CN118150607B - Method for selecting a subsurface reservoir - Google Patents
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Abstract
The embodiment of the application provides a rock fracture structure characterization method and a rock fracture structure characterization device. Relates to the technical field of underground energy storage experiments, and the method comprises the following steps: preparing a rock sample; placing a rock sample in a core holder for transmitting X-rays, and applying pressure to simulate formation confining pressure to perform initial rock structure scanning; injecting a fluid into the rock sample and performing continuous X-ray scanning to obtain a three-dimensional gray scale image; extracting rock fracture structure information under the continuous action of fluid in the three-dimensional gray image to realize quantitative characterization; wherein the fluid comprises fluids of different phases. According to the characterization method of the rock fracture structure, provided by the application, the change characteristics of the rock fracture structure when the fluid phase changes can be clearly and quantitatively characterized, continuous research on the same rock sample can be realized, the heterogeneous difference caused by replacing the rock sample is avoided, and the method has important significance in exploring the interaction of multiphase fluid rocks under complex geological conditions.
Description
Technical Field
The present application relates to the field of underground energy storage technology, and in particular to a method for selecting a subsurface reservoir.
Background
Cracks are widely present in subterranean rock, and developing cracks in reservoirs provide a wider space for fluid to accumulate and also play an important role in enhancing permeability, whereas developing cracks in overburden can cause damage to the closure and integrity and thus fluid leakage.
In recent years, X-ray tomography is used as a nondestructive three-dimensional visualization technology, and is effectively applied to crack identification and characterization, but most of current researches are based on static CT scanning of cracks developed in the rock, and the dynamic change of the cracks under the action of the fluid is relatively less depicted. The common laboratory micro-nano CT core scanning time is relatively long (up to tens or even tens of hours), and the appearance of the crack can be changed by the influence of confining pressure or other environmental factors before the end of such long CT scanning, which is not beneficial to capturing the original structure of the crack. In addition, the underground temperature and pressure are different at different depths and different places, the change of the surrounding environment can cause the change of the fluid phase state, and the change characteristics of the fracture structure when the fluid phase state is changed are not clear at present.
The choice of subsurface reservoirs requires a combination of factors in addition to the rock fracture structure.
Disclosure of Invention
Methods for selecting a subsurface reservoir are provided in embodiments of the application.
In a first aspect of the embodiment of the present application, there is provided a method for characterizing a rock fracture structure, including:
Preparing a rock sample;
Placing the rock sample in a core holder for transmitting X-rays, and applying pressure to simulate formation confining pressure to perform initial rock structure scanning;
Injecting a fluid into the rock sample and performing continuous X-ray scanning to obtain a three-dimensional gray scale image;
extracting rock fracture structure information under the continuous action of the fluid in the three-dimensional gray level image to realize quantitative characterization;
wherein the fluid comprises fluids of different phases.
In an alternative embodiment of the application, the step of injecting a fluid into the rock sample and performing a continuous X-ray scan to obtain a three-dimensional gray scale image is preceded by the steps of:
The environmental conditions for phase inversion of the fluid are configured to cause inversion of the fluid between different phases.
In an optional embodiment of the present application, the step of extracting rock fracture structure information under the continuous action of the fluid in the three-dimensional gray scale image to realize quantitative characterization includes:
importing the three-dimensional gray scale image into an imaging data analysis device;
extracting a rock fracture structure of the same rock fracture under the action of different phase fluids;
and quantitatively characterizing the rock fracture structure under the action of different phase fluids.
In an alternative embodiment of the present application, the step of preparing a rock sample specifically includes:
And preparing the rock sample into a rock sample which meets the preset scanning resolution and meets the size requirement of the core holder.
In an alternative embodiment of the application, the step of injecting a fluid into the rock sample and performing a continuous X-ray scan to obtain a three-dimensional gray scale image comprises:
The fluid is injected into the rock sample and subjected to continuous synchrotron radiation X-ray scanning to obtain a three-dimensional gray scale image.
In an alternative embodiment of the present application, the step of placing the rock sample in a core holder for X-ray transmission and applying pressure to simulate formation confining pressure for initial rock structure scanning includes:
Placing the rock sample in a core holder for penetrating X rays, and continuously injecting water into the core holder until the pressure generated by the core holder reaches the preset formation confining pressure;
and performing initial rock structure scanning based on the pressure generated by the core holder reaching the preset stratum confining pressure.
In an alternative embodiment of the present application, the step of continuously injecting water into the core holder until the pressure generated by the core holder reaches a preset formation confining pressure includes:
And continuously injecting water into the core holder through a plunger pump until the pressure generated by the core holder reaches the preset formation confining pressure.
In an alternative embodiment of the application, the step of injecting a fluid into the rock sample and performing a continuous X-ray scan is preceded by the step of:
And (5) carrying out saturation treatment on the rock sample by brine.
In a second aspect of the embodiment of the present application, there is provided a device for characterizing a rock fracture structure, for use in a method for characterizing a rock fracture structure as described, the device for characterizing a rock fracture structure comprising:
the rock core holder is used for holding a rock sample and simulating formation confining pressure, and the rock core holder is used for transmitting X rays;
a fluid injection device for injecting fluids of different phases into the rock sample;
The X-ray scanning device is used for scanning the rock sample in the core holder so as to obtain a three-dimensional gray level image;
And the imaging data analysis device is used for extracting rock fracture structure information under the continuous action of different phases of fluid in the three-dimensional gray level image to realize quantitative characterization.
In a third aspect of embodiments of the present application, there is provided a method for selecting a subsurface reservoir, comprising the steps of the method for characterizing a rock fracture structure, further comprising:
Preparing a rock sample;
Performing X-ray scanning on the rock sample to obtain an initial three-dimensional structural image of the rock sample;
Applying different confining pressures to the rock sample, and performing continuous in-situ X-ray scanning to obtain three-dimensional structure images of the rock sample in different time and different deformation states;
Post-processing the initial three-dimensional structure image and the three-dimensional structure image of the rock sample under different deformation states at different times to obtain a gray level image for strain calculation;
determining the strain and distribution mode of the rock sample under different surrounding pressures based on the gray level image so as to realize the representation of rock continuous strain;
the subsurface reservoir is selected based on the rock fracture structure and the strain of the rock.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:
FIG. 1 is a flow chart of a method for characterizing a rock fracture structure according to a first embodiment of the present invention;
FIG. 2 is a flow chart of a method for characterizing a rock fracture structure according to a second embodiment of the present invention;
FIG. 3 is a flow chart of a method for characterizing a rock fracture structure according to a third embodiment of the present invention;
FIG. 4 is a flow chart of a method for characterizing a rock fracture structure according to a fourth embodiment of the present invention;
FIG. 5 is an original three-dimensional structural image of a rock fracture structure provided by one embodiment of the present invention;
FIG. 6 is a three-dimensional structural image of a rock fracture after the gaseous CO 2 is applied, in accordance with one embodiment of the present invention;
fig. 7 is a three-dimensional structural image of a rock fracture after supercritical CO 2 is applied according to one embodiment of the present invention.
Detailed Description
In carrying out the present application, the inventors have found that the change characteristics of the fracture structure upon the change of the fluid phase state are currently unknown.
Aiming at the problems, the embodiment of the application provides a characterization method of a rock fracture structure, which comprises the steps of preparing a rock sample, placing the rock sample in a core holder, applying pressure to the core holder to simulate formation confining pressure, generating a fracture structure on the rock sample, simulating the real rock fracture structure to the greatest extent, injecting fluids in different phases into the rock sample at the moment, performing continuous X-ray scanning, obtaining a three-dimensional gray image, and extracting rock fracture structure information under the continuous action of the fluids in the three-dimensional gray image according to the three-dimensional gray image to realize quantitative characterization. It can be understood that the application can clearly and quantitatively characterize the change characteristics of the rock crack structure when the fluid phase changes, can realize continuous research on the same rock sample, avoids the heterogeneous difference caused by replacing the rock sample, and has important significance for exploring the interaction of multiphase fluid rocks under complex geological conditions. Compared with qualitative characterization, the quantitative characterization can quantify the change of the rock fracture structure by numbers, so that the change of the rock fracture structure is more visual.
Referring to fig. 1, an embodiment of the present invention provides a method for characterizing a rock fracture structure, which may include the steps of:
S101, preparing a rock sample.
S102, placing the rock sample in a core holder for transmitting X rays, and applying pressure to simulate formation confining pressure to scan an initial rock structure.
S103, injecting fluid into the rock sample and performing continuous X-ray scanning to obtain a three-dimensional gray scale image, wherein the fluid comprises fluids in different phases.
S104, extracting rock fracture structure information under the continuous action of fluid in the three-dimensional gray level image to realize quantitative characterization.
According to the method for characterizing the rock fracture structure, provided by the application, the rock sample is prepared, the rock sample is placed in the rock core holder, then the rock core holder is applied with pressure to simulate the formation confining pressure, and the fracture structure can be generated on the rock sample, so that the real rock fracture structure can be simulated to the greatest extent, at the moment, fluids in different phases are injected into the rock sample and continuous X-ray scanning is carried out, a three-dimensional gray image can be obtained, and then quantitative characterization can be realized by extracting the rock fracture structure information under the continuous action of the fluids in the three-dimensional gray image according to the three-dimensional gray image. It can be understood that the application can clearly and quantitatively characterize the change characteristics of the rock crack structure when the fluid phase changes, can realize continuous research on the same rock sample, avoids the heterogeneous difference caused by replacing the rock sample, and has important significance for exploring the interaction of multiphase fluid rocks under complex geological conditions. Compared with qualitative characterization, the quantitative characterization can quantify the change of the rock fracture structure by numbers, so that the change of the rock fracture structure is more visual.
As shown in fig. 2, an embodiment of the present invention provides a method for characterizing a rock fracture structure, which may include the following steps:
S201, preparing a rock sample.
S202, placing a rock sample in a core holder for transmitting X rays, and applying pressure to simulate formation confining pressure to scan an initial rock structure.
S203, configuring environmental conditions which meet the phase state conversion of the fluid so that the fluid can be converted between different phase states.
S204, injecting fluid into the rock sample and performing continuous X-ray scanning to obtain a three-dimensional gray scale image, wherein the fluid comprises fluids in different phases.
S205, extracting rock fracture structure information under the continuous action of fluid in the three-dimensional gray level image to realize quantitative characterization.
According to the method for characterizing the rock fracture structure, provided by the application, the rock sample is prepared, the rock sample is placed in the rock core holder, then the rock core holder is applied with pressure to simulate the formation confining pressure, and the fracture structure can be generated on the rock sample, so that the real rock fracture structure can be simulated to the greatest extent, at the moment, fluids in different phases are injected into the rock sample and continuous X-ray scanning is carried out, a three-dimensional gray image can be obtained, and then quantitative characterization can be realized by extracting the rock fracture structure information under the continuous action of the fluids in the three-dimensional gray image according to the three-dimensional gray image. It can be understood that the application can clearly and quantitatively characterize the change characteristics of the rock crack structure when the fluid phase changes, can realize continuous research on the same rock sample, avoids the heterogeneous difference caused by replacing the rock sample, and has important significance for exploring the interaction of multiphase fluid rocks under complex geological conditions. The fluid can be converted between different phases by configuring environmental conditions conforming to the phase conversion of the fluid, so that the fluid can be subjected to phase conversion in the scanning process, and the change characteristics of the rock fracture structure when the fluid phase is changed are simulated.
In the above embodiments, the environmental conditions include temperature conditions and pressure conditions that are in accordance with the fluid phase inversion.
In this embodiment, the fluid may be converted between different phases by configuring the temperature and pressure conditions to meet the phase conversion of the fluid, which is relatively easy to achieve.
As shown in fig. 3, an embodiment of the present invention provides a method for characterizing a rock fracture structure, which may include the following steps:
S301, preparing a rock sample.
S302, placing a rock sample in a core holder for transmitting X rays, and applying pressure to simulate formation confining pressure to scan an initial rock structure.
S303, injecting fluid into the rock sample and performing continuous X-ray scanning to obtain a three-dimensional gray scale image, wherein the fluid comprises fluids in different phases.
S304, the three-dimensional gray scale image is imported into an imaging data analysis device.
S305, extracting the rock fracture structure of the same rock fracture under the action of different phase fluids.
S306, quantitatively characterizing the rock fracture structure under the action of different phase fluids.
According to the method for characterizing the rock fracture structure, provided by the application, the rock sample is prepared, the rock sample is placed in the rock core holder, then the rock core holder is applied with pressure to simulate the formation confining pressure, and the fracture structure can be generated on the rock sample, so that the real rock fracture structure can be simulated to the greatest extent, at the moment, fluids in different phases are injected into the rock sample and continuous X-ray scanning is carried out, a three-dimensional gray image can be obtained, and then quantitative characterization can be realized by extracting the rock fracture structure information under the continuous action of the fluids in the three-dimensional gray image according to the three-dimensional gray image. It can be understood that the application can clearly and quantitatively characterize the change characteristics of the rock crack structure when the fluid phase changes, can realize continuous research on the same rock sample, avoids the heterogeneous difference caused by replacing the rock sample, and has important significance for exploring the interaction of multiphase fluid rocks under complex geological conditions. The three-dimensional gray level image can be led into the imaging data analysis device, then the rock crack structure of the same rock crack under the action of different phase state fluids is extracted, and the rock crack structure under the action of different phase state fluids is quantitatively represented, so that the structural change of the rock crack of the same rock crack under the action of different phase state fluids can be clearly represented.
In the above embodiment, the step of importing the three-dimensional gray-scale image into the imaging data analysis apparatus includes: the three-dimensional gray-scale image is imported into an imaging data analysis device, and denoising processing and image position processing are performed.
In the embodiment, the three-dimensional gray level image is led into an imaging data analysis device, and denoising treatment and image position treatment can be carried out, so that the rock fracture structure finally characterized is more definite.
Further, the imaging data analysis apparatus includes Avizo.
As shown in fig. 4, an embodiment of the present invention provides a method for characterizing a rock fracture structure, which may include the following steps:
s401, preparing a rock sample.
S402, placing a rock sample in a core holder for penetrating X rays, and continuously injecting water into the core holder until the pressure generated by the core holder reaches the preset formation confining pressure.
S403, performing initial rock structure scanning based on the fact that the pressure generated by the core holder reaches the preset stratum confining pressure.
S404, injecting fluid into the rock sample and performing continuous synchrotron radiation X-ray scanning to obtain a three-dimensional gray scale image, wherein the fluid comprises fluids in different phases.
S405, extracting rock fracture structure information under the continuous action of fluid in the three-dimensional gray level image to realize quantitative characterization.
According to the method for characterizing the rock fracture structure, provided by the application, the rock sample is prepared, the rock sample is placed in the rock core holder, then the rock core holder is applied with pressure to simulate the formation confining pressure, and the fracture structure can be generated on the rock sample, so that the real rock fracture structure can be simulated to the greatest extent, at the moment, fluids in different phases are injected into the rock sample and continuous X-ray scanning is carried out, a three-dimensional gray image can be obtained, and then quantitative characterization can be realized by extracting the rock fracture structure information under the continuous action of the fluids in the three-dimensional gray image according to the three-dimensional gray image. It can be understood that the application can clearly and quantitatively characterize the change characteristics of the rock crack structure when the fluid phase changes, can realize continuous research on the same rock sample, avoids the heterogeneous difference caused by replacing the rock sample, and has important significance for exploring the interaction of multiphase fluid rocks under complex geological conditions. The fluid is injected into the rock sample to perform continuous synchrotron radiation X-ray scanning so as to obtain a three-dimensional gray scale image, and thus continuous change of cracks in the rock sample can be obtained by utilizing the advantages of high spatial resolution and high time resolution of the synchrotron radiation X-ray. Placing a rock sample in a core holder for penetrating X rays, continuously injecting water into the core holder until the pressure generated by the core holder reaches the preset formation confining pressure, then scanning an initial rock structure based on the pressure generated by the core holder reaching the preset formation confining pressure, and injecting water into the core holder to realize the preset formation confining pressure is relatively simple and easy to realize. Wherein, preset stratum confining pressure can be set manually.
In the above embodiment, the step of continuously injecting water into the core holder until the pressure generated by the core holder reaches the preset formation confining pressure includes: water is continuously injected into the core holder through the plunger pump until the pressure generated by the core holder reaches the preset formation confining pressure.
In this embodiment, continuous injection into the core holder may be achieved by injecting water using a plunger pump.
In any of the above embodiments, the quantitative characterization dimensions of the rock fracture structure include: the length, width and volume are calculated as the maximum feret diameter, minimum feret diameter and the number of pixels multiplied by the pixel size, respectively.
In these embodiments, the quantitative characterization dimensions of the rock fracture structure include: length, width and volume. That is, the rock fracture structure can be quantitatively characterized in terms of length, width, volume, etc.
In any of the above embodiments, the step of preparing a rock sample specifically comprises: and preparing the rock sample into the rock sample which meets the preset scanning resolution and meets the size requirement of the core holder.
In these embodiments, when preparing the rock sample, the rock sample needs to be prepared into a rock sample that meets the preset scanning resolution and meets the size requirements of the core holder, so that scanning and clamping are facilitated. The preset scanning resolution may be set manually or the scanning resolution of the scanning device itself.
In any of the above embodiments, the scanning pixels for scanning the rock structure are larger than 1 μm and smaller than 3 μm.
Further, the scanning pixel for scanning the rock structure is 1.6 μm.
In any of the above embodiments, the rock sample prepared comprises at least one of: cylindrical rock sample, rectangular rock sample, and square rock sample.
In these embodiments, the rock sample prepared includes at least one of: a cylindrical rock sample, a rectangular rock sample, and a square rock sample. By setting rock samples of different shapes, different rock structures can be simulated, so that the crack structure changes of the different rock structures can be represented. Meanwhile, different rock samples can be selected according to different core holders so as to facilitate clamping.
Further, the rock sample can be prepared into a cylinder that meets the optimal scanning resolution and meets the core holder size requirements.
In any of the above embodiments, the core holder has an inner diameter greater than 5mm and less than 15mm.
Further, the core holder had an inner diameter of 10mm.
In any of the above embodiments, the predetermined formation confining pressure is greater than 8MPa and less than 15MPa.
Further, the preset formation confining pressure is 10MPa.
In any of the above embodiments, the step of injecting a fluid into the rock sample and performing a continuous X-ray scan further comprises: and (5) carrying out saturation treatment on the rock sample by brine.
In these embodiments, the rock sample may be saturated with brine prior to injection of the fluid into the rock sample and subsequent X-ray scanning, so that cracks present in the rock sample may be filled, avoiding affecting subsequent characterization of the crack structure.
In any of the above embodiments, the fluid comprises CO 2 in different phases.
In any of the above embodiments, the phase of the injected rock sample fluid may be controlled by varying the pressure of the injected fluid and the temperature surrounding the core holder.
In a specific embodiment, a core holder with an inner diameter of 10mm is selected, and a cylindrical core with a diameter of about 3mm is drilled for maximally satisfying the optimal scanning pixel of 1.6 mu m. The X-rays are synchrotron radiation X-rays, water is gradually injected into the rock holder through the plunger pump until the confining pressure is 10MPa, underground rock is difficult to be completely in a dry state due to stratum water, and in order to further approach stratum environment, a rock sample is saturated with brine before different phase fluids are injected, wherein the plunger pump is provided with a pressure monitor, and whether the water pressure in the rock holder reaches 10MPa is judged according to the reading of the pressure monitor.
The fluid is gaseous CO 2 and supercritical CO 2, wherein the critical temperature pressure of the supercritical CO 2 is 31.1 ℃ and 7.38MPa respectively, and the supercritical CO 2 experimental environment is configured to exceed the critical temperature pressure and be lower than the upper limit which can be born by the core holder. The two phases of CO 2 are injected sequentially at a high flow rate, the gaseous CO 2 is realized by injecting CO 2 gas into the core through a plunger pump at normal temperature, and the supercritical CO 2 is realized by heating the periphery of the core to 45 ℃ and injecting CO 2 at a high speed to exceed the critical pressure but not to exceed the confining pressure.
In the embodiment, three-dimensional gray images of the rock sample after the original state and the two phase states of CO 2 are imported Avizo for denoising and image position alignment, so that cracks of the three groups of data bodies at the same position are guaranteed to be comparable, then a watershed algorithm is adopted for carrying out threshold segmentation on the cracks, the target cracks are sequentially extracted to obtain structural information, and the three-dimensional distribution of the cracks is shown as fig. 5, 6 and 7 (the scales of fig. 5, 6 and 7 are 200 μm). The whole length 1454.5 mu m, the width 999.4 mu m and the volume are 2.3 multiplied by 10 7µm3 of the rock crack in the original state, the partial area of the crack is closed due to the fact that the rock sample is saturated with brine, the effect of the gaseous CO 2 does not have a remarkable enhancement effect on the expansion of the crack, the length is reduced to 1441.5 mu m, the width is increased to 1113.4 mu m, the volume is increased to 2.6 multiplied by 10 7µm3, compared with the supercritical CO 2, the crack distribution range is remarkably increased, the development and the expansion of secondary small cracks are initiated, the crack length is finally increased to 1493.5 mu m, the width is increased to 1153.8 mu m, and the volume is even increased to be twice to 4.9 multiplied by 10 7µm3.
From the above description, it can be seen that the following technical effects are achieved in the embodiments of the present invention: the method combines the formation temperature and pressure environments, quantitatively characterizes the real-time change of the three-dimensional structure of the crack under the action of different phase fluid, further clearly determines the action effect of the fluid, provides a basis for predicting crack spreading characteristics and development modes under different formation environments, and the different formation environments refer to different temperature and pressure environments, and the different formation environments are low in temperature and low in pressure, the different formation environments are high in temperature and pressure, even the different areas of the same basin can have abnormal low pressure or abnormal high pressure, so that CO 2 presents different phase states in different formation environments, even phase state conversion is likely to exist in the flowing process of CO 2, and predicts the crack spreading characteristics by comparing the three-dimensional structure characteristics of the crack under the different formation temperature and pressure environments, such as length, width, thickness, volume and the like. The method provided by the invention can also be used for quantitative research on the influence of underground fluid states on the pore structure of the porous medium after being changed by environmental factors, a lot of pores exist in the rock except for cracks, the information of the pore structure before and after the fluid action, such as porosity, pore size distribution, pore connectivity and the like, can be extracted to determine the influence on the pore structure of the porous medium, and the rapid quantitative evaluation on the distribution mode of mineral particles under the fluid-solid coupling action, and can be used for extracting the geometric information of the mineral particles before and after the fluid action, such as particle size, volume, connectivity, orientation and the like, so as to quantitatively evaluate the distribution characteristics of the mineral particles.
An embodiment of the second aspect of the present invention provides a rock fracture structure characterization device, which is used in the rock fracture structure characterization method in any one of the embodiments of the first aspect, where the rock fracture structure characterization device includes: the rock core holder is used for holding a rock sample and simulating formation confining pressure, and the rock core holder is used for transmitting X rays; a fluid injection device for injecting fluids of different phases into the rock sample; the X-ray scanning device is used for scanning the rock sample in the core holder so as to obtain a three-dimensional gray image; and the imaging data analysis device is used for extracting rock fracture structure information under the continuous action of different phases of fluid in the three-dimensional gray level image to realize quantitative characterization.
According to the rock fracture structure characterization device provided by the invention, the rock fracture structure characterization device is used for the rock fracture structure characterization method in any embodiment of the first aspect, and comprises a core holder, a fluid injection device, an X-ray scanning device and an imaging data analysis device. The rock core holder can hold rock samples and simulate formation confining pressure, and the rock core holder is used for transmitting X rays. The fluid injection device is capable of injecting fluids of different phases into a rock sample. The X-ray scanning device can scan the rock sample in the core holder to obtain a three-dimensional gray scale image. The imaging data analysis device can extract rock fracture structure information under the continuous action of different phases of fluid in the three-dimensional gray level image to realize quantitative characterization. Since the characterization device of the rock fracture structure is a characterization method for realizing the rock fracture structure as in any one of the embodiments of the first aspect. Therefore, the device for characterizing a rock fracture structure provided by the invention also has all the beneficial effects of the method for characterizing a rock fracture structure in any one of the embodiments of the first aspect, and will not be described in detail herein.
Embodiments of the present application provide a method for selecting a subsurface reservoir, comprising the steps of the method for characterizing a rock fracture structure, further comprising:
Preparing a rock sample;
Performing X-ray scanning on the rock sample to obtain an initial three-dimensional structural image of the rock sample;
Applying different confining pressures to the rock sample, and performing continuous in-situ X-ray scanning to obtain three-dimensional structure images of the rock sample in different time and different deformation states;
Post-processing the initial three-dimensional structure image and the three-dimensional structure image of the rock sample under different deformation states at different times to obtain a gray level image for strain calculation;
determining the strain and distribution mode of the rock sample under different surrounding pressures based on the gray level image so as to realize the representation of rock continuous strain;
The subsurface reservoir is selected based on the rock fracture structure and the strain of the rock, i.e., in a plurality of alternative subsurface reservoirs, the rock fracture structure is selected such that the length, width, volume change, and rock expansion strain of the rock fracture structure are minimized when the gas phase state of the gas to be stored is changed.
In an embodiment of the present application, the step of determining the strain and distribution pattern of the rock sample under different surrounding pressures based on the gray level image specifically includes: and calculating a strain field of the rock sample subjected to stress deformation relative to the previous moment based on the gray level image so as to determine the strain and distribution modes of the rock sample under different surrounding pressures. The step of calculating the strain field of the rock sample deformed by stress relative to the previous moment based on the gray level image specifically comprises the following steps: and calculating the strain field of the rock sample deformed by stress relative to the previous moment by adopting a digital correlation method based on the gray level image. The step of calculating the strain field of the rock sample deformed by stress relative to the previous moment by adopting a digital correlation method based on the gray level image specifically comprises the following steps: importing the gray scale image into an imaging data analysis device; dividing the three-dimensional structure image of the rock sample deformed under different confining pressures and the three-dimensional structure image of the rock sample at the previous moment into a plurality of subvolumes; matching a plurality of said sub-volumes by correlation, the center of each of said sub-volumes being used to estimate and map a displacement field; the displacement field is converted to the strain field by a central finite difference. The steps of applying different confining pressures to the rock sample and performing continuous in-situ X-ray scanning specifically comprise: the rock sample was placed in an X-ray transparent core holder and successive in situ X-ray scans were performed with different confining pressures applied. The rock sample is placed in a rock core holder capable of transmitting X rays, and different confining pressures are applied to perform continuous in-situ X ray scanning, and the method specifically comprises the following steps of: the rock sample is placed in an X-ray transparent core holder, water is continuously injected into the core holder, and continuous in-situ X-ray scanning is performed. The step of post-processing the initial three-dimensional structure image and the three-dimensional structure image of the rock sample under different deformation states at different times specifically comprises the following steps: and carrying out image registration and noise removal processing on the initial three-dimensional structure image and the three-dimensional structure image of the rock sample under different deformation states at different times. Before the steps of performing image registration and noise removal processing on the initial three-dimensional structure image and the three-dimensional structure image of the rock sample under different deformation states at different times, the method further comprises: and pre-registering the initial three-dimensional structure image and the three-dimensional structure image of the rock sample under different deformation states at different times through aligning centers or aligning principal coordinate axes. The noise removal includes non-local mean filtering, gaussian filtering, and median filtering. The rock sample prepared comprises at least one of the following: a cylindrical rock sample, a rectangular rock sample, and a square rock sample. The step of X-ray scanning the rock sample is preceded by: the rock sample is placed in the range of an X-ray scanning view. the step of performing X-ray scanning on the rock sample to obtain an initial three-dimensional structural image of the rock sample specifically includes: and carrying out continuous synchrotron radiation X-ray scanning on the rock sample to obtain a high-resolution initial three-dimensional structure image of the rock sample. The step of X-ray scanning the rock sample to obtain an initial three-dimensional structural image of the rock sample is preceded by: fluid is injected into the rock sample. The fluid comprises fluids of different phases.
A method for selecting a subsurface reservoir provided according to the present application further comprises:
Preparing a sandstone sample to be tested;
Applying confining pressure to the sandstone sample to be detected, slowly injecting potassium iodide solution into the sandstone sample to be detected, and simultaneously continuously scanning the sandstone sample to be detected by X rays until the sandstone sample to be detected is completely saturated;
Injecting a second fluid into the sandstone sample to be detected, and simultaneously carrying out X-ray continuous scanning on the sandstone sample to be detected until the potassium iodide solution is completely displaced;
Acquiring a three-dimensional image, and acquiring a first volume fraction after potassium iodide saturation and a second volume fraction after complete filling of a second fluid according to the three-dimensional image;
The first volume fraction and the second volume fraction are compared for wettability characterization to select a subsurface reservoir based on sandstone wettability, rock fracture structure, and rock continuous strain.
In an embodiment of the present application, the applying a confining pressure to the sandstone sample to be measured, slowly injecting a potassium iodide solution into the sandstone sample to be measured, and continuously scanning the sandstone sample to be measured by X-rays until the sandstone sample to be measured is completely saturated, specifically includes: applying confining pressure to the sandstone sample to be tested; slowly injecting potassium iodide solution into the sandstone sample to be detected, and simultaneously carrying out X-ray continuous scanning on the sandstone sample to be detected to obtain a three-dimensional digital core; and quantitatively dividing the three-dimensional digital rock core until the saturation value of the sandstone sample to be detected is unchanged. The quantitative segmentation is carried out on the three-dimensional digital rock core until the saturation value of the sandstone sample to be detected is unchanged, and the quantitative segmentation specifically comprises the following steps: quantitatively dividing the three-dimensional digital rock core to obtain a saturation value of the sandstone sample to be detected; judging whether the saturation value changes or not; if not, the sandstone sample to be detected is completely saturated, and the injection of the potassium iodide solution is stopped. Injecting a second fluid into the sandstone sample to be detected, and simultaneously carrying out X-ray continuous scanning on the sandstone sample to be detected until the potassium iodide solution is completely displaced, wherein the method specifically comprises the following steps of: injecting a second fluid into the sandstone sample to be detected, and simultaneously carrying out X-ray continuous scanning on the sandstone sample to be detected to obtain a two-dimensional X-ray image and a three-dimensional digital rock core; judging whether the potassium iodide solution is completely discharged out of the sandstone sample to be tested according to the two-dimensional X-ray image; if yes, quantitatively dividing the three-dimensional digital rock core to confirm that the displacement of the second fluid is completed. The method for obtaining the three-dimensional image comprises the steps of obtaining a first volume fraction after potassium iodide saturation and a second volume fraction after complete filling of a second fluid according to the three-dimensional image, and specifically comprises the following steps: acquiring a first three-dimensional image of the sandstone sample to be detected after being completely saturated, and carrying out filtering and position alignment on the first three-dimensional image to obtain a first image gray level difference; obtaining original porosity and residual porosity after filling potassium iodide according to the gray level difference of the first image; and obtaining a first volume fraction after potassium iodide saturation according to the difference between the original porosity and the residual porosity. The three-dimensional image is obtained, and a first volume fraction after potassium iodide saturation and a second volume fraction after complete filling of a second fluid are obtained according to the three-dimensional image, and the method further comprises the following steps: acquiring a second three-dimensional image after the potassium iodide solution is completely displaced, and filtering and aligning the second three-dimensional image to obtain a second image gray level difference; and dividing according to the gray level difference of the second image to obtain a second volume fraction of the second fluid after the second fluid is completely filled. The wettability characterization by comparing the first volume fraction with the second volume fraction specifically comprises the following steps: and calculating according to the first volume fraction and the second volume fraction to obtain a wettability index. And when the wettability index is larger than a preset value, representing hydrophilicity, and when the wettability index is smaller than the preset value, representing hydrophobicity.
A method for selecting a subsurface reservoir provided according to the present application further comprises:
Scanning the rock sample to obtain a rock structure image;
Constructing a rock pore network model according to the rock structure image;
And constructing a gas mutual flooding model of the rock according to the rock pore network model, wherein the gas mutual flooding model is used for determining the gas mutual flooding characteristic of the rock so as to select a subsurface reservoir according to the wettability of sandstone, the rock fracture structure, the rock continuous strain and the gas mutual flooding characteristic of the rock.
In an embodiment of the application, said constructing a pore network model from said rock structure image comprises: dividing the rock structure image to obtain a rock pore distribution image; and constructing the rock pore network model according to the rock pore distribution image. The constructing the rock pore network model according to the rock pore distribution image comprises the following steps: separating the rock pore distribution image to obtain a rock pore phase model; and constructing the rock pore network model according to the rock pore phase model. The step of separating the rock pore distribution image to obtain a rock pore phase model comprises the following steps: and separating the rock pore distribution image according to the pixel value to obtain the rock pore phase model. The constructing a gas mutual flooding model according to the rock pore network model comprises the following steps: optimizing the rock pore network model to obtain a rock grid structure model; and constructing a rock gas mutual driving model according to the rock grid structure model. The optimizing the rock pore network model to obtain a rock grid structure model comprises the following steps: converting the rock pore network model into a rock three-dimensional structure model; and carrying out optimization treatment on the rock three-dimensional structure model to obtain a rock grid structure model. The optimizing the rock three-dimensional structure model to obtain a rock grid structure model comprises the following steps: converting the rock three-dimensional structure model into a first grid model according to the first grid density; and carrying out optimization treatment on the first grid model to obtain the rock grid structure model. The optimization processing at least comprises overlapping grid removing processing, grid hole filling processing and special-shaped grid adjusting processing. The building of the rock gas mutual driving model according to the rock grid structure model comprises the following steps: and training the rock grid structure model according to a sample data set to obtain the rock gas mutual flooding model. The sample data set includes at least a training data set and a test data set. The scanning of the rock to obtain the rock structure image comprises the following steps: and carrying out X-ray scanning on the rock to obtain the rock structure image. The rock structure image is a gray image with preset storage capacity.
A method for selecting a subsurface reservoir provided according to the present application further comprises:
preparing a rock sample, and determining a marker corresponding to an organic matter to be detected on the rock sample;
determining first position information of the organic matter to be detected through a nano infrared spectrometer and the marker;
determining second position information of the organic matter to be detected through the atomic force probe of the nanometer infrared spectrometer and the first position information;
based on the second position information, acquiring infrared spectrums of the organic matters to be detected through the nanometer infrared spectrometer;
and determining the gas adsorption capacity of the organic matter to be detected according to the infrared spectrum, and taking the gas adsorption capacity as the adsorption capacity of the rock to gas, so as to select the underground reservoir according to the wettability of sandstone, the crack structure of the rock, the continuous strain of the rock, the gas mutual driving characteristic of the rock and the adsorption capacity of the rock to gas.
In an embodiment of the present application, the determining, by using a nano infrared spectrometer and the marker, the first position information of the organic matter to be detected specifically includes: and observing the marker through an optical microscope in the nanometer infrared spectrometer, and determining the first position information of the organic matter to be detected. The determining, by the atomic force probe of the nano infrared spectrometer and the first position information, the second position information of the organic matter to be detected specifically includes: according to the first position information, controlling the atomic force probe to be close to the organic matter to be detected, and determining third position information of the atomic force probe; and determining the second position information of the organic matter to be detected according to the third position information. And controlling the atomic force probe to be close to the organic matter to be detected according to the first position information, and determining third position information of the atomic force probe, wherein the method specifically comprises the following steps of: setting a test distance between the surface of the rock sample and the atomic force probe based on the first position information; and according to the test distance, enabling the atomic force probe to approach the organic matter to be tested, and determining the third position information. Based on the second position information, the infrared spectrum of the organic matter to be detected is collected through the nanometer infrared spectrometer, and the method specifically comprises the following steps: determining a laser position of the nano infrared spectrometer according to the second position information, wherein the laser position maximizes a light spot in a sample surface contact area; And acquiring the infrared spectrum of the organic matter to be detected according to the laser position. The determining the laser position of the nanometer infrared spectrometer according to the second position information specifically includes: according to the second position information, determining a plurality of target wave numbers of laser emitted by the nanometer infrared spectrometer; and carrying out position calibration on laser emitted by the nanometer infrared spectrometer according to the plurality of target wave numbers so as to obtain the laser position. The step of collecting the infrared spectrum of the organic matter to be detected according to the laser position specifically comprises the following steps: determining a plurality of target wave bands corresponding to the nanometer infrared spectrometer according to the laser positions; And based on the target wave bands, carrying out spectrum acquisition on the organic matter to be detected to obtain the infrared spectrum. The determining the gas adsorption capacity of the organic matter to be detected according to the infrared spectrum specifically comprises the following steps: according to the infrared spectrum, the original adsorption capacity and humidity influence coefficient of the organic matters to be detected are truly determined; and determining the gas adsorption capacity according to the original adsorption capacity and the humidity influence coefficient. The method for determining the original adsorption capacity of the organic matter to be detected according to the infrared spectrum specifically comprises the following steps: determining a plurality of absorption intensities corresponding to the organic matter to be detected according to the infrared spectrum; and determining the original adsorption capacity according to the plurality of absorption intensities. The method for determining the humidity influence coefficient of the organic matter to be detected according to the infrared spectrum specifically comprises the following steps: determining a plurality of absorption intensities corresponding to the organic matter to be detected according to the infrared spectrum; and determining the humidity influence coefficient according to the plurality of absorption intensities. The method for determining the gas adsorption capacity according to the original adsorption capacity and the humidity influence coefficient specifically comprises the following steps: and carrying out numerical correction on the original adsorption capacity according to the humidity influence coefficient to obtain the gas adsorption capacity. The determining of the marker corresponding to the organic matter to be detected on the rock sample specifically comprises the following steps: and observing the organic matter to be detected on the rock sample through an optical instrument, and determining the marker corresponding to the organic matter to be detected. The markers are mineral particles on the rock sample. The markers are markings engraved on the rock sample. After the first position information of the organic matter to be detected is determined, the method further comprises the following steps: collecting a plurality of spectral background values of the nano infrared spectrometer; and removing the measurement error of the nanometer infrared spectrometer through the plurality of spectrum background values. The gas adsorption capacity is the adsorption capacity of functional groups such as hydroxyl, aromatic ring, carboxyl, carbonyl and the like in the organic matter to be detected on gas substances.
A method for selecting a subsurface reservoir provided according to the present application further comprises:
acquiring a rock sample to be tested; wherein the rock sample to be tested is taken from organic shale;
obtaining the distribution position of kerogen in the rock sample to be detected by using a first scanning instrument;
Obtaining the surface morphology features of each kerogen in the rock sample to be detected by using a second scanning instrument based on the distribution positions of the kerogen in the rock sample to be detected; wherein the surface topography features comprise at least: surface relief and roughness;
Carrying out spectrum test on each kerogen in the rock sample to be tested by utilizing a spectrum test instrument based on the distribution position of the kerogen in the rock sample to be tested to obtain the surface molecular structural characteristics of each kerogen in the rock sample to be tested;
And determining the storage capacity of each kerogen in the rock sample to be tested to the target gas according to the surface morphology features and the surface molecular structure features of each kerogen in the rock sample to be tested, so as to select a subsurface reservoir according to the wettability of sandstone, the rock fracture structure, the rock continuous strain, the gas mutual driving characteristics of the rock, the adsorption capacity of the rock to the gas and the storage capacity of each kerogen in the rock sample to the target gas.
In an embodiment of the present application, the obtaining a rock sample to be measured includes: obtaining a rock sample from the shale rich in organic matter; preparing the rock sample into a rock sample to be polished with a preset size and a preset shape; and polishing the rock sample to be polished to obtain the rock sample to be polished. The first scanning instrument is a scanning electron microscope, and the obtaining of the distribution position of kerogen in the rock sample to be detected by using the first scanning instrument comprises the following steps: scanning the rock sample to be detected by using the scanning electron microscope under a preset condition to obtain the distribution position of kerogen in the rock sample to be detected; wherein the preset conditions at least comprise a low vacuum condition. The second scanning instrument is an atomic force microscope, and based on the distribution position of the kerogen in the rock sample to be detected, the surface topography features of each kerogen in the rock sample to be detected are obtained by using the second scanning instrument, and the method comprises the following steps: scanning each kerogen in the rock sample to be detected by utilizing the atomic force microscope based on the distribution position of the kerogen in the rock sample to be detected, so as to obtain a scanning image of each kerogen in the rock sample to be detected; and determining the surface morphology features of each kerogen in the rock sample to be detected according to the scanning images of each kerogen in the rock sample to be detected. The determining the surface topography features of each kerogen in the rock sample to be tested according to the scanned images of each kerogen in the rock sample to be tested comprises the following steps: determining the highest point and the lowest point of the surface of each kerogen in the rock sample to be tested according to the scanned image of each kerogen in the rock sample to be tested; and obtaining the surface waviness of each kerogen in the rock sample to be tested according to the distance between the highest point and the lowest point of the surface of each kerogen in the rock sample to be tested. The determining the surface topography features of each kerogen in the rock sample to be tested according to the scanned images of each kerogen in the rock sample to be tested comprises the following steps: the roughness of each kerogen in the rock sample to be measured was calculated using the following formula: ; wherein R a is the roughness average of kerogen; n x and N y represent the number of data points scanned in the X and Y coordinate axis directions, respectively, and Z (i, j) represents the height of the data point scanned; z mean represents the average height of the baseline of the scanned data points. The surface molecular structure characteristics of the kerogen include the relative absorption intensity of the characteristic functional groups on the surface of the kerogen to infrared light of a preset wave band, and the spectral test is performed on each kerogen in the rock sample to be tested by utilizing a spectral test instrument based on the distribution position of the kerogen in the rock sample to be tested to obtain the surface molecular structure characteristics of each kerogen in the rock sample to be tested, and the method comprises the following steps: based on the distribution position of kerogen in the rock sample to be tested, carrying out atomic force-based nanometer infrared spectrum test on each kerogen in the rock sample to be tested by utilizing a spectrum test instrument to obtain the relative absorption intensity of various characteristic functional groups on the surfaces of each kerogen in the rock sample to be tested on infrared light of the preset wave band; the absorption intensity of the characteristic functional group to the infrared light of the preset wave band is related to the absorption capacity of the characteristic functional group to target gas. The determining the storage capacity of each kerogen in the rock sample to be tested to the target gas according to the surface morphology feature and the surface molecular structure feature of each kerogen in the rock sample to be tested comprises the following steps: for each kerogen in the rock sample to be tested, the following steps are performed: determining the surface area of the kerogen available for adsorbing gas according to the surface waviness and roughness of the kerogen; determining the adsorption capacity of the kerogen to the target gas according to the relative absorption intensity of various characteristic functional groups on the surface of the kerogen to the infrared light of the preset wave band; the storage capacity of the kerogen for the target gas is determined based on the amount of surface area of the kerogen available for adsorption of gas and the amount of adsorption capacity of the kerogen for the target gas.
A method for selecting a subsurface reservoir provided according to the present application further comprises:
Preparing a rock sample to be tested;
carrying out X-ray scanning on a rock sample to be detected to obtain a three-dimensional structure image;
determining a gridding image for flow simulation according to the three-dimensional structure image;
performing fluid flow simulation on the gridded image;
The fluid flow characteristics of the different rock samples are compared for evaluation of the rock micro-pore structure to select a subsurface reservoir based on sandstone wettability, rock fracture structure, rock continuous strain, gas mutual drive characteristics of the rock, adsorption capacity of the rock to gas, storage capacity of the respective kerogen in the rock sample to target gas, and the rock micro-pore structure.
In an embodiment of the present application, determining a gridded image for flow simulation from a three-dimensional structure image specifically includes: noise removing is carried out on the three-dimensional structure image; carrying out pore segmentation on the denoised image according to the gray value; the segmented pores are extracted, and a tetrahedron grid is generated through edge overturning, edge folding and vertex translation and is used as a gridding image for flow simulation. Performing fluid flow simulation on the gridded image, specifically including: introducing the pores of the gridding image into a multiphase flow model; the same fluid is injected into the pores of the gridding image according to the same flow velocity under the same temperature and pressure condition in the multiphase flow model. The evaluation of the rock micro-pore structure specifically comprises the following steps: and selecting the highest flow velocity point in the pore as a key node, and calculating the average pressure difference of the flow velocity according to the key node to judge the complexity of the microscopic pore throat.
A method for selecting a subsurface reservoir provided according to the present application further comprises:
preparing a rock sample to be detected, wherein the rock is shale;
Identifying target organic matters in a rock sample to be detected;
Acquiring the surface morphology, elastic modulus characteristics and surface components of the target organic matter;
The surface morphology, elastic modulus characteristics and surface composition of the target organic matter determine the microstructure of the target organic matter to select a subsurface reservoir based on sandstone wettability, rock fracture structure, rock continuous strain, gas mutual drive characteristics of the rock, adsorption capacity of the rock to gas, storage capacity of each kerogen in the rock sample to the target gas, rock micro-pore structure and microstructure of the organic matter in the rock.
In the embodiment of the application, the target organic matter is identified by observing the rock sample to be detected through an optical microscope and a scanning electron microscope, wherein the optical microscope adopts reflected light for observation, and the scanning electron microscope adopts a low vacuum condition for observation. The obtaining the surface morphology and the elastic modulus of the target organic matter comprises the following steps: testing the root mean square roughness of a target organic matter by an atomic force microscope and taking the root mean square roughness as the surface morphology of the target organic matter; the elastic modulus of the target organic material was tested by the Derjaguar-Muller-Toporov model of an atomic force microscope, which is a model used to describe the interaction between the sample and the probe. The obtaining the surface component of the target organic matter comprises the following steps: and testing the surface components of the target organic matters by utilizing an atomic force infrared combined system based on a photo-thermal induced nano infrared technology. Before testing the surface composition of the target organic matter, the method further comprises: the atomic force infrared combined system was laser calibrated at 1450-1460 cm -1、1600-1620 cm-1 and 2920-2930 cm -1 wavenumbers. The method for determining the microstructure of the organic matter according to the surface morphology, the elastic modulus and the surface composition of the target organic matter, as the characteristic of the organic matter, comprises the following steps: determining the reduction degree of the fatty chain according to the surface component of the target organic matter, wherein the reduction degree of the fatty chain is the ratio of methyl to methylene content in an infrared spectrogram; comparing the root mean square roughness, the elastic modulus and the fatty chain reduction degree of the first rock sample to be tested and the second rock sample to be tested; under the condition that the root mean square roughness of the first rock sample to be measured is larger than that of the second rock sample to be measured, the elastic modulus of the first rock sample to be measured is larger than that of the second rock sample to be measured, and the reduction degree of the fatty chain of the first rock sample to be measured is smaller than that of the second rock sample to be measured, the hydrocarbon generation and emission potential of the first rock sample to be measured is larger than that of the second rock sample to be measured.
In an embodiment of the application, the subsurface reservoir is selected to include two application scenarios: first, a target subsurface reservoir is selected from a plurality of subsurface reservoirs based on the gas to be stored, and second, a reservoir gas adapted to the subsurface reservoir is selected from a plurality of reservoir gases based on characteristics of the rock in the subsurface reservoir, including but not limited to fracture structure of the rock, strain of the rock, gas mutual drive characteristics in the rock, adsorption capacity of the rock to gas, wettability of the rock, gas storage capacity of kerogen in the rock, microscopic pore structure of the rock, microscopic structure of rock organic matter, reservoir gas including but not limited to carbon dioxide, hydrogen, natural gas.
In embodiments of the application, in selecting a subsurface reservoir, the smaller the length, width and volume changes of the rock fracture structure as the gas phase of the gas to be stored changes, the better the fracture structure is to avoid the risk of leakage of the gas to be stored during the storage.
In embodiments of the application, in selecting a subsurface reservoir, the subsurface reservoir rock is subject to significant expansion strain as the gas phase of the gas to be stored changes, if the rock expansion strain is small, the subsurface reservoir is selected, if the expansion strain is large, the rock aperture is easily caused to close significantly, reducing gas storage capacity.
In embodiments of the application, where the gas to be stored is carbon dioxide and methane is present in the rock in the subsurface reservoir, in selecting the subsurface reservoir, the displacement effect of carbon dioxide on methane is determined based on the characteristics of the mutual displacement between carbon dioxide and methane, i.e., the change in the volumetric flow rates of carbon dioxide and methane in the pore structure, the better the displacement effect of carbon dioxide on methane, the greater the probability of selecting the current subsurface reservoir.
In the embodiment of the application, in the case that the gas to be stored is carbon dioxide, in the selective subsurface reservoir, the more the oxygen-containing functional group content is, the more the adsorption capacity of kerogen to carbon dioxide gas can be enhanced, and the greater the probability of selecting the current subsurface reservoir.
In embodiments of the application, where the gas to be stored is carbon dioxide, the blocking capacity of the rock is reduced when the rock wettability is hydrophobic in the selected subsurface reservoir, and the current subsurface reservoir is selected when the rock wettability is hydrophilic.
In an embodiment of the application, where the gas to be stored is carbon dioxide, in selecting the subsurface reservoir, the gas storage capacity of kerogen in the rock is determined by the size of the surface area of kerogen available for adsorption of gas and the size of the capacity of said kerogen for adsorption of carbon dioxide gas, the larger the surface area of kerogen available for adsorption of gas and the larger the capacity of said kerogen for adsorption of carbon dioxide gas, the greater the probability of selecting the current subsurface reservoir.
In embodiments of the present application, the more complex the subsurface reservoir rock micro-pore structure is in selecting a subsurface reservoir, the worse the permeability, and the more resistance to fluid flow tends to be created, and therefore the more simple the subsurface reservoir rock micro-pore structure is, the greater the probability of selecting the current subsurface reservoir when the permeability is better.
In embodiments of the present application, in selecting a subsurface reservoir, the microstructure of the rock organic matter is the roughness and elastic modulus of the rock organic matter, the greater the roughness of the subsurface reservoir rock organic matter is, the more advantageous the gas enrichment, the greater the elastic modulus is, the more the shale bulk stiffness can be enhanced, and therefore the greater the roughness and elastic modulus of the subsurface reservoir rock organic matter is, the greater the probability of selecting a current subsurface reservoir.
While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features of specific embodiments of particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. On the other hand, the various features described in the individual embodiments may also be implemented separately in the various embodiments or in any suitable subcombination. Furthermore, although features may be acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.
Thus, particular embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results. Furthermore, the processes depicted in the accompanying drawings are not necessarily required to be in the particular order shown, or sequential order, to achieve desirable results. In some implementations, multitasking and parallel processing may be advantageous.
It should be noted that in this document, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The foregoing is only a specific embodiment of the invention to enable those skilled in the art to understand or practice the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (8)
1. A method for selecting a subsurface reservoir, characterized by comprising the steps of a method for characterizing a rock fracture structure,
The characterization method of the rock fracture structure comprises the following steps:
Preparing a rock sample;
Placing the rock sample in a core holder for transmitting X-rays, and applying pressure to simulate formation confining pressure to perform initial rock structure scanning;
Injecting a fluid into the rock sample and performing continuous X-ray scanning to obtain a three-dimensional gray scale image;
extracting rock fracture structure information under the continuous action of the fluid in the three-dimensional gray level image to realize quantitative characterization;
wherein the fluid comprises fluids in different phases,
The method for selecting a subsurface reservoir further comprises:
Preparing a rock sample;
Performing X-ray scanning on the rock sample to obtain an initial three-dimensional structural image of the rock sample;
Applying different confining pressures to the rock sample, and performing continuous in-situ X-ray scanning to obtain three-dimensional structure images of the rock sample in different time and different deformation states;
Post-processing the initial three-dimensional structure image and the three-dimensional structure image of the rock sample under different deformation states at different times to obtain a gray level image for strain calculation;
determining the strain and distribution mode of the rock sample under different surrounding pressures based on the gray level image so as to realize the representation of rock continuous strain;
the subsurface reservoir is selected based on the rock fracture structure and strain of the rock,
Wherein the method for selecting a subsurface reservoir further comprises:
Preparing a sandstone sample to be tested;
Applying confining pressure to the sandstone sample to be detected, slowly injecting potassium iodide solution into the sandstone sample to be detected, and simultaneously continuously scanning the sandstone sample to be detected by X rays until the sandstone sample to be detected is completely saturated;
Injecting a second fluid into the sandstone sample to be detected, and simultaneously carrying out X-ray continuous scanning on the sandstone sample to be detected until the potassium iodide solution is completely displaced;
Acquiring a three-dimensional image, and acquiring a first volume fraction after potassium iodide saturation and a second volume fraction after complete filling of a second fluid according to the three-dimensional image;
The first volume fraction and the second volume fraction are compared for wettability characterization to select a subsurface reservoir based on sandstone wettability, rock fracture structure, and rock continuous strain.
2. The method of claim 1, wherein the step of injecting fluid into the rock sample and performing a continuous X-ray scan to obtain a three-dimensional gray scale image is preceded by the step of:
The environmental conditions for phase inversion of the fluid are configured to cause inversion of the fluid between different phases.
3. The method of claim 1, wherein the step of extracting the rock fracture structure information under the continuous action of the fluid in the three-dimensional gray scale image for quantitative characterization comprises:
importing the three-dimensional gray scale image into an imaging data analysis device;
extracting a rock fracture structure of the same rock fracture under the action of different phase fluids;
and quantitatively characterizing the rock fracture structure under the action of different phase fluids.
4. The method according to claim 1, characterized in that the step of preparing a rock sample, in particular, comprises:
And preparing the rock sample into a rock sample which meets the preset scanning resolution and meets the size requirement of the core holder.
5. The method of claim 1, wherein the step of injecting fluid into the rock sample and performing a continuous X-ray scan to obtain a three-dimensional gray scale image comprises:
The fluid is injected into the rock sample and subjected to continuous synchrotron radiation X-ray scanning to obtain a three-dimensional gray scale image.
6. The method of claim 1, wherein the step of placing the rock sample in a core holder for X-ray transmission and applying pressure to simulate formation confining pressure for initial rock structure scanning comprises:
Placing the rock sample in a core holder for penetrating X rays, and continuously injecting water into the core holder until the pressure generated by the core holder reaches the preset formation confining pressure;
and performing initial rock structure scanning based on the pressure generated by the core holder reaching the preset stratum confining pressure.
7. The method of claim 6, wherein the step of continuously injecting water into the core holder until the pressure generated by the core holder reaches a predetermined formation confining pressure comprises:
And continuously injecting water into the core holder through a plunger pump until the pressure generated by the core holder reaches the preset formation confining pressure.
8. The method of any one of claims 1 to 5, wherein prior to the step of injecting fluid into the rock sample and performing a continuous X-ray scan, further comprises:
And (5) carrying out saturation treatment on the rock sample by brine.
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| CN107741390A (en) * | 2017-08-21 | 2018-02-27 | 中国石油大学(北京) | The physical simulating method that water filling induces microcrack Extending Law is reproduced under formation condition |
| CN109298162A (en) * | 2018-12-03 | 2019-02-01 | 重庆大学 | Different phase carbon dioxide fracturing shale device and experimental method |
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| CN107741390A (en) * | 2017-08-21 | 2018-02-27 | 中国石油大学(北京) | The physical simulating method that water filling induces microcrack Extending Law is reproduced under formation condition |
| CN109298162A (en) * | 2018-12-03 | 2019-02-01 | 重庆大学 | Different phase carbon dioxide fracturing shale device and experimental method |
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