Method and system for measuring porosity of high-argillaceous shale oil reservoir

Abstract

The invention relates to the technical field of petroleum and natural gas exploration, and provides a method and system for measuring the porosity of a high-argillaceous shale oil reservoir, and the method comprises the following steps: obtaining two standard plunger samples and a crushed sample; measuring a standard plunger sample saturated oil one-dimensional nuclear magnetic resonance T2 spectrum and a standard plunger sample saturated water one-dimensional nuclear magnetic resonance T2 spectrum; performing normalization processing to obtain a parallel sample cross saturation T2 spectrum; establishing a linear relation between the standard sample signal intensity and the porosity; substituting the cross saturation T2 spectrum of the parallel sample and the 350 DEG C heating nuclear magnetic resonance T2 spectrum of the crushed sample into a linear relation to obtain the cross saturation porosity of the parallel sample and the 350 DEG C heating porosity of the crushed sample; and obtaining the total porosity based on the cross saturation porosity of the parallel sample and the 350 DEG C heating porosity of the crushed sample. According to the method, the parallel plunger samples are subjected to oil saturation and water saturation nuclear magnetism respectively, normalization processing analysis is carried out, and the pore space occupied by lost components can be fully obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration, and in particular to a method and system for measuring the porosity of a high-mud shale oil reservoir. Background Art

[0002] Unconventional oil and gas resources with huge resource potential have gradually become a research hotspot in recent years. Shale oil and gas reservoirs, as an unconventional oil and gas reservoir, have attracted more and more attention in recent years. Shale is both a source rock and a reservoir, with typical "self-generation and self-storage" accumulation characteristics, and the reservoir space is complex, with primary pores, secondary pores and micro-fractures. Since shale oil and gas reservoirs are obviously different from conventional oil and gas reservoirs, the evaluation methods of conventional oil and gas reservoirs are also difficult to meet the comprehensive evaluation of shale oil and gas reservoirs. Shale oil reservoir porosity is an important parameter for unconventional reservoir evaluation. Accurately obtaining it is helpful for rapid and effective evaluation of shale reservoirs, production capacity prediction and reserve calculation. The cores used in core analysis porosity research under ground experimental conditions inevitably have the loss of oil, gas and water, and it is difficult for conventional methods to fully detect the porosity occupied by the lost components, resulting in the inconsistency between the shale oil and gas reservoir porosity measured in the laboratory under different methods and the actual underground porosity.

[0003] The porosity measurement of shale rocks is usually obtained by the pressure saturation method, but the high-mud shale reservoir is affected by the reservoir wettability, micropore development and high mud content, and the conventional pressure saturation method has disadvantages. Only pressurizing oil saturation will lead to inaccurate measurement of clay bound space, and only pressurizing water saturation will not fully measure the oil-wet pore space. Summary of the invention

[0004] The purpose of the present invention is to solve at least one technical problem in the background technology and to provide a method and system for measuring the porosity of high-mud shale oil reservoirs.

[0005] To achieve the above object, the present invention provides a method for measuring the porosity of a high-mud shale oil reservoir, comprising:

[0006] Obtain shale samples, cut and process the shale samples to form two standard plunger samples of similar length, crush the remaining shale samples to 60 meshes using a core crusher, and take out crushed samples with the same mass as the average mass of the two standard plunger samples for later use;

[0007] One of the standard plunger samples was evacuated, then saturated with aviation kerosene and pressurized, and the one-dimensional nuclear magnetic resonance T2 spectrum of the saturated oil of the standard plunger sample was measured after it was taken out; the other standard plunger sample was evacuated, then saturated with distilled water and pressurized, and the one-dimensional nuclear magnetic resonance T2 spectrum of the saturated water of the standard plunger sample was measured after it was taken out; the one-dimensional nuclear magnetic resonance T2 spectrum of the saturated oil of the standard plunger sample and the one-dimensional nuclear magnetic resonance T2 spectrum of the saturated water of the standard plunger sample were normalized by mass, and then placed in the same coordinate system, and the maximum value of the signal intensity component at each distribution point of the two was taken to obtain a new T2 spectrum, which was recorded as the parallel sample cross-saturated T2 spectrum;

[0008] The crushed sample was heated at 350°C for 10 hours to remove hydrocarbons in the crushed sample. The remaining part was rock skeleton and kerogen. The nuclear magnetic resonance signal was measured as the core background signal. The measured nuclear magnetic resonance signal was inverted to obtain the nuclear magnetic resonance T2 spectrum of the crushed sample heated at 350°C.

[0009] Putting the standard samples of 1%, 3%, 5%, 10% and 15% porosity of the nuclear magnetic resonance instrument into the holder respectively, measuring the standard sample nuclear magnetic resonance signal, and establishing a linear relationship between the standard sample signal intensity and the porosity; substituting the parallel sample cross saturation T2 spectrum and the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum into the linear relationship, and obtaining a T2 spectrum with porosity as the ordinate and transverse relaxation time as the abscissa, thereby calibrating the parallel sample cross saturation T2 spectrum and the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum to the porosity, and obtaining the parallel sample cross saturation porosity and the crushed sample 350°C heating porosity of the standard plunger sample respectively;

[0010] The total porosity was obtained based on the cross-saturation porosity of the parallel samples and the porosity of the crushed samples heated at 350°C.

[0011] According to one aspect of the present invention, the nuclear magnetic resonance signal of the standard plunger sample in its original state is measured by a nuclear magnetic resonance instrument, and then the nuclear magnetic resonance T2 spectrum is obtained by inverting the measured signal:

[0012] The nuclear magnetic resonance signals of the standard plunger sample in its original state were measured using a MesoMR23-060H-I nuclear magnetic resonance instrument, including the nuclear magnetic resonance signals of kerogen, structural water, asphalt and all hydrogen-containing components with higher fluidity than asphalt. The measured signals were then inverted to obtain the nuclear magnetic resonance T2 spectrum, with the following parameters: TE = 0.06 ms, TW = 2000 ms; NECH = 32.

[0013] According to one aspect of the present invention, one of the standard plunger samples is vacuumed for 4 hours, then saturated with aviation kerosene for 72 hours, pressurized to 35 MPa, and taken out to measure the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with oil; another standard plunger sample is vacuumed for 4 hours, then saturated with distilled water for 72 hours, pressurized to 35 MPa, and taken out to measure the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with water.

[0014] According to one aspect of the present invention, the total porosity obtained based on the cross-saturation porosity of the parallel samples and the porosity of the crushed samples heated at 350°C is:

[0015] φ 总 =φ CPMG(交叉饱和) ―φ CPMG(350℃) ;

[0016] In the formula, φ 总 is the calculated total porosity, φ CPMG(交叉饱和) is the cross-saturation porosity of the parallel samples, φ CPMG(350℃) It is the porosity of the crushed sample heated at 350℃.

[0017] To achieve the above object, the present invention also provides a high-mud shale oil reservoir porosity measurement system, comprising:

[0018] The sample acquisition module acquires shale samples, cuts and processes the shale samples into two standard plunger samples of similar length, crushes the remaining shale samples into 60 meshes using a core crusher, and takes out crushed samples with the same mass as the average mass of the two standard plunger samples for standby use;

[0019] The NMR T2 spectrum acquisition module uses a NMR instrument to measure the NMR signal of the standard plunger sample in its original state, and then inverts the measured signal to obtain the NMR T2 spectrum;

[0020] A parallel sample cross-saturation T2 spectrum acquisition module is used to evacuate one of the standard plunger samples, then saturate it with aviation kerosene and pressurize it, and then measure the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with oil after taking it out; another standard plunger sample is evacuated, then saturated with distilled water and pressurized, and then measure the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with water after taking it out; the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with oil and the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with water are normalized by mass, and then put into the same coordinate system, and the maximum value of the signal intensity component at each distribution point of the two is taken to obtain a new T2 spectrum, which is recorded as the parallel sample cross-saturation T2 spectrum;

[0021] The crushed sample nuclear magnetic resonance signal measurement module heats the crushed sample at 350°C for 10 hours to remove hydrocarbons in the crushed sample. The remaining part is the rock skeleton and kerogen. The nuclear magnetic resonance signal is measured as the core background signal. The measured nuclear magnetic resonance signal is inverted to obtain the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum;

[0022] A standard plunger sample porosity acquisition module is provided, wherein the standard samples of 1%, 3%, 5%, 10% and 15% porosity provided by the nuclear magnetic resonance instrument are placed in the holder respectively, and the standard sample nuclear magnetic resonance signals are measured to establish a linear relationship between the signal intensity of the standard sample and the porosity; the parallel sample cross saturation T2 spectrum and the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum are substituted into the linear relationship to obtain a T2 spectrum with porosity as the ordinate and transverse relaxation time as the abscissa, thereby calibrating the parallel sample cross saturation T2 spectrum and the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum to the porosity, and obtaining the parallel sample cross saturation porosity and the crushed sample 350°C heating porosity of the standard plunger sample respectively;

[0023] The shale porosity calculation module obtains the total porosity based on the cross-saturation porosity of parallel samples and the porosity of crushed samples heated at 350℃.

[0024] To achieve the above objectives, the present invention also provides an electronic device, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the porosity measurement method for high-mud shale oil reservoirs as described above.

[0025] To achieve the above objectives, the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the porosity measurement method of high-mud shale oil reservoir is implemented as described above.

[0026] According to the solution of the present invention, in order to solve the problem of wettability influence that conventional saturation method fails to solve, the present invention proposes a method of cross-saturation of parallel samples, and performs oil-saturated and water-saturated NMR on parallel plug samples respectively, fully considering the influence of wettability on saturation, and then performing normalized processing and analysis, which can more fully obtain the pore space occupied by the lost components and avoid the problems existing in single saturation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the T2 spectrum of the T2 signal intensity of the plunger sample saturated oil;

[0028] Figure 2 is the T2 spectrum of the T2 signal intensity of the plunger sample saturated with water;

[0029] Figure 3 It is the T2 spectrum of plunger sample parallel sample cross saturation T2 signal intensity;

[0030] Figure 4 T2 spectrum of T2 signal intensity of crushed sample heated at 350℃;

[0031] Figure 5 Calibrate the fitting graph for the porosity standard;

[0032] Figure 6 is the porosity T2 spectrum of the original plug sample;

[0033] Figure 7 It is the T2 spectrum of the plug-like oil-saturated porosity;

[0034] Figure 8 is the T2 spectrum of the water-saturated porosity of the plug sample;

[0035] Fig. 9 It is the cross-saturation porosity T2 spectrum of the plunger sample parallel sample;

[0036] Fig.10 This is the porosity T2 spectrum of the crushed sample heated at 350℃. DETAILED DESCRIPTION

[0037] The present invention will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are only to enable those skilled in the art to better understand and thus implement the present invention, rather than implying any limitation on the scope of the present invention.

[0038] As used herein, the term “including” and variations thereof are to be interpreted as open-ended terms meaning “including, but not limited to.” The term “based on” is to be interpreted as “based, at least in part, on.” The terms “one embodiment” and “an embodiment” are to be interpreted as “at least one embodiment.”

[0039] According to one embodiment of the present invention, a method for measuring the porosity of a high-mud shale oil reservoir comprises:

[0040] Obtain shale samples, cut and process the shale samples to form two standard plunger samples of similar length, crush the remaining shale samples to 60 meshes using a core crusher, and take out crushed samples with the same mass as the average mass of the two standard plunger samples for later use;

[0041] One of the standard plunger samples was evacuated, then saturated with aviation kerosene and pressurized, and the one-dimensional nuclear magnetic resonance T2 spectrum of the saturated oil of the standard plunger sample was measured after it was taken out. Figure 1 As shown; another standard plunger sample is evacuated, then saturated with distilled water and pressurized, and the standard plunger sample saturated with water is taken out and measured with a one-dimensional nuclear magnetic resonance T2 spectrum, as shown Figure 2As shown; the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated oil and the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated water are normalized by mass, and then placed in the same coordinate system, and the maximum value of the signal intensity component at each distribution point of the two is taken to obtain a new T2 spectrum, which is recorded as the parallel sample cross saturation T2 spectrum, as shown Figure 3 As shown;

[0042] The crushed sample was heated at 350℃ for 10 hours to remove hydrocarbons in the crushed sample. The remaining part was rock skeleton and kerogen. The nuclear magnetic resonance signal was measured as the core background signal. The background signal value was eliminated during the T2 spectrum analysis and calculation. The measured nuclear magnetic resonance signal was inverted to obtain the 350℃ heated nuclear magnetic resonance T2 spectrum of the crushed sample, as shown in Figure 2. Figure 4 As shown;

[0043] Put the standard samples with porosity of 1%, 3%, 5%, 10% and 15% that come with the nuclear magnetic resonance instrument into the holder respectively, and measure the standard sample nuclear magnetic resonance signal to establish a linear relationship between the signal intensity of the standard sample and the porosity; substitute the parallel sample cross saturation T2 spectrum and the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum into the above linear relationship to obtain the T2 spectrum with porosity as the ordinate and the transverse relaxation time as the abscissa, so as to calibrate the parallel sample cross saturation T2 spectrum and the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum to the porosity, and obtain the parallel sample cross saturation porosity and the crushed sample 350°C heating porosity of the standard plunger sample respectively;

[0044] In this embodiment, the porosity standard calibration fitting diagram is as follows: Figure 5 As shown, Figure 5 The linear relationship between the signal intensity measured by the standard samples with 1%, 3%, 5%, 10%, and 15% porosity in the NMR experiment and the NMR T2 spectrum is shown; where x is the T2 time, y is the signal intensity measured respectively, and R is the formula fitting correlation coefficient. The porosity T2 spectrum of the standard plunger sample is as follows Figure 6 As shown, the standard plug sample saturated oil porosity T2 spectrum is as follows Figure 7 As shown, the standard plug sample saturated water porosity T2 spectrum is as follows Figure 8 As shown, the cross-saturation porosity T2 spectrum of the standard plunger sample parallel sample is as follows Fig. 9 As shown, the porosity T2 spectrum of the crushed sample heated at 350°C is as follows Fig.10 shown.

[0045] The total porosity was obtained based on the cross-saturation porosity of the parallel samples and the porosity of the crushed samples heated at 350°C.

[0046] Further, according to one embodiment of the present invention, a nuclear magnetic resonance signal of a standard plunger sample in its original state is measured using a nuclear magnetic resonance instrument, and then the measured signal is inverted to obtain a nuclear magnetic resonance T2 spectrum as follows:

[0047] The nuclear magnetic resonance signals of the standard plunger sample in its original state were measured using a MesoMR23-060H-I nuclear magnetic resonance instrument, including the nuclear magnetic resonance signals of kerogen, structural water, asphalt and all hydrogen-containing components with higher fluidity than asphalt. The measured signals were then inverted to obtain the nuclear magnetic resonance T2 spectrum, with the following parameters: TE = 0.06 ms, TW = 2000 ms; NECH = 32.

[0048] Further, according to one embodiment of the present invention, one of the standard plunger samples was vacuumed for 4 hours, then saturated with aviation kerosene for 72 hours, pressurized to 35 MPa, and taken out to measure the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with oil; another standard plunger sample was vacuumed for 4 hours, then saturated with distilled water for 72 hours, pressurized to 35 MPa, and taken out to measure the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with water.

[0049] Further, according to one embodiment of the present invention, the total porosity is obtained based on the cross saturation porosity of the parallel sample and the porosity of the crushed sample heated at 350°C:

[0050] φ 总 =φ CPMG(交叉饱和) ―φ CPMG(350℃) ;

[0051] In the formula, is the calculated total porosity, is the cross-saturation porosity of the parallel samples, It is the porosity of the crushed sample heated at 350℃.

[0052] According to the above scheme of the present invention, in view of the fact that the conventional saturation method fails to solve the problem of wettability influence, a method of parallel sample cross-saturation is proposed, and parallel plunger samples are subjected to oil-saturated and water-saturated NMR respectively, fully considering the influence of wettability on saturation, and then normalized processing and analysis are performed, which can more fully obtain the pore space occupied by the lost components and avoid the problems existing in single saturation.

[0053] Nuclear magnetic resonance measurement technology has the advantages of non-destructive, rapid, and multi-parameter measurement. More importantly, it can realize online measurement under high temperature and high pressure during oil production flow experiments, and obtain various seepage physical parameters of formation conditions such as porosity, pore size distribution, permeability, oil saturation, etc., which has opened up a new way for experimental research on shale oil and gas. The distribution of tiny pores and cracks in shale reservoirs is clearly distinguished in the nuclear magnetic T2 spectrum. The present invention uses a nuclear magnetic resonance experimental method to measure the residual component signal of shale, and then converts it into porosity. Since the research object is high-mud shale, no oil washing operation is required during the experiment. Nuclear magnetic resonance can measure the residual part of shale, i.e., the pore space occupied by participating components such as clay bound water, adsorbed hydrocarbons, residual oil, and residual water, as well as components in non-porous space but with nuclear magnetic signals such as structural water, kerogen, and asphaltene. When the temperature is heated to 350°C, the light hydrocarbons and medium hydrocarbons remaining in the shale have all been lost, while asphaltene, kerogen, and high molecular hydrocarbons still remain. Therefore, 350°C pyrolysis nuclear magnetic resonance is added to distinguish the pore space from the non-porous space in the nuclear magnetic signal, thereby obtaining the pore space occupied by the residual components. To this end, the present invention uses a parallel sample cross-saturation nuclear magnetic resonance experimental method based on a laboratory 23MHz nuclear magnetic resonance to study the experimental method of high-mud shale porosity, avoiding the influence of wettability on the saturation porosity measurement, accurately obtaining the porosity of shale oil reservoirs, and effectively solving the problem that the experimental porosity of shale reservoirs is lower than the underground porosity.

[0054] Furthermore, to achieve the above-mentioned purpose, the present invention also provides a high-mud shale oil reservoir porosity measurement system, comprising:

[0055] The sample acquisition module acquires shale samples, cuts and processes the shale samples into two standard plunger samples of similar length, crushes the remaining shale samples into 60 meshes using a core crusher, and takes out crushed samples with the same mass as the average mass of the two standard plunger samples for standby use;

[0056] The parallel sample cross-saturation T2 spectrum acquisition module evacuates one of the standard plunger samples, then saturates it with aviation kerosene and pressurizes it. After taking it out, the one-dimensional nuclear magnetic resonance T2 spectrum of the saturated oil of the standard plunger sample is measured, such as Figure 1 As shown; another standard plunger sample is evacuated, then saturated with distilled water and pressurized, and the standard plunger sample saturated with water is taken out and measured with a one-dimensional nuclear magnetic resonance T2 spectrum, as shown Figure 2 As shown; the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated oil and the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated water are normalized by mass, and then placed in the same coordinate system, and the maximum value of the signal intensity component at each distribution point of the two is taken to obtain a new T2 spectrum, which is recorded as the parallel sample cross saturation T2 spectrum, as shown Figure 3 As shown;

[0057] The crushed sample nuclear magnetic resonance signal measurement module heats the crushed sample at 350℃ for 10 hours to remove hydrocarbons in the crushed sample. The remaining part is rock skeleton and kerogen. The measured nuclear magnetic resonance signal is used as the core background signal. The background signal value is eliminated during the T2 spectrum analysis and calculation. The measured nuclear magnetic resonance signal is inverted to obtain the crushed sample 350℃ heating nuclear magnetic resonance T2 spectrum, such as Figure 4 As shown;

[0058] The standard plunger sample porosity acquisition module is used to measure the standard sample nuclear magnetic resonance signal after placing the standard samples of 1%, 3%, 5%, 10% and 15% porosity of the nuclear magnetic resonance instrument into the holder, thereby establishing a linear relationship between the signal intensity of the standard sample and the porosity; the parallel sample cross saturation T2 spectrum and the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum are substituted into the linear relationship to obtain a T2 spectrum with porosity as the ordinate and transverse relaxation time as the abscissa, thereby calibrating the parallel sample cross saturation T2 spectrum and the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum to the porosity, and obtaining the parallel sample cross saturation porosity and the crushed sample 350°C heating porosity of the standard plunger sample respectively;

[0059] In this embodiment, the porosity standard calibration fitting diagram is as follows: Figure 5 As shown, Figure 5 The linear relationship between the signal intensity measured by the standard samples with 1%, 3%, 5%, 10%, and 15% porosity in the NMR experiment and the NMR T2 spectrum is shown; where x is the T2 time, y is the signal intensity measured respectively, and R is the formula fitting correlation coefficient. The porosity T2 spectrum of the standard plunger sample is as follows Figure 6 As shown, the standard plug sample saturated oil porosity T2 spectrum is as follows Figure 7 As shown, the standard plug sample saturated water porosity T2 spectrum is as follows Figure 8 As shown, the cross-saturation porosity T2 spectrum of the standard plunger sample parallel sample is as follows Fig. 9 As shown, the porosity T2 spectrum of the crushed sample heated at 350°C is as follows Fig.10 shown.

[0060] The shale porosity calculation module obtains the total porosity based on the cross-saturation porosity of parallel samples and the porosity of crushed samples heated at 350℃.

[0061] Further, according to one embodiment of the present invention, a nuclear magnetic resonance signal of a standard plunger sample in its original state is measured using a nuclear magnetic resonance instrument, and then the measured signal is inverted to obtain a nuclear magnetic resonance T2 spectrum as follows:

[0062] The nuclear magnetic resonance signals of the standard plunger sample in its original state were measured using a MesoMR23-060H-I nuclear magnetic resonance instrument, including the nuclear magnetic resonance signals of kerogen, structural water, asphalt and all hydrogen-containing components with higher fluidity than asphalt. The measured signals were then inverted to obtain the nuclear magnetic resonance T2 spectrum, with the following parameters: TE = 0.06 ms, TW = 2000 ms; NECH = 32.

[0063] Further, according to one embodiment of the present invention, one of the standard plunger samples was vacuumed for 4 hours, then saturated with aviation kerosene for 72 hours, pressurized to 35 MPa, and taken out to measure the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with oil; another standard plunger sample was vacuumed for 4 hours, then saturated with distilled water for 72 hours, pressurized to 35 MPa, and taken out to measure the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with water.

[0064] Further, according to one embodiment of the present invention, the total porosity is obtained based on the cross saturation porosity of the parallel sample and the porosity of the crushed sample heated at 350°C:

[0065] φ 总 =φ CPMG(交叉饱和) ―φ CPMG(350℃) ;

[0066] In the formula, is the calculated total porosity, is the cross-saturation porosity of the parallel samples, It is the porosity of the crushed sample heated at 350℃.

[0067] According to the above scheme of the present invention, in view of the fact that the conventional saturation method fails to solve the problem of wettability influence, a method of parallel sample cross-saturation is proposed, and parallel plunger samples are subjected to oil-saturated and water-saturated NMR respectively, fully considering the influence of wettability on saturation, and then normalized processing and analysis are performed, which can more fully obtain the pore space occupied by the lost components and avoid the problems existing in single saturation.

[0068] Nuclear magnetic resonance measurement technology has the advantages of non-destructive, rapid, and multi-parameter measurement. More importantly, it can realize online measurement under high temperature and high pressure during oil production flow experiments, and obtain various seepage physical parameters of formation conditions such as porosity, pore size distribution, permeability, oil saturation, etc., which has opened up a new way for experimental research on shale oil and gas. The distribution of tiny pores and cracks in shale reservoirs is clearly distinguished in the nuclear magnetic T2 spectrum. The present invention uses a nuclear magnetic resonance experimental method to measure the residual component signal of shale, and then converts it into porosity. Since the research object is high-mud shale, no oil washing operation is required during the experiment. Nuclear magnetic resonance can measure the residual part of shale, i.e., the pore space occupied by participating components such as clay bound water, adsorbed hydrocarbons, residual oil, and residual water, as well as components in non-porous space but with nuclear magnetic signals such as structural water, kerogen, and asphaltene. When the temperature is heated to 350°C, the light hydrocarbons and medium hydrocarbons remaining in the shale have all been lost, while asphaltene, kerogen, and high molecular hydrocarbons still remain. Therefore, 350°C pyrolysis nuclear magnetic resonance is added to distinguish the pore space from the non-porous space in the nuclear magnetic signal, thereby obtaining the pore space occupied by the residual components. To this end, the present invention uses a parallel sample cross-saturation nuclear magnetic resonance experimental method based on a laboratory 23MHz nuclear magnetic resonance to study the experimental method of high-mud shale porosity, avoiding the influence of wettability on the saturation porosity measurement, accurately obtaining the porosity of shale oil reservoirs, and effectively solving the problem that the experimental porosity of shale reservoirs is lower than the underground porosity.

[0069] Furthermore, to achieve the above-mentioned purpose, the present invention also provides an electronic device, including a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, the porosity measurement method of high-mud shale oil reservoir as described above is implemented.

[0070] Furthermore, to achieve the above-mentioned purpose, the present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the porosity measurement method of high-mud shale oil reservoir as described above is implemented.

[0071] Those skilled in the art will appreciate that the modules and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0072] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and equipment can refer to the corresponding processes in the aforementioned method implementation methods, and will not be repeated here.

[0073] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0074] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the embodiments of the present invention.

[0075] In addition, each functional module in the embodiment of the present invention may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0076] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the energy-saving signal sending / receiving method of each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical disks.

[0077] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other.

[0078] It should be understood that the size of the serial numbers of each step in the content of the invention and the implementation methods of the present invention does not absolutely mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation methods of the present invention.

Claims

1. A method for measuring the porosity of a high-mud shale oil reservoir, characterized in that: include: Obtain shale samples, cut and process the shale samples to form two standard plunger samples of similar length, crush the remaining shale samples to 60 meshes using a core crusher, and take out crushed samples with the same mass as the average mass of the two standard plunger samples for later use; One of the standard plunger samples was evacuated, then saturated with aviation kerosene and pressurized, and the one-dimensional nuclear magnetic resonance T2 spectrum of the saturated oil of the standard plunger sample was measured after it was taken out; the other standard plunger sample was evacuated, then saturated with distilled water and pressurized, and the one-dimensional nuclear magnetic resonance T2 spectrum of the saturated water of the standard plunger sample was measured after it was taken out; the one-dimensional nuclear magnetic resonance T2 spectrum of the saturated oil of the standard plunger sample and the one-dimensional nuclear magnetic resonance T2 spectrum of the saturated water of the standard plunger sample were normalized by mass, and then placed in the same coordinate system, and the maximum value of the signal intensity component at each distribution point of the two was taken to obtain a new T2 spectrum, which was recorded as the parallel sample cross-saturated T2 spectrum; The crushed sample was heated at 350°C for 10 hours to remove hydrocarbons in the crushed sample. The remaining part was rock skeleton and kerogen. The nuclear magnetic resonance signal was measured as the core background signal. The measured nuclear magnetic resonance signal was inverted to obtain the nuclear magnetic resonance T2 spectrum of the crushed sample heated at 350°C. Putting the standard samples of 1%, 3%, 5%, 10% and 15% porosity of the nuclear magnetic resonance instrument into the holder respectively, measuring the standard sample nuclear magnetic resonance signal, and establishing a linear relationship between the standard sample signal intensity and the porosity; substituting the parallel sample cross saturation T2 spectrum and the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum into the linear relationship, and obtaining a T2 spectrum with porosity as the ordinate and transverse relaxation time as the abscissa, thereby calibrating the parallel sample cross saturation T2 spectrum and the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum to the porosity, and obtaining the parallel sample cross saturation porosity and the crushed sample 350°C heating porosity of the standard plunger sample respectively; The total porosity was obtained based on the cross-saturation porosity of the parallel samples and the porosity of the crushed samples heated at 350°C.

2. The method for measuring the porosity of a high-mud shale oil reservoir according to claim 1, characterized in that: The nuclear magnetic resonance signal of the standard plunger sample in its original state is measured by a nuclear magnetic resonance instrument, and then the nuclear magnetic resonance T2 spectrum is obtained by inverting the measured signal: The nuclear magnetic resonance signals of the standard plunger sample in its original state were measured using a MesoMR23-060H-I nuclear magnetic resonance instrument, including the nuclear magnetic resonance signals of kerogen, structural water, asphalt and all hydrogen-containing components with higher fluidity than asphalt. The measured signals were then inverted to obtain the nuclear magnetic resonance T2 spectrum, with the following parameters: TE = 0.06 ms, TW = 2000 ms; NECH = 32.

3. The method for measuring the porosity of a high-mud shale oil reservoir according to claim 1, characterized in that: One of the standard plunger samples was evacuated for 4 hours, then saturated with aviation kerosene for 72 hours, pressurized to 35 MPa, and taken out to measure the one-dimensional nuclear magnetic resonance T2 spectrum of the saturated oil of the standard plunger sample; the other standard plunger sample was evacuated for 4 hours, then saturated with distilled water for 72 hours, pressurized to 35 MPa, and taken out to measure the one-dimensional nuclear magnetic resonance T2 spectrum of the saturated water of the standard plunger sample.

4. The method for measuring the porosity of a high-mud shale oil reservoir according to any one of claims 1 to 3, characterized in that: The total porosity obtained based on the cross-saturation porosity of the parallel samples and the porosity of the crushed samples heated at 350°C is: f 总 =φ CPMG(交叉饱和) ―φ CPMG(350℃) ; In the formula, φ 总 is the calculated total porosity, φ CPMG(交叉饱和) is the cross-saturation porosity of the parallel samples, φ CPMG(350℃) It is the porosity of the crushed sample heated at 350℃.

5. High-mud shale oil reservoir porosity measurement system, characterized by: include: The sample acquisition module acquires shale samples, cuts and processes the shale samples into two standard plunger samples of similar length, crushes the remaining shale samples into 60 meshes using a core crusher, and takes out crushed samples with the same mass as the average mass of the two standard plunger samples for standby use; The NMR T2 spectrum acquisition module uses a NMR instrument to measure the NMR signal of the standard plunger sample in its original state, and then inverts the measured signal to obtain the NMR T2 spectrum; A parallel sample cross-saturation T2 spectrum acquisition module is used to evacuate one of the standard plunger samples, then saturate it with aviation kerosene and pressurize it, and then measure the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with oil after taking it out; another standard plunger sample is evacuated, then saturated with distilled water and pressurized, and then measure the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with water after taking it out; the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with oil and the one-dimensional nuclear magnetic resonance T2 spectrum of the standard plunger sample saturated with water are normalized by mass, and then put into the same coordinate system, and the maximum value of the signal intensity component at each distribution point of the two is taken to obtain a new T2 spectrum, which is recorded as the parallel sample cross-saturation T2 spectrum; The crushed sample nuclear magnetic resonance signal measurement module heats the crushed sample at 350°C for 10 hours to remove hydrocarbons in the crushed sample. The remaining part is the rock skeleton and kerogen. The nuclear magnetic resonance signal is measured as the core background signal. The measured nuclear magnetic resonance signal is inverted to obtain the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum; A standard plunger sample porosity acquisition module is provided, wherein the standard samples of 1%, 3%, 5%, 10% and 15% porosity provided by the nuclear magnetic resonance instrument are placed in the holder respectively, and the standard sample nuclear magnetic resonance signals are measured to establish a linear relationship between the signal intensity of the standard sample and the porosity; the parallel sample cross saturation T2 spectrum and the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum are substituted into the linear relationship to obtain a T2 spectrum with porosity as the ordinate and transverse relaxation time as the abscissa, thereby calibrating the parallel sample cross saturation T2 spectrum and the crushed sample 350°C heating nuclear magnetic resonance T2 spectrum to the porosity, and obtaining the parallel sample cross saturation porosity and the crushed sample 350°C heating porosity of the standard plunger sample respectively; The shale porosity calculation module obtains the total porosity based on the cross-saturation porosity of parallel samples and the porosity of crushed samples heated at 350℃.

6. An electronic device, characterized in that The method comprises a processor, a memory and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, the method for measuring the porosity of a high-mud shale oil reservoir as described in any one of claims 1 to 4 is implemented.

7. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for measuring the porosity of a high-mud shale oil reservoir as described in any one of claims 1-4 is implemented.

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