A four-detector lithologic density plate device and detection method

Abstract

This invention belongs to the technical field of oil well logging equipment and discloses a four-detector lithology density electrode device and detection method, comprising: a housing assembly, inside which are arranged sequentially a first far detector, a first near detector, a source chamber, a second near detector, and a second far detector; the distances of each detector from the source chamber, from largest to smallest, are: second far detector, first far detector, first near detector, and second near detector. This invention uses four detectors, namely the first far detector, the first near detector, the second far detector, and the second near detector. Each detector acquires density logging curves and lithology logging curves by collecting data. Moreover, if any one detector fails, the remaining three detectors can still generate two volumetric density values ​​and at least one formation photoelectric absorption index cross-section value, obtaining the volumetric density and formation photoelectric absorption index cross-section. The entire machine can still guarantee measurement accuracy and perform normal well logging.

Description

Technical Field

[0001] This invention belongs to the field of oil well logging equipment technology, and specifically relates to a four-detector lithology density electrode device and detection method. Background Technology

[0002] The lithology density logging instrument is a type of oil well logging instrument that uses a gamma source to irradiate the formation. Based on the photoelectric effect and Compton effect, it uses long- and short-source-pitch gamma detectors to measure the gamma rays scattered by the formation, and uses energy spectrum analysis to measure the count rate of the corresponding energy, thereby calculating the photoelectric absorption cross-section index P of the target formation. e and bulk density ρ b The long and short source distance detectors and source chamber of the lithology density logging tool are all installed in a single electrode plate. During logging, the electrode plate is pressed tightly against the well wall by the push-fit system. As a result, lithology density logging is greatly affected by the wellbore environment. If the wellbore environment is harsh, it may lead to reduced accuracy and repeatability and consistency exceeding the standard range.

[0003] The shortcomings of existing lithology density logging instruments are as follows:

[0004] 1. Generally, it uses dual-detector lithological density. Dual-detector lithological density results in a vertical resolution difference, and the formation photoelectric absorption index cross section P... e The low porosity formation count rate fluctuates significantly due to the large influence of barite in the wellbore.

[0005] 2. The density logging curves and lithology logging curves from the lithology density logging tool have poor repeatability and poor consistency.

[0006] 3. The logging curves of lithology density logging tools are greatly affected by the well environment. Influencing factors include, but are not limited to, mud cake composition and thickness, wellbore smoothness and roundness.

[0007] 4. Existing rock density detectors have reached a bottleneck, with limited improvement in accuracy and stability, making it impossible to obtain detectors with higher accuracy and stability.

[0008] 5. If one detector in an existing lithology density logging instrument malfunctions, the entire instrument will cease to function, resulting in low instrument redundancy. Summary of the Invention

[0009] To address at least one of the problems in the background art, the present invention proposes a four-detector lithology density electrode device and detection method.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A four-detector lithology density electrode device, comprising:

[0012] The housing assembly contains, in sequence, a first far-field detector, a first near-field detector, a source chamber, a second near-field detector, and a second far-field detector.

[0013] The distances from the source chamber to the first far detector, the first near detector, the second near detector, and the second far detector, in descending order, are: second far detector, first far detector, first near detector, and second near detector.

[0014] Preferably, the source compartment has a trapezoidal structure with a blind hole inside that is closed at one end and open at the other, and the blind hole is perpendicular to the trapezoidal cross section of the trapezoidal structure.

[0015] The blind hole is also connected to the first radioactive isotope source ray emission hole and the second radioactive isotope source ray emission hole.

[0016] The first and second radioactive isotope source ray emission holes are both located in the ladder structure, and their openings face one side of the ladder structure.

[0017] Preferably, the angle between the first and second radioactive isotope source emission holes and the housing assembly is 45°±5°.

[0018] Preferably, the source chamber is made of tungsten alloy with a density of 18±2 g / cm3.

[0019] Preferably, one end of the housing assembly is also connected to an electronic instrument nacelle, which is used to seal the housing assembly and to receive and transmit data collected by the first proximity detector, the second proximity detector, and the second distance detector.

[0020] A detection method for the aforementioned four-detector rock-dense electrode device includes the following steps:

[0021] Collect formation density data and formation photoelectric absorption index cross-sectional values;

[0022] Construct well logging density curves based on density values;

[0023] Simultaneously, lithological logging curves are constructed based on the numerical values ​​of the formation photoelectric absorption index cross section.

[0024] Preferably, the acquisition of formation density data and formation photoelectric absorption index cross-sectional values ​​includes the following steps:

[0025] Formation density data were collected using the first remote detector, the first near detector, the second near detector, and the second remote detector, respectively.

[0026] Simultaneously, the cross-sectional values ​​of the formation photoelectric absorption index are collected using the first and second teledetectors.

[0027] Preferably, constructing a well logging density curve based on density values ​​includes the following steps:

[0028] The first density value is obtained by collecting density data from the first far detector and the first near detector;

[0029] The second density value is obtained by collecting density data from the first far-field detector and the second near-field detector;

[0030] The third density value is obtained by collecting density data from the second far-field detector and the second near-field detector;

[0031] The fourth density value is obtained by collecting density data from the second far detector and the first near detector;

[0032] Calculate the weighted average of the first, second, third, and fourth density values ​​to obtain the composite density value. Construct a logging density curve using the composite density value and logging depth.

[0033] Preferably, constructing lithological logging curves based on formation photoelectric absorption index cross-sectional values ​​includes the following steps:

[0034] The first lithology value was obtained by collecting the cross-sectional value of the formation photoelectric absorption index from the first teledetector.

[0035] The cross-sectional values ​​of the formation photoelectric absorption index collected by the second teledetector constitute the second lithology value.

[0036] A synthetic lithology value is constructed by combining the first lithology logging curve and the second lithology logging curve, and a lithology logging curve is constructed by combining the synthetic lithology value with the logging depth.

[0037] Preferably:

[0038] When any one of the first far detector, the first near detector, the second near detector, and the second far detector is damaged, at least two of the density values ​​from the first to the fourth density values ​​obtained from the undamaged detector are combined to obtain a composite density value. Then, the composite density value and the logging depth are used to construct a logging density curve.

[0039] When either the first or second remote detector is damaged, the lithology value obtained from the data of the undamaged remote detector is used as the synthetic lithology value, and the synthetic lithology value is used to construct a logging lithology curve with the logging depth.

[0040] When either the first far-field detector or the second far-field detector is damaged, and either the first near-field detector or the second near-field detector is also damaged, the density value calculated from the density values ​​collected by the undamaged far-field detector and the undamaged near-field detector is used as the composite density value. The composite density value is then used to construct a logging density curve with the logging depth.

[0041] The beneficial effects of this invention are:

[0042] 1. This invention uses four detectors: a first far detector, a first near detector, a second far detector, and a second near detector. Each detector acquires density logging curves and lithology logging curves by collecting data. Moreover, if any one detector fails, the remaining three detectors can still generate two volumetric density values ​​and at least one formation photoelectric absorption index cross-section value, thus obtaining the volumetric density and formation photoelectric absorption index cross-section. The entire instrument can still guarantee measurement accuracy and perform logging normally. Similarly, if one near detector and one far detector fail simultaneously, the instrument can still perform logging normally, thereby improving the redundancy of the instrument.

[0043] 2. Without significantly increasing costs or using the highest-performance components, this invention increases the measurement area to 210% of the original area, expands the amount of formation information collected, improves the measurement accuracy of the lithology density logging tool, and ensures the repeatability and consistency of the curves, meeting the curve acceptance requirements.

[0044] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 A schematic diagram of the structure of a four-detector lithology density electrode device according to the present invention is shown;

[0047] Figure 2 A schematic diagram of the source chamber of the present invention is shown;

[0048] Figure 3 A schematic diagram of the detector and source chamber distribution of the present invention is shown;

[0049] Figure 4 A schematic diagram of the four detectors forming curves of the present invention is shown;

[0050] Figure 5 An application diagram of the four-detector lithology density electrode device of the present invention is shown.

[0051] In the diagram: 1. Electronic instrument nacelle; 2. First remote detector; 3. First near detector; 4. Source chamber; 401. Blind hole; 402. First radioactive isotope source ray emission hole; 403. Second radioactive isotope source ray emission hole; 5. Second near detector; 6. Second remote detector; 7. Housing assembly; 8. Right well wall; 9. Left well wall; 10. Well shaft; 11. Downward push arm; 12. Hydraulic actuator; 13. Front pull arm; 14. Rear pull arm; 15. Upward push arm; 16. Instrument body. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] Example 1

[0054] A four-detector lithology density electrode device, such as Figure 1 As shown, it includes several detectors and a housing assembly 7. Specifically, the housing assembly 7 contains, in sequence, a first far detector 2, a first near detector 3, a source chamber 4, a second near detector 5, and a second far detector 6; the distances of each detector from the source chamber 4 also differ, and the distances from the first far detector 2, the first near detector 3, the second near detector 5, and the second far detector 6 to the source chamber 4 from largest to smallest are: second far detector 6, first far detector 2, first near detector 3, and second near detector 5.

[0055] Furthermore, Figure 2 The source chamber 4 has a trapezoidal structure with a blind hole 401 inside that is closed at one end and open at the other. The blind hole 401 is perpendicular to the trapezoidal cross section of the trapezoidal structure. The blind hole 401 is also connected to a first radioactive isotope source ray emission hole 402 and a second radioactive isotope source ray emission hole 403. The first radioactive isotope source ray emission hole 402 and the second radioactive isotope source ray emission hole 403 are both located in the trapezoidal structure and their openings face one side of the trapezoidal structure.

[0056] It should be noted that a radioactive isotope source is also installed inside source chamber 4, which can be emitted through the first radioactive isotope source emission port 402 and the second radioactive isotope source emission port 403. Furthermore, the radioactive isotope source is only installed inside source chamber 4 during instrument logging; after logging is completed, the radioactive isotope source is immediately removed and safely stored in the source reservoir.

[0057] Furthermore, the source chamber 4 is made of tungsten alloy with a density of 18±2 g / cm3.

[0058] It should be noted that the source chamber 4 is made of high-density tungsten steel, which is used to shield the radiation from the radioactive isotope source, so that the radiation can only be emitted in a directional manner according to the emission window.

[0059] Furthermore, in this embodiment, there are two detectors on each side of the source chamber 4, and the distances between the four detectors and the source chamber 4, i.e. the source distances, are not equidistantly distributed.

[0060] Furthermore, one end of the housing assembly 7 is also connected to an electronic instrument nacelle 1. The electronic instrument nacelle 1 is used to seal the housing assembly 7 and to receive and transmit data collected by the first proximity detector 3, the second proximity detector 5, and the second distance detector 6.

[0061] It should be noted that the electronic instrument nacelle 1 contains a pressure-bearing terminal assembly. This assembly's sealing plug seals the four-detector electrode assembly and is electrically connected to the first far-field detector 2, the first near-field detector 3, the source chamber 4, the second near-field detector 5, and the second far-field detector 6. Its functions include receiving low-voltage power and control signals, and outputting detector pulse signals. The electronic nacelle's functions are: receiving low-voltage power from the lithology density logging instrument's electronic section; providing high-voltage power to each of the four detectors; processing the pulses output from the four detectors, amplifying the pulses, and transmitting the amplified pulses to the lithology density logging instrument's electronic section. Furthermore, the electronic nacelle is located at the front end of the electrode plates and has a total of 11 input and output cables, including +24V, -12V, GND, S1, S2, S3, S4, HVC1, HVC2, HVC3, and HVC4. The electronic nacelle uses four signal processing assemblies and four high-voltage power supplies. The external equipment used with the four-detector rock density electrode plate device of the present invention includes, but is not limited to, calibration devices, ground systems, etc., and is the same as the external equipment used with the dual-detector rock density instrument.

[0062] like Figure 3 As shown, four detectors generate four source distances, and the logging values ​​are respectively R1 / R2, R1 / L2, L1 / R2, L1 / L2 (corresponding to...). Figure 2 The four density values ​​(DEN1, DEN2, DEN3, DEN4) are composed of A, B, C, and D; R2 and L2 form two lithological Pe values ​​(Pe1, Pe2). The DEN0 value is obtained by combining the four DEN values, and this DEN0 value is the optimal density value. Similarly, the Pe0 value is obtained from the two Pe values, and this Pe0 value is the optimal lithological value. The detection method will be explained in detail below with reference to Example 2.

[0063] Example 2

[0064] A detection method, such as Figure 4As shown, the four-detector rock-dense electrode device described above includes the following steps:

[0065] S1: Collect formation density data and formation photoelectric absorption index cross-sectional values;

[0066] S2: Constructing synthetic logging density curves based on density values;

[0067] S3: Construct synthetic lithological logging curves based on the numerical values ​​of the formation photoelectric absorption index cross section.

[0068] It should be noted that steps S2 and S3 can be performed simultaneously.

[0069] Further, step S1 includes the following steps:

[0070] S101: Collect formation density data through the first far detector 2, the first near detector 3, the second near detector 5, and the second far detector 6 respectively; and collect formation photoelectric absorption index cross-sectional values ​​through the first far detector 2 and the second far detector 6.

[0071] Further, step S2 includes the following steps:

[0072] S201: Obtain the first density value using density data collected by the first far-field detector 2 and the first near-field detector 3; S202: Obtain the second density value using density data collected by the first far-field detector 2 and the second near-field detector 5; S203: Obtain the third density value using density data collected by the second far-field detector 6 and the second near-field detector 5; S204: Obtain the fourth density value using density data collected by the second far-field detector 6 and the first near-field detector 3; S205: Combine the first density value, the second density value, the third density value, and the fourth density value to obtain a composite density value, and construct a logging density curve using the composite density value and the logging depth.

[0073] It should be noted that the synthetic density value is obtained by calculating the weighted average of the first to fourth density values.

[0074] Further, step S3 includes the following steps:

[0075] S301: The formation photoelectric absorption index cross-sectional value collected by the first remote detector 2 constitutes the first lithology value; S302: The formation photoelectric absorption index cross-sectional value collected by the second remote detector 6 constitutes the second lithology value; S303: The first lithology logging curve and the second lithology logging curve constitute the synthetic lithology value, and the synthetic lithology value and logging depth are used to construct the lithology logging curve.

[0076] It should be noted that steps S301 and S302 are data acquisition processes, which can be performed simultaneously in the four-detector rock density electrode device. Furthermore, the synthesized lithology value is obtained by calculating the weighted average of the first and second lithology values.

[0077] Furthermore, in this embodiment, a redundant structure is formed among the detectors. For example, when any one of the first far-field detector 2, the first near-field detector 3, the second near-field detector 5, and the second far-field detector 6 is damaged, at least two of the density values ​​from the first to the fourth density values ​​obtained from the undamaged detector are synthesized to obtain a composite density value. Then, the composite density value is used to construct a logging density curve with the logging depth. When any one of the first far-field detector 2 and the second far-field detector 6 is damaged, the lithology value obtained from the data of the undamaged far-field detector is used as the composite lithology value, and the composite lithology value is used to construct a logging lithology curve with the logging depth. When any one of the first far-field detector 2 and the second far-field detector 6 is damaged, and simultaneously any one of the first near-field detector 3 and the second near-field detector 5 is damaged, the density value calculated from the density values ​​collected by the undamaged far-field detector and the density values ​​collected by the undamaged near-field detector is used as the composite density value, and the composite density value is used to construct a logging density curve with the logging depth.

[0078] It should be noted that, because this invention employs multiple detectors arranged at different distances, even if one or more detectors are damaged during use, as long as one of the four density values ​​exists, it can be used as the basis for synthesizing density logging curves. Similarly, as long as one lithology value exists, it can also be used as a basis for synthesizing lithology logging curves.

[0079] like Figure 5 The image shows an application of a four-detector lithology density electrode device, in which...

[0080] Inside the wellbore 10, the instrument body 16 is installed, and a hydraulic actuator 12 is mounted on its surface. A front guide arm 13 is connected to one end of the hydraulic actuator 12, and the front guide arm 13 is connected to the housing assembly 7. At the same time, the other end of the housing assembly 7 is connected to the rear guide arm 14, and the middle section is slidably connected to the upper push arm 15. On the other side of the instrument body 16, a lower push arm 11 is provided. During operation, the hydraulic actuator 12 operates, and through the internal hinge, the upper push arm 15 and the lower push arm 11 are simultaneously pushed open to the right and left, forming an open "scissor" shape. Then, the upper push arm 15 lifts the housing assembly 7 out of the instrument body 16. The front guide arm 13 and the rear guide arm 14 simultaneously pull the housing assembly 7 to ensure its smooth movement. At the same time, the housing assembly 7 is pressed tightly against the right well wall 8, and the lower push arm 11 pushes against the left well wall 9, so that the housing assembly 7 is always in contact with the right well wall 8.

[0081] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A four-detector lithology density electrode device, characterized in that, include: The housing assembly (7) contains, in sequence, a first far detector (2), a first near detector (3), a source chamber (4), a second near detector (5), and a second far detector (6); The distances from the first far detector (2), the first near detector (3), the second near detector (5), and the second far detector (6) to the source chamber (4) from largest to smallest are: second far detector (6), first far detector (2), first near detector (3), and second near detector (5); The source compartment (4) has a trapezoidal structure and a blind hole (401) with one end closed and the other end open is provided inside. The blind hole (401) is perpendicular to the trapezoidal cross section of the trapezoidal structure. The blind hole (401) is also connected to the first radioactive isotope source ray emission hole (402) and the second radioactive isotope source ray emission hole (403). The first radioactive isotope source ray emission hole (402) and the second radioactive isotope source ray emission hole (403) are both opened in the ladder structure, and the openings of both face the ladder structure. The angle between the first radioactive isotope source ray emission hole (402) and the second radioactive isotope source ray emission hole (403) and the housing assembly (7) is 45°±5°.

2. The four-detector lithology density electrode device according to claim 1, characterized in that, The source chamber (4) is made of tungsten alloy with a density of 18±2 g / cm3.

3. The four-detector lithology density electrode device according to claim 1, characterized in that, One end of the housing assembly (7) is also connected to an electronic instrument nacelle (1). The electronic instrument nacelle (1) is used to seal the housing assembly (7) and to receive and transmit data collected by the first proximity detector (3), the second proximity detector (5), and the second distance detector (6).

4. A detection method for the four-detector lithology density electrode device according to any one of claims 1-3, characterized in that, Includes the following steps: The formation density data and formation photoelectric absorption index cross-sectional values ​​are collected, including: the formation density data are collected by the first far detector (2), the first near detector (3), the second near detector (5) and the second far detector (6); and the formation photoelectric absorption index cross-sectional values ​​are collected by the first far detector (2) and the second far detector (6). Construct well logging density curves based on density values; Simultaneously, lithological logging curves are constructed based on the numerical values ​​of the formation photoelectric absorption index cross section.

5. The detection method according to claim 4, characterized in that, Constructing well logging density curves based on density values ​​includes the following steps: The first density value is obtained by collecting density data from the first far detector (2) and the first near detector (3); The second density value is obtained by collecting density data from the first far detector (2) and the second near detector (5); The third density value is obtained by collecting density data from the second far detector (6) and the second near detector (5); The fourth density value is obtained by collecting density data from the second far detector (6) and the first near detector (3); Calculate the weighted average of the first, second, third, and fourth density values ​​to obtain the composite density value. Construct a logging density curve using the composite density value and logging depth.

6. The detection method according to claim 5, characterized in that, Constructing lithological logging curves based on formation photoelectric absorption index cross-sections includes the following steps: The first lithology value is obtained by collecting the cross-sectional value of the photoelectric absorption index of the strata by the first remote detector (2); The cross-sectional values ​​of the photoelectric absorption index of the strata collected by the second remote detector (6) constitute the second lithology value; A synthetic lithology value is constructed by combining the first lithology logging curve and the second lithology logging curve, and a lithology logging curve is constructed by combining the synthetic lithology value with the logging depth.

7. The detection method according to claim 6, characterized in that: When any one of the first far detector (2), the first near detector (3), the second near detector (5), and the second far detector (6) is damaged, at least two of the first to fourth density values ​​obtained from the undamaged detector are combined to obtain a composite density value. Then, the composite density value and the logging depth are used to construct a logging density curve. When either the first remote detector (2) or the second remote detector (6) is damaged, the lithology value obtained from the data of the undamaged remote detector is used as the synthetic lithology value, and the synthetic lithology value and the logging depth are used to construct a logging lithology curve; When either the first remote detector (2) or the second remote detector (6) is damaged, and either the first near detector (3) or the second near detector (5) is damaged, the density value calculated by combining the density value collected by the undamaged remote detector and the density value collected by the undamaged near detector is used as the composite density value. The composite density value and the logging depth are used to construct a logging density curve.

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