detector output 201a that the direction of movement of the probe 2 has changed. This yo-yo detector output 202b will then cause the adder 203 to prevent depth pulses on the adder subtractor output 199b or pulse shaper output 204a from the pulse shaper 204 from being forwarded for counting in the depth counter 240.

It is noted that there are cases where it is not desirable for detector 202 to prevent the passage of depth pulses through adder 203 due to detector output 201a. For example, probe 2 may be intentionally steered in an opposite direction to remeasure a portion of the wellbore. It is further noted that a predetermined minimum time interval may be required during each probe 2 pauses at a depth interval before effecting an intended direction reversal. Thus, the yo-yo detector 202 may be provided with an appropriate circuit to prevent its activation due to a directional change output 201a unless, in addition to the presence of such an output 201a, the probe 2 during has paused a preselected time interval before continuing in the reverse direction. The yo-yo detector 202 may further include an up-counter, which will begin to increment adding incremental depth pulses present on yo-yo detector input 5 199a when a change in direction present on detector output 201a is received. When the probe 2 changes direction again and starts moving in the desired direction, the detector output 201a will reflect this change of direction and thus cause the 10 up-count of the yo-yo detector 202 to start counting down from the last number, accumulated as a result of depth pulses present on the yo-yo detector input 199a. When the up-countdown of the yo-yo detector 202 has reached zero, this means that the probe 2 is now at the point where it is moving from direction 15. changed and started moving in the undesired direction. Thus, when the up-countdown of the yo-yo detector 202 reaches zero, an output 202b will be produced which activates the adder 203 so that the adder 203 begins to pass depth pulses on its output 203a to the depth counter 240 To increment or decrement as described above. In summary, it will thus be appreciated that the direction change detector 201 and the yo-yo detector 202 provide the function of determining when the probe 2 has started oscillating in an undesired direction. The detectors 201-202 provide the further function of allowing depth pulses to pass for counting when the probe 2 has returned to the point where it started moving in the undesired direction and now resumes moving in the desired direction. has. Thus, it will be appreciated that the yo-yo detector 202 is generally intended to filter out depth pulses 30 produced while probe 2 oscillates from a detected point within the wellbore.

The yo-yo detector 202 may now be designed so that when the deflection of the probe 2 after a change of direction exceeds a predetermined distance corresponding to exceeding the up-count of yo-yo detector 202 of a preselected number, 790 7 404 31 the detector 202 will be reset to zero and the adder 203 will still operate, causing depth pulses to continue to depth counter 240. In such a case, it may further be desirable to produce depth correction pulses to replace the depth 5 pulses, which are not counter 203 was allowed to go while the on-off counter of the yo-yo detector 202 was counting. Thus, the yo-yo detector 202 may be provided with a yo-yo detector output 202a, which will activate the correction switch 193 in the same manner as the activation caused by the depth add subtract input settings of the switch 10 193. The correction switch output 193a of the correction switch 193a of the correction switch 193, produced as a result of the yo-yo detector output 202a, will activate the instantaneous yo-yo correction circuit 195, which in turn will produce the appropriate depth correction pulses in a manner equal to the production of depth correction pulses caused by the settings of the switch 193. These depth correction pulses appearing on the correction circuit output 195a will then be supplied to a conventional pulse shaper circuit 204, the output 204a of which will cause the adder 20 203 to depth correction pulses produced add to the depth pulses at the adder output 199b.

Figure 4 shows an embodiment of the present invention, which is a more detailed functional representation of the method of the invention when it is in an "auto-correlation" mode to be described below. For illustrative purposes, it will be assumed that the downward logging operation has begun, where as the probe 2 comes deeper into the wellbore, measurements will be produced by the probe 2 at depth intervals functionally related to the control signal from the depth adjuster 12. It is recalled that the depth encoder 6 preferably produces a depth measurement signal 7 in the form of pulses, each pulse corresponding to a preselected angular displacement of the pulley wheel 4. Assuming that each displacement corresponds to a grain length of motion 35 of the logging cable 3 across the wheel 4, and that this movement in its turn corresponds to a granular movement of the probe 2, it will be clear that the signal 7 from the depth encoder 6 can be used to detect depth of probe 2 within the wellbore. In addition, it can be seen that the depth information carried by the signal 7 5 can be further used to produce control signals 21 functionally related thereto, which when supplied to the probe 2 result in the probe 2 taking measurements at a preselected depth interval. However, it is further recalled that due to the known phenomenon, such as stretching of the logging cable 3 or slipping of the logging cable 3 over the pulley 4 and the like, the depth pulses produced by the encoder 6 do not have to correspond exactly with the movement of the probe 2 within the wellbore.

Moreover, even if they do correspond, it may be desirable to vary these depth pulses at encoder 6 in a preselected manner to correspondingly vary the command signals 21 produced as a result. It is noted that this in turn allows variable control over the depth increments where the measurements of the probe 2 are performed. One reason for this may be the regulation of the depth, where future measurements must be made by the probe 2, in order to correspond to the depth where the historical measurements are made.

It should be noted that these historical measurements may have been made on varying depth increments due to the above-mentioned cable stretching phenomenon and the like. Therefore, it would be highly desirable to ensure that each real-time measurement was produced at a depth that is granular with its historical counterpart, to allow verification of accuracy and integrity of data obtained later, and to combination of these two data sets in functional relationships and the like.

Probe 2 is believed to move in a downward direction and produce measurements due to the control signal 21.

It is also believed that these measurements are visualized on 790 7 4 04 33 cathode ray tube 40, along with the depth indications where they were produced, in the manner described in U.S. patent application serial no. 949,592, filed October 10, 1978 in the United States of America. In addition, it is believed that in addition to each measurement, a granular historical measurement of, for example, an identical logging parameter, such as the spontaneous potential measurement known in the logging art, which was assumed to have been produced at identical depth and in identical depth increments, is taken off. For example, due to the graphical visual image on the cathode ray tube, an inspection of the image can determine that there is a depth "shift" between the two columns. Notably, from an identifiably similar appearing disturbance in both curves, it can be seen that the disturbance does not occur in the same horizontal plane on the image, but instead, the real-time data of the disturbance for illustrative purposes appears to have been produced in a depth increment that half fet is shallower than the granular historical measurement. Thus, it will be desirable to adjust the depth increments where the later true time measurements are taken to align the two curves horizontally. Because the historical measurements appear to have been produced half a fet deeper within the well than any granular real time measurement, it will be appreciated that it is desirable to have the successive true time measurements produced in greater depth increments than before if the probe 2 continues its downward movement in the wellbore until it appears that the real time historical measurements at identically indicated depths in large grain, thus indicating that they were produced at identical depths.

In Fig. 4 it can be seen that a receiver output 9 has been produced, which preferably consists of a series pulses, each pulse corresponding to a preselected angular ratio of pulley wheel 4. In the present example, it is assumed for illustrative purposes that the circumference of the pulley wheel 4 is It has been chosen that the 256 pulses for each complete rotation thereof be produced 790 7 4 04 34, corresponding to the movement of a foot of the logging cable 3 over the pulley wheel 4. Moreover, it is assumed that after the occurrence of every 256th pulse , the depth logic 10 will produce an output 11 in order for the depth controller 12 to produce a control signal 21, which in turn will cause the probe 2 to produce a subsequent sample in real time. Thus, it will be appreciated that assuming a one-to-one correspondence between the movement of the logo shell 3 over the pulley wheel 4 and a granular vertical movement of the probe 2 downward in the well bore, the probe 2 will produce a measurement with each fetal movement. through the well. It is noted that by adding or subtracting five further pulses to or from each series of 2B6 pulses, which normally arrive at the receiver output 9, and using every 256th pulse after this correction to track another sample in real time through the probe 2 as a result of the command signal 21, the net effect will be that this sample is produced at a depth increment of 251 / 256th and 261 / 256th of a foot, respectively, deeper than the previous measurement. Thus, by adding or subtracting these correction pulses, depth shifts of plus or minus 5/256 or approximately plus or minus 1/50 part of a foot per foot can be corrected. In addition, when this correction was consistently introduced 25 times in succession for each incoming series of 256 pulses, a depth shift between the real time and historical curves of half a foot can thus be corrected over an interval of 25 feet.

In Figure 4, it can be seen that an uncorrected pulse train, where a pulse is produced with every 360 / 256th part of a degree rotation of the pulley wheel, can be delivered from the receiver output 9 on the pulse output 190a and 190b to a direction flip-flop 191. These pulses may also be supplied the pulse line 190e to a conventional adder / subtractor 199 and as a correction input 190d to the instantaneous correction circuit 195 for purposes described below. With regard to the pulse output 190a and 190b, it is noted that when the occurrence of a pulse corresponds only to an angular rotation of the pulley 790 7 4 04 35 wheel over a pre-selected value, regardless of its direction of movement, a device must be present for find out whether these pulses should be added to or subtracted from the pre-occurring pulses in functional relationship the direction of movement of the probe 2 rotates. For example, in the present illustration, it is assumed that the probe 2 has moved downward a distance of 100 / 256th of a foot in the wellbore, 100 pulses will be produced on the receiver output 9. Without a direction indication of the direction of movement of the probe 2 after the next reception of such a pulse 10, however, there will be no hasis to determine whether this pulse should be added to or subtracted from the existing 100 pulses. One method of accomplishing this is to provide the pulley wheel 4 with an encoding wheel, which produces two sets of pulses shifted by a known phase difference, which is granular with the points on the encoding wheel from where they were produced. By detecting the phase difference between such a pulse from one set of pulses supplied to pulse output 190a and the granular pulse from the other set produced on pulse output 190b, the direction of movement of probe 2 can be detected by the direction flip-flop 191. This direction information will be supplied at the flip-flop output 191a to the logic controller 198. The logic controller 198 in turn will produce a logic controller output 198a to add or subtract correction pulses at the pulse shaper output 200a from the pulses on the pulse line 190e, 25 supplied to the adder / subtractor 199 as a result of input to the logic controller 198, which are the flip-flop output 191a and the correction output 243. It is noted that a change in the signal from the flip-flop output 191a or the correction output 243 will cause the logic control output 198a to change so as to have the adder / subtractor 199 perform the scientific operation opposite to that performed prior to this change in the correction output 243 or the flip-flop output 191a. Here, it will be assumed that the probe 2 continues to move in a downward direction, with the flip-flop output 790 7 404 36 191a remaining constant and thus informing logic control 198 that the direction of movement of the probe 2 is downward.

As noted above, it has been determined that the half foot depth shift between the historical and real time logging curves is such that it is desirable to obtain subsequent real time measurements in greater depth increments within the wellbore. As mentioned, it is desirable to subtract five depth pulses from the pulse train of each 256 pulses supplied to receiver output 9. Thus, in Figure 4, it can be seen that this decision can be functionally represented as the "increase or decrease depth" decision 241, which may correspond to the manual switch setting 242 of a correction switch 193. Due to the switch setting 242, the correction switch 193 will provide correction output 243 to the logic controller 15 198. The logic controller is thus instructed by the occurrence of the flip-flop output 191a and the subtract decision present on the correction output 243 to produce a log controller output 198a, in order to receive correction pulses input from the adder / subtractor 199. subtract a pulse former output 200a from the incoming pulse-20 train on the pulse line 190e. When the decision is made to obtain future true time measurements at smaller increments within the wellbore, corresponding to the adjustment of the correction switch 193 as a result of its addition decision 241, the granular correction output 243 will assume that the probe 2 is still in a moves downward, causing the logic controller 198 to produce an output 198a to cause the adder / subtractor 199 to operate in the add mode. In this mode, pulses received at the pulse shaper output 200a will be added to the incoming pulse train of 256 pulses on the pulse line 30 190e. In Figure 4, it can be seen that a moment correction circuit 195 is used. It is noted that the correction circuit 195 is provided with a correction input 190d, which consists of the incoming pulse train of 256 pulses per foot movement of the logging cable over the pulley wheel 4. As a result of the correction output 193a, the correction circuit 195 will preferably count 790 7 4 04 37 pulses delivered on the correction input 190d. Each time the count reaches 256 and starts at 1 again, when a correction output 193a is received, the instantaneous correction circuit 195 will produce five correction pulses, which will be delivered on output 195a to a conventional pulse shaper 200, and then on the pulse shaper output 200a to the adder / subtractor 199. Depending on the setting of the adder / subtractor 199 due to the logic control output 198a, these five pulses will be added to or subtracted from the next incoming sequence of 256 pulses. on the pulse line 190e. Thus, the number of pulses that would normally occur as a result of a complete rotation of the pulley wheel 4 will be incremented or decremented by five, as they will now appear at the pulse output 245 due to the granular condition of the logic control output 198a. For example, in the present illustration where it was decided to obtain subsequent true time measurements over larger wellbore depth increments due to the visual image on the cathode ray tube 40, the adjustment of correction switch 193 accordingly results in logic control output 198a adding / subtracting 199 in the deduction mode. After activation of the correction switch 193, the instantaneous correction circuit 195, as a result of the correction output 193a, delivers five correction pulses at the pulse output 195a, via the pulse shaper 200 to the adder / subtractor 199 at the pulse output 200a. Due to the correction output 253, the adder / subtractor 199 is set in the subtract mode, these five pulses causing the removal of five pulses from the next incoming series of 256 pulses on the pulse line 190e. Thus, although 256 pulses have been received by the adder / subtractor 199 over a granular period of time, only 251 pulses are delivered to pulse output 245. Figure 4 shows a depth circuit 240 to which these pulses are preferably supplied to pulse output 245. The depth circuit will preferably hold a cumulative count of these pulses at the pulseout well 245. In addition, the depth circuit 240 will also preferably translate this cumulative count into a granular visual digital depth indication. This digital depth indication can be supplied on the depth log output 11 to the depth controller 12. It will now be clear that the operation of the invention 5 is variable adjustment of the number of pulses produced granularly by the angular rotation of the pulley wheel 4 in a preselected manner. which pulses are present on the receiver output 9 prior to adjustment. In this manner, the addition or subtraction decision 241 preselectably changes the number of 10 depth pulses on the receiver output 9 produced per known angular movement of the pulley 4. This adjusted pulses appearing on pulse output 245 can be accumulated by the depth circuit 240 to produce a signal that is correlative to the depth of the probe 2 adjusted or compensated by the addition or subtraction decision 241. In Figure 4 further shows a logging speed circuit 81a, the purpose of which is to count the number of adjusted pulse and to the pulse output 245 received per unit time. It is noted that this count without the granular addition or subtraction of pulses from the pulley wheel 4 will normally correspond to the angular speed of the pulley wheel 4, which in turn will correlate with the vertical speed of the probe 2. However, it should be noted that by as a result of the addition or subtraction decision 241 adjusting the number of pulses of the pulley wheel 4, which will be set per unit of time, the net effect is the adjustment of the apparent logging speed of the probe 2 in order to grain with that of the probe movements during the production of the historical data. It is further noted that a depth interrupt generator 219 is preferably used. The purpose of the generator 30 219 is to produce a signal at the depth logic output 11, which is supplied to the depth controller 12 with a pre-selected number of pulses to be received by the interrupt generator 219 at the pulse output 245. In the present illustration, each time generator 219 receives 256 pulses at pulse output 245, a signal will be produced and output will be delivered to 790 7 4 04 39 depth controller 12. As a result of. the output 11 will then produce the depth controller 12 command signals 21 to cause the production of a next true time measurement in the probe 2 as a result. By adjusting the incoming pulses on the 5 pulse line 190e as a result of the addition or subtraction decision 241, the net result is the adjustment of the length of the movement of the probe 2 following the production of a sample, before a subsequent sample is drawn through probe 2 as a result of interrupt generator output 11. In Figure 4 it can be seen that a reset circuit 197 is used. The reset circuit 197 will preferably be adjusted to provide a reset output 197b to the correction switch 193 when sets of five correction pulses are each received by the reset circuit 197 at the pulse output 195a. After receipt of the reset output 197b by the correction switch 193, the correction switch 193 will be turned off, so that no correct output 193a is subsequently supplied to the instantaneous correction circuit 195, until the correction switch 193 receives a next switch setting 242, corresponding to an add-20 or subtract decision 241. Thus, it can be seen that as a result of each activation of the correction switch 193 by the switch setting 242, a total of 25 ft x 1/50 ft / ft or 1/2 ft correction over a 25 ft interval can be obtained.

In the preceding illustration, the decision to add or subtract correction pulses from or subtract from the pulse train of the receiver output 9 was made visually and as a result of a manually operated input. It will be understood, however, that an apparatus can be provided for automatically comparing measurements of two sets of logging data, which are assumed to have been obtained at the same height within the wellbore, and subsequently producing an automatic correction in the pulse train of the receiver output 9 as a result of this comparison. In addition, it will be appreciated that these two sets of logging data may correspond to two historically obtained sets of logging data, or may even include the comparison of real time measurements when produced 79074 04 * * 40, with measurements of a historical data set obtained granularly at functionally related depths. In the latter case, a device is provided for automatically performing true time measurements through the probe 2 in 5 depth correlation, where historically obtained logging measurements were made.

Referring to Figure 4, it is recalled that the well logging system of the invention preferably includes a primary and a secondary storage 35 and 36, respectively, which can be used to store additional real time data as it is produced, as well as to store and recovering historical data. In addition, master controller 20 can read historical measurements obtained at a number of depths within the wellbore on storage output 38 as a result of an input signal 37 from master controller 20. Similarly, master controller 20 can be further removed from the primary storage device 35. on the storage output 38 as a result of the input 36 real time measurements when produced by the probe 2 as well as historical measurements of a logging pass that are different from those stored in the secondary storage device 36, and which may also be stored in read out the primary storage device 35 for further processing. As mentioned, the master controller 20 can preferably read the samples stored in the primary storage device and the secondary storage device 35 and 36, respectively. The master controller 20 can read from the primary storage means 35 one or more samples obtained at known depth intervals, with one or more samples stored in the secondary storage means 36, obtained at depths correlative with those obtained from the primary storage member 35 can be read. A functional comparison between the samples read from the primary and secondary storage members 35 and 36 can thus be performed. Due to the processing power of the controller 20, this functional equation can be extremely refined, or for illustrative purposes in the present example, the comparison between two sample points can be so simple that only the apparent depth shift between peaks of two appears. 790 74 04 41 similarly disturbances are noted on the cathode ray tube 40. Whenever the master controller 20 detects an adjustment of the depth pulses of the receiver output 9 required by such a comparison, a correction signal 250 will preferably be supplied by the master controller 20 to an appropriate auto-correction circuit 253. The auto-correction circuit 253 will also receive a pulse input signal 251, which is correlated with the correction input signal 190d supplied to the instantaneous correction circuit 195. This pulse input 251 will consist of the 10 pulse train of the received output 9, correlated with the pulse train supplied on the correction input 190d to the instantaneous correction circuit 195. In the same manner as the operation of the instantaneous correction circuit 195, the auto-correction circuit will 253 provide a correction output 254, which is correlated with the pulse output 15 295a of the instantaneous correction circuit 195, each time that the auto-correction circuit 253 is activated by the correction signal 250. In the same manner as the correction pulses produced by the correction circuit 195, the auto-correction circuit 253 will preferably, supplying a preselected number of correction pulses as a result of another preselected number of pulses on pulse input 251. In the present example, in the same manner as instantaneous correction circuit 195, auto-correction circuit 253 will supply, for example, five correction pulses due to correction output 254. 256 in incoming pulses at the pulse input 251. Also in the same manner as the manual correction of depth pulses, it can be seen that the correction signal 250 from the master controller 20 is also preferably supplied to the logic controller 198 in order to provide a logic control output 198a by the logic controller 198 to determine , whether the adder / subtractor 199 will operate in addition mode or 30 in subtraction mode. The correction output 254, after being conventionally formed in the pulse shaper 200 as pulse shaper output 200a, will be supplied to the addition / subtraction circuit 199. Also in the same manner as the manual operation of the apparatus of Figure 4, the logic control output 198a will result. have the adder / subtractor 35 199 add five pulses making up the pulse shaper output 200a to 790 74 04 42 or subtract from the incoming pulse train of 256 depth pulses on the pulse line 190e. It is noted that the autocorrect circuit 253 can further be provided with a pulse output 195a of the instantaneous correction circuit 195. The reason for this is to prevent the production of correction pulses by the autocorrect circuit 253 at a time when these correction pulses are also produced by the instantaneous correction circuit 195, because this will allow the adder / subtractor 199 to add or subtract pulses from both pulse output 195a and correction output 254 without treating simultaneous pulses from both sources as a single pulse.

In Figure 1, a filter 257 can be seen, which obtains an input from the recovery controller output 32b and a filter output 32d, which is supplied to the master controller 20. Bij. the correlation of two sets of logging data, it is practice to ensure that an identical parameter is measured during each passage through the well along with other parameters that may be of interest. The reason for this is that it is often easy to compare measurements of the same parameter, produced at different times, to determine whether they were obtained at the same depth within the wellbore. This, in turn, is often beneficial because when two curves or sets of data produced at different times are aggregated granularly with respect to depth, other such parameters or curves obtained simultaneously during the same wells through the well and at the same depth. increments, therefore, will also be aggregated relative to the depth. Two of these measurements, which have been found suitable for granular adjustment with respect to depth measurements of two or more sets of data, obtained during two or more passes through the well are the spontaneous potential and gamma ray measurements. A problem with the measurements is that they will often be obscured by noise signals, such as other parts of the measured curve, so that they become unusable or unreliable when adjusting two sets of logging data relative to the same depth.

790 7 4 04 43

The invention therefore uses a filter 257, which will filter out noise on the controller output 32b in order to provide a filter output 32d to the master controller 20, which is free from noise, and thus provides indications of parameter measurements that are more useful for correlation purposes in the obtaining more accurate correlation of logging data samples.

790 7 4 04

Claims (78)

1. Apparatus for examining the character of downhole traversed underground earth materials and the like, characterized by a command signal device for producing an electrical command signal as a function of the wellbore depth; a first signal device for producing a first electrical measurement of the earth materials as a result of the command signal; a second signal device for producing a second electrical measurement of the earth materials; and an adjusting device for adjusting the command signal in functional relation to the first and second measurements. Apparatus according to claim 1, characterized by a generator device for producing depth indicia functionally related to the first and second measurements; 15 and a correlation device for adjusting the command signal in correlation with the depth indications. 3. Apparatus according to claim 2, characterized in that the first and second signal devices further comprise first and second measuring devices for measuring an identical earth parameter, respectively. 4. Apparatus according to claim 3, characterized in that the generator device further comprises a device for producing a first indication of the borehole depth functionally related to the depth in the borehole, where the first electrical measurement was obtained; and an apparatus for producing a second indication of the borehole depth functionally related to the depth in the borehole, where the second electrical measurement was obtained. 5. Apparatus according to claim 4, characterized by a device for granulating the electrical measurements in functional relation to at least one of the drilling depth indications. Apparatus according to claim 5, characterized by an apparatus for selecting and comparing portions of the correlated electrical measurements as a function of the first and second well depth indications; and a command signal adjustment device as a function of the comparison of the measurements. An apparatus according to claim 6, characterized by a display device for displaying the first and second indicia in spatial relationship to depth indication, and wherein the adjusting device further comprises a device for producing the adjustment signal as a function of the spatial ratio. 8. Apparatus according to claim 7, characterized in that the command signal device further comprises a device for producing the command signal as a function of discrete ear well depths. 9. Apparatus according to claim 8, characterized by an apparatus for producing a third electrical measurement of the earth materials as a function of the adjusted command signal. Device according to claim 9, characterized by a recording device for recording the first and second measurements for adjusting the command signal. 11. Apparatus according to claim 10, characterized by a display device for displaying the first and second measurements for adjusting the command signal. Apparatus according to claim 11, characterized in that the display device further comprises a device for graphically and visually displaying the first and second measurements. Apparatus according to claim 12, characterized in that the first signal device further comprises a first sampling device for sampling the first measurements as a function of the depth; and wherein the second signal device further comprises a second sampling device for sampling the second measurements as a function of the depth. Apparatus according to claim 13, characterized in that the first and second signal devices further comprise a device for producing the first and second measurements as a function of depth, respectively. 15. An apparatus for examining lithological properties of well-traversed underground earth materials, characterized by a first conversion device for producing a first digital real-time measurement of a selected characteristic of the borehole. materials; a second conversion device for producing a second digital measurement of a selected characteristic of the materials on a historical basis; a display device for electrically displaying a visual representation of the first and second digital measurements on a real time basis in functional correlation 10 with the well depth; a sampling device for activating the first conversion device progressively along the length of the wellbore; a generator device for producing a visual representation of a granular fixed increment of the length of the well bore; a coupling device for coupling the generator-device and the first and second conversion devices to the imaging device; a first selector device for selecting a portion of the displayed second measurement; a first granulator for electrically granulating the selected portion of the second measurement with the granular portion of the depicted first measurement; a measuring device for producing an electrical representation of the magnitude of each displacement between the portions of the measurements relative to the well depth increment; and a second granulator for granulating the portion of the second measurement with the portion of the first measurement as a function of the magnitude of displacement. Apparatus according to claim 15, characterized by a second selector device for electrically selecting a number of other parts of the second measurement in functional ratio to the magnitude of the displacement; and a sequencer for sequentially mapping any other portion in conjunction with the depicted increment of the length of the wellbore within a discrete time interval. Apparatus according to claim 16, characterized by a timing device for visually imaging the other parts 790 7 4 04 in sequence with a preselected discrete time interval for granulating the first and second measurements with respect to the increment of the length of the well within the time interval. 18. Apparatus according to claim 17, characterized by a first recording device for recording the first measurement on a real time basis; and a second recording device for recording the second measurement in functional relationship to the recorded first measurement. 19. Apparatus for examining the character of downhole traversed earth materials and the like, characterized by a command device for producing an electrical command signal as a function of depth in the wellbore; a first signal device for producing a first electrical measurement of the earth materials as a result of the command signal; a second signal device for producing a second electrical measurement of the earth materials; a recording device for the granular recording of the first and second measuring signals as a function of the command signal; a grain device for recording the second measurement on the recording device together with an indication of the borehole depth and the first measurement in combination with the second measurement and in functional response to the command signal; and a granulation device for granulating the command signal with the second measuring signal. Apparatus according to claim 19, characterized by a device for granulating the command signal with the second measuring signal, while the first measuring signal is recorded in functional response to the command signal. 21. Apparatus according to claim 20, characterized by an adjustment device for incrementally adjusting the command signal to record the first measuring signal in correlation with the second measuring signal and the depth indication. 22. Apparatus for examining downhole traversed underground earth materials, characterized by a first measuring device for progressively measuring a selected earth material along a portion of the length of the well; a command signal device for producing an electrical command signal consisting of a series of pulses which are functionally indicative of being related to 5 different selected depths in and along the portion of the wellbore; a first generator device for producing a first electrical data signal as a result of the command signal pulses, which is functionally related to digital representations of the measured characteristic of the earth materials at granular depths of the different selected depths in the wellbore portion; a second generator device for functionally producing a second electrical data signal in functional relationship to the command signal pulses, consisting of digital representations of a measured characteristic of the earth materials 15 at a series of functionally granular depths in the well * a depth indicator device for producing a electrical indication of the depth in the wellbore to which the representations making up the first data signal are related; an imaging device for producing a granular visible image of the first and second data signals and the electrical depth indications; an adjustment device for incrementally adjusting the command signal as a function of a determined difference between the representations that comprise the first and second data signals in the depth indication in the wellbore; and a recording device for granularly recording the first and second data signals in a functional relationship to the incrementally adjusted command signal. 23, Apparatus for examining the lithological characteristics of downhole traversed underground earth materials, characterized by a first measuring device for producing a first digital measurement of a selected characteristic of the materials; a first imaging device for electrically imaging a visual representation of the first digital measurement on a real time basis and in functional correlation with the well depth; a second measuring device for producing a second digital measurement of a selected characteristic of the materials on a historical basis; and a second imaging device for electrically imaging a visual representation of the digital measurement in functional grain with the visual representation of the first digital measurement. The apparatus of claim 23, characterized by an apparatus for producing the first measurement progressively along the length of the well; and a first coupling device for electrically imaging the first measurement on the first and second imaging devices together with a visual representation of a granular fixed increment of the length of the wellbore, and for electrically imaging the second measurement in correlation with the increment of the length of the well. 25. The apparatus of claim 24, characterized by a selection device for selecting a portion of the displayed second measurement; and a first granulator for electrically granulating the selected portion of the second measurement with the granular portion of the depicted first measurement. The apparatus of claim 25, characterized by a displacement size detection device for producing an electrical representation of the magnitude of each displacement between the portions of the measurements with respect to the well depth increment; and a second granulator for granulating the portion of the second measurement with the portion of the first measurement as a function of the magnitude of displacement, 27. Apparatus for producing depth indications of a logging tool within a wellbore, characterized by a sensor device for progressively sensing at least one characteristic of the materials along a selected portion of the length of the wellbore; a signal generator device for progressively producing an electrical logging signal in functional response to the sensed characteristic of the materials along the portion of the wellbore; a depth signal device for producing an electrical depth signal consisting of marker pulses, each indicative of an apparent sequential increment of the length of the well along the selected portion thereof; a counter for progressively counting the marker pulses in correlation with the logging signal; and a depth indicator device for producing a total of marker pulses as an indication of the apparent well depth, where the granular portion of the logging signal is obtained. 28. An apparatus according to claim 26, characterized by a direction control device for producing a direction control signal functionally indicative of the direction in which the earth characteristics are observed along the wellbore; and a first total counter for progressively counting and totalizing the marker pulses in functional correlation with the direction control signal. An apparatus according to claim 28, characterized in that the direction control device further comprises a device for producing the control signal on a time-dependent basis. An apparatus according to claim 29, characterized by a supplemental pulse generator device for producing supplemental pulses as a predetermined function of the obtained total number of marker pulses; and a second total counter device for producing the total of the supplemental pulses and the total number of marker pulses as an indication of the real depth in the wellbore where the granular portions of the logging signal are obtained. 31. An apparatus according to claim 30, characterized by a timer device for determining a preselected discrete time interval as a result of an interruption in the occurrence of the marking pulses; a direction change device for producing from the direction control signal and within the discrete time interval an indication of a change in the direction in which the earth characteristic is sensed along the wellbore; 35 and a first interrupt device for interrupting the 790 7 404 a -? progressive count of the brand pulses due to the obtained indication of direction change, 32. An apparatus according to claim 31, characterized in that the first interrupt device further comprises a device for interrupting the counting of the marker pulses during the occurrence of no more than one preselected number of marker pulses. 33. The apparatus of claim 32, characterized by a first indicator device for producing from the direction control signal an indication of another further change in the direction in which the ground characteristic is sensed along the wellbore; and a second interrupt device for interrupting the progressive count of the mark pulses due to the indication of the further direction change, until the occurrence of the same number of counted mark pulses following the indication of further direction change as the number of counted mark pulses following the first one. said indication of direction change. 34. An apparatus according to claim 33, characterized by a real time generator device for progressively producing a real time electrical indication of the obtained total of supplemental and brand pulses in correlation with the progressively obtained electrical logging signal; and a recorder for recording the progressively obtained electrical indication of the obtained totals and the logging signal as a function of the true depth, where the characteristic of the materials is observed along the wellbore. 35. An apparatus according to claim 34, characterized by a historical generator device for producing a compatible electrical representation of a historically obtained measurement of a characteristic of the materials; and a coupling device for coupling the compatible representation in correlation with the obtained representation of the totals and the logging signal with the recording device. 36. An apparatus according to claim 35, characterized by a device for visually displaying the recorded compatible 790 7404 * V representation and the representation of the totals and the logging signal at a location remote from the well site. 37. A method of examining the character of underground earth materials and the like traversed through a wellbore, characterized by producing an electrical command signal as a function of the wellbore depth; producing a first electrical measurement of the ground materials due to the command signal; producing a second electrical measurement of the earth materials? and adjusting the command signal 10 in a functional relationship to the first and second measurements. A method according to claim 37, characterized by producing depth indicia functionally related to the first and second measurements; and adjusting the command signal in functional correlation with the depth indications. A method according to claim 38, characterized in that producing depth indications comprises producing a first indication of the borehole depth, which is functionally related to the depth in the borehole, where the first electrical measurement was obtained; and producing a second indication of the well depth which is functionally related to the depth in the well where the second measurement was obtained. The method of claim 39, characterized by granulating the electrical measurements in a functional relationship to at least one of the borehole depth indications. A method according to claim 40, characterized by selecting and comparing the portions of the correlated electrical measurements as a function of the first and second wellbore depth indications? and adjusting the command signal as a function of the comparison of the measurements. A method according to claim 41, characterized by displaying the first and second measurements in spatial relation to the depth indications; and adjusting the command signal as a function of the spatial relationship. 43. A method according to claim 42, characterized in that the command signal is obtained as a function of discrete well depths of 790 7 4 04. Method according to claim 43, characterized by producing a third electrical measurement of the earth materials as a function of the adjusted command signal. A method according to claim 44, characterized by recording the first and second measurements prior to adjusting the command signal. 46. A method according to claim 45, characterized by displaying the first and second measurements prior to adjusting the command signal. A method according to claim 46, characterized in that the imaging consists of imaging graphical and visual images of the first and second measurements. 48. A method according to claim 47, characterized in that the first and second measurements are sampled as a function of the depth. A method according to claim 48, characterized in that the first and second measurements are produced as a function of depth. A method according to claim 37, characterized in that obtaining the first and second electrical measurements further comprises producing a first measurement of earth materials traversed through a first well; and producing a second measurement of ground materials traversed through another well 25. A method according to claim 37, characterized in that the first and second measurements each comprise measurements of an identical earth parameter. 52. A method of examining the character of downhole traversed underground earth materials and the like, characterized by producing a first measurement of the earth materials, consisting of a first portion obtained over a first increment of the well, and a second portion obtained over a second increment of the wellbore; producing a second measurement of the earth materials over a third increment of the 790 7404 * * well; graphically depicting the first portion of the first measurement and the second measurement; selecting granular portions of the mapped first portion of the first measurement and the mapped second measurement; producing a differential sew which is functionally related to any difference between the apparent depths where the granular portions were obtained; producing a third measurement of the earth materials over a well bore increment, which is functionally related to the difference signal; and displaying the second portion of the first measurement along with the third measurement. 53. A method according to claim 52, characterized in that the selection of granular portions consists of selecting portions of the imaged first portion of the first measurement and the imaged second measurement, which have one substantially similar appearance. 54. A method of examining the lithological characteristics of downhole traversed subterranean earth materials, characterized by producing a first digital real-time measurement of a selected characteristic of the materials, progressively along the length of the wellbore; producing a second digital measurement of a selected characteristic of the materials on a historical basis, electrically imaging the visual representation of the first and second digital measurements on a real time basis in functional correlation with the well depth; producing a visual representation of a granular solid increment of the well length and the first and second measurements; selecting a portion of the imaged second measurement; electrically graining the selected portion of the second measurement with the grainative portion of the depicted first measurement; and producing an electrical representation of the magnitude of each displacement between the portions of the measurements with respect to the well depth increment; and granulating the portion of the second measurement with the portion of the first measurement 35 as a function of the magnitude of the displacement. 790 7 404 The method of claim 54, characterized by electrically selecting a plurality of other portions of the second measurement in functional relationship to the displacement size; and sequentially mapping any other portion in conjunction with the displayed well length increment within a discrete time interval. 56. A method according to claim 55, characterized by visually imaging the other sections in a sequence within a preselected discrete time interval for granulating the first and second measurements with respect to the increment of the length of the well within the time interval. 57. A method according to claim 56, characterized by recording the first measurement on a real time basis and recording the second measurement in functional ratio to the recorded first measurement. 58. A method of examining the character of downhole traversed underground earth materials and the like, characterized by producing an electrical command signal as a function of depth in the wellbore; producing a first electrical measurement of the earth materials due to the command signal; producing a first electrical measurement of the earth materials as a result of the command signal; producing a second electrical measurement of the earth materials; registering the first and second measurement signals correlatively as a function of the command signal; recording the second measurement along with an indication of the borehole depth; and recording the first measurement in combination with the second measurement and in functional response to the command signal. 59. A method according to claim 58, characterized by granulating the command signal with the second measuring signal. A method according to claim 59, characterized by granulating the command signal with the second measurement signal, while the first measurement signal is recorded in functional response to the command signal. The method of claim 60, characterized by 790 74 04 f <Γ incrementally adjusting the command signal to record the first measurement signal in. correlation with the second measuring signal and the depth indication. 62. A method of examining underground earth materials traversed by a well bore, characterized by progressively measuring a selected characteristic of the earth materials along a portion of the length of the well bore; producing an electrical command signal consisting of a series of pulses that are functionally indicative of and related to different selected depths in and along the wellbore portion; producing, as a result of the command signal pulses, a first electrical data signal consisting of digital representations of the measured characteristic of the earth materials at granular depths of the different selected depths in the wellbore portion; producing a second electrical data signal in a functional relationship to the command signal pulses consisting of digital representations of a measured characteristic of the ground materials at a range of functionally granular depths in the wellbore; producing an electrical indication 20 of the depth in the wellbore to which the representations of the first data signal are related; producing a granular visible image of the first and second data signals and the electrical depth indications; incrementally adjusting the command signal as a function of a determined difference between the representations of the first and second data signals and the depth indication in the wellbore; and graining the first and second data signals in a functional relationship to the incrementally adjusted command signals. 63. A method of examining the lithological characteristics of well traversed underground earth materials, characterized by producing a digital measurement of a selected characteristic of the materials; electrically imaging a visual representation of the first digital measurement on a real time basis and in functional correlation with the well depth; producing a second 790 7 4 04 'digital measurement of a selected characteristic of the materials on a historical basis; and electrically imaging a visual representation of the second digital measurement in functional correlation with the visual representation of the first digital measurement. The method of claim 63, characterized by producing the first measurement progressively along the length of the wellbore; electrically imaging the first measurement along with a visual representation of a granular solid increment in the length of the wellbore; and electrically imaging the second measurement in correlation with the increment of the length of the wellbore. 65. The method of claim 64, characterized by selecting a portion of the imaged second measurement, and electric grouting the selected portion of the second measurement with the granular portion of the imaged first measurement. 66. A method according to claim 65, characterized by producing an electrical representation of the magnitude of each displacement between the portions of the measurements with respect to the well depth increment; and granulating the portion of the second measurement with the portion of the first measurement as a function of the magnitude of the displacement. 67. A method of producing depth indications of a logging tool within a wellbore, characterized by progressively sensing at least one characteristic of the materials along a selected portion of the length of the wellbore; progressively producing an electrical logging signal in functional response to the observed characteristics of the materials along the wellbore portion; producing an electrical depth signal consisting of marker pulses, each indicative of an apparent sequential increment of the length of the well along the selected portion thereof; progressively counting the marker pulses in correlation with the logging signal; and producing a total of mark pulses as 790 74 04 τ ¢ - * an indication of the apparent depth where the grainy portions of the logging signal are obtained. 68. A method according to claim 67, characterized by producing a direction control signal which is functionally indicative of the direction in which the earth characteristic is observed along the wellbore; and progressively counting and totalizing the brand pulses in functional correlation with the direction control signal. 69. A method according to claim 68, characterized in that the direction control signal is obtained on a time-dependent basis. The method of claim 69, characterized by producing supplemental pulses as a predetermined function of the obtained total number of marker pulses; and producing the further total of supplemental pulses and the total number of marker pulses as an indication of the true depth in the wellbore, where the grain portion of the logging signal is obtained, 71. A method according to claim 70, characterized by determining a preselected discrete time interval as a result of an interruption in the occurrence of the marking pulses; producing from the direction control signal and within the discrete time interval an indication of a change in the direction in which the ground characteristic is sensed along the wellbore; and interrupting the progressive count of the brand pulses due to the obtained direction change indication. 72. A method according to claim 71, characterized in that the counting of the marker pulses is interrupted during the occurrence of no more than a preselected number of marker pulses. A method according to claim 72, characterized by producing from the direction control signal an indication of another further change in the direction in which the ground characteristic is sensed along the wellbore; and interrupting the progressive count of the mark pulses as 790 74 04 'f' 4 due to the indication of further direction change until the occurrence of the same number of counted mark pulses following the indication of further direction change following the number of counted mark pulses following on the former indication of 5 direction change. 74. A method according to claim 73, characterized by progressively producing a real time electrical indication of the obtained total of the supplemental and brand pulses in correlation with the progressively obtained electrical logging signal; and recording the progressively obtained electrical indication of the obtained totals and the logging signal as a function of the true depth, where the characteristic of the materials is observed along the wellbore. 75. A method according to claim -74, characterized by producing a compatible electrical representation of a historically obtained measurement of a characteristic of the materials; and registering the compatible representation in correlation with the obtained representation of the totals and the logging signal. The method of claim 75, characterized by visually displaying the recorded compatible representation and the representation of the totals and the logging signal at a location remote from the well site. 77. Device substantially as described in the description and shown in the drawings. 78. Method as described in the description. 790 74 04