Oil-water saturation measuring method and system based on oxygen activation, terminal and medium

Abstract

The invention discloses an oil-water saturation measuring method and system based on oxygen activation, a terminal and a medium, and belongs to the technical field of geological prospecting, specifically, the sum of gamma ray counts generated in the oxygen activation process of a through cased well to be measured is measured through a pulsed neutron instrument; through numerical simulation, the oxygen activation counting response of the oil-rich stratum and the oxygen activation counting response of the water-rich stratum corresponding to the specific well under different porosities are obtained; and calculating to obtain the water saturation of the through cased well to be measured under different porosities. Gamma rays generated in the oxygen activation process are used for calculating the oil-water saturation of the stratum, and the obtained result is irrelevant to the mineralization degree; as an alternative method for C / O well logging, the method can improve the well logging speed while guaranteeing the same calculation accuracy as C / O well logging, the maximum actual well logging speed can reach 16 feet / min, and the operation time is remarkably shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of geological exploration, and in particular relates to an oil-water saturation measurement method, system, terminal and medium based on oxygen activation. Background Art

[0002] Since the mid-1970s, carbon-oxygen ratio (C / O) pulsed neutron logging has been widely used for saturation monitoring in cased wells. As an important means of oilfield development monitoring, C / O logging can directly determine the parameters of the production layer, the distribution of remaining oil saturation and the degree of water flooding in the cased well. It is an important supporting technology for stable oilfield production and is currently widely used in various oilfields. C / O logging determines the saturation of formation water and oil by measuring the ratio of gamma rays produced by inelastic neutron scattering of carbon and oxygen. A key advantage of C / O logging is that it provides measurement results that are independent of mineralization, that is, the measurement results are not affected by the mineralization of formation water.

[0003] For example, the Chinese patent application number 200710018164.7 discloses a "pulsed neutron dual spectrum saturation logging method", which includes the following steps: 1. Collect logging data; 2. Perform depth-time two-dimensional filtering on thermal neutron time spectrum and captured gamma time spectrum, and perform depth-energy two-dimensional filtering on captured gamma energy spectrum and natural gamma energy spectrum; 3. Normalize the filtered data; 4. Perform multi-scale decomposition on the normalized data; 5. Reconstruct and fuse the decomposed data; 6. Display logging images and logging curves; 7. Perform geological interpretation. This patent collects thermal neutron time spectrum and captured gamma time spectrum simultaneously in the same environment in one trip, so that the advantages of the two neutron lifetime logging methods complement each other and expand the scope of environmental adaptability.

[0004] Chinese patent application number 201310555768.0 discloses a method for calculating the mineral composition of formation rocks using element content. The method uses the formation element content curve obtained by element logging and conventional logging curve as input information, combined with regional geological parameters, to calculate the volume content of rock mineral components in complex lithological formations.

[0005] However, in order to achieve the necessary statistical accuracy, C / O logging requires a very slow logging speed, typically 2 feet per minute, and requires many repeated measurements, such as at least 3 times. This limits the scope of use of C / O pulsed neutron logging. Summary of the invention

[0006] In view of the problem of low logging speed of existing C / O pulse neutron logging, the present invention provides an oil-water saturation measurement method, system, terminal and medium based on oxygen activation, which uses gamma rays generated by the oxygen activation (OA) process to calculate the oil-water saturation of the formation, thereby ensuring the calculation accuracy while improving the logging speed.

[0007] In order to achieve the above purpose, the technical method adopted by the present invention is as follows:

[0008] The oil-water saturation measurement method based on oxygen activation includes the following steps:

[0009] Step 1: In the cased well to be tested, a pulsed neutron instrument is lowered to perform logging, and the total gamma ray counts generated by the oxygen activation process are measured, which is recorded as the total gamma ray counts OASUM. measured ;

[0010] Step 2: Through numerical simulation, obtain the oxygen activation count response OASUM of the oil-saturated formation corresponding to a specific well at different porosities (i.e. different well conditions or different well depths) oil , and the corresponding oxygen activation count response OASUM for water-saturated formations water ;

[0011] The physical parameters of the specific well are the same as those of the cased well to be tested, including the type of formation minerals, cement thickness, the material and size of the drill bit / tubing / casing combination, the type of wellbore fluid, and the flow rate in the wellbore;

[0012] Step 3: Calculate the water saturation S of the cased well under different porosities w , the formula is:

[0013]

[0014] Furthermore, the pulsed neutron instrument comprises, from bottom to top, a pulsed neutron source, a first detector, a second detector and a third detector, then OASUM measured is the sum of the gamma-ray counts measured by the first, second and third detectors, OASUM oil OASUM is the sum of the oxygen activation count responses of the first, second and third detectors corresponding to the oil-saturated formation obtained by simulation. water It is the sum of the oxygen activation count responses of the first detector, the second detector and the third detector corresponding to the water-saturated formation obtained by simulation.

[0015] Furthermore, the lowering logging speed of the pulsed neutron instrument is lower than the flow rate in the wellbore to avoid being affected by different water / oil retention in the flowing well.

[0016] Furthermore, the lowering logging speed of the pulsed neutron instrument may be 6, 8, 10, 12, 14, 16, etc. feet per minute.

[0017] Furthermore, the specific process of step 2 is:

[0018] Through numerical simulation, the distribution of N-16 (nitrogen-16) atomic nucleus density in the three-dimensional space of a specific well with logging time during the lowering of the pulsed neutron instrument is obtained, and then the total simulated gamma-ray counts in the three-dimensional space of the specific well with the change of porosity are calculated;

[0019] When a specific well is an oil-saturated formation, the corresponding sum of simulated gamma-ray counts is the oxygen activation count response of the oil-saturated formation, denoted as OASUM oil ;

[0020] When a specific well is a water-saturated formation, the corresponding sum of simulated gamma-ray counts is the oxygen activation count response of the water-saturated formation, denoted as OASUM water .

[0021] Furthermore, in step 2, the distribution formula of the density of N-16 nuclei in the three-dimensional space of a specific well with the logging time during the lowering of the pulsed neutron instrument is:

[0022]

[0023] Where N N-16 is the density of N-16 nuclei; N-16 is the decay constant of N-16; represents the source term of N-16; is the spatial position of the formation; t is the logging time; E is the neutron energy; (n, p) represents the (neutron, proton) reaction induced between the neutron and the O-16 (oxygen-16) nucleus; represents the reaction cross section of (n,p); represents the neutron flux.

[0024] Furthermore, the numerical simulation is a Monte Carlo numerical simulation.

[0025] A simulated well for verifying the oil-water saturation measurement method based on oxygen activation, based on the formation mineral type of the cased well to be measured, the material and size of the drill bit / tubing / casing combination, and the flow rate in the wellbore, to construct a simulated well simulating the formation at a certain porosity;

[0026] Wherein, the wellbore of the simulated well is an uncemented casing, and the casing extends below the bottom of the simulated formation;

[0027] In the simulated formation, water is first added to form a water-saturated simulated formation; oil is then added to form an oil-saturated simulated formation; finally, no material is added to form a gas-saturated simulated formation; and then a water-saturated simulated formation, an oil-saturated simulated formation and a gas-saturated simulated formation with the same depth from bottom to top are formed, and a neutron shield is set at the top of the gas-saturated simulated formation to cover the simulated well;

[0028] Filling the wellbore with water or oil results in a corresponding water-filled wellbore or oil-filled wellbore.

[0029] Furthermore, the pulsed neutron instrument placed in the simulated well was driven by an electric logging vehicle to achieve uniform logging, and the total gamma-ray counts OASUM and measured , and the measured gamma-ray count sum OASUM of the simulated oil-saturated formation measured ;

[0030] If the measured gamma-ray counts of the simulated formation saturated with water are summed up to OASUM measured The oxygen activation count response OASUM of the water-saturated formation corresponding to the specific well obtained in step 2 at the same porosity water The total gamma-ray counts of the same simulated formation saturated with oil (OASUM) measured OASUM is the oxygen activation count response of the oil-saturated formation corresponding to the specific well obtained in step 2 at the same porosity. oil If the values ​​of the oxygen activation parameters are the same, it is considered that the oil-water saturation measurement method based on oxygen activation is more accurate.

[0031] The oil-water saturation measurement system based on oxygen activation is used to implement the oil-water saturation measurement method based on oxygen activation, and specifically includes a pulsed neutron instrument, an oxygen activation count response calculation module and a data processing module; wherein:

[0032] The pulsed neutron instrument is used to measure the total gamma ray count OASUM generated by the oxygen activation process in the cased well to be tested. measured , input to the data processing module;

[0033] The oxygen activation count response calculation module is used to determine the oxygen activation count response OASUM corresponding to the oil-saturated formation at different porosities of the configured specific well through numerical simulation. oil , and the corresponding oxygen activation count response OASUM for water-saturated formations water , input to the data processing module;

[0034] The data processing module is used to calculate the water saturation S of the tested cased well at different porosities. w .

[0035] A terminal comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the oil-water saturation measurement method based on oxygen activation.

[0036] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the oil-water saturation measurement method based on oxygen activation.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention proposes an oil-water saturation measurement method, system, terminal and medium based on oxygen activation, which utilizes gamma rays generated in the oxygen activation process to calculate formation oil-water saturation, and the obtained result is independent of salinity. As an alternative to C / O logging, the present invention can improve the logging speed while ensuring the same calculation accuracy as C / O logging. The maximum actual logging speed can reach 16 feet per minute, which significantly shortens the operation time. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only 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.

[0040] Figure 1 is a schematic diagram of the structure of the pulsed neutron instrument used in Example 1;

[0041] Figure 2 is a schematic diagram of a simulated well for verifying the oil-water saturation measurement method based on oxygen activation proposed in Example 1;

[0042] Figure 3 It is the oxygen activation response curve of the first detector in Example 1 corresponding to the oil-saturated formation and the water-saturated formation, and the schematic diagram of the measured gamma ray counts in the oil simulation well and the water simulation well;

[0043] Figure 4 It is the oxygen activation response curve of the second detector in Example 1 corresponding to the oil-saturated formation and the water-saturated formation, and the schematic diagram of the measured gamma ray counts in the oil simulation well and the water simulation well;

[0044] Figure 5 It is the oxygen activation response curve of the third detector in Example 1 corresponding to the oil-saturated formation and the water-saturated formation, and the schematic diagram of the measured gamma ray counts in the oil simulation well and the water simulation well;

[0045] Figure 6 It is a schematic diagram of the total oxygen activation response curves of the first detector, the second detector and the third detector corresponding to the oil-saturated formation and the water-saturated formation in Example 1, and the total measured gamma ray counts in the oil simulation well and the water simulation well. DETAILED DESCRIPTION

[0046] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention.

[0047] Example 1

[0048] This embodiment proposes a method for measuring oil-water saturation based on oxygen activation, using Figure 1 The pulsed neutron instrument shown completes the well logging, specifically including a pulsed neutron source, a first detector (i.e., detector 1), a second detector (i.e., detector 2), and a third detector (i.e., detector 3) arranged in sequence from bottom to top. The pulsed neutron source generates high-energy neutrons with an energy of 14.2 MeV, which propagate into the formation and interact with the nuclei in the formation and fluid through elastic scattering, inelastic scattering, thermal neutron capture, or activation processes. In addition to elastic scattering, other interactions will generate gamma radiation, which is measured by the first detector, the second detector, and the third detector in the pulsed neutron instrument placed at different distances from the neutron source. The gamma radiation is analyzed according to its arrival time and energy to generate a series of measurements for determining formation parameters (such as saturation, lithology, and porosity).

[0049] The specific process of oxygen activation is: a high-energy neutron with an energy greater than about 10 MeV reacts with the O-16 nucleus as shown in formula (1), and triggers a (n, p) (neutron, proton) reaction, thereby producing a radioactive N-16 nuclide. The unstable N-16 nuclide releases a series of gamma rays through β decay, among which the energies of 6.13 MeV and 7.12 MeV are the most significant. The half-life of this process is 7.13 seconds.

[0050]

[0051] Therefore, when water flows through a pulsed neutron instrument and the direction of the water flow is directed from the pulsed neutron source to the gamma-ray detector, gamma rays are produced.

[0052] To determine formation water saturation, the formation (water-containing pores) is stationary, while the pulsed neutron tool is traveling through the wellbore at a constant speed for logging. This actually creates an oxygen flow in the formation and water relative to the pulsed neutron tool, thereby achieving the generation and detection of oxygen-activated gamma rays. Figure 1 The pulsed neutron instrument shown has a pulsed neutron source located below, and logging needs to be performed by lowering the pulsed neutron instrument. If the pulsed neutron source is located above, logging needs to be performed by lifting the pulsed neutron instrument.

[0053] The lowering logging speed of the pulse neutron instrument is lower than the flow rate in the wellbore to avoid being affected by different water / oil retention in the flowing well.

[0054] At a constant logging rate, the detected oxygen activation count rate is proportional to the amount of oxygen in the measured volume. The oxygen activation count rate includes gamma rays from multiple oxygen sources, including the formation, water in the pore space, cement, and wellbore fluids. The oxygen content of common oilfield lithologies and materials is shown in Table 1. The count rate is also affected by the logging rate, which determines the time the neutron source irradiates the formation and the time it takes for the detector to reach the irradiated formation. If the lithology, porosity, and details of the well to be logged are known, numerical simulation methods can be used to predict the oxygen activation count rate response under oil and water-containing pore conditions at a specific logging rate. Water saturation can then be determined by comparing the measured oxygen activation count rate with the modeled oxygen activation oil-water response.

[0055] Table 1

[0056]

[0057] During the logging process, the gamma ray source generated by oxygen activation is driven by the accumulation and decay of the N-16 nuclide concentration in the formation. This accumulation and decay process can be expressed as:

[0058]

[0059] Where N N-16 is the density of N-16 nuclei; N-16 is the decay constant of N-16; represents the source term of N-16; is the spatial position of the formation; t is the logging time.

[0060] It is driven by 14.2 MeV neutrons produced by a pulsed neutron source. Since the pulsed neutron source is in constant motion, the will change with time, that is, it has a three-dimensional distribution in space, which can be expressed as:

[0061]

[0062] Where, E is the neutron energy; represents the reaction cross section of (n,p); represents the neutron flux.

[0063] Since the pulsed neutron instrument is constantly moving during the logging process, the distribution of N-16 nucleus density in three-dimensional space with logging time can be simulated by numerical simulation.

[0064] After the above analysis, the specific steps of the oil-water saturation measurement method based on oxygen activation proposed in this embodiment are as follows:

[0065] Step 1: In the cased well to be tested, a pulsed neutron instrument is lowered to perform logging, and the total gamma ray counts generated by the oxygen activation process are measured, which is recorded as the total gamma ray counts OASUM. measured , specifically, the sum of the measured gamma-ray counts of the first detector, the second detector, and the third detector;

[0066] Step 2: In the Monte Carlo N-Particle (MCNP) software, the neutron transport modeling of a specific well is performed based on equation (3) to obtain the neutron flux distribution of the stationary pulsed neutron instrument in three-dimensional space: The physical parameters of the specific well are the same as those of the cased well to be tested, including the type of formation minerals (possibly sandstone, limestone, dolomite, anhydrite), cement thickness, the material and size of the drill bit / tubing / casing combination, the type of wellbore fluid, and the flow rate in the wellbore;

[0067] Taking into account the influence of the logging speed of the pulsed neutron instrument during logging, based on formula (2), the distribution of the density of N-16 nuclei in the three-dimensional space of a specific well with the logging time during the logging process of the pulsed neutron instrument is calculated;

[0068] Based on the N-16 three-dimensional distribution, Monte Carlo numerical simulation was used to model gamma-ray transport, and the sum of simulated gamma-ray counts varying with porosity in the three-dimensional space of a specific well was calculated;

[0069] When a specific well is an oil-saturated formation, the corresponding sum of simulated gamma-ray counts is the oxygen activation count response of the oil-saturated formation, denoted as OASUM oil , specifically, the sum of the oxygen activation count responses of the first detector, the second detector and the third detector corresponding to the oil-saturated formation obtained by simulation;

[0070] When a specific well is a water-saturated formation, the corresponding sum of simulated gamma-ray counts is the oxygen activation count response of the water-saturated formation, denoted as OASUM water , specifically, the sum of the oxygen activation count responses of the first detector, the second detector and the third detector corresponding to the water-saturated formation obtained by simulation;

[0071] Step 3: Calculate the water saturation S of the cased well under different porosities w , the formula is:

[0072]

[0073] In order to verify the accuracy of the oil-water saturation measurement method based on oxygen activation proposed in this embodiment, this embodiment also proposes a simulated well.

[0074] One approach is to build a database of simulated well measurements at different logging speeds, with different drill bit sizes, casing sizes, cements, formation types, porosity, etc. However, this approach is very expensive in terms of both cost (building multiple simulated wells) and time (data acquisition).

[0075] Another approach, based on modeling simulation, combines the Monte Carlo N-particle transport code (MCNP) and deterministic methods to obtain measurement data of simulated wells under specific conditions and compare them with selected simulation test data, so that the oxygen activation response under any desired scenario can be inferred.

[0076] Considering cost and time, this embodiment specifically constructs a simulated well of a certain porosity of the simulated formation based on the type of formation minerals in the cased well to be tested, the material and size of the drill bit / tubing / casing combination, and the flow rate in the wellbore.

[0077] Assuming that the mineral type of the formation to be tested through the cased well is sandstone, the simulation well adopts a simulated formation with a loose sand structure porosity of about 37%, and specifically uses C / O (carbon / oxygen) logging to verify the formation porosity.

[0078] like Figure 2 As shown, the wellbore of the simulated well is a 5.5-inch uncemented casing (in line with production requirements), and the casing extends to 10 feet below the bottom of the simulated formation to allow continuous logging in air, oil and water-bearing formations;

[0079] In the simulated formation, tap water is first added to form a water-saturated simulated formation (i.e., a water simulated well) with a thickness of about 4 feet; Isopar M oil (density of about 0.77 g / cm3) is then added to form an oil-saturated simulated formation (i.e., an oil simulated well) with a thickness of about 4 feet; finally, no material is added to form a gas-saturated simulated formation with a thickness of about 4 feet; and then a water-saturated simulated formation, an oil-saturated simulated formation, and a gas-saturated simulated formation with the same depth from bottom to top are formed, and a neutron shield is set on the top of the gas-saturated simulated formation to cover the simulated well;

[0080] Fill the wellbore with tap water or Isopar M oil to obtain a water-filled wellbore or an oil-filled wellbore, respectively.

[0081] The pulsed neutron instrument placed in the simulated well is driven by an electric logging vehicle to realize the lowering logging at a uniform speed. The lowering logging speed can be 6, 8, 10, 12, 14, 16 feet per minute, etc. The measured gamma ray counts of the first detector (OA1), the second detector (OA2) and the third detector (OA3) corresponding to the saturated water simulated formation are measured respectively. The sum of the three is the total measured gamma ray counts OASUM of the saturated water simulated formation measured ; Then, the measured gamma-ray counts of the first detector (OA1), the second detector (OA2) and the third detector (OA3) corresponding to the oil-saturated simulated formation are measured respectively, and the sum of the three is the total measured gamma-ray counts of the oil-saturated simulated formation OASUM measured ; Since the MCNP software needs to normalize individual neutrons when modeling the neutron transport of a specific well, the measured gamma-ray counts of the first detector (OA1), the second detector (OA2), and the third detector (OA3) in the simulated well also need to be normalized.

[0082] When the formation mineral type of the cased well to be tested is sandstone and the wellbore is filled with Isopar M oil, the oxygen activation count response curves of the first detector obtained in step 2 corresponding to the oil-saturated formation and the water-saturated formation are as follows: Figure 3 As shown, the measured gamma-ray counts of the first detector in the oil simulation well and the water simulation well are represented by green solid circles and blue solid circles respectively, and the individual data passing through the water-saturated simulated formation, the oil-saturated simulated formation and the oil-water contact surface are displayed in red. It can be seen that the measured gamma-ray counts of the first detector in the oil simulation well and the water simulation well are respectively located on the oxygen activation count response curves of the first detector corresponding to the oil-saturated formation and the water-saturated formation obtained in step 2.

[0083] Similarly, the oxygen activation count response curves of the second detector obtained in step 2 corresponding to the oil-saturated formation and the water-saturated formation are as follows: Figure 4 As shown, the oxygen activation count response curves of the third detector obtained in step 2 corresponding to the oil-saturated formation and the water-saturated formation are as follows: Figure 5 As shown, the measured gamma-ray counts of the second detector in the oil simulation well and the water simulation well are respectively located on the oxygen activation count response curves of the second detector obtained in step 2 corresponding to the oil-saturated formation and the water-saturated formation, and the measured gamma-ray counts of the third detector in the oil simulation well and the water simulation well are respectively located on the oxygen activation count response curves of the third detector obtained in step 2 corresponding to the oil-saturated formation and the water-saturated formation.

[0084] Then, the oxygen activation count responses of the first detector, the second detector and the third detector corresponding to the oil-saturated formation and the water-saturated formation are summed to obtain: Figure 6The total response curve of oxygen activation is shown. The total measured gamma-ray counts of the oil simulation well and the water simulation well are represented by green solid circles and blue solid circles, respectively, and are also located on the total response curve of oxygen activation corresponding to the oil-saturated formation and the water-saturated formation.

[0085] It can be seen that the oil-water saturation measurement method based on oxygen activation proposed in this embodiment still has relatively accurate calculation results at logging speeds of 6, 8, 10, 12, 14, and 16 feet per minute, and the logging speed is greatly improved compared with C / O logging.

[0086] The above embodiments are intended to provide a better understanding of the present invention, but are not limited to the optimal implementation mode and do not constitute a limitation on the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the present invention with the features of other prior arts shall be within the protection scope of the present invention.

Claims

1. The oil-water saturation measurement method based on oxygen activation is characterized in that: The following steps are involved: Step 1: In the cased well to be tested, a pulsed neutron instrument is lowered to perform logging, and the total gamma ray counts generated by the oxygen activation process are measured, which is recorded as the total gamma ray counts OASUM. measured ; Step 2: Through numerical simulation, obtain the oxygen activation count response OASUM of the oil-saturated formation corresponding to a specific well at different porosities oil , and the corresponding oxygen activation count response OASUM for water-saturated formations water ; The physical parameters of the specific well are the same as those of the cased well to be tested, including the type of formation minerals, cement thickness, the material and size of the drill bit / tubing / casing combination, the type of wellbore fluid, and the flow rate in the wellbore; Step 3: Calculate the water saturation S of the cased well under different porosities w , the formula is:

2. The method for measuring oil-water saturation based on oxygen activation according to claim 1, characterized in that: The pulsed neutron instrument comprises a pulsed neutron source, a first detector, a second detector and a third detector in order from bottom to top. measured is the sum of the gamma-ray counts measured by the first, second and third detectors, OASUM oil OASUM is the sum of the oxygen activation count responses of the first, second and third detectors corresponding to the oil-saturated formation obtained by simulation. water It is the sum of the oxygen activation count responses of the first detector, the second detector and the third detector corresponding to the water-saturated formation obtained by simulation.

3. The method for measuring oil-water saturation based on oxygen activation according to claim 2, characterized in that: The lowering logging speed of the pulse neutron instrument is lower than the flow velocity in the wellbore.

4. The method for measuring oil-water saturation based on oxygen activation according to claim 2, characterized in that: The specific process of step 2 is: Through numerical simulation, the distribution of N-16 nucleus density in the three-dimensional space of a specific well with logging time during the logging process of the pulsed neutron instrument is obtained, and then the total simulated gamma-ray counts in the three-dimensional space of the specific well with the change of porosity are calculated; When a specific well is an oil-saturated formation, the corresponding sum of simulated gamma-ray counts is the oxygen activation count response of the oil-saturated formation, denoted as OASUM oil ; When a specific well is a water-saturated formation, the corresponding sum of simulated gamma-ray counts is the oxygen activation count response of the water-saturated formation, denoted as OASUM water .

5. The method for measuring oil-water saturation based on oxygen activation according to claim 4, characterized in that: In step 2, the formula for the distribution of the N-16 nucleus density in the three-dimensional space of a specific well with the logging time during the lowering of the pulsed neutron instrument is: Where N N-16 is the density of N-16 nuclei; N-16 is the decay constant of N-16; represents the source term of N-16; is the spatial position of the formation; t is the logging time; E is the neutron energy; (n, p) represents the (neutron, proton) reaction induced between the neutron and the O-16 nucleus; represents the reaction cross section of (n,p); represents the neutron flux.

6. A simulated well for verifying the oil-water saturation measurement method based on oxygen activation according to any one of claims 1 to 5, characterized in that: Based on the type of formation minerals in the cased well to be tested, the material and size of the drill bit / tubing / casing combination, and the flow rate in the wellbore, a simulation well is constructed to simulate the formation at a certain porosity; Wherein, the wellbore of the simulated well is an uncemented casing, and the casing extends below the bottom of the simulated formation; In the simulated formation, water is first added to form a water-saturated simulated formation; oil is then added to form an oil-saturated simulated formation; finally, no material is added to form a gas-saturated simulated formation; and then a water-saturated simulated formation, an oil-saturated simulated formation and a gas-saturated simulated formation with the same depth from bottom to top are formed, and a neutron shield is set at the top of the gas-saturated simulated formation to cover the simulated well; Filling the wellbore with water or oil results in a corresponding water-filled wellbore or oil-filled wellbore.

7. The simulated well according to claim 6, characterized in that: The pulsed neutron instrument placed in the simulated well was driven by an electric logging vehicle to achieve uniform logging, and the total gamma-ray counts (OASUM) of the simulated formation saturated with water were measured. measured , and the measured gamma-ray count sum OASUM of the simulated oil-saturated formation measured ; If the measured gamma-ray counts of the simulated formation saturated with water are summed up to OASUM measured The oxygen activation count response OASUM of the water-saturated formation corresponding to the specific well obtained in step 2 at the same porosity water The total gamma-ray counts of the same simulated formation saturated with oil (OASUM) measured OASUM is the oxygen activation count response of the oil-saturated formation corresponding to the specific well obtained in step 2 at the same porosity. oil If the values ​​of the oxygen activation parameters are the same, it is considered that the oil-water saturation measurement method based on oxygen activation is more accurate.

8. An oil-water saturation measurement system based on oxygen activation, used to implement the oil-water saturation measurement method based on oxygen activation according to any one of claims 1 to 5, characterized in that: It includes a pulsed neutron instrument, an oxygen activation counting response calculation module and a data processing module; wherein: The pulsed neutron instrument is used to measure the total gamma ray count OASUM generated by the oxygen activation process in the cased well to be tested. measured , input to the data processing module; The oxygen activation count response calculation module is used to determine the oxygen activation count response OASUM corresponding to the oil-saturated formation at different porosities of the configured specific well through numerical simulation. oil , and the corresponding oxygen activation count response OASUM for water-saturated formations water , input to the data processing module; The data processing module is used to calculate the water saturation S of the tested cased well at different porosities. w .

9. A terminal comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method for measuring oil-water saturation based on oxygen activation according to any one of claims 1 to 5.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the oil-water saturation measurement method based on oxygen activation according to any one of claims 1 to 5 are implemented.

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