Four-detector lithologic density polar plate device and detection method

Abstract

The invention belongs to the technical field of petroleum logging equipment, and discloses a four-detector lithologic density polar plate device and a detection method, and the device comprises a housing assembly which is internally provided with a first far detector, a first near detector, a source bin, a second near detector and a second far detector in sequence; and the distances from the detectors to the source bin are sequentially as follows from large to small: the second far detector, the first far detector, the first near detector and the second near detector. According to the invention, four detectors, namely a first far detector, a first near detector, a second far detector and a second near detector, are used, and each detector obtains a density logging curve and a lithologic logging curve by collecting data; the rest three detectors can still generate two volume density values and at least one stratum photoelectric absorption index section value, the volume density and the stratum photoelectric absorption index section are obtained, the whole machine can still guarantee the measurement accuracy, and well logging is carried out normally.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum logging equipment, and in particular relates to a four-detector lithology density plate device and a detection method. Background Art

[0002] The lithology density logging instrument is a petroleum logging instrument. It uses a gamma source to irradiate the formation, and based on the photoelectric effect and Compton effect, uses long and short source distance gamma detectors to measure the gamma rays scattered by the formation, and uses the energy spectrum analysis method to measure the counting rate of the corresponding energy, and then calculates the photoelectric absorption cross-section index P of the target formation. e and volume density ρ b The long and short source distance detectors and source chamber of the lithology density logging instrument are installed in a plate. During logging, the plate is pressed against the well wall by the pushing system. Therefore, the lithology density logging is greatly affected by the wellbore environment. If the wellbore environment is bad, the accuracy may be reduced, and the repeatability and consistency may exceed the standard range.

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

[0004] 1. Generally, it is a dual-detector lithology density. The vertical resolution of the dual-detector lithology density is poor. The photoelectric absorption index cross section P of the formation e Due to the great influence of borehole barite, the counting rate statistics of low-porosity formations fluctuate greatly.

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

[0006] 3. The logging curve of the lithology density logging tool is seriously affected by the well environment. The influencing factors include but are not limited to the composition and thickness of the mud cake, the flatness and roundness of the well wall.

[0007] 4. The development of existing rock density detectors has reached a bottleneck period, and the improvement of accuracy and stability is limited, and it is impossible to obtain detectors with higher accuracy and stability.

[0008] 5. If one detector of the existing lithology density logging instrument fails, the entire instrument will not work, and the instrument fault redundancy is low. Summary of the invention

[0009] In order to solve at least one problem in the background technology, the present invention proposes a four-detector lithology density plate device and a detection method.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

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

[0012] A shell assembly, in which a first far detector, a first near detector, a source chamber, a second near detector and a second far detector are sequentially arranged;

[0013] The distances of the first far detector, the first near detector, the second near detector and the second far detector from the source warehouse are, from largest to smallest, the second far detector, the first far detector, the first near detector and the second near detector.

[0014] Preferably, the source bin is in a step-shaped structure, and a blind hole with one end closed and the other end open is provided inside, and the blind hole is perpendicular to the trapezoidal cross-section of the step-shaped structure;

[0015] The blind hole is also connected to the first radioisotope source ray emitting hole and the second radioisotope source ray emitting hole;

[0016] The first radioactive isotope source ray emitting hole and the second radioactive isotope source ray emitting hole are both opened in the step structure, and the openings are both facing one side of the step structure.

[0017] Preferably, the included angle between the first radioisotope source ray emitting hole and the second radioisotope source ray emitting hole and the shell assembly is 45°±5°.

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

[0019] Preferably, the first remote detector is 415±5cm away from the source chamber;

[0020] The first near detector is 420±5cm away from the source chamber;

[0021] The second near detector is 442±10cm away from the source chamber;

[0022] The second remote detector is 447±10 cm away from the source chamber.

[0023] Preferably, one end of the shell assembly is also connected to an electronic instrument nacelle, and the electronic instrument nacelle is used to seal the shell assembly and to receive and send data collected by the first near detector, the second near detector and the second far detector.

[0024] A detection method, used in the above-mentioned four-detector rock-tight plate device, comprises the following steps:

[0025] Collecting formation density data and formation photoelectric absorption index cross-section values;

[0026] Construct well logging density curve based on density values;

[0027] At the same time, the lithology logging curve is constructed based on the numerical value of the photoelectric absorption index cross section of the formation.

[0028] Preferably, collecting the density data of the formation and the cross-sectional value of the photoelectric absorption index of the formation comprises the following steps:

[0029] The formation density data is collected by a first far detector, a first near detector, a second near detector and a second far detector respectively;

[0030] Simultaneously, the first remote detector and the second remote detector are used to collect the cross-section value of the photoelectric absorption index of the formation.

[0031] Preferably, constructing a well logging density curve based on the density value comprises the following steps:

[0032] Obtaining a first density value through density data collected by the first far detector and the first near detector;

[0033] Obtaining a second density value through density data collected by the first far detector and the second near detector;

[0034] Obtaining a third density value through density data collected by the second far detector and the second near detector;

[0035] Obtaining a fourth density value through density data collected by the second far detector and the first near detector;

[0036] A weighted average of the first density value, the second density value, the third density value and the fourth density value is calculated to obtain a composite density value, and a logging density curve is constructed according to the composite density value and the logging depth.

[0037] Preferably, constructing a lithology logging curve based on the formation photoelectric absorption index cross section numerical value includes the following steps:

[0038] Obtaining a first lithology value through a formation photoelectric absorption index cross-section value collected by a first remote detector;

[0039] The formation photoelectric absorption index cross-section value collected by the second remote detector constitutes the second lithology value;

[0040] A synthetic lithology value is formed by the first lithology logging curve and the second lithology logging curve, and a lithology logging curve is constructed by the synthetic lithology value and the logging depth.

[0041] Preferably:

[0042] 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 first to fourth density values ​​obtained by the undamaged detector are synthesized to obtain a synthesized density value, and then the well logging density curve is constructed by combining the synthesized density value and the logging depth;

[0043] When any one of the first remote detector and the second remote detector is damaged, the lithology value obtained from the undamaged remote detector data is used as a synthetic lithology value, and the synthetic lithology value and the logging depth are used to construct a logging lithology curve;

[0044] When either the first far detector or the second far detector is damaged and either the first near detector or the second near detector is damaged at the same time, the density value calculated by the density value collected by the undamaged far detector and the density value collected by the undamaged near detector is used as the composite density value, and the composite density value and the logging depth are used to construct a logging density curve.

[0045] Beneficial effects of the present invention:

[0046] 1. The present invention uses four detectors, namely, a first far detector, a first near detector, a second far detector, and a second near detector. Each detector acquires a density logging curve and a lithology logging curve by collecting data. When any detector fails, the remaining three detectors can still generate two volume density values ​​and at least one formation photoelectric absorption index cross-section value to obtain the volume density and the formation photoelectric absorption index cross-section. The whole machine can still ensure the measurement accuracy and perform logging normally. Similarly, when a near detector and a far detector fail at the same time, the instrument can still perform logging normally, thereby improving the redundancy of the instrument.

[0047] 2. The present invention increases the measurement area to 210% of the original without significantly increasing the cost and using the highest performance components, thereby expanding the amount of formation information collected, improving the measurement accuracy of the lithology density logging instrument, and ensuring the repeatability of the curve and the consistency meets the curve acceptance requirements.

[0048] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0050] Figure 1 A schematic structural diagram of a four-detector lithology density plate device of the present invention is shown;

[0051] Figure 2 A schematic diagram of the structure of the source bin of the present invention is shown;

[0052] Figure 3 A schematic diagram of the distribution of detectors and source bins of the present invention is shown;

[0053] Figure 4 A schematic diagram of a curve formed by four detectors of the present invention is shown;

[0054] Figure 5 An application diagram of the four-detector lithology density plate device of the present invention is shown.

[0055] In the figure: 1. electronic instrument nacelle; 2. first far detector; 3. first near detector; 4. source compartment; 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 far detector; 7. shell assembly; 8. right well wall; 9. left well wall; 10. wellbore; 11. push-down arm; 12. hydraulic actuator; 13. front guide arm; 14. rear guide arm; 15. push-up arm; 16. instrument body. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] Embodiment 1

[0058] A four-detector lithology density plate device, such as Figure 1 As shown, it includes several detectors and a shell assembly 7. Specifically, the first far detector 2, the first near detector 3, the source chamber 4, the second near detector 5 and the second far detector 6 are sequentially arranged inside the shell assembly 7; the distances between each detector and the source chamber 4 are also different, and the distances between the first far detector 2, the first near detector 3, the second near detector 5 and the second far detector 6 and the source chamber 4 are, from large to small, the second far detector 6, the first far detector 2, the first near detector 3 and the second near detector 5.

[0059] Further, Figure 2The source bin 4 is in a step structure, with a blind hole 401 having one closed end and the other open end provided inside, and the blind hole 401 is perpendicular to the trapezoidal cross-section of the step structure, and the blind hole 401 is also connected to a first radioactive isotope source ray emitting hole 402 and a second radioactive isotope source ray emitting hole 403; the first radioactive isotope source ray emitting hole 402 and the second radioactive isotope source ray emitting hole 403 are both provided in the step structure, and the openings are both facing one side of the step structure.

[0060] It should be noted that a radioisotope source is also installed inside the source compartment 4, which can be emitted through the first radioisotope source ray emission hole 402 and the second radioisotope source ray emission hole 403. In addition, the radioisotope source is installed inside the source compartment 4 only when the instrument is logging. After the logging is completed, the radioisotope source is immediately unloaded and safely stored in the source library.

[0061] Furthermore, the source chamber 4 is made of tungsten alloy with a density of 18±2 g / cm3.

[0062] It should be noted that the source chamber 4 is made of high-density tungsten steel, which is used to shield the radiation of the radioactive isotope source so that the radiation can only be emitted in a direction according to the emission window.

[0063] Furthermore, in the present embodiment, there are two detectors on each side of the source warehouse 4, and the distances between the four detectors and the source warehouse 4, i.e., the source distances, are not equidistantly distributed. Specifically, the distance between the first far detector 2 and the source warehouse 4 is 415±5cm; the distance between the first near detector 3 and the source warehouse 4 is 420±5cm; the distance between the second near detector 5 and the source warehouse 4 is 442±10cm; and the distance between the second far detector 6 and the source warehouse 4 is 447±10cm.

[0064] Furthermore, one end of the shell assembly 7 is also connected to an electronic instrument nacelle 1, which is used to seal the shell assembly 7 and is also used to receive and send data collected by the first near detector 3, the second near detector 5 and the second far detector 6.

[0065] It should be noted that the inside of the electronic instrument nacelle 1 is a pressure-bearing terminal assembly, and the sealing plug of the assembly seals the four-detector plate device. In addition, it is electrically connected to the first remote detector 2, the first near detector 3, the source chamber 4, the second near detector 5 and the second remote detector 6, and plays the role of receiving low-voltage power supply and control signals, detector pulse signal output, etc. The functions of this electronic nacelle are: receiving low-voltage power from the electronic instrument part of the lithology density logging instrument; providing high-voltage power to the four detectors respectively; processing the pulses output by the four detectors respectively, amplifying the pulses, and transmitting the amplified pulses to the electronic instrument part of the lithology density logging instrument. In addition, the electronic nacelle is located at the front end of the plate, with a total of 11 cables for input and output, including +24V, -12V, GND, S1, S2, S3, S4, HVC1, HVC2, HVC3, HVC4. The electronic nacelle uses 4 signal processing assemblies and 4 high-voltage power supplies. The external equipment matched with the four-detector rock density plate device of the present invention, including but not limited to the calibration device, the ground system, etc., are the same as the external equipment used in the dual-detector rock density instrument.

[0066] like Figure 3 As shown, the four detectors generate four source distances, and the logging values ​​are respectively R1 / R2, R1 / L2, L1 / R2, L1 / L2 (corresponding to Figure 2 A, B, C and D) form four density values ​​(DEN1, DEN2, DEN3, DEN4); R2, L2, form two lithology Pe values ​​(Pe1, Pe2), and the four DEN values ​​are combined to obtain the DEN0 value, which is the optimal density value. Similarly, the two Pe values ​​are used to obtain the Pe0 value, which is the optimal lithology value. The detection method is described in detail below in conjunction with Example 2.

[0067] Embodiment 2

[0068] A detection method such as Figure 4 As shown, the above-mentioned four-detector rock-tight plate device includes the following steps:

[0069] S1: Collect the density data of the formation and the cross-section value of the photoelectric absorption index of the formation;

[0070] S2: Construct synthetic logging density curve based on density values;

[0071] S3: Construct synthetic lithology logging curves based on the numerical cross-section of the formation photoelectric absorption index.

[0072] It should be noted that steps S2 and S3 can be performed simultaneously.

[0073] Furthermore, in step S1, the following steps are included:

[0074] S101: The first remote detector 2, the first near detector 3, the second near detector 5 and the second remote detector 6 respectively collect formation density data; at the same time, the first remote detector 2 and the second remote detector 6 collect formation photoelectric absorption index cross-section values.

[0075] Furthermore, in step S2, the following steps are included:

[0076] S201: Obtain a first density value through the density data collected by the first far detector 2 and the first near detector 3; S202: Obtain a second density value through the density data collected by the first far detector 2 and the second near detector 5; S203: Obtain a third density value through the density data collected by the second far detector 6 and the second near detector 5; S204: Obtain a fourth density value through the density data collected by the second far detector 6 and the first near detector 3; S205: Synthesize the first density value, the second density value, the third density value and the fourth density value to obtain a synthesized density value, and construct a logging density curve through the synthesized density value and the logging depth.

[0077] It should be noted that the composite density value is obtained by calculating the weighted average of the first density value to the fourth density value.

[0078] Furthermore, in step S3, the following steps are included:

[0079] S301: The cross-sectional values ​​of the formation photoelectric absorption index collected by the first remote detector 2 constitute the first lithology value; S302: The cross-sectional values ​​of the formation photoelectric absorption index collected by the second remote detector 6 constitute the second lithology value; S303: The first lithology logging curve and the second lithology logging curve constitute a synthetic lithology value, and the lithology logging curve is constructed by the synthetic lithology value and the logging depth.

[0080] It should be noted that step S301 and step S302 are data collection processes, which can be performed simultaneously in the four-detector rock-tight plate device. In addition, the synthetic lithology value is obtained by calculating the weighted average of the first lithology value and the second lithology value.

[0081] Furthermore, in this embodiment, a redundant structure is formed between the detectors. For example, when any one of the first remote detector 2, the first near detector 3, the second near detector 5, and the second remote detector 6 is damaged, at least two of the first to fourth density values ​​obtained by the undamaged detector are synthesized to obtain a synthetic density value, and then the synthetic density value and the logging depth are used to construct a logging density curve. When any one of the first remote detector 2 and the second remote detector 6 is damaged, the lithology value obtained from the undamaged remote detector data 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 any one of the first remote detector 2 and the second remote detector 6 is damaged, and at the same time any one of the first near detector 3 and the second near detector 5 is damaged, the density value calculated by the density value collected by the undamaged remote detector and the density value collected by the undamaged near detector is used as the synthetic density value, and the synthetic density value and the logging depth are used to construct a logging density curve.

[0082] It should be noted that, since the present invention uses 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 the synthetic density logging curve. Similarly, as long as one lithology value exists, it can also be used as the basis for the synthetic lithology logging curve.

[0083] like Figure 5 As shown, it is an application of a four-detector lithology density plate device, in which

[0084] In the wellbore 10, the instrument body 16 is installed, and the hydraulic cylinder 12 is installed on its surface. Then, the front guide arm 13 is connected to one end of the hydraulic cylinder 12, and the front guide arm 13 is connected to the shell assembly 7. At the same time, the other end of the shell 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 set. When working, the hydraulic cylinder 12 works, and the upper push arm 15 and the lower push arm 11 are pushed to the right and left at the same time through the internal hinge, forming an open "scissors" shape; then the upper push arm 15 lifts the shell assembly 7 out of the instrument body 16; the front guide arm 13 and the rear guide arm 14 pull the shell assembly 7 at the same time to ensure its smooth movement; at the same time, the shell assembly 7 is close to the right well wall 8, and the lower push arm 11 is pushed against the left well wall 9, so that the shell assembly 7 is always in contact with the right well wall 8.

[0085] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A four-detector lithology density plate device, characterized in that: include: A housing assembly (7) is provided with a first far detector (2), a first near detector (3), a source bin (4), a second near detector (5) and a second far detector (6) in sequence; The distances of the first far detector (2), the first near detector (3), the second near detector (5) and the second far detector (6) from the source bin (4) are, from largest to smallest, the second far detector (6), the first far detector (2), the first near detector (3) and the second near detector (5).

2. A four-detector lithology density plate device according to claim 1, characterized in that: The source bin (4) is in a step-shaped structure, and has a blind hole (401) with one end closed and the other end open, wherein the blind hole (401) is perpendicular to the trapezoidal cross-section of the step-shaped structure; The blind hole (401) is also connected to a first radioisotope source ray emitting hole (402) and a second radioisotope source ray emitting hole (403); The first radioisotope source ray emission hole (402) and the second radioisotope source ray emission hole (403) are both opened in the step structure, and the openings are both facing one side of the step structure.

3. A four-detector lithology density plate device according to claim 2, characterized in that: The angle between the first radioisotope source ray emission hole (402) and the second radioisotope source ray emission hole (403) and the shell assembly (7) is 45°±5°.

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

5. A four-detector lithology density plate device according to claim 1, characterized in that: The first remote detector (2) is 15±5 cm away from the source chamber (4); The first near detector (3) is 20±5 cm away from the source chamber (4); The second near detector (5) is 42±10 cm away from the source chamber (4); The second remote detector (6) is 47±10 cm away from the source chamber (4).

6. A four-detector lithology density plate device according to claim 5, characterized in that: One end of the housing assembly (7) is also connected to an electronic instrument nacelle (1), and the electronic instrument nacelle (1) is used to seal the housing assembly (7) and is also used to receive and send data collected by the first near detector (3), the second near detector (5) and the second far detector (6).

7. A detection method, used in the four-detector rock-tight plate device according to any one of claims 1 to 6, characterized in that: The following steps are involved: Collecting formation density data and formation photoelectric absorption index cross-section values; Construct well logging density curve based on density values; At the same time, the lithology logging curve is constructed based on the numerical value of the photoelectric absorption index cross section of the formation.

8. A detection method according to claim 7, characterized in that: Collecting the density data of the formation and the cross-section value of the photoelectric absorption index of the formation includes the following steps: The formation density data are collected respectively by a first far detector (2), a first near detector (3), a second near detector (5) and a second far detector (6); Simultaneously, the first remote detector (2) and the second remote detector (6) are used to collect the cross-section value of the stratum photoelectric absorption index.

9. A detection method according to claim 7, characterized in that: Constructing a well logging density curve based on density values ​​includes the following steps: Obtaining a first density value through density data collected by a first far detector (2) and a first near detector (3); Obtaining a second density value through density data collected by the first far detector (2) and the second near detector (5); Obtaining a third density value through density data collected by the second far detector (6) and the second near detector (5); Obtaining a fourth density value through density data collected by the second far detector (6) and the first near detector (3); A weighted average of the first density value, the second density value, the third density value and the fourth density value is calculated to obtain a composite density value, and a logging density curve is constructed according to the composite density value and the logging depth.

10. A detection method according to claim 9, characterized in that: The lithology logging curve is constructed based on the numerical value of the formation photoelectric absorption index cross section, including the following steps: Obtaining a first lithology value through a formation photoelectric absorption index cross-section value collected by a first remote detector (2); The cross-sectional values ​​of the photoelectric absorption index of the formation collected by the second remote detector (6) constitute the second lithology value; A synthetic lithology value is formed by the first lithology logging curve and the second lithology logging curve, and a lithology logging curve is constructed by the synthetic lithology value and the logging depth.

11. A detection method according to claim 10, 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 density value to the fourth density value are obtained by the undamaged detector and synthesized to obtain a synthesized density value, and then the synthesized density value and the logging depth are used to construct a logging density curve; When any one of the first remote detector (2) and the second remote detector (6) is damaged, the lithology value obtained from the undamaged remote detector data is used as a synthetic lithology value, and the synthetic lithology value and the logging depth are combined to construct a logging lithology curve; When any one of the first remote detector (2) and the second remote detector (6) is damaged, and at the same time any one of the first near detector (3) and the second near detector (5) is damaged, a density value calculated by using the density value collected by the undamaged remote detector and the density value collected by the undamaged near detector is used as a composite density value, and a well logging density curve is constructed by combining the composite density value and the logging depth.

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