While-drilling neutron porosity density measuring device and clock labeling method

Abstract

The invention provides a while-drilling neutron porosity density measuring device and a clock labeling method, and the while-drilling neutron porosity density measuring device comprises an ultra-short pulse neutron generator which is used for generating ultra-short pulse neutrons with a specified time sequence; the fast neutron detector is used for monitoring the yield of the ultrashort pulse neutron generator; the thermal neutron detector group is used for recording thermal neutron flux; and the gamma detector group is used for recording inelastic gamma flux. According to the technical scheme, through the double-epithermal neutron double-gamma structure model, the influence of the stratum density on porosity measurement is effectively eliminated, and the measurement precision is improved.

Description

Background Art

[0002] Neutron porosity logging is one of the most direct and effective methods to measure the hydrogen content of formations. Neutron porosity measurement utilizes the physical principle of the interaction between neutrons and layers, that is, high-energy fast neutrons emitted by a neutron source to the surrounding formations are used to measure the energy and intensity changes of neutrons in the formations in real time, thereby obtaining the porosity and other lithological parameters of the formations encountered.

[0003] Due to health, safety and environmental protection requirements, controlled source pulsed neutron generators have replaced chemical source neutron generators and become the current development direction of neutron logging instruments while drilling. The narrow pulse and burst characteristics of ultrashort pulse neutrons can achieve a clearer secondary neutron time spectrum in detection, and the instantaneous count rate and signal-to-noise ratio of the prompt gamma energy spectrum are also good. Therefore, based on the statistical time distribution of the ultrashort pulse neutron transport physical process and the design of the timing relationship between the ultrashort pulse neutron generator and multiple detectors, a data recording method based on time tags is established, which can achieve high-precision and effective measurement of neutron porosity density. In addition, the measurement results of near- and far-neutron detector count rates and near- and far-gamma count rates directly affect the calculation accuracy of formation porosity and density.

[0004] Therefore, it is an effective way to improve instrument performance to improve the validity of measurement data by optimizing the detector source distance, logging instrument structural parameters, etc., and to improve the accuracy of logging models by optimizing the relationship between the near-far thermal neutron count ratio and porosity response, and the relationship between the near-far gamma count ratio and formation density response.

[0005] The invention patent authorized in China (authorization announcement number: CN 110454147 B) discloses a controlled source integrated nuclear logging instrument and a logging method. The logging instrument includes a neutron generator, a near thermal neutron detector, a thermal neutron detector, a near gamma detector, a far gamma detector, and a far thermal neutron detector. The values ​​detected by the detectors are used to simultaneously calculate the yield of each element in the formation, the formation porosity, and the formation density.

[0006] A controlled source density logging device while drilling is disclosed in a Chinese invention patent (CN 110056341 A). The patent describes the structure of the device in detail, including an independent controlled neutron source chamber while drilling, a detector, a near-source detector, a thermal neutron detector, a far-source detector, a central processing circuit and an ultrasonic caliper. The formation density and porosity information can be obtained by further processing the measurement data of the detector of the device.

[0007] A method and device for determining formation volume density in gamma density logging is disclosed in a Chinese invention patent (authorization announcement number: CN 110486002 B). The method obtains formation volume density by establishing a response relationship between formation volume density and inelastic gamma technology ratio and epithermal neutron count ratio.

[0008] The count value measured by the detector is a statistical value, which has certain measurement errors and directly affects the measurement effect. Summary of the invention

[0009] The present application provides a while-drilling neutron porosity density measurement device and a clock label method, which give full play to the excellent time series synchronization and high signal-to-noise ratio of ultrashort pulse neutrons in neutron detection, thereby improving measurement accuracy and achieving high-precision and effective measurement of formation porosity and density.

[0010] In a first aspect, a neutron porosity density measurement device while drilling is provided, comprising:

[0011] An ultrashort pulse neutron generator is used to generate ultrashort pulse neutrons of specified timing;

[0012] A fast neutron detector, used to monitor the yield of the ultrashort pulse neutron generator;

[0013] A thermal neutron detector set to record thermal neutron flux;

[0014] Gamma detector array to record inelastic gamma flux.

[0015] In the above technical scheme, an ultrashort pulse neutron generator is used to generate ultrashort pulse neutrons of specified timing; a fast neutron detector is used to monitor the output of the ultrashort pulse neutron generator; a thermal neutron detector group is used to record the thermal neutron flux; a gamma detector group is used to record the inelastic gamma flux; and a dual-epitothermal neutron dual-gamma structural model is used to effectively eliminate the influence of formation density on porosity measurement and improve measurement accuracy.

[0016] In a specific embodiment, the thermal neutron detector group includes a proximal thermal neutron detector group and a distal thermal neutron detector group.

[0017] In a specific implementation manner, the gamma detector group includes a proximal gamma detector group and a distal gamma detector group.

[0018] In a specific implementation manner, the proximal thermal neutron detector group includes a first proximal thermal neutron detector and a second proximal thermal neutron detector; the distal thermal neutron detector group includes a first distal thermal neutron detector and a second distal thermal neutron detector.

[0019] In a specific implementation manner, the proximal gamma detector group includes a first proximal gamma detector and a second proximal gamma detector; the distal gamma detector group includes a first distal gamma detector and a second distal gamma detector.

[0020] In a specific embodiment, the thermal neutron detector adopts 3 He detector.

[0021] In a specific embodiment, the gamma detector is a lanthanum bromide scintillation detector.

[0022] In a specific embodiment, it also includes:

[0023] The neutron generator driving and control circuit is used to drive the ultrashort pulse neutron generator.

[0024] In a specific embodiment, it also includes:

[0025] The detector driving and control circuit is used to drive the fast neutron detector, the thermal neutron detector group and the gamma detector group.

[0026] In a second aspect, a clock label method for a neutron porosity density measurement device while drilling is provided, comprising the following steps:

[0027] An ultrashort pulse neutron generator is used to generate ultrashort pulse neutrons of a specified time sequence;

[0028] monitoring the yield of the ultrashort pulse neutron generator using a fast neutron detector;

[0029] Thermal neutron flux was recorded using a thermal neutron detector array;

[0030] The inelastic gamma flux was recorded using a gamma detector array.

[0031] In the above technical scheme, an ultrashort pulse neutron generator is used to generate ultrashort pulse neutrons of specified time sequence; a fast neutron detector is used to monitor the output of the ultrashort pulse neutron generator; a thermal neutron detector group is used to record thermal neutron flux; and a gamma detector group is used to record inelastic gamma flux. The time label characteristics of ultrashort pulses are fully utilized, and the measurement data of the detector group are weighted to improve the measurement accuracy of neutron counting rate and gamma counting rate. According to the response relationship between the inelastic gamma counting ratio and the epithermal neutron counting ratio and the formation porosity and density, accurate formation porosity and density values ​​are calculated. A high-precision time label method is used to ensure the accuracy and traceability of the measurement data, providing a reliable basis for subsequent data analysis and processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the structure of a neutron porosity density measurement device while drilling provided in an embodiment of the present application;

[0033] Figure 2 A schematic diagram of the structure of a proximal thermal neutron detector group provided in an embodiment of the present application;

[0034] Figure 3A schematic diagram of the arrangement of the proximal thermal neutron detector group provided in an embodiment of the present application;

[0035] Figure 4 A flowchart of a clock label method for a while-drilling neutron porosity density measurement device provided in an embodiment of the present application.

[0036] Among them, 1-instrument outer wall, 2-neutron generator drive and control circuit, 3-ultra-short pulse neutron generator, 4-shielding layer, 5-fast neutron detector, 6-proximal thermal neutron detector group, 7-proximal gamma detector group, 8-distal thermal neutron detector group, 9-distal gamma detector group, 601-first proximal thermal neutron detector, 602-second proximal thermal neutron detector, 701-first proximal gamma detector, 702-second proximal gamma detector, 801-first distal thermal neutron detector, 802-second distal thermal neutron detector, 901-first distal gamma detector, 902-second distal gamma detector. DETAILED DESCRIPTION

[0037] The present application is further described in detail below through the accompanying drawings and embodiments. Through these descriptions, the characteristics and advantages of the present application will become clearer and more specific.

[0038] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0039] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0040] To facilitate understanding of the neutron porosity density measurement device and clock label method provided by the embodiment of the present application, its application scenario is first explained. The neutron porosity density measurement device and clock label method provided by the embodiment of the present application give full play to the good time series synchronization and high signal-to-noise ratio of ultrashort pulse neutrons in neutron detection, improve the measurement accuracy, and calculate accurate formation porosity and density values. Neutron porosity logging is one of the most direct and effective methods for measuring the hydrogen content of formations. Neutron porosity measurement utilizes the physical principle of the interaction between neutrons and layers, that is, high-energy fast neutrons emitted by a neutron source to the surrounding formations are used to measure the energy and intensity changes of neutrons in the formation in real time, thereby obtaining the porosity and other lithological parameters of the drilled formation. Due to health, safety and environmental protection requirements, controlled source pulsed neutron generators have replaced chemical source neutron generators to become the current development direction of neutron logging instruments while drilling. The narrow pulse and burst characteristics of ultrashort pulse neutrons can achieve a clearer secondary neutron time spectrum in detection, and the instantaneous count rate and signal-to-noise ratio of the prompt gamma energy spectrum are also good. Therefore, based on the statistical time distribution of the ultrashort pulse neutron transport physical process and the design of the timing relationship between the ultrashort pulse neutron generator and multiple detectors, a data recording method based on time tags is established, which can achieve high-precision and effective measurement of neutron porosity density. In addition, the measurement results of near and far neutron detector count rates and near and far gamma count rates directly affect the calculation accuracy of formation porosity and density. Therefore, it is an effective method to improve the performance of the instrument to improve the effectiveness of the measurement data by optimizing the detector source distance, the structural parameters of the logging instrument, etc., and to improve the accuracy of the logging model by optimizing the relationship between the near and far thermal neutron count ratio and the porosity response, the near and far gamma count ratio and the formation density response, etc. To this end, the embodiment of the present application provides a neutron porosity density measurement device and a clock tag method while drilling to improve the measurement accuracy and calculate accurate formation porosity and density values. It is described in detail below with specific drawings and embodiments.

[0041] refer to Figures 1 to 4 , Figure 1 A schematic diagram of the structure of a neutron porosity density measurement device while drilling provided in an embodiment of the present application; Figure 2 A schematic diagram of the structure of a proximal thermal neutron detector group provided in an embodiment of the present application; Figure 3 A schematic diagram of the arrangement of the proximal thermal neutron detector group provided in an embodiment of the present application; Figure 4 A flowchart of a clock label method for a while-drilling neutron porosity density measurement device provided in an embodiment of the present application.

[0042] exist Figures 1 to 3 In the embodiment of the present application, a neutron porosity density measurement device while drilling is provided, comprising:

[0043] An ultrashort pulse neutron generator is used to generate ultrashort pulse neutrons of specified timing;

[0044] A fast neutron detector, used to monitor the yield of the ultrashort pulse neutron generator;

[0045] A thermal neutron detector set to record thermal neutron flux;

[0046] Gamma detector array to record inelastic gamma flux.

[0047] In the above technical scheme, an ultrashort pulse neutron generator is used to generate ultrashort pulse neutrons of specified timing; a fast neutron detector is used to monitor the output of the ultrashort pulse neutron generator; a thermal neutron detector group is used to record the thermal neutron flux; a gamma detector group is used to record the inelastic gamma flux; and a dual-epitothermal neutron dual-gamma structural model is used to effectively eliminate the influence of formation density on porosity measurement and improve measurement accuracy.

[0048] In a specific embodiment, the thermal neutron detector group includes a proximal thermal neutron detector group and a distal thermal neutron detector group.

[0049] In a specific implementation manner, the gamma detector group includes a proximal gamma detector group and a distal gamma detector group.

[0050] In a specific implementation manner, the proximal thermal neutron detector group includes a first proximal thermal neutron detector and a second proximal thermal neutron detector; the distal thermal neutron detector group includes a first distal thermal neutron detector and a second distal thermal neutron detector.

[0051] In a specific implementation manner, the proximal gamma detector group includes a first proximal gamma detector and a second proximal gamma detector; the distal gamma detector group includes a first distal gamma detector and a second distal gamma detector.

[0052] In a specific embodiment, the thermal neutron detector adopts 3 He detector.

[0053] In a specific embodiment, the gamma detector is a lanthanum bromide scintillation detector.

[0054] In a specific embodiment, it also includes:

[0055] The neutron generator driving and control circuit is used to drive the ultrashort pulse neutron generator.

[0056] In a specific embodiment, it also includes:

[0057] The detector driving and control circuit is used to drive the fast neutron detector, the thermal neutron detector group and the gamma detector group.

[0058] Specifically, the neutron porosity density measurement device while drilling includes: a neutron generator drive and control circuit, an ultrashort pulse neutron generator, a fast neutron detector, a long and short source distance 3 He detector set, long and short source distance lanthanum bromide (LaBr3) scintillation detector set.

[0059] Among them, the neutron generator drive and control circuit is used to drive the ultrashort pulse neutron generator to generate ultrashort pulses of specified timing, and the fast neutron detector is used to monitor the output of the ultrashort pulse neutron generator. 3 He detectors are used to record thermal neutron flux, and lanthanum bromide (LaBr3) scintillation detectors are used to record inelastic gamma flux.

[0060] Two detectors with the same parameters are staggered in each detector group, and the detector measurement position can be moved within a limited range, thereby changing the measurement source distance.

[0061] refer to Figures 1 to 3 The neutron porosity density measurement device while drilling includes: an instrument outer wall 1, a neutron generator drive and control circuit 2, an ultrashort pulse neutron generator 3, a shielding layer (cadmium) 4, a fast neutron detector 5, a proximal thermal neutron detector group 6, a proximal gamma detector group 7, a distal thermal neutron detector group 8, a distal gamma detector group 9, and a detector drive and control circuit.

[0062] Among them, the proximal thermal neutron detector group 6 includes a first proximal thermal neutron detector 601 and a second proximal thermal neutron detector 602 placed at a distance of L, the proximal gamma detector group 7 includes a first proximal gamma detector 701 and a second proximal gamma detector 702 placed at a distance of L, the distal thermal neutron detector group 8 includes a first distal thermal neutron detector 801 and a second distal thermal neutron detector 802 placed at a distance of L, and the distal gamma detector group 9 includes a first distal gamma detector 901 and a second distal gamma detector 902.

[0063] refer to Figure 2 and Figure 3 Taking the proximal thermal neutron detector group 6 as an example, the detector position structure in the detector group is explained. Specifically, the proximal thermal neutron detector group 6 includes a first proximal thermal neutron detector 601 and a second proximal thermal neutron detector 602 placed at a distance L; since the first proximal thermal neutron detector 601 and the second proximal thermal neutron detector 602 can move in the detector housing, the following can be obtained: Figure 3 The four position structures shown are used to better detect signals.

[0064] In a specific implementation scheme, taking the proximal thermal neutron detector group as an example, the method of using the detector group data is described, including:

[0065] The proximal thermal neutron detector group is used to measure the count values, which are n1 and n2 respectively; according to the actual application requirements, the proximal thermal neutron count value n=f(n1,n2) is set.

[0066] Preferably, but not limited to: n=a*n1+b*n2, wherein a and b are coefficients, and the coefficient values ​​are determined by instrument calibration optimization.

[0067] Preferably, but not limited to: n = a1*e a2*n1 +b1*e b2*n2 , where a1, a2, b1, and b2 are coefficients, and the coefficient values ​​are determined by instrument calibration optimization.

[0068] In the present embodiment, a while-drilling neutron porosity and density measurement device is provided. By arranging a thermal neutron detector group and a gamma detector group in the measurement device, an integrated measurement instrument for the porosity and density of the target formation is realized. An ultrashort pulse neutron generator is used, and the detection accuracy and signal-to-noise ratio of the detector are improved by controlling the ultrashort pulse neutron generator to generate pulsed neutrons of a specified timing, thereby realizing high-precision measurement of the formation porosity and density.

[0069] exist Figure 4 In the embodiment of the present application, a clock label method of a neutron porosity density measurement device while drilling is provided, comprising the following steps:

[0070] An ultrashort pulse neutron generator is used to generate ultrashort pulse neutrons of a specified time sequence;

[0071] Monitoring the yield of the ultrashort pulse neutron generator using a fast neutron detector;

[0072] Thermal neutron flux was recorded using a thermal neutron detector array;

[0073] The inelastic gamma flux was recorded using a gamma detector array.

[0074] In the above technical scheme, an ultrashort pulse neutron generator is used to generate ultrashort pulse neutrons of specified time sequence; a fast neutron detector is used to monitor the output of the ultrashort pulse neutron generator; a thermal neutron detector group is used to record thermal neutron flux; and a gamma detector group is used to record inelastic gamma flux. The time label characteristics of ultrashort pulses are fully utilized, and the measurement data of the detector group are weighted to improve the measurement accuracy of neutron counting rate and gamma counting rate. According to the response relationship between the inelastic gamma counting ratio and the epithermal neutron counting ratio and the formation porosity and density, accurate formation porosity and density values ​​are calculated. A high-precision time label method is used to ensure the accuracy and traceability of the measurement data, providing a reliable basis for subsequent data analysis and processing.

[0075] Specifically, the ultrashort pulse neutron generator is stimulated to emit high-energy fast neutrons, which enter the formation and undergo a deceleration and diffusion effect. The fast neutron detector first detects the neutron count value to monitor the neutron generator yield;

[0076] Neutrons entering the formation are decelerated and diffused, and the decelerated thermal neutrons are detected by the near-end thermal neutron detector group and the far-end thermal neutron detector group in turn, and the gamma rays released by the reaction with the formation elements are detected by the far-end gamma detector group and the near-end gamma detector group in turn;

[0077] According to the response relationship between the inelastic gamma count ratio and epithermal neutron count ratio and the formation porosity and density, accurate formation porosity and density values ​​are calculated; the high-precision time label method is used to ensure the accuracy and traceability of the measurement data, providing a reliable basis for subsequent data analysis and processing.

[0078] Those skilled in the art will appreciate that the present application may be implemented as a system, method or computer program product.

[0079] Therefore, the present disclosure may be specifically implemented in the following forms, namely: it may be completely hardware, it may be completely software (including firmware, resident software, microcode, etc.), or it may be a combination of hardware and software, generally referred to herein as a "circuit", "module" or "system". In addition, in some embodiments, the present application may also be implemented in the form of a computer program product in one or more computer-readable media, and the computer-readable medium may contain computer-readable program code.

[0080] Any combination of one or more computer-readable media can be used. Computer-readable media can be computer-readable signal media or computer-readable storage media. Computer-readable storage media can be, for example, but not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or devices, or any combination of the above. More specific examples (non-exhaustive list) of computer-readable storage media include: electrical connections with one or more wires, portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), optical fibers, portable compact disk read-only memories (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the above. In this document, computer-readable storage media can be any tangible medium containing or storing a program, which can be used by an instruction execution system, device or device or used in combination with it.

[0081] Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art can change, modify, replace and modify the above embodiments within the scope of the present application. On this basis, a variety of replacements and improvements can be made to the present application, all of which fall within the scope of protection of the present application.

Claims

1. A neutron porosity density measurement device while drilling, characterized in that: include: An ultrashort pulse neutron generator is used to generate ultrashort pulse neutrons of specified timing; A fast neutron detector, used to monitor the yield of the ultrashort pulse neutron generator; A thermal neutron detector set to record thermal neutron flux; Gamma detector array to record inelastic gamma flux.

2. The neutron porosity density measurement device while drilling according to claim 1, characterized in that: The thermal neutron detector group includes a proximal thermal neutron detector group and a distal thermal neutron detector group.

3. The neutron porosity density measurement device while drilling according to claim 2, characterized in that: The gamma detector group includes a proximal gamma detector group and a distal gamma detector group.

4. The neutron porosity density measurement device while drilling according to claim 3, characterized in that: The proximal thermal neutron detector group includes a first proximal thermal neutron detector and a second proximal thermal neutron detector; the distal thermal neutron detector group includes a first distal thermal neutron detector and a second distal thermal neutron detector.

5. The neutron porosity density measurement device while drilling according to claim 4, characterized in that: The proximal gamma detector group includes a first proximal gamma detector and a second proximal gamma detector; the distal gamma detector group includes a first distal gamma detector and a second distal gamma detector.

6. The neutron porosity density measurement device while drilling according to claim 5, characterized in that: The thermal neutron detector adopts 3 He detector.

7. The neutron porosity density measurement device while drilling according to claim 6, characterized in that: The gamma detector adopts a lanthanum bromide scintillation detector.

8. The neutron porosity density measurement device while drilling according to claim 7, characterized in that: Also includes: The neutron generator driving and control circuit is used to drive the ultrashort pulse neutron generator.

9. The neutron porosity density measurement device while drilling according to claim 8, characterized in that: Also includes: The detector driving and control circuit is used to drive the fast neutron detector, the thermal neutron detector group and the gamma detector group.

10. A clock labeling method for a neutron porosity density measurement device while drilling, characterized in that: The following steps are involved: An ultrashort pulse neutron generator is used to generate ultrashort pulse neutrons of a specified time sequence; Monitoring the yield of the ultrashort pulse neutron generator using a fast neutron detector; Thermal neutron flux was recorded using a thermal neutron detector array; The inelastic gamma flux was recorded using a gamma detector array.

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