Gas saturation evaluation method based on core nuclear magnetic experiment and related equipment

Abstract

The invention discloses a gas saturation evaluation method based on a core nuclear magnetic experiment and related equipment, the method adopts a method of combining a field experiment and an indoor experiment and accurately calculating the gas saturation through linkage of multiple experiments, and the gas saturation in a core is effectively calculated in a mode of compensating gas pores through the indoor experiment; according to the method, the porosity and pore structure information of the reservoir is rapidly obtained through full-diameter rock core nuclear magnetic field measurement, and fluid information is effectively identified through a two-dimensional nuclear magnetic spectrum; performing an indoor rock core nuclear magnetic experiment, and calculating a movable gas pore proportion; full-diameter rock core field nuclear magnetic measurement and indoor rock core experiments are combined, the gas saturation of the reservoir is effectively calculated, rapid and quantitative evaluation of the oil-gas possibility of the gas reservoir is achieved, and technical and data support is provided for reserve estimation. The method is a necessary technical means for economically developing shale gas and tight gas resources according to pore characteristics, reservoir capacity, enrichment conditions and gas-bearing reserves of different oil field shale gas and tight gas reservoirs.

Description

Technical Field

[0001] The present invention belongs to the technical field of complex oil and gas reservoir evaluation, and in particular relates to a gas saturation evaluation method based on core nuclear magnetic resonance experiments and related equipment. Background Art

[0002] In recent years, shale gas and tight gas, as important strategic replacement resources, have become the focus of attention in the field of oil and gas exploration and development. The quantitative calculation of the physical properties, pore structure and gas saturation of such reservoirs is one of the difficulties in oilfield exploration and development and logging evaluation. Domestically, the relevant data on the gas saturation of gas layers are mainly obtained through logging data and indoor core experiments, but they have certain limitations and can no longer meet the production needs of reservoir evaluation. Well logging data are affected by the wellbore environment, instrument measurement parameters, reservoir environment, etc. The applicability of the method for calculating gas saturation in various types of reservoirs needs to be further verified; indoor core experiments require plug sampling, and it is difficult to sample plugs in some types of reservoirs (such as shale). The experimental cycle is long, and the measurement results cannot be quickly applied, and the cost is high. The experimental results are point measurement data, which are discontinuous and cannot fully reflect the characteristics of fluid components under the original formation conditions, which seriously reduces the credibility of reservoir evaluation.

[0003] The full-diameter core 2D NMR scanning is a vehicle-mounted device. It does not take plunger samples. It conducts full-diameter core NMR measurements at the drilling site to quickly obtain standard T2 spectrum and T1-T2 spectrum data to evaluate reservoir porosity, pore structure, fluid properties and oil and gas content. However, for gas layers, the gas quickly escapes when the core is separated from the formation. Even rapid on-site measurements cannot reflect the gas content of the formation. The on-site measurement of cores has certain limitations. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned technology, the present invention provides a gas saturation assessment method and related equipment based on core nuclear magnetic resonance experiments, which can solve the technical problems of difficulty in calculating reservoir gas saturation, difficulty in accurately estimating reserves, difficulty in indoor experimental sampling, long experimental cycle, rapid gas escape in the core, and difficulty in effectively measuring gas signals.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A gas saturation assessment method based on core nuclear magnetic resonance experiments, comprising:

[0007] Obtain the full-diameter core nuclear magnetic resonance porosity and two-dimensional nuclear magnetic resonance spectrum of the core on site, and obtain the oil and gas saturation of the full-diameter core based on the two-dimensional nuclear magnetic resonance spectrum;

[0008] Obtain the original nuclear magnetic porosity of the core in the laboratory and the porosity after helium injection, and calculate the total porosity of the core;

[0009] The gas saturation of the reservoir is calculated based on the porosity measured by nuclear magnetic resonance of the full-diameter core, the oil and gas saturation in the full-diameter core and the total porosity of the core.

[0010] Furthermore, the porosity and two-dimensional nuclear magnetic resonance spectrum of the full-diameter core are obtained on site, and the oil and gas saturation in the full-diameter core is obtained according to the two-dimensional nuclear magnetic resonance spectrum. The specific steps of the above process include:

[0011] For gas-bearing reservoirs, full-diameter core nuclear magnetic resonance (NMR) scanning is performed on the coring site to obtain full-diameter core NMR porosity and two-dimensional NMR T1-T2 spectra. The oil and gas saturation in the full-diameter core is calculated based on the two-dimensional NMR T1-T2 spectra.

[0012] Furthermore, the specific steps of obtaining the original nuclear magnetic porosity of the core in the laboratory and the helium injection porosity include:

[0013] The core is brought into the indoor laboratory, and the nuclear magnetic porosity of the original core is first measured to obtain the original nuclear magnetic porosity of the core; then the core is injected with helium to obtain the helium-injected porosity of the core.

[0014] Furthermore, the total porosity of the core = original nuclear magnetic porosity + helium injection porosity.

[0015] Furthermore, the diffused gas porosity is calculated based on the total core porosity and the full-diameter core NMR porosity; the oil and gas porosity obtained by the full-diameter core NMR on-site is calculated based on the full-diameter core NMR porosity and the oil and gas saturation in the full-diameter core; the reservoir gas saturation is calculated by combining the oil and gas porosity obtained by the full-diameter core NMR on-site, the diffused gas porosity and the total core porosity.

[0016] Furthermore, the oil and gas porosity in the original formation is calculated based on the oil and gas porosity and escaped gas porosity obtained by full-diameter core nuclear magnetic resonance on-site. The gas saturation of the reservoir is calculated by combining the oil and gas porosity in the original formation and the total porosity of the core.

[0017] Furthermore, the reservoir gas saturation S og总 The calculation formula is as follows:

[0018] S og总 =[Φ 全直径 *S og(T1-T2) +(Φ NMR +Φ He -Φ 全直径 )] / (Φ NMR +Φ He )

[0019] Among them, Φ 全直径S is the porosity measured by nuclear magnetic resonance of the full-diameter core; og(T1-T2) is the oil and gas saturation in the full diameter core; Φ NMR is the original sample NMR porosity; Φ He is the porosity of helium injection.

[0020] A gas saturation evaluation system based on core nuclear magnetic resonance experiments is used to implement the steps of the gas saturation evaluation method based on core nuclear magnetic resonance experiments, including:

[0021] The first acquisition module is used to obtain the full-diameter core nuclear magnetic resonance porosity and two-dimensional nuclear magnetic resonance images of the core on site, and obtain the oil and gas saturation of the full-diameter core according to the two-dimensional nuclear magnetic resonance images;

[0022] The second acquisition module is used to obtain the original nuclear magnetic porosity of the core in the laboratory and the helium injection porosity, and calculate the total porosity of the core;

[0023] The calculation module is used to calculate the gas saturation of the reservoir based on the porosity measured by nuclear magnetic resonance of the full-diameter core, the oil and gas saturation in the full-diameter core and the total porosity of the core.

[0024] A device comprising:

[0025] Memory for storing computer programs;

[0026] A processor is used to implement the steps of the above-mentioned gas saturation assessment method based on core nuclear magnetic resonance experiments when executing the computer program.

[0027] A computer-readable storage medium stores a computer program, which, when executed by a processor, is used to implement the steps of the gas saturation assessment method based on core nuclear magnetic resonance experiments.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention also provides a gas saturation assessment method based on core nuclear magnetic resonance experiments. The method adopts a method of combining field experiments with indoor experiments, and a method of accurately calculating gas saturation by linking multiple experiments. The gas saturation in the core is effectively calculated by compensating gas pores through indoor experiments; the method quickly obtains reservoir porosity and pore structure information through full-diameter core nuclear magnetic resonance field measurement, and effectively identifies fluid information through two-dimensional nuclear magnetic resonance spectrum; indoor core nuclear magnetic resonance experiments calculate the proportion of movable gas pores; full-diameter core field nuclear magnetic resonance measurements are combined with indoor core experiments to effectively calculate reservoir gas saturation, realize rapid and quantitative evaluation of oil and gas content of gas layers, and provide technical and data support for reserve estimation. The method can be used to measure the pore characteristics, storage capacity, enrichment, and gas reserves of shale gas and tight gas reservoirs in different oil fields, and is a necessary technical means for the economic development of shale gas and tight gas resources.

[0030] Preferably, the two-dimensional nuclear magnetic resonance spectrum of the present method adopts a two-dimensional nuclear magnetic resonance T1-T2 spectrum, which can quickly and efficiently identify fluid information. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A flow chart of a method for evaluating gas saturation based on core nuclear magnetic resonance experiments provided in an embodiment of the present invention;

[0032] Figure 2 Estimation of gas saturation of a dense gas layer under the T2 spectrum provided in an embodiment of the present invention;

[0033] Figure 3 The estimated gas saturation of the tight gas layer at 6997.55 m provided in the embodiment of the present invention;

[0034] Figure 4 The estimated gas saturation of the tight gas layer at 6998.9 m provided in the embodiment of the present invention;

[0035] Figure 5 A flow chart of a gas saturation assessment method based on core nuclear magnetic resonance experiments provided by the present invention;

[0036] Figure 6 A schematic diagram of the structure of a gas saturation evaluation system based on core nuclear magnetic resonance experiments provided by the present invention. DETAILED DESCRIPTION

[0037] The present invention provides a gas saturation evaluation method based on core nuclear magnetic resonance experiments, such as Figure 5 As shown, the following steps are included:

[0038] A gas saturation assessment method based on core nuclear magnetic resonance experiments, comprising:

[0039] S1; obtaining the full-diameter core nuclear magnetic resonance porosity and two-dimensional nuclear magnetic resonance spectrum of the core on site, and obtaining the oil and gas saturation of the full-diameter core according to the two-dimensional nuclear magnetic resonance spectrum;

[0040] The specific steps of the above process include:

[0041] For gas-bearing reservoirs, full-diameter core nuclear magnetic resonance (NMR) scanning is performed on the coring site to obtain full-diameter core NMR porosity and two-dimensional NMR T1-T2 spectra. The oil and gas saturation in the full-diameter core is calculated based on the two-dimensional NMR T1-T2 spectra.

[0042] S2; Obtain the original nuclear magnetic porosity of the core in the laboratory and the porosity after helium injection, and calculate the total porosity of the core;

[0043] The specific steps include:

[0044] The core is brought into the indoor laboratory, and the nuclear magnetic porosity of the original core is first measured to obtain the original nuclear magnetic porosity of the core; then the core is injected with helium to obtain the helium-injected porosity of the core.

[0045] Among them, the total porosity of the core = original nuclear magnetic porosity + helium injection porosity.

[0046] S3: Calculate the gas saturation of the reservoir based on the porosity measured by nuclear magnetic resonance of the full-diameter core, the oil and gas saturation in the full-diameter core and the total porosity of the core.

[0047] Among them, the diffused gas porosity is calculated based on the total core porosity and the full-diameter core NMR porosity; the oil and gas porosity obtained by full-diameter core NMR on-site is calculated based on the full-diameter core NMR porosity and the oil and gas saturation in the full-diameter core; the reservoir gas saturation is calculated by combining the oil and gas porosity obtained by full-diameter core NMR on-site, the diffused gas porosity and the total core porosity.

[0048] That is to say, based on the oil and gas porosity and escaped gas porosity obtained by full-diameter core nuclear magnetic resonance on-site, the oil and gas porosity in the original formation is calculated; combined with the oil and gas porosity in the original formation and the total porosity of the core, the gas saturation of the reservoir is calculated.

[0049] Here, the reservoir gas saturation S og总 The calculation formula is as follows:

[0050] S og总 =[Φ 全直径 *S og(T1-T2) +(Φ NMR +Φ He -Φ 全直径 )] / (Φ NMR +Φ He )

[0051] Among them, Φ 全直径 S is the porosity measured by nuclear magnetic resonance of the full-diameter core; og(T1-T2) is the oil and gas saturation in the full diameter core; Φ NMR is the original sample NMR porosity; Φ He is the porosity of helium injection.

[0052] like Figure 6 As shown, the present invention also provides a gas saturation evaluation system based on core nuclear magnetic resonance experiments, including: a first acquisition module, used to obtain the full-diameter core nuclear magnetic resonance porosity and two-dimensional nuclear magnetic resonance map of the core on site, and obtain the oil and gas saturation in the full-diameter core according to the two-dimensional nuclear magnetic resonance map; a second acquisition module, used to obtain the original nuclear magnetic resonance porosity and helium injection porosity of the core in the laboratory, and calculate the total porosity of the core; a calculation module, used to calculate the gas saturation of the reservoir according to the full-diameter core nuclear magnetic resonance porosity, the oil and gas saturation in the full-diameter core and the total porosity of the core.

[0053] The present invention also provides a device, comprising: a memory for storing a computer program; and a processor for implementing the steps of the gas saturation assessment method based on core nuclear magnetic resonance experiments when executing the computer program.

[0054] When the processor executes the computer program, the above-mentioned steps of gas saturation assessment based on core nuclear magnetic resonance experiment are implemented, for example: obtaining the full-diameter core nuclear magnetic resonance porosity and two-dimensional nuclear magnetic resonance map of the core on site, and obtaining the oil and gas saturation in the full-diameter core according to the two-dimensional nuclear magnetic resonance map; obtaining the original nuclear magnetic resonance porosity and helium injection porosity of the core in the laboratory, and calculating the total porosity of the core; calculating the gas saturation of the reservoir according to the full-diameter core nuclear magnetic resonance porosity, the oil and gas saturation in the full-diameter core and the total porosity of the core.

[0055] Alternatively, the processor implements the functions of each module in the above system when executing the computer program, for example: a first acquisition module is used to obtain the full-diameter core nuclear magnetic resonance porosity and two-dimensional nuclear magnetic resonance image of the core on site, and obtain the oil and gas saturation in the full-diameter core according to the two-dimensional nuclear magnetic resonance image; a second acquisition module is used to obtain the original nuclear magnetic resonance porosity and helium injection porosity of the core in the laboratory, and calculate the total porosity of the core; a calculation module is used to calculate the gas saturation of the reservoir according to the full-diameter core nuclear magnetic resonance porosity, the oil and gas saturation in the full-diameter core and the total porosity of the core.

[0056] Exemplarily, the computer program can be divided into one or more modules / units, and the one or more modules / units are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units can be a series of computer program instruction segments that can complete the preset functions, and the instruction segments are used to describe the execution process of the computer program in the gas saturation assessment device based on the core nuclear magnetic resonance experiment. For example, the computer program can be divided into a first acquisition module, a second acquisition module and a calculation module; the specific functions of each module are as follows: the first acquisition module is used to obtain the full-diameter core nuclear magnetic resonance porosity and two-dimensional nuclear magnetic resonance map of the core on site, and obtain the oil and gas saturation in the full-diameter core according to the two-dimensional nuclear magnetic resonance map; the second acquisition module is used to obtain the original nuclear magnetic resonance porosity and helium injection porosity of the core in the laboratory, and calculate the total porosity of the core; the calculation module is used to calculate the gas saturation of the reservoir according to the full-diameter core nuclear magnetic resonance porosity, the oil and gas saturation in the full-diameter core and the total porosity of the core.

[0057] The gas saturation assessment device based on core nuclear magnetic experiment can be a computing device such as a desktop computer, a notebook, a PDA, and a cloud server. The gas saturation assessment device based on core nuclear magnetic experiment may include, but is not limited to, a processor and a memory. Those skilled in the art can understand that the above is an example of a gas saturation assessment device based on core nuclear magnetic experiment, and does not constitute a limitation on the gas saturation assessment device based on core nuclear magnetic experiment, and may include more components than the above, or a combination of certain components, or different components. For example, the gas saturation assessment device based on core nuclear magnetic experiment may also include input and output devices, network access devices, buses, etc.

[0058] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc. The processor is the control center of the gas saturation assessment based on core nuclear magnetic resonance experiments, and uses various interfaces and lines to connect various parts of the gas saturation assessment device based on core nuclear magnetic resonance experiments.

[0059] The memory can be used to store the computer program and / or module, and the processor implements various functions of the gas saturation assessment device based on core nuclear magnetic resonance experiments by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.

[0060] The memory may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area may store data created according to the use of the mobile phone (such as audio data, a phone book, etc.), etc. In addition, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (SmartMediaCard, SMC), a secure digital (SecureDigital, SD) card, a flash card (FlashCard), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0061] The present invention also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps of the gas saturation assessment method based on core nuclear magnetic resonance experiments are implemented.

[0062] If the integrated module / unit of the gas saturation assessment system based on core nuclear magnetic resonance experiments is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium.

[0063] Based on such understanding, the present invention implements all or part of the processes in the above-mentioned gas saturation assessment method based on core nuclear magnetic resonance experiment, and can also be completed by instructing related hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the above-mentioned gas saturation assessment method based on core nuclear magnetic resonance experiment can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or preset intermediate form, etc.

[0064] The computer-readable storage medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0065] It should be noted that the content contained in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable storage media do not include electrical carrier signals and telecommunication signals.

[0066] The present invention will be further described below in conjunction with the embodiments and drawings:

[0067] Example

[0068] In order to solve the technical problems mentioned in the background technology: the existing reservoir gas saturation assessment method has the problems of difficult calculation, difficult to accurately estimate reserves, difficult indoor experimental sampling, long experimental cycle, fast gas escape in the core, and difficult to effectively measure the gas signal. Therefore, new measurement processes and methods are needed to measure and calculate the gas signal content and calculate the gas saturation. In order to achieve the above purpose, the present embodiment provides a gas saturation assessment method based on core nuclear magnetic resonance experiments. This method adopts a method of combining field experiments with indoor experiments, a method of accurately calculating gas saturation through multiple experimental linkage, and a method of compensating gas pores in indoor experiments to effectively calculate the gas saturation in the core, that is, the gas saturation of the reservoir.

[0069] It should be noted that:

[0070] like Figure 1 As shown, the fluid components of gas-bearing reservoirs such as tight gas and shale gas mainly include gas, bound oil, movable oil, movable water, residual oil and gas, clay bound water and capillary bound water. The gas contained in the reservoir quickly escapes when the core is separated from the formation. The on-site core measurement cannot reflect the gas-bearing information of the formation. Therefore, a combination of multiple experiments is adopted. The porosity and T1-T2 spectrum of the on-site full-diameter core are used to identify fluid properties and calculate the oil and gas saturation; the total porosity of the core is measured through indoor experiments, and the content of the escaped gas is estimated by the porosity difference between different experiments. The oil and gas saturation of the reservoir is calculated in combination with the on-site full-diameter core measurement results. The above principle is the invention of this evaluation method.

[0071] This embodiment provides a gas saturation assessment method based on core nuclear magnetic resonance experiments, and the specific steps include:

[0072] Step 1: Perform full-diameter core nuclear magnetic resonance scanning on the coring site of the gas-bearing reservoir to obtain the full-diameter core nuclear magnetic resonance porosity φ 全直径 The oil and gas saturation S in the full-diameter core is estimated by using the two-dimensional nuclear magnetic T1-T2 spectrum. og(T1-T2) ;

[0073] Step 2: Bring the core into the indoor laboratory and measure the original core nuclear magnetic porosity (without washing oil and salt), that is, the original core nuclear magnetic porosity ΦNMR Then, the core is injected with helium to measure the porosity of the injected helium part, i.e., the helium injected porosity Φ He , calculate and obtain the total porosity of the core.

[0074] Step 3: Based on the total core porosity and the full-diameter core nuclear magnetic resonance porosity, calculate the pores occupied by the escaped gas during the on-site full-diameter measurement, that is, the escaped gas porosity;

[0075] Escaped gas porosity = total core porosity - full-diameter core nuclear magnetic resonance porosity.

[0076] Step 4: Based on the full-diameter core nuclear magnetic resonance porosity and the oil and gas saturation in the full-diameter core, the oil and gas porosity obtained by the full-diameter core nuclear magnetic resonance on-site is calculated;

[0077] The oil and gas porosity obtained by full-diameter core nuclear magnetic resonance on-site = full-diameter core nuclear magnetic resonance measured porosity * oil and gas saturation in full-diameter core.

[0078] Step 5: Obtain the oil and gas porosity in the original formation based on the oil and gas porosity and the escaped gas porosity obtained on-site by full-diameter core nuclear magnetic resonance;

[0079] The oil and gas porosity in the original formation = the oil and gas porosity obtained by full-diameter core nuclear magnetic resonance on-site + the escaped gas porosity.

[0080] Step 6: Obtain the oil and gas saturation in the gas-bearing layer, i.e., the gas saturation of the reservoir, based on the oil and gas porosity in the original formation and the total porosity of the core;

[0081] In other words, the gas saturation of the reservoir is obtained by the ratio of the oil and gas porosity in the original formation to the total porosity of the core.

[0082] So far, the gas saturation of the reservoir has been evaluated using this method.

[0083] The specific calculation formula is as follows:

[0084] S og总 =[Φ 全直径 *S og(T1-T2) +(Φ NMR +Φ He -Φ 全直径 )] / (Φ NMR +Φ He )

[0085] Among them, Φ 全直径 S is the porosity measured by nuclear magnetic resonance of the full-diameter core; og(T1-T2) is the oil and gas saturation in the full diameter core; Φ NMR is the original sample NMR porosity; Φ Heis the porosity of helium injection.

[0086] like Figure 2 , Figure 3 and Figure 4 As shown, in the H6 well, the tight gas reservoir, the full-diameter core nuclear magnetic resonance porosity Φ full diameter at 6997.55m and 6998.9m is 3.8 and 3.99% respectively, the total porosity measured by indoor experiments is 9.5 and 9.6% respectively, and the gas saturation calculated by two-dimensional nuclear magnetic resonance T1-T2 spectrum is 36.96 and 40.4% respectively. According to the double experiment scheme combined with the above calculation formula, the estimated total gas saturation of the original formation of the reservoir is 74.78 and 75.23% respectively, which is consistent with the oil test and production data of the neighboring wells in the area. It can be seen that the use of this method to evaluate the gas saturation of the original formation of the reservoir is not only efficient but also accurate.

[0087] In summary, the gas saturation assessment method based on core nuclear magnetic resonance experiment provided in this embodiment measures the core porosity through on-site full-diameter core nuclear magnetic resonance, identifies fluid properties through two-dimensional nuclear magnetic resonance T1-T2 spectrum, and calculates the oil and gas saturation; measures the total porosity of the core through indoor experiments, estimates the content of the escaped gas through the porosity difference between different experiments, and calculates the oil and gas saturation of the reservoir in combination with the on-site full-diameter core measurement results. Compared with existing assessment measures, this method has the following advantages:

[0088] Through full-diameter core nuclear magnetic resonance field measurement, reservoir porosity and pore structure information can be quickly obtained, and fluid information can be effectively identified through T1-T2 spectra; indoor core nuclear magnetic resonance experiments can calculate the proportion of movable gas pores; full-diameter core field nuclear magnetic resonance measurements are combined with indoor core experiments to effectively calculate reservoir gas saturation, realize rapid and quantitative evaluation of gas layer oil and gas properties, and provide technical and data support for reserve estimation. This innovative achievement is a brand-new innovation in the quantitative calculation of gas saturation through fresh full-diameter core nuclear magnetic resonance T2 and T1-T2 measurements of shale gas and tight gas reservoirs. It can be used to analyze the pore characteristics, storage capacity, enrichment, and gas reserves of shale gas and tight gas reservoirs in different oil fields in my country. It is a necessary technical means for the economic development of shale gas and tight gas resources. This technology will be promoted and applied in many domestic oil fields such as North China, Daqing, Qinghai, Southwest China, Xinjiang, and Changqing. It has been applied in Xinjiang and Changqing with remarkable results.

[0089] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention.

Claims

1. A gas saturation assessment method based on core nuclear magnetic resonance experiments, characterized in that: include: Obtain the full-diameter core nuclear magnetic resonance porosity and two-dimensional nuclear magnetic resonance spectrum of the core on site, and obtain the oil and gas saturation of the full-diameter core based on the two-dimensional nuclear magnetic resonance spectrum; Obtain the original nuclear magnetic porosity of the core in the laboratory and the porosity after helium injection, and calculate the total porosity of the core; The gas saturation of the reservoir is calculated based on the porosity measured by nuclear magnetic resonance of the full-diameter core, the oil and gas saturation in the full-diameter core and the total porosity of the core.

2. The gas saturation assessment method based on core nuclear magnetic resonance experiment according to claim 1 is characterized in that: in, Obtain the full-diameter core nuclear magnetic resonance porosity and two-dimensional nuclear magnetic resonance spectrum of the core on site, and obtain the oil and gas saturation of the full-diameter core according to the two-dimensional nuclear magnetic resonance spectrum. The specific steps of the above process include: For gas-bearing reservoirs, full-diameter core nuclear magnetic resonance (NMR) scanning is performed on the coring site to obtain full-diameter core NMR porosity and two-dimensional NMR T1-T2 spectra. The oil and gas saturation in the full-diameter core is calculated based on the two-dimensional NMR T1-T2 spectra.

3. The gas saturation assessment method based on core nuclear magnetic resonance experiment according to claim 1 is characterized in that: in, The specific steps to obtain the original nuclear magnetic porosity of the core in the laboratory and the porosity of helium injection include: The cores are brought into the indoor laboratory, and the nuclear magnetic porosity of the original cores is first measured to obtain the original nuclear magnetic porosity of the cores; then the cores are injected with helium to obtain the helium-injected porosity of the cores.

4. The gas saturation assessment method based on core nuclear magnetic resonance experiment according to claim 1 is characterized in that: Total core porosity = original NMR porosity + helium injection porosity.

5. The gas saturation assessment method based on core nuclear magnetic resonance experiment according to claim 1 is characterized in that: The diffused gas porosity is calculated based on the total core porosity and the full-diameter core NMR porosity. The oil and gas porosity obtained by the full-diameter core NMR on-site is calculated based on the full-diameter core NMR porosity and the oil and gas saturation in the full-diameter core. The reservoir gas saturation is calculated by combining the oil and gas porosity obtained by the full-diameter core NMR on-site, the diffused gas porosity and the total core porosity.

6. A gas saturation assessment method based on core nuclear magnetic resonance experiment according to claim 5, characterized in that: The oil and gas porosity in the original formation is calculated based on the oil and gas porosity and escaped gas porosity obtained by full-diameter core nuclear magnetic resonance on-site. The gas saturation of the reservoir is calculated by combining the oil and gas porosity in the original formation and the total porosity of the core.

7. The gas saturation assessment method based on core nuclear magnetic resonance experiment according to claim 1 is characterized in that: Reservoir gas saturation S og总 The calculation formula is as follows: S og总 =[Φ 全直径 *S og(T1-T2) +(Φ NMR +F He -F 全直径 )] / (Φ NMR +F He ) Among them, Φ 全直径 S is the porosity measured by nuclear magnetic resonance of the full-diameter core; og(T1-T2) is the oil and gas saturation in the full diameter core; Φ NMR is the original sample NMR porosity; Φ He is the porosity of helium injection.

8. A gas saturation assessment system based on core nuclear magnetic resonance experiments, used to implement the steps of the gas saturation assessment method based on core nuclear magnetic resonance experiments according to any one of claims 1 to 7, characterized in that: include: The first acquisition module is used to obtain the full-diameter core nuclear magnetic resonance porosity and two-dimensional nuclear magnetic resonance images of the core on site, and obtain the oil and gas saturation of the full-diameter core according to the two-dimensional nuclear magnetic resonance images; The second acquisition module is used to obtain the original nuclear magnetic porosity of the core in the laboratory and the helium injection porosity, and calculate the total porosity of the core; The calculation module is used to calculate the gas saturation of the reservoir based on the porosity measured by nuclear magnetic resonance of the full-diameter core, the oil and gas saturation in the full-diameter core and the total porosity of the core.

9. A device, characterized in that: include: Memory for storing computer programs; A processor is used to implement the steps of the gas saturation assessment method based on core nuclear magnetic resonance experiments as described in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, it is used to implement the steps of the gas saturation assessment method based on core nuclear magnetic resonance experiments as described in any one of claims 1 to 7.

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