Neutron well logging system and method with self-adjustment of neutron source yield

Abstract

The present invention provides a neutron logging system and method with self-regulation of neutron source yield, the system comprising a neutron source controller, a power module, a controllable neutron source, a neutron yield monitor, and a neutron logging detector, wherein the neutron source controller is connected to the power module; the power module is connected to the controllable neutron source; the neutron yield monitor is arranged in the zero source distance zone of the controllable neutron source, and the neutron yield monitor is communicatively connected to the neutron source controller; the neutron logging detector is arranged in the positive source distance zone of the controllable neutron source. The present invention adopts a controllable neutron source, avoids the risk of radiation of an isotope neutron source, and has high environmental protection and safety; and realizes self-regulation of neutron source yield, overcomes the application difficulties caused by the unstable yield of domestic controllable neutron sources, and improves the accuracy of neutron logging measurement results; it can be used for both D-T controllable neutron sources and D-D controllable neutron sources.

Description

Technical Field

[0001] The invention relates to the technical field of oil and natural gas well logging, and in particular to a neutron well logging system and method with self-regulation of neutron source yield. Background Art

[0002] In the process of geological logging, neutron logging technology is an indispensable logging method. This technology uses the principle of interaction between neutrons and formation materials. Through a neutron source, high-energy neutrons are emitted to the surrounding formations, and the energy and intensity changes of neutrons or gamma rays in the formations are detected in real time, thereby obtaining information on the porosity, density and even element content of the formation.

[0003] Among the existing neutron logging instruments, those based on natural isotope neutron sources are mature and widely used. However, due to the strong radioactivity of isotope neutron sources, it is difficult to avoid health hazards to on-site operators. In addition, the risk of isotope source loss and jamming during logging will cause huge economic losses and environmental pollution. People are paying more and more attention to the radiation hazards of isotope sources.

[0004] In order to solve the safety problem of isotope sources, controllable accelerator neutron sources are gradually used as substitutes in neutron logging instruments. However, the current processing and manufacturing level of controllable neutron sources in China is average, and the neutron yield is not stable, which will lead to inaccurate measurement results of neutron logging detectors and increased errors. Summary of the invention

[0005] The technical problems to be solved by the present invention are: how to avoid the risk of radiation from isotope neutron sources of neutron logging instruments and improve environmental protection and safety; and how to stabilize the yield of controllable neutron sources and improve the accuracy of measurement results of neutron logging detectors.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] The invention provides a neutron well logging system with self-adjusting neutron source yield, comprising a neutron source controller, a power module, a controllable neutron source, a neutron yield monitor, and a neutron well logging detector, wherein the power module is connected to the controllable neutron source; the neutron yield monitor is arranged in a zero source distance zone of the controllable neutron source, and the neutron yield monitor is communicatively connected with the neutron source controller; the neutron source controller is connected to the power module, and the neutron source controller receives data from the neutron yield monitor and controls the voltage or current of the power module according to the received data; and the neutron well logging detector is arranged in a positive source distance zone of the controllable neutron source.

[0008] The beneficial effects of the present invention are as follows: the present invention adopts a controllable neutron source, avoids the risk of radiation from an isotope neutron source, and is highly environmentally friendly and safe; and realizes self-regulation of the neutron source yield, overcomes the difficulty in application caused by the unstable yield of domestic controllable neutron sources, and improves the accuracy of neutron logging measurement results; it can be used for both DT controllable neutron sources and DD controllable neutron sources. In addition, the neutron yield monitor of the present invention is installed in the zero source distance area, and the counting rate is not affected by factors such as formation porosity, so the instrument is suitable for a variety of geological environments and has a wide range of applications; and it is at a certain distance from the controllable neutron source, saving installation space at the neutron source and reducing the outer diameter of the neutron logging instrument.

[0009] Based on the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, the power supply module is used to supply power to the controllable neutron source, the neutron yield monitor is used to monitor the neutron flux density of the controllable neutron source and send the detected neutron flux density data to the neutron source controller, and the neutron source controller is used to control the output voltage or current of the power supply module according to the received neutron flux density data.

[0011] The beneficial effect of the above further solution is that feedback control is formed on the neutron yield of the controllable neutron source so that the neutron yield is maintained at a rated value.

[0012] Furthermore, the neutron source controller is used to control the output voltage or current of the power module according to the received neutron flux density data, specifically including: the neutron source controller obtains the neutron yield by inversion calculation of the neutron flux density detected by the neutron yield monitor, and compares the calculated neutron yield with the rated neutron yield value, and controls the output voltage or current of the power module according to the comparison result.

[0013] The beneficial effect of the above further solution is: the neutron yield is kept at the rated value, thereby achieving self-regulation of the neutron yield and improving the accuracy of the neutron logging measurement results.

[0014] Furthermore, the calculated neutron yield is compared with the rated neutron yield value, and the output voltage or current of the power module is controlled according to the comparison result, specifically including: when the calculated neutron yield is less than the rated neutron yield value, the neutron source controller increases the output voltage or current of the power module to improve the neutron yield; when the calculated neutron yield is greater than the rated neutron yield value, the neutron source controller reduces the output voltage or current of the power module to reduce the neutron yield; when the calculated neutron yield is equal to the rated neutron yield value, the neutron source controller does not act, maintains the output voltage or current of the power module, and maintains the neutron yield.

[0015] The beneficial effect of the above further solution is that it is easy to program and realize self-regulation of neutron yield.

[0016] Furthermore, the neutron logging detector is used to detect the flux distribution or energy spectrum distribution information of neutrons or gamma rays in the formation.

[0017] The beneficial effect of the above further scheme is: using neutron or gamma detectors to measure the neutron or gamma flux distribution in the formation to reflect the rate at which the neutron or gamma density in the formation decays with the source distance, and by calculating and processing the recorded curves, information on the formation porosity, density and even the formation element content can be obtained.

[0018] Furthermore, the neutron logging detector includes either or both of a gamma detector and a neutron detector.

[0019] The beneficial effect of the above further solution is that the corresponding neutron logging detector can be flexibly selected according to different detection objects, so the neutron logging system has a wide applicability.

[0020] Furthermore, the controllable neutron source is a DT controllable neutron source or a DD controllable neutron source.

[0021] The beneficial effects of the above further solution are good controllability and good applicability.

[0022] The present invention also provides a neutron well logging method with self-adjustment of neutron source yield, comprising the following steps:

[0023] Step 1: The power module supplies power to the controllable neutron source, and the controllable neutron source emits neutrons outward;

[0024] Step 2: The neutron yield monitor monitors the neutron flux density in the zero source distance area of ​​the controllable neutron source, and sends the detected neutron flux density data to the neutron source controller;

[0025] Step 3: The neutron source controller controls the output voltage or current of the power module according to the received neutron flux density data, thereby controlling the neutron yield of the controllable neutron source;

[0026] Step 4: The neutron logging detector detects the flux distribution or energy spectrum distribution information of neutrons or gamma rays in the formation in the positive source distance area of ​​the controllable neutron source.

[0027] The beneficial effects of the present invention are: it can be implemented on the existing controllable neutron logging instrument, and has good practicality; it realizes the self-regulation of neutron source yield, overcomes the application difficulties caused by the unstable yield of domestic controllable neutron sources, and improves the accuracy of neutron logging measurement results; it can be used for both DT controllable neutron sources and DD controllable neutron sources. In addition, the neutron yield monitor of the present invention is installed in the zero source distance area, and the counting rate is not affected by factors such as formation porosity, so the instrument is suitable for a variety of geological environments and has a wide range of applications; and it is at a certain distance from the controllable neutron source, saving the installation space at the neutron source and reducing the outer diameter size of the neutron logging instrument.

[0028] Furthermore, the step three specifically includes: the neutron source controller obtains the neutron yield by inverse calculation of the neutron flux density detected by the neutron yield monitor, compares the calculated neutron yield with the rated neutron yield value, and controls the output voltage or current of the power module according to the comparison result.

[0029] The beneficial effect of the above further solution is that feedback control is formed on the neutron yield of the controllable neutron source so that the neutron yield is maintained at a rated value.

[0030] Further, comparing the calculated neutron yield with the rated neutron yield value, and controlling the output voltage or current of the power module according to the comparison result, specifically includes:

[0031] When the calculated neutron yield is less than the rated neutron yield value, the neutron source controller increases the output voltage or current of the power module to increase the neutron yield; when the calculated neutron yield is greater than the rated neutron yield value, the neutron source controller reduces the output voltage or current of the power module to reduce the neutron yield; when the calculated neutron yield is equal to the rated neutron yield value, the neutron source controller does not act, maintains the output voltage or current of the power module, and maintains the neutron yield.

[0032] The beneficial effects of the above further solution are: keeping the neutron yield at the rated value, thereby achieving self-regulation of the neutron yield and improving the accuracy of the neutron logging measurement results; and being easy to implement through programming. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the present invention.

[0034] Figure 2 This is a graph showing the change of neutron counts with source distance under different porosities.

[0035] In the accompanying drawings, the technical features represented by the reference numerals are as follows:

[0036] 1- neutron source controller; 2- power module; 3- controllable neutron source; 4- neutron yield monitor; 5- neutron logging detector; 6- formation; 7- wellbore. DETAILED DESCRIPTION

[0037] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0038] The present invention refers to Figure 1-2 .

[0039] Embodiment 1, as Figure 1-2 As shown:

[0040] The present invention provides a neutron well logging system with self-adjustment of neutron source yield, comprising a neutron source controller 1, a power module 2, a controllable neutron source 3, a neutron yield monitor 4, and a neutron well logging detector 5, wherein the power module 2 is connected to the controllable neutron source 3; the neutron yield monitor 4 is arranged in a zero source distance zone of the controllable neutron source 3, and the neutron yield monitor 4 is communicatively connected to the neutron source controller 1; the neutron source controller 1 is connected to the power module 2, the neutron source controller 1 receives data from the neutron yield monitor 4, and controls the voltage or current of the power module 2 according to the received data; and the neutron well logging detector 5 is arranged in a positive source distance zone of the controllable neutron source 3.

[0041] Principle: During the use of the neutron logging system with self-adjusting neutron source yield, the whole is placed in the wellbore 7, and the controllable neutron source 3 emits high-energy neutrons to the formation 6. After the neutrons are decelerated and slowed down by the formation 6, they are detected by the neutron yield monitor 4 installed at the zero source distance. The neutron flux density detected by the neutron yield monitor 4 is transmitted to the neutron source controller 1. The neutron source controller 1 compares the neutron yield obtained by inversion calculation of the detected neutron flux with the rated neutron yield value, and adjusts the parameters (power supply voltage, current) of the controllable neutron source 3 in real time according to the yield deviation value to keep the neutron yield at the rated value, thereby realizing self-adjustment of neutron yield. For example, when the neutron yield detected by the neutron yield monitor 4 is less than the rated neutron yield value through inversion calculation of the neutron flux, the neutron source controller 1 increases the power supply voltage or current output by the power module 2 to the controllable neutron source 3 to increase the neutron yield; otherwise, the neutron source controller 1 reduces the power supply voltage or current output by the power module 2 to the controllable neutron source 3 to reduce the neutron yield. In this way, under the current situation that the neutron yield of the domestic controllable neutron source 3 is unstable, the present invention can also adjust the neutron yield in real time, ensure the accuracy of the measurement results of the neutron logging detector 5, and reduce the logging error.

[0042] Note: Rated neutron yield value (rated value) is set according to the logging principle, and its allowable fluctuation range can be determined according to the accuracy requirements of the logging site.

[0043] If the detection accuracy requirement is small, the allowable error of neutron yield will be large and the rated range will be large; conversely, the rated range will be small.

[0044] The controllable neutron source 3 can be a DD source or a DT source.

[0045] The neutron yield monitor 4 is a neutron detector that receives neutrons from all directions and counts them.

[0046] The concept of source distance (such as Figure 2 As shown in the figure): A general term, source distance is the distance from the neutron source. The neutron count measurement value of the neutron detector varies with the source distance. According to the gradual increase of the source distance, it can be divided into three intervals: negative source distance zone, zero source distance zone, and positive source distance zone. Definition: In the negative source distance zone, the neutron detector count value increases with the increase of the porosity of formation 6; in the zero source distance zone, the detector count value does not change with the porosity of formation 6 (the change is very small, which is regarded as no change, and the count values ​​of each porosity are similar); in the positive source distance zone, the count value decreases with the increase of the porosity of formation 6. Figure 2 In the figure, different curves represent the relationship between the neutron flux density measured by the neutron yield monitor 4 and the source distance under different formation porosities. The horizontal axis represents the source distance (the distance between the neutron yield monitor 4 and the neutron source), and the vertical axis represents the neutron flux density measured by the neutron yield monitor 4.

[0047] from Figure 2 It can be seen that in the zero source distance area, the counting values ​​of the neutron yield monitor 4 under different formation 6 porosities are basically in the same order of magnitude and the difference is very small. It can be considered that the counting value does not change with the porosity of the formation 6. Therefore, the neutron yield monitor 4 is installed in this area to avoid the counting value of the neutron yield monitor 4 being affected by the porosity of the formation 6. After the inversion calculation, the counting value of the neutron yield monitor 4 can well reflect the neutron yield change of the controllable neutron source 3.

[0048] The beneficial effects of the present invention are as follows: the present invention adopts a controllable neutron source 3, avoids the risk of radiation from an isotope neutron source, and is highly environmentally friendly and safe; and realizes self-regulation of the neutron source yield, which is particularly suitable for the application requirements of the domestic controllable neutron source 3, and improves the accuracy of the neutron logging measurement results; and can be used for both DT controllable neutron sources and DD controllable neutron sources. In addition, the neutron yield monitor 4 of the present invention is installed in the zero source distance area, and the counting rate is not affected by factors such as the porosity of the formation 6, so the instrument is suitable for a variety of geological environments and has a wide range of applications; and it is at a certain distance from the controllable neutron source 3, which saves installation space at the neutron source and reduces the outer diameter size of the neutron logging instrument.

[0049] Furthermore, the power module 2 is used to supply power to the controllable neutron source 3, the neutron yield monitor 4 is used to monitor the neutron flux density of the controllable neutron source 3, and send the detected neutron flux density data to the neutron source controller 1, and the neutron source controller 1 is used to control the output voltage or current of the power module 2 according to the received neutron flux density data.

[0050] The beneficial effect of the above further solution is that feedback control is formed on the neutron yield of the controllable neutron source 3 so that the neutron yield is maintained at a rated value.

[0051] Furthermore, the neutron source controller 1 is used to control the output voltage or current of the power module 2 according to the received neutron flux density data, specifically including: the neutron source controller 1 obtains the neutron yield by inversion calculation of the neutron flux density detected by the neutron yield monitor 4, and compares the calculated neutron yield with the rated neutron yield value, and controls the output voltage or current of the power module 2 according to the comparison result.

[0052] The beneficial effect of the above further solution is: the neutron yield is kept at the rated value, thereby achieving self-regulation of the neutron yield and improving the accuracy of the neutron logging measurement results.

[0053] Furthermore, the calculated neutron yield is compared with the rated neutron yield value, and the output voltage or current of the power module 2 is controlled according to the comparison result, specifically including: when the calculated neutron yield is less than the rated neutron yield value, the neutron source controller 1 increases the output voltage or current of the power module 2 to increase the neutron yield; when the calculated neutron yield is greater than the rated neutron yield value, the neutron source controller 1 reduces the output voltage or current of the power module 2 to reduce the neutron yield; when the calculated neutron yield is equal to the rated neutron yield value, the neutron source controller 1 does not act, maintains the output voltage or current of the power module 2, and maintains the neutron yield.

[0054] The beneficial effect of the above further solution is that it is easy to program and realize self-regulation of neutron yield.

[0055] Furthermore, the neutron logging detector 5 is used to detect the flux distribution or energy spectrum distribution information of neutrons or gamma rays in the formation.

[0056] The beneficial effect of the above further scheme is: using neutron or gamma detectors to measure the neutron or gamma flux distribution in the formation to reflect the rate at which the neutron or gamma density in the formation decays with the source distance, and by calculating and processing the recorded curves, the formation porosity, density and even formation element content information can be obtained.

[0057] Furthermore, the neutron logging detector 5 includes either or both of a gamma detector and a neutron detector.

[0058] Note: The neutron logging detectors 5 are all in the positive source distance zone. The number and type of neutron logging detectors 5 should be reasonably configured according to different detection objects. For example, two thermal neutron detectors with different source distances are used to measure formation porosity information, and four gamma detectors with different source distances are used to measure formation water velocity information. (See Example 3 and Example 4 for details)

[0059] The beneficial effect of the above further solution is that the corresponding neutron logging detector 5 can be flexibly selected according to different detection objects, so the neutron logging system has a wide applicability.

[0060] Embodiment 2:

[0061] The present invention also provides a neutron well logging method with self-adjustment of neutron source yield, comprising the following steps:

[0062] Step 1: The power module 2 supplies power to the controllable neutron source 3, and the controllable neutron source 3 emits neutrons outward;

[0063] Step 2: The neutron yield monitor 4 monitors the neutron flux density in the zero source distance area of ​​the controllable neutron source 3, and sends the detected neutron flux density data to the neutron source controller 1;

[0064] Step 3: The neutron source controller 1 controls the output voltage or current of the power module 2 according to the received neutron flux density data, thereby controlling the neutron yield of the controllable neutron source 3;

[0065] Step 4: The neutron logging detector 5 detects the flux distribution or energy spectrum distribution information of neutrons or gamma rays in the formation 6 in the positive source distance area of ​​the controllable neutron source 3 .

[0066] The beneficial effects of the present invention are: it can be implemented on the existing controllable neutron logging instrument, and has good practicality; it realizes the self-regulation of neutron source yield, and is particularly suitable for the application requirements of the domestic controllable neutron source 3, and improves the accuracy of the neutron logging measurement results; it can be used for both DT controllable neutron sources and DD controllable neutron sources. In addition, the neutron yield monitor 4 of the present invention is installed in the zero source distance area, and the counting rate is not affected by factors such as the porosity of the formation 6, so the instrument is suitable for a variety of geological environments and has a wide range of applications; and it is at a certain distance from the controllable neutron source 3, which saves the installation space at the neutron source and reduces the outer diameter size of the neutron logging instrument.

[0067] Furthermore, the step three specifically includes: the neutron source controller 1 obtains the neutron yield by inverse calculation of the neutron flux density detected by the neutron yield monitor 4, compares the calculated neutron yield with the rated neutron yield value, and controls the output voltage or current of the power module 2 according to the comparison result.

[0068] The beneficial effect of the above further solution is that feedback control is formed on the neutron yield of the controllable neutron source 3 so that the neutron yield is maintained at a rated value.

[0069] Further, the calculated neutron yield is compared with the rated neutron yield value, and the output voltage or current of the power module 2 is controlled according to the comparison result, specifically including:

[0070] When the calculated neutron yield is less than the rated neutron yield value, the neutron source controller 1 increases the output voltage or current of the power module 2 to increase the neutron yield; when the calculated neutron yield is greater than the rated neutron yield value, the neutron source controller 1 reduces the output voltage or current of the power module 2 to reduce the neutron yield; when the calculated neutron yield is equal to the rated neutron yield value, the neutron source controller 1 does not act, maintains the output voltage or current of the power module 2, and maintains the neutron yield.

[0071] The beneficial effects of the above further solution are: keeping the neutron yield at the rated value, thereby achieving self-regulation of the neutron yield and improving the accuracy of the neutron logging measurement results; and being easy to implement through programming.

[0072] Embodiment 3: Neutron well logging instrument with self-adjusting neutron source yield:

[0073] Compared with the first embodiment, the present embodiment has the following features:

[0074] According to the first embodiment, the number and type of neutron logging detectors 5 should be reasonably configured according to different detection objects, such as compensated neutron porosity logging.

[0075] According to the first embodiment: the neutron logging detector 5 includes one or both of a gamma detector and a neutron detector. Specifically: the neutron logging detector 5 is composed of two thermal neutron detectors with different source distances.

[0076] Note: Thermal neutron detector is a type of neutron detector.

[0077] Principle: During the use of the neutron logging instrument with self-adjusting neutron source yield, the entire instrument is placed in the wellbore 7, and the controllable neutron source 3 emits high-energy neutrons to the formation 6. After the neutrons are decelerated and moderated by the formation 6, they are detected by the neutron yield monitor 4 installed at the zero source distance. The neutron flux density detected by the neutron yield monitor 4 is transmitted to the neutron source controller 1. The neutron source controller 1 compares the neutron yield obtained by inversion calculation of the detected neutron flux with the set rated neutron yield value, and adjusts the parameters (power supply voltage, current) of the controllable neutron source 3 in real time according to the yield deviation value, so that the neutron yield is maintained at the rated value, thereby realizing self-regulation of the neutron yield in the compensated neutron porosity logging process.

[0078] In addition, the high-energy neutrons emitted by the controllable neutron source 3 become thermal neutrons after being decelerated and moderated by the formation. In this process, since the hydrogen atoms in the formation have the closest mass to that of neutrons and have the strongest deceleration ability for neutrons, the counting rate of the thermal neutron detector is directly related to the hydrogen content of the formation, that is, the lower the counting rate, the higher the hydrogen content of the formation and the greater the porosity of the formation.

[0079] In order to eliminate the influence of other elements in the rock on the measurement results, porosity logging usually adopts compensation, that is, thermal neutron detectors with long and short source distances are used to measure the thermal neutrons slowed down by the formation and scattered back into the wellbore, and the counting rates of the two detectors are obtained. The ratio of the counting rates of the two detectors directly reflects the changes in formation porosity.

[0080] The beneficial effects of the present invention are as follows: the present invention adopts a controllable neutron source 3, avoids the risk of isotope neutron source radiation, and has high environmental protection and safety; and realizes self-regulation of neutron source yield, ensures the stability of neutron source yield during neutron porosity logging, and improves the accuracy of neutron porosity logging results. In addition, the neutron yield monitor 4 of the present invention is installed in the zero source distance area, and the counting rate is not affected by factors such as the porosity of the formation 6, so the instrument is suitable for a variety of geological environments and has a wide range of applications; and it is at a certain distance from the controllable neutron source 3, saving installation space at the neutron source and reducing the outer diameter size of the neutron porosity logging instrument.

[0081] Embodiment 4: Neutron well logging instrument with self-adjusting neutron source yield:

[0082] Compared with the first embodiment, the present embodiment has the following features:

[0083] According to the first embodiment, the number and type of neutron logging detectors 5 should be reasonably configured according to different detection objects. The detection object is: neutron oxygen activated water flow logging.

[0084] According to the first embodiment, the neutron logging detector 5 includes one or both of a gamma detector and a neutron detector. Specifically, the neutron logging detector 5 is composed of four gamma detectors with different source distances.

[0085] Principle: During the use of the neutron oxygen activated water flow logging instrument with self-adjusting neutron source yield, the entire instrument is placed in the wellbore 7, and the controllable neutron source 3 emits high-energy neutrons to the formation 6. After the neutrons are decelerated and moderated by the formation 6, they are detected by the neutron yield monitor 4 installed at the zero source distance. The neutron flux density detected by the neutron yield monitor 4 is transmitted to the neutron source controller 1. The neutron source controller 1 compares the neutron yield obtained by inversion calculation of the detected neutron flux with the set rated neutron yield value, and adjusts the parameters (power supply voltage, current) of the controllable neutron source 3 in real time according to the yield deviation value, so that the neutron yield is maintained at the rated value, thereby realizing self-regulation of the neutron yield in the oxygen activation logging process.

[0086] In addition, the high-energy neutrons emitted by the controlled neutron source 3 simultaneously interact with the oxygen nuclei in the water. 16 O undergoes activation reaction to produce radioactive isotopes 16 N, unstable 16 N decay produces 16O and high-energy gamma rays, 4 gamma detectors with different source distances form a neutron logging detector 5 to measure gamma counts at different positions. When the activated water passes through these gamma detectors, a peak will be generated on the time spectrum. The time when the activated water flow reaches the detector is known according to the position of the peak on the time spectrum, and then the flow rate is obtained based on the detector source distance. The calculation results of the 4 detectors are selected as the final measurement value.

[0087] The beneficial effects of the present invention are as follows: the present invention adopts a controllable neutron source 3, avoids the risk of isotope neutron source radiation, is environmentally friendly and safe, and realizes self-regulation of neutron source yield, ensures the stability of neutron source yield during oxygen activation logging, and improves the accuracy of neutron oxygen activation logging results. In addition, the neutron yield monitor 4 of the present invention is installed in the zero source distance area, which is at a certain distance from the controllable neutron source 3, saves installation space at the neutron source, and reduces the outer diameter of the neutron oxygen activation logging instrument.

[0088] In the description of the present invention, it should be understood that if there are descriptive terms indicating orientation, direction or positional relationship, such as “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., the orientation or positional relationship indicated in this specification is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of understanding the present invention and simplifying the description, and does not indicate or imply that the referred part, element or whole must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0089] In addition, if there are order description terms, such as "first", "second", etc., their purpose in this specification is to facilitate understanding or simplify description. For example, in order to distinguish multiple technical features of the same type or function, but they have to be mentioned separately, this specification may use prefix or suffix order description terms to distinguish them. Therefore, it cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0090] In the present invention, if the terms describing the relative functional relationship of structures are used, such as "install", "connect", "connect", "fix", etc., they should be understood in a broad sense unless otherwise clearly specified and limited. For example, "install", "connect", "connect", etc. can be a fixed connection, a detachable connection, or an integrated one; can be a mechanical connection or an electrical connection; can be a direct connection or an indirect connection through an intermediate medium, can be the internal connection of two elements or the interaction relationship between two elements; "fix" can be an integrated fixation or a detachable fixation through fasteners; can be a direct fixation or a fixation through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above-mentioned descriptive terms in the present invention can be understood according to the specific circumstances, the context, the coherence of the context, etc.

[0091] In the present invention, if there are descriptive terms with subsidiary or connecting meanings, for example, a first feature is "on" or "below" a second feature, unless otherwise clearly specified and limited, it should not be understood in a restrictive manner. For example, "on" or "below" may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above descriptive terms in the present invention can be understood according to the specific circumstances, the context, the coherence of the context, etc.

[0092] Furthermore, the first feature being “above”, “above”, and “above” the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being “below”, “below”, and “below” the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0093] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments, examples and features of the different embodiments and examples described in this specification without contradiction, and these combinations or combinations shall all fall within the scope summarized by the present invention.

[0094] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of information available from public channels and in combination with the technical inspiration provided by the present application documents.

Claims

1. A neutron logging system with self-adjusting neutron source yield, characterized in that: The invention comprises a neutron source controller (1), a power module (2), a controllable neutron source (3), a neutron yield monitor (4), and a neutron logging detector (5), wherein the power module (2) is connected to the controllable neutron source (3); the neutron yield monitor (4) is arranged in the zero source distance zone of the controllable neutron source (3), and the neutron yield monitor (4) is communicatively connected to the neutron source controller (1); the neutron source controller (1) is connected to the power module (2), the neutron source controller (1) receives data from the neutron yield monitor (4), and controls the voltage or current of the power module (2) according to the received data; and the neutron logging detector (5) is arranged in the positive source distance zone of the controllable neutron source (3); The neutron yield monitor (4) is a neutron detector; The power module (2) is used to supply power to the controllable neutron source (3); the neutron yield monitor (4) is used to monitor the neutron flux density of the controllable neutron source (3) and send the detected neutron flux density data to the neutron source controller (1); the neutron source controller (1) is used to control the output voltage or current of the power module (2) according to the received neutron flux density data; The neutron source controller (1) is used to control the output voltage or current of the power module (2) according to the received neutron flux density data, specifically comprising: the neutron source controller (1) obtains the neutron yield by inversion calculation of the neutron flux density detected by the neutron yield monitor (4), compares the calculated neutron yield with the rated neutron yield value, and controls the output voltage or current of the power module (2) according to the comparison result; The calculated neutron yield is compared with the rated neutron yield value, and the output voltage or current of the power module (2) is controlled according to the comparison result, specifically comprising: when the calculated neutron yield is less than the rated neutron yield value, the neutron source controller (1) increases the output voltage or current of the power module (2) to increase the neutron yield; when the calculated neutron yield is greater than the rated neutron yield value, the neutron source controller (1) decreases the output voltage or current of the power module (2) to reduce the neutron yield; when the calculated neutron yield is equal to the rated neutron yield value, the neutron source controller (1) does not act, maintains the output voltage or current of the power module (2), and maintains the neutron yield.

2. The neutron logging system with self-adjusting neutron source yield according to claim 1, characterized in that: The neutron logging detector (5) is used to detect the flux distribution or energy spectrum distribution information of neutrons or gamma rays in the formation.

3. The neutron logging system with self-adjusting neutron source yield according to claim 1, characterized in that: The neutron logging detector (5) comprises either one or both of a gamma detector and a neutron detector.

4. The neutron logging system with self-adjusting neutron source yield according to claim 1, characterized in that: The controllable neutron source (3) is a DT controllable neutron source or a DD controllable neutron source.

5. A neutron well logging method with self-adjustment of neutron source yield, characterized in that: The method is implemented by using the neutron logging system according to any one of claims 1 to 4, comprising the following steps: Step 1: The power module (2) supplies power to the controllable neutron source (3), and the controllable neutron source (3) emits neutrons outward; Step 2: The neutron yield monitor (4) monitors the neutron flux density in the zero source distance area of ​​the controllable neutron source (3), and sends the detected neutron flux density data to the neutron source controller (1); Step 3, the neutron source controller (1) controls the output voltage or current of the power module (2) according to the received neutron flux density data, thereby controlling the neutron yield of the controllable neutron source (3); Step 4: The neutron logging detector (5) detects the flux distribution or energy spectrum distribution information of neutrons or gamma rays in the formation (6) in the positive source distance area of ​​the controllable neutron source (3).

6. The neutron well logging method with self-adjustment of neutron source yield according to claim 5, characterized in that: The step three specifically comprises: the neutron source controller (1) obtains the neutron yield by inverse calculation of the neutron flux density detected by the neutron yield monitor (4), compares the calculated neutron yield with the rated neutron yield value, and controls the output voltage or current of the power module (2) according to the comparison result.

7. The neutron well logging method with self-adjustment of neutron source yield according to claim 6, characterized in that: The step of comparing the calculated neutron yield with the rated neutron yield value and controlling the output voltage or current of the power module (2) according to the comparison result specifically includes: When the calculated neutron yield is less than the rated neutron yield value, the neutron source controller (1) increases the output voltage or current of the power module (2) to increase the neutron yield; when the calculated neutron yield is greater than the rated neutron yield value, the neutron source controller (1) decreases the output voltage or current of the power module (2) to reduce the neutron yield; when the calculated neutron yield is equal to the rated neutron yield value, the neutron source controller (1) does not act, maintains the output voltage or current of the power module (2), and maintains the neutron yield.

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