Rock water content obtaining method based on one-dimensional nuclear magnetism, pyrolysis and extraction experiments
By combining one-dimensional nuclear magnetic resonance, pyrolysis, and extraction experiments, the problem of low accuracy in rock water content determination was solved, and hydrocarbon substances were effectively removed, thus improving the accuracy of water content determination. This method is particularly suitable for shale samples.
Patent Information
- Application Number
- CN202511626616.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-07
- Publication Date
- 2026-03-17
AI Technical Summary
Existing methods for determining rock water content suffer from low accuracy and susceptibility to interference. In particular, traditional nuclear magnetic resonance (NMR) technology cannot accurately distinguish the NMR signals of water and hydrocarbons, leading to inaccurate water content measurements.
By combining one-dimensional nuclear magnetic resonance, pyrolysis, and extraction experiments, hydrocarbons in rocks are removed by Soxhlet extraction. The hydrocarbon content is determined by combining rock pyrolysis and extraction, and the fluid content is obtained by nuclear magnetic resonance technology. Finally, the water content of the rocks is calculated.
It improves the accuracy of rock water content determination, especially in organic-rich shale, enabling convenient and accurate water content measurement. It also reduces the interference of hydrocarbons on NMR signals and is suitable for pressure-controlled and frozen core sampling.
Smart Images
Figure CN121678740A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of geological exploration, and in particular to a method for obtaining rock water content based on one-dimensional nuclear magnetic resonance, pyrolysis and extraction experiments. Background Technology
[0002] In oil and gas exploration and development, water cut is one of the key parameters for assessing reservoir properties and optimizing development plans. Accurate measurement of water cut is of great significance for determining the oil content of reservoirs, calculating resource quantities, and predicting water production patterns during development.
[0003] Currently, commonly used methods for determining water content mainly include the drying and weighing method, the distillation method, and the capacitance method. The drying and weighing method involves drying the rock sample to a constant weight and calculating the water content based on the mass difference before and after drying. This method is simple to operate, but it has the problem that light hydrocarbons in the rock may volatilize during the drying process, leading to an overestimation of the measured water content. The distillation method utilizes the principle of azeotropic reaction between solvent and water to separate and measure the water in the sample. While this method can reduce the influence of hydrocarbon volatilization, it is cumbersome to operate and has low accuracy for rock samples with low water content. The capacitance method is based on the difference in dielectric constants between water and oil, calculating the water content by measuring the capacitance value of the sample. Although this method allows for rapid determination, it is easily affected by factors such as the rock's mineral composition and pore structure, resulting in poor stability of the measurement results.
[0004] Nuclear magnetic resonance (NMR) technology, as a non-destructive testing technique, analyzes the fluid content in a sample by detecting the NMR signal of hydrogen protons. It offers advantages such as fast detection speed and non-destructive sample structure. However, rocks contain not only water but also hydrocarbons. The hydrogen protons in hydrocarbons also generate NMR signals. If NMR is used alone, the hydrogen proton signal from hydrocarbons will be included in the fluid signal, leading to an overestimation of the fluid content and an inability to accurately distinguish between water and oil, thus affecting the accuracy of water content determination. Summary of the Invention
[0005] The purpose of this invention is to provide a method for obtaining rock water content based on one-dimensional nuclear magnetic resonance, pyrolysis, and extraction experiments, in order to solve the problems of low accuracy and susceptibility to interference in existing methods for determining the water content of rock samples.
[0006] The above-mentioned objective of this application is achieved through the following technical solution: S1. Extract hydrocarbon-containing fluids from rock samples using amphiphilic solvents; S2. Conduct rock pyrolysis experiments on the pre-extracted samples to obtain the pre-extracted samples. Value and advance draw value; S3. Conduct rock pyrolysis experiments on the extracted samples to obtain the extracted... value; S4, according to the aforementioned pre-drawing... Value, draw in advance Value and extraction Calculate the hydrocarbon content of the sample. ; S5. Conduct a one-dimensional nuclear magnetic resonance experiment on the sample before extraction to obtain the nuclear magnetic resonance signal of the sample before extraction; S6. Conduct a one-dimensional nuclear magnetic resonance experiment on the extracted sample to obtain the extracted nuclear magnetic resonance signal; S7. Based on the pre-extraction NMR signal and the post-extraction NMR signal, obtain the fluid content of the sample. ; S8. Based on the hydrocarbon content and fluid content Calculate the water content of the sample. .
[0007] Optionally, step S1 includes: The rock sample was prepared as a powder sample crushed to 200 mesh. The extraction experiment used Soxhlet extraction, and the extraction solvent was a ternary azeotropic solvent or a mixture of toluene and methanol. The ternary azeotropic solvent is prepared from acetone, chloroform and methanol in a preset volume ratio; The extraction temperature is the boiling point of the solvent, and the extraction time is preset until the extraction solvent becomes colorless and transparent.
[0008] Optionally, step S1 may further include: The extracted rock samples were dried for at least 24 hours until the sample mass was constant, i.e., the difference between two weighings was ≤0.0002g.
[0009] Optionally, step S4 includes: The hydrocarbon content The calculation formula is: .
[0010] Optionally, step S5 includes: The test parameters for the nuclear magnetic resonance experiment satisfy: The magnetic field strength stability is ≤ ±0.1 Hz / h, the relaxation time measurement range covers 0.01 ms to 10 s, and the test temperature is controlled at 25 ± 2 ℃. In the nuclear magnetic resonance experiment, the sample is scanned multiple times, with no fewer than 8 scans, and the average value of the stable nuclear magnetic resonance signal obtained from the multiple scans is taken as the final test result of the nuclear magnetic resonance signal.
[0011] Optionally, step S7 includes: The fluid content The difference between the pre- and post-extraction nuclear magnetic resonance signals is calculated by combining the pre-established calibration curve of nuclear magnetic resonance signal and fluid content. The calibration curve is obtained by using a standard fluid sample and testing it under the same nuclear magnetic resonance test parameters as the sample to be tested, and plotting the relationship between the nuclear magnetic resonance signal and the fluid content.
[0012] Optionally, step S8 includes: The moisture content The calculation formula is: .
[0013] An electronic device includes a processor, a memory, a user interface, and a network interface. The memory is used to store instructions, the user interface and the network interface are used to communicate with other devices, and the processor is used to execute the instructions stored in the memory to enable the electronic device to perform a method for obtaining rock water content based on one-dimensional nuclear magnetic resonance, pyrolysis and extraction experiments.
[0014] A computer-readable storage medium storing instructions that, when executed, perform a method for obtaining rock water content based on one-dimensional nuclear magnetic resonance, pyrolysis, and extraction experiments.
[0015] The beneficial effects of the technical solution provided in this application are: This invention effectively eliminates the interference of hydrogen protons from hydrocarbons in rock samples on the NMR signal by combining nuclear magnetic resonance (NMR) with rock pyrolysis and extraction. Traditional NMR techniques, when used alone, include the hydrogen proton signals from hydrocarbons in the water content signal, leading to an overestimation of water content. This invention accurately obtains the hydrocarbon content of the rock sample through combined rock pyrolysis and extraction, then uses one-dimensional NMR to obtain the fluid content, and finally subtracts the hydrocarbon content from the difference in fluid content to obtain the water content. This method, based on the differentiated NMR signal intensity response of different hydrogen-containing substances in hydrocarbon-bearing rock samples before and after solvent extraction, provides a more convenient way to obtain the water content of rock samples while simultaneously measuring the hydrocarbon content. It shows promising application prospects in the determination of water content in rock samples, especially organic-rich shale. The nuclear magnetic resonance used in this application is one-dimensional nuclear magnetic resonance. A one-dimensional nuclear magnetic resonance experiment only takes 1-2 minutes, which is short. Two-dimensional nuclear magnetic resonance experiments are much slower, usually taking 20 minutes or more, and are not suitable for pressure-controlled core samples or frozen core samples. Attached Figure Description
[0016] The present application will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1This is a step diagram of an embodiment of this application; Figure 2 This is a correlation diagram between the moisture content measured for samples 1-8 in the embodiments of this application and the moisture content measured by Karl Fischer method; Figure 3 This is a schematic diagram of the electronic device structure in the embodiments of this application. Detailed Implementation
[0017] To provide a clearer understanding of the technical features, objectives, and effects of this application, the specific embodiments of this application will now be described in detail with reference to the accompanying drawings.
[0018] The embodiments of this application provide a method for obtaining rock water content based on one-dimensional nuclear magnetic resonance, pyrolysis and extraction experiments.
[0019] Please refer to Figure 1 , Figure 1 This is a flowchart illustrating the steps of a method for obtaining rock water content based on one-dimensional NMR, pyrolysis, and extraction experiments in an embodiment of this application, including: S1. Extract hydrocarbon-containing fluids from rock samples using amphiphilic solvents; S2. Conduct rock pyrolysis experiments on the pre-extracted samples to obtain the pre-extracted samples. Value and advance draw Value; advance extraction The value represents the free hydrocarbons extracted prematurely; extraction prematurely The value is the premature extraction of pyrolyzed hydrocarbons; S3. Conduct rock pyrolysis experiments on the extracted samples to obtain the extracted... Value; after extraction The value is the extracted pyrolytic hydrocarbon; S4, according to the aforementioned pre-drawing... Value, draw in advance Value and extraction Calculate the hydrocarbon content of the sample. ; S5. Conduct a one-dimensional nuclear magnetic resonance experiment on the sample before extraction to obtain the nuclear magnetic resonance signal of the sample before extraction; S6. Conduct a one-dimensional nuclear magnetic resonance experiment on the extracted sample to obtain the extracted nuclear magnetic resonance signal; S7. Based on the pre-extraction NMR signal and the post-extraction NMR signal, obtain the fluid content of the sample. ; S8. Based on the hydrocarbon content and fluid content Calculate the water content of the sample. .
[0020] As one embodiment, the nuclear magnetic resonance (NMR) used in this application is one-dimensional NMR: a single one-dimensional NMR experiment only takes 1-2 minutes. Two-dimensional NMR experiments, on the other hand, are much slower, typically requiring 20 minutes or more. For samples obtained by pressure-controlled or frozen core sampling, some of the fluid in the sample will rapidly dissipate after the sample is removed from the pressure-controlled or frozen state, making two-dimensional NMR experiments unsuitable.
[0021] As one example, the combined analysis of rock pyrolysis and Soxhlet extraction can accurately calculate the hydrocarbon content in rocks. By combining nuclear magnetic resonance (NMR) technology with rock pyrolysis and extraction experiments, the oil content in shale can be determined using the combined analysis of rock pyrolysis and extraction. Then, NMR technology can be used to determine the total fluid content in the shale. Finally, the water content can be obtained by subtracting the oil content from the total fluid content. This solves the problem that NMR technology alone cannot distinguish between oil and water, thus improving the accuracy of shale water content determination.
[0022] Step S1 includes: The rock sample was prepared as a powder sample crushed to 200 mesh. The extraction experiment used Soxhlet extraction, and the extraction solvent was a ternary azeotropic solvent or a mixture of toluene and methanol. The ternary azeotropic solvent is prepared from acetone, chloroform and methanol in a preset volume ratio; The extraction temperature is the boiling point of the solvent, and the extraction time is preset until the extraction solvent becomes colorless and transparent.
[0023] In one specific embodiment of this application, the sample used for the extraction experiment is a 200-mesh powder sample, because Soxhlet extraction is difficult to completely extract oil or water from block samples.
[0024] Step S1 also includes: The extracted rock samples were dried for at least 24 hours until the sample mass was constant, i.e., the difference between two weighings was ≤0.0002g.
[0025] Step S4 includes: The hydrocarbon content The calculation formula is: .
[0026] Step S5 includes: The test parameters for the nuclear magnetic resonance experiment satisfy: The magnetic field strength stability is ≤ ±0.1 Hz / h, the relaxation time measurement range covers 0.01 ms to 10 s, and the test temperature is controlled at 25 ± 2 ℃. In the nuclear magnetic resonance experiment, the sample is scanned multiple times, with no fewer than 8 scans, and the average value of the stable nuclear magnetic resonance signal obtained from the multiple scans is taken as the final test result of the nuclear magnetic resonance signal.
[0027] As one example, the nuclear magnetic resonance (NMR) test parameters should be set to meet the following requirements: magnetic field strength stability ≤ ±0.1 Hz / h, relaxation time measurement range covering 0.01 ms-10 s, test temperature controlled at 25 ± 2 ℃, test sample mass controlled at around 8 g, and the sample should be scanned multiple times during the test, with no less than 8 scans, in order to reduce test errors. Finally, the average value of the stable NMR signal obtained from multiple scans is taken as the test result of this step.
[0028] Step S7 includes: The fluid content The difference between the pre- and post-extraction nuclear magnetic resonance signals is calculated by combining the pre-established calibration curve of nuclear magnetic resonance signal and fluid content. The calibration curve is obtained by using a standard fluid sample and testing it under the same nuclear magnetic resonance test parameters as the sample to be tested, and plotting the relationship between the nuclear magnetic resonance signal and the fluid content.
[0029] In one embodiment, the present invention is explained using measured data as an example.
[0030] The examples used eight shale samples obtained by conventional coring methods, numbered 1-8. The hydrocarbon content and fluid content of the shale samples were obtained using the methods described above. The water content of the rock sample was calculated based on the hydrocarbon content and fluid content, and the test results are shown in Table 1 below.
[0031] To verify the accuracy of the moisture content measured by the above method, the moisture content of samples 1-8 was also measured by the Karl Fischer method for comparison. The results showed that the measured moisture content was in good agreement with the moisture content measured by the Karl Fischer method. Figure 2 ).
[0032] Table 1. Statistical table of water saturation parameters of shale samples
[0033] This application also discloses an electronic device. (See reference...) Figure 3 , Figure 3 This is a schematic diagram of the structure of an electronic device disclosed in an embodiment of this application. The electronic device 500 may include: at least one processor 501, at least one network interface 504, a user interface 503, a memory 505, and at least one communication bus 502.
[0034] The communication bus 502 is used to enable communication between these components.
[0035] The user interface 503 may include a display screen, and optionally, the user interface 503 may also include a standard wired interface or a wireless interface.
[0036] The network interface 504 may optionally include a standard wired interface or a wireless interface (such as a Wi-Fi interface).
[0037] This application also discloses a computer-readable storage medium storing multiple instructions adapted for loading by a processor to execute the above-described method for obtaining rock water content based on one-dimensional NMR, pyrolysis, and extraction experiments.
[0038] The above are merely exemplary embodiments of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure.
[0039] This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described in this disclosure. The specification and embodiments are to be considered exemplary only, and the scope and spirit of this disclosure are defined by the claims.
Claims
1. A method for obtaining water content of a rock based on one-dimensional nuclear magnetic, pyrolysis and extraction experiments, characterized in that, The method comprises the following steps: S1, extracting hydrocarbon-containing fluid in a rock sample by using an oil-water amphiphilic solvent; S2, carry out rock pyrolysis experiment of the sample before extraction, to obtain the value of the sample before extraction and the value of the sample before extraction ; S3, carry out rock pyrolysis experiment of the sample after extraction, obtain rock pyrolysis data of the sample after extraction values; S4. The method of claim 1, wherein the extraction front is determined based on the value of the parameter value, the extraction front value, and the post-extraction value value to calculate a hydrocarbon content of the sample ; S5, performing one-dimensional nuclear magnetic resonance experiment on the sample before extraction to obtain nuclear magnetic resonance signals before extraction; S6, performing one-dimensional nuclear magnetic resonance experiment on the sample after extraction to obtain nuclear magnetic resonance signals after extraction; S7. Based on the pre-extraction NMR signal and the post-extraction NMR signal, obtain the fluid content of the sample. ; S8. The hydrocarbon content and fluid content calculating the water content of the sample .
2. The method for obtaining water content of rock based on one-dimensional nuclear magnetic, pyrolysis and extraction experiments according to claim 1, characterized in that, Step S1 comprises: The rock sample is crushed into a powder sample of 200 mesh; The extraction experiment adopts Soxhlet extraction method, and the extraction solvent is a ternary azeotropic solvent or a mixed solvent of toluene and methanol; The ternary azeotropic solvent is prepared by acetone, chloroform and methanol according to a preset volume ratio; The extraction temperature is the boiling point temperature of the solvent, and the extraction is carried out for a preset time until the extraction solvent becomes colorless and transparent.
3. The method of claim 1, wherein the method is characterized by: Step S1 further comprises: The rock sample after extraction is subjected to drying treatment, and the drying time is not less than 24 h until the sample mass is constant, that is, the mass difference of two times of weighing is less than or equal to 0.0002 g.
4. The method of claim 1, wherein the method is characterized by: Step S4 comprises: The hydrocarbon content The calculation formula is: .
5. The method of claim 1, wherein the method is characterized by: Step S5 comprises: The test parameters of the nuclear magnetic resonance experiment meet: The magnetic field strength stability is less than or equal to ±0.1 Hz / h, the relaxation time measurement range covers 0.01 ms to 10 s, and the test temperature is controlled at 25±2℃; In the nuclear magnetic resonance experiment, the sample is scanned for multiple times, the scanning times are not less than 8 times, and the average value of the stable nuclear magnetic signals obtained by multiple scanning is taken as the final test result of the nuclear magnetic resonance signals.
6. The method of claim 1, wherein the method is characterized by: Step S7 comprises: The fluid content The fluid content is calculated by the difference of the NMR signals before and after extraction, combined with the calibration curve of NMR signals versus fluid content previously established. The calibration curve is obtained by using a standard fluid sample, testing under the same nuclear magnetic resonance test parameters as the sample to be tested, and drawing a relationship curve of nuclear magnetic resonance signals and fluid content.
7. The method of claim 1, wherein the method is characterized by: Step S8 comprises: The water content The calculation formula is: .
8. An electronic device, comprising: The electronic device comprises a processor, a memory, a user interface and a network interface, the memory is used to store instructions, the user interface and the network interface are used to communicate with other devices, and the processor is used to execute the instructions stored in the memory to enable the electronic device to perform the rock water content acquisition method based on one-dimensional nuclear magnetic resonance, pyrolysis and extraction experiment according to any one of claims 1-7.
9. A computer-readable storage medium, characterized in that, The computer readable storage medium stores instructions, when the instructions are executed by a computer, the method for acquiring rock water content based on one-dimensional nuclear magnetic resonance, pyrolysis and extraction experiment according to any one of claims 1-7 is executed.