Detection method and testing device for shale surface oil-gas-water occurrence capacity

Abstract

The invention provides a detection method and a test device for shale surface oil-gas-water occurrence capacity. The shale surface oil-gas-water occurrence capacity detection method comprises the steps that a shale sample with grooves is prepared, the shale sample comprises a test surface, water drops are dropwise added to a first plane, and oil drops are dropwise added to a second plane; dripping water drops on the first inclined wall, and dripping oil drops on the second inclined wall; acquiring first contact angle data of water drops on a first plane and a first inclined wall, determining a single occurrence capability index of the water drops according to the first contact angle data, acquiring second contact angle data of oil drops on a second plane and a second inclined wall, determining a single occurrence capability index of the oil drops according to the second contact angle data, and determining a single occurrence capability index of the oil drops according to the second contact angle data; and according to the first contact angle data and the second contact angle data, determining an oil drop and liquid drop competitive occurrence capability index. According to the detection method for the shale surface oil-gas-water occurrence capacity, comprehensive simulation monitoring of the shale surface oil-gas-water occurrence capacity can be achieved.

Description

Technical Field

[0001] This application relates to the field of detection technology, and in particular to a method and testing device for detecting the oil, gas and water storage capacity of shale surfaces. Background Technology

[0002] In the field of unconventional oil and gas resource development, the efficient development of shale gas and shale oil depends on the accurate characterization of the oil, gas, and water occurrence states in shale. Shale, as a typical low-permeability reservoir, has a complex microscopic pore structure, and its surface wettability is influenced by the combined effects of organic matter, clay minerals, and the chemical properties of pore fluids. Existing research indicates that the wettability of the shale surface determines the priority of oil, gas, and water occurrence: oleophilic surfaces tend to adsorb oil and gas, while hydrophilic surfaces are more likely to retain the water phase. This occurrence characteristic directly affects the fluid flow behavior, recovery rate, and reservoir damage degree after hydraulic fracturing.

[0003] In existing technologies, the roughness and heterogeneity of shale surfaces, as well as the chemical damage introduced during processing, make it difficult for traditional contact angle measurement methods to accurately reflect its intrinsic wettability. At the same time, since the fluid occurrence behavior in shale fractures and micropores is affected by gravity, capillary force and fluid competition, existing technologies are mostly limited to single-plane contact angle measurement and cannot simulate the dynamic occurrence process in the inclined walls of fractures or narrow spaces.

[0004] Existing technologies have the following limitations: Shale sample surface preparation is not standardized, and surface roughness is not quantitatively controlled, leading to contact angle measurement results being affected by morphological randomness. Furthermore, there is a lack of measures to inhibit processing thermal damage and chemical erosion, potentially destroying the original organic matter and mineral composition of the shale surface. The contact angle measurement scenario is limited, measuring only planar contact angles, failing to simulate the occurrence behavior in shale fractured inclined walls or narrow spaces. A quantitative method for occurrence capacity is lacking, providing only static contact angle data and lacking quantitative analysis of single-item occurrence and multi-fluid competitive occurrence under slope contact, making it difficult to directly guide development practices. Data processing lacks standardization; some studies estimate wettability using empirical formulas, but no occurrence capacity index system based on contact angle changes has been established, resulting in insufficient comparability and engineering applicability of the results. Summary of the Invention

[0005] This application provides a method and testing device for detecting the oil, gas and water storage capacity on shale surfaces. Through the integrated design of standardized sample preparation, multi-dimensional contact angle measurement and dynamic quantitative evaluation of storage capacity, it can accurately simulate and detect the oil, gas and water storage capacity on shale surfaces.

[0006] In a first aspect, this application provides a method for detecting the oil, gas and water storage capacity of a shale surface, comprising: preparing a shale sample with grooves, the shale sample including a test surface, the grooves being disposed on the test surface, the grooves having opposing first and second inclined walls, the roughness of the first and second inclined walls being less than 1 μm, the test surface further including a first plane located on one side of the first inclined wall and a second plane located on one side of the second inclined wall, the roughness of the first and second planes being less than 1 μm; adding water droplets to the first plane and oil droplets to the second plane; adding water droplets to the first inclined wall and oil droplets to the second inclined wall.

[0007] Acquire first contact angle data of water droplets on the first plane and the first inclined wall, determine the single-item retention capacity index of water droplets based on the first contact angle data, acquire second contact angle data of oil droplets on the second plane and the second inclined wall, determine the single-item retention capacity index of oil droplets based on the second contact angle data, and determine the competitive retention capacity index of oil droplets and water droplets based on the first contact angle data and the second contact angle data.

[0008] The method for detecting the oil, gas, and water storage capacity of shale surfaces provided in this application employs a more rational processing method to manufacture a standardized test surface that retains its original components and has controllable roughness (roughness less than 1 μm), eliminating the influence of morphology interference on contact angle measurements. It provides angle measurement scenarios for planes and inclined walls, allowing for the measurement of first and second contact angle data. This yields individual storage capacity indices for water droplets, oil, and the competitive storage capacity index between oil and liquid droplets, comprehensively simulating the storage behavior of oil, gas, and water in shale in horizontal, inclined, and fractured spaces. Furthermore, it establishes a storage capacity index system based on contact angle changes, improving the comparability and engineering applicability of the results. Thus, through standardized sample preparation, multi-scenario contact angle measurement, and storage capacity index calculation, a reliable technical means is provided for the efficient and quantitative evaluation of shale oil, gas, and water storage capacity, which can be widely applied in reservoir evaluation, fracturing scheme design, and development strategy optimization.

[0009] In some embodiments, the preparation of the shale sample with grooves includes: cutting the shale to obtain a cut body; roughing the cut body; finely machining the rough-machined cut body to give it a test surface; and machining the grooves on the test surface to obtain the shale sample.

[0010] In some embodiments, cutting the shale includes: cutting the shale along a preset direction of the shale core, wherein the preset direction is parallel to or perpendicular to the bedding plane of the shale.

[0011] In some embodiments, rough machining of the cutting body includes: determining a machining area; and leveling the machining area using an inert liquid as a machining cooling medium.

[0012] In some embodiments, the finishing process of the rough-machined cut body to give it a test surface includes: polishing the machined area after planarization multiple times, wherein the roughness of the polishing pads used in the multiple polishings decreases; and using a suspension to finely polish the machined area to obtain the test surface, wherein the test surface exhibits specular reflection under a microscope.

[0013] In some embodiments, the suspension includes an alumina suspension or a colloidal silica suspension.

[0014] In some embodiments, the groove is machined on the test surface, including: machining the test surface using an ultra-precision CNC machine tool with a single-crystal diamond tool or a focused ion beam to obtain the groove; and purging the test surface with a high-purity inert gas to remove machining debris.

[0015] In some embodiments, the angle between the first inclined wall and the second inclined wall is 60°-120°.

[0016] In some embodiments, adding water droplets to the first plane, adding oil droplets to the second plane, and adding water droplets to the first inclined wall and adding oil droplets to the second inclined wall all include: the volume of the water droplets and oil droplets being 2 μL - 10 μL; and / or, the dripping rate of the water droplets and oil droplets being 0.2 μL / s - 2 μL / s; and / or, the distance between the water droplets and oil droplets and the test surface before dripping being 1 mm - 2 mm.

[0017] In some embodiments, acquiring the first contact angle data of the water droplet on the first plane and the first inclined wall, and determining the single-item retention capacity index of the water droplet based on the first contact angle data, includes: the first contact angle data includes the first static contact angle θ0 (water) of the water droplet on the first plane, the first upper contact angle θ1 (water) and the first lower contact angle θ2 (water) of the water droplet on the first inclined wall, and the first competing contact angle θ3 (water) between the water droplet and the oil droplet; the single-item retention capacity index S (water) of the water droplet is:

[0018] ;

[0019] The step of acquiring the second contact angle data of the oil droplet on the second plane and the second inclined wall, and determining the single-item retention capacity index of the oil droplet based on the second contact angle data, includes: the second contact angle data includes the second static contact angle θ0 (oil) of the oil droplet on the second plane, the second upper contact angle θ1 (oil) and the second lower contact angle θ2 (oil) of the oil droplet on the second inclined wall, and the second competing contact angle θ3 (oil) of the oil droplet and the water droplet. The single-item retention capacity index S (oil) of the oil droplet is:

[0020] ;

[0021] The competitive retention capacity index of oil droplets and water droplets is determined based on the first contact angle data and the second contact angle data, including:

[0022] The competitive endowment capability index is:

[0023] in, , .

[0024] Secondly, this application provides a testing device for the oil, gas and water storage capacity of shale surfaces, used to perform the detection method for the oil, gas and water storage capacity of shale surfaces as described in any one of the claims, comprising: a base; a stage disposed on the base, the stage being used to place a shale sample to be tested, the test surface being located on the side of the shale sample facing away from the stage; a support frame disposed on the base; and a fluid competition control baffle vertically disposed on the support frame, the fluid competition control baffle being vertically opposite to the intersection of the first inclined wall and the second inclined wall of the groove of the shale sample, wherein when the fluid competition control baffle abuts against the intersection, it separates the water droplets on the first inclined wall and the oil droplets on the second inclined wall.

[0025] A titration mechanism includes: a first titration unit and a second titration unit, wherein the first titration unit is used to titrate water droplets onto a first plane and a first inclined wall of the test surface, and the second titration unit is used to titrate oil droplets onto a second plane and a second inclined wall of the test surface; a camera unit is used to acquire first contact angle data of water droplets and second contact angle data of liquid droplets; and a control unit electrically connected to the camera unit, wherein the control unit is configured to determine a single-item retention capacity index of water droplets based on the first contact angle data, and to determine a single-item retention capacity index of oil droplets based on the second contact angle data, and to determine a competitive retention capacity index between oil droplets and liquid droplets based on the first contact angle data and the second contact angle data.

[0026] The testing device for the oil, gas and water storage capacity of shale surfaces provided in this application automates the experimental process. It integrates a base, stage, support frame, fluid competition control baffle, titration mechanism, camera unit, and control unit, enabling precise control of shale sample tilt angle, standardization of droplet deposition parameters, and high-precision capture of dynamic processes. The camera unit can capture side-view contour images of oil and water droplets. The control unit is electrically connected to the camera unit, and imports the images from the camera unit into professional contact angle analysis software and fits the Young-Laplace equation to calculate the individual storage capacity index of water droplets, the individual storage capacity index of oil droplets, and the competitive storage capacity index of oil and droplets, thus achieving standardized data processing.

[0027] In some embodiments, the testing device for the oil, gas and water storage capacity of shale surfaces further includes: a lifting mechanism, which is movably mounted on the support frame, and the fluid competition control baffle is mounted on the lifting mechanism.

[0028] In some embodiments, the first titration unit includes: a first mounting bracket disposed on one side of the base where the first plane is located; and a first titrator disposed on the first mounting bracket, the first titrator being used to titrate water droplets onto the first plane and the first inclined wall. The second titration unit includes: a second mounting bracket disposed on one side of the base where the second plane is located; and a second titrator disposed on the second mounting bracket, the second titrator being used to titrate oil droplets onto the second plane and the second inclined wall. Attached Figure Description

[0029] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0030] Figure 1 A flowchart for the shale surface oil, gas and water storage capacity testing experiment provided in this application;

[0031] Figure 2 A schematic diagram of the testing device for the oil, gas and water storage capacity of shale surface provided in this application;

[0032] Figure 3 This is a schematic diagram illustrating the presence of water droplets and oil droplets in the shale sample provided in this application.

[0033] Figure label:

[0034] A testing device for the oil, gas and water storage capacity of 100-shale surface;

[0035] 1-Base; 2-Stage; 3-Support frame; 4-Fluid competition control baffle; 5-Titting mechanism; 6-Camera unit; 7-Control unit; 8-Lifting mechanism; 9-First light source; 10-Second light source;

[0036] 51 - First titration unit; 52 - Second titration unit;

[0037] 51a - First mounting bracket; 51b - First titrator;

[0038] 52a - Second mounting bracket; 52b - Second titrator;

[0039] 200-shale sample;

[0040] 21-First plane; 22-Second plane; 23-First inclined wall; 24-Second inclined wall.

[0041] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0042] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0043] In the field of unconventional oil and gas resource development, the efficient development of shale gas and shale oil depends on the accurate characterization of the oil, gas, and water occurrence states in shale. Shale, as a typical low-permeability reservoir, has a complex microscopic pore structure, and its surface wettability is influenced by the combined effects of organic matter, clay minerals, and the chemical properties of pore fluids. Existing research indicates that the wettability of the shale surface determines the priority of oil, gas, and water occurrence: oleophilic surfaces tend to adsorb oil and gas, while hydrophilic surfaces are more likely to retain the water phase. This occurrence characteristic directly affects the fluid flow behavior, recovery rate, and reservoir damage degree after hydraulic fracturing.

[0044] In existing technologies, the roughness and heterogeneity of shale surfaces, as well as the chemical damage introduced during processing, make it difficult for traditional contact angle measurement methods to accurately reflect its intrinsic wettability. At the same time, since the fluid occurrence behavior in shale fractures and micropores is affected by gravity, capillary force and fluid competition, existing technologies are mostly limited to single-plane contact angle measurement and cannot simulate the dynamic occurrence process in the inclined walls of fractures or narrow spaces.

[0045] Existing technologies have the following limitations: Shale sample surface preparation is not standardized, and surface roughness is not quantitatively controlled, leading to contact angle measurement results being affected by morphological randomness. Furthermore, there is a lack of measures to inhibit processing thermal damage and chemical erosion, potentially destroying the original organic matter and mineral composition of the shale surface. The contact angle measurement scenario is limited, measuring only planar contact angles, failing to simulate the occurrence behavior in shale fractured inclined walls or narrow spaces. A quantitative method for occurrence capacity is lacking, providing only static contact angle data and lacking quantitative analysis of single occurrence and multi-fluid competitive occurrence under slope contact, making it difficult to directly guide development practices. Data processing lacks standardization; some studies estimate wettability using empirical formulas, but no occurrence capacity index system based on contact angle changes has been established, resulting in insufficient comparability and engineering applicability of the results.

[0046] This application provides a method and testing device for detecting the oil, gas, and water storage capacity of shale surfaces. Specifically, it employs a more rational processing method to manufacture a standardized test surface that retains its original components and has controllable roughness, eliminating the influence of morphology interference on contact angle measurements. It provides angle measurement scenarios for planes and inclined walls, allowing for the measurement of first and second contact angle data. This yields individual storage capacity indices for water droplets, oil, and the competitive storage capacity index between oil and liquid droplets, thus comprehensively simulating the storage behavior of oil, gas, and water in shale in horizontal, inclined, and fractured spaces. Furthermore, it establishes a storage capacity index system based on contact angle changes, improving the comparability and engineering applicability of the results. Therefore, through standardized sample preparation, multi-scenario contact angle measurement, and storage capacity index calculation, it provides a reliable technical means for the efficient and quantitative evaluation of shale oil, gas, and water storage capacity, which can be widely applied in reservoir evaluation, fracturing scheme design, and development strategy optimization.

[0047] Firstly, this application provides a method for detecting the oil, gas, and water storage capacity of shale surfaces, including the preparation of a shale sample 200 with grooves. Combined with... Figure 3 The shale sample 200 includes a test surface, a groove disposed on the test surface, the groove having a first inclined wall 23 and a second inclined wall 24 opposite each other, the roughness of the first inclined wall 23 and the second inclined wall 24 being less than 1 μm; the test surface also includes a first plane 21 located on one side of the first inclined wall 23 and a second plane 22 located on one side of the second inclined wall 24, the roughness of the first plane 21 and the second plane 22 being less than 1 μm.

[0048] The groove on shale sample 200 is a V-shaped groove; the left side of the groove is the first inclined wall 23, and the right side is the second inclined wall 24; the first plane 21 is located to the upper left of the first inclined wall 23, and the second plane 22 is located to the upper right of the second inclined wall 24. Shale is a fine-grained sedimentary rock composed of particles with a diameter of less than 0.0625 mm and well-developed foliation. Shale samples refer to representative rock samples collected from shale layers. Shale samples have obvious thin-layer foliation structures, easily split into thin sheets along the foliation, generally have low hardness, dull surface luster, and diverse colors, commonly gray-black and black, while iron-bearing shale is brownish-red and reddish-brown.

[0049] Understandably, the test surface includes a first inclined wall 23 and a second inclined wall 24 of a V-shaped groove, as well as a first plane 21 and a second plane 22. This allows for preparation of subsequent contact angle measurements on the test surface. The contact angle includes first contact angle data and second contact angle data, discussed below.

[0050] Specifically, the roughness of the first inclined wall 23, the second inclined wall 24, the first plane 21, and the second plane 22 must be less than 1 μm, meaning the roughness of the test surface must be less than 1 μm. Optionally, atomic force microscopy can be used to quantitatively verify the roughness; this verification is a key quality control step in determining whether the test surface is suitable for subsequent standardized experiments.

[0051] Specifically, firstly, the atomic force microscope (AFM) was used in tapping mode to scan the polished test surface (discussed below), with at least three different locations randomly selected for scanning. Each location's scan range should include at least two scales: 10 μm × 10 μm and 5 μm × 5 μm. Secondly, the arithmetic mean roughness value of each scanned area was calculated, using Ra as the roughness evaluation index. Ra is an internationally recognized two-dimensional roughness evaluation index that effectively characterizes the overall smoothness of the surface. Finally, experimental verification showed that only when the Ra value at all measurement points on the test surface remained consistently less than 1 μm did the shale sample 200 meet the requirements of a standardized test surface, allowing subsequent experiments to be conducted to test the oil, gas, and water storage capacity of the shale surface.

[0052] Understandably, when the Ra value is less than 1 μm, the random interference of surface morphology on contact angle measurement can be controlled within the allowable range, and the measurement results can stably reflect the intrinsic chemical wettability of the test surface.

[0053] A water droplet is added to the first plane 21, and an oil droplet is added to the second plane 22; a water droplet is added to the first inclined wall 23, and an oil droplet is added to the second inclined wall 24. The oil droplet simulates bottom crude oil or standard alkanes, and the water droplet simulates formation water or deionized water. The device for titrating the water and oil droplets can be the titration mechanism 5 discussed below. The titration process performed by the titration mechanism 5 can be manually operated or controlled by the control unit 7 discussed below.

[0054] Specifically, water droplets are added to the first plane 21 and the first inclined wall 23. The selection of water droplet volume, dripping speed, and dripping distance should be reasonable to ensure that the water droplets are gently and quasi-statically deposited on the surfaces of the first plane 21 and the first inclined wall 23, avoiding the dynamic effects caused by impact, and thus realistically reproducing the occurrence process of formation water or deionized water on the shale surface. Oil droplets are added to the second plane 22 and the second inclined wall 24. The selection of oil droplet volume, dripping speed, and dripping distance should be reasonable to ensure that the oil droplets are gently and quasi-statically deposited on the surfaces of the second plane 22 and the second inclined wall 24, avoiding the dynamic effects caused by impact, and thus realistically reproducing the occurrence process of crude oil or standard alkanes in the bottom layer of the shale surface.

[0055] Understandably, this step aims to obtain the first and second contact angle data of the test surface to both water and oil fluids, providing data support for the subsequent calculation of the retention capacity index.

[0056] The first contact angle data of a water droplet on the first plane 21 and the first inclined wall 23 are obtained, and the individual retention capacity index of the water droplet is determined based on the first contact angle data. The second contact angle data of an oil droplet on the second plane 22 and the second inclined wall 24 are obtained, and the individual retention capacity index of the oil droplet is determined based on the second contact angle data. Furthermore, the competitive retention capacity index between the oil droplet and the liquid droplet is determined based on the first and second contact angle data. The calculation methods for the individual retention capacity index of the water droplet, the individual retention capacity index of the oil droplet, and the competitive retention capacity index between the oil droplet and the water droplet are described below.

[0057] In this way, calculating the individual occurrence capacity index of water droplets can determine the strength of the occurrence capacity of bottom crude oil or standard alkanes on the shale surface; calculating the individual occurrence capacity index of oil droplets can determine the strength of the occurrence capacity of formation water or deionized water on the shale surface; and calculating the competitive occurrence capacity index of oil droplets and water droplets can clarify the dominant occurrence between bottom crude oil and formation water, and between standard alkanes and formation water.

[0058] Combination Figure 3The first contact angle data and the second contact angle data can also be divided according to the detection scenario, into planar contact angle, inclined wall contact angle, and V-groove center contact angle. Specifically, the planar contact angle includes the first static contact angle θ0 (water) and the second static contact angle θ0 (oil) discussed below; the inclined wall contact angle includes the first upper contact angle θ1 (water), the first lower contact angle θ2 (water), the second upper contact angle θ1 (oil), and the second lower contact angle θ2 (oil) discussed below; the V-groove center contact angle includes the first competing contact angle θ3 (water) and the second competing contact angle θ3 (oil) discussed below.

[0059] In the process of measuring the planar contact angle, after a water droplet is placed on the first plane 21, it needs to stand for 5 seconds to reach thermodynamic equilibrium or a metastable state; similarly, after an oil droplet is placed on the second plane 22, it also needs to stand for 5 seconds to reach thermodynamic equilibrium or a metastable state. Only then can the imaging unit 6 (discussed below) capture images to obtain images containing the first static contact angle θ0 (water) data and the second static contact angle θ0 (oil) data. The titration of each water droplet needs to be repeated at least 3 times under the same conditions, and the average value is taken as the final result; the titration of each oil droplet also needs to be repeated at least 3 times under the same conditions, and the average value is taken as the final result.

[0060] Understandably, the smaller the value of the first static contact angle θ0 (water), the stronger the wettability of the water droplet on the test surface, i.e., the stronger the wettability of formation water or deionized water on the shale surface; similarly, the smaller the value of the second static contact angle θ0 (oil), the stronger the wettability of the oil droplet on the test surface, i.e., the stronger the wettability of bottom crude oil or standard alkanes on the shale surface. In this way, the basic wettability of the shale test surface to water and oil can be obtained.

[0061] During the measurement of the contact angle of the inclined walls, the water droplet is positioned in the middle of the first inclined wall 23 to avoid being too close to the bottom of the groove; the oil droplet is positioned in the middle of the second inclined wall 24 to avoid being too close to the bottom of the groove. The water droplet on the first inclined wall 23 exhibits an asymmetrical shape due to gravity; the oil droplet on the second inclined wall 24 also exhibits an asymmetrical shape due to gravity.

[0062] In the process of measuring the contact angle at the center of the V-groove, a fluid competition control baffle 4 (described below) is placed at the center of the bottom of the groove, physically dividing the groove into two independent regions. Oil droplets and water droplets are dripped onto both sides of the baffle and at the bottom tip of the groove, respectively. After standing for 10 seconds to reach thermodynamic equilibrium or metastable state, the fluid competition control baffle 4 is rapidly and vertically raised within milliseconds by the control unit 7 (described below). At this time, the camera unit 6 (described below) captures the dynamic changes of the three-phase contact interface of the water droplets, oil droplets, and shale sample 200. The final first competition contact angle θ3 (water) and second competition contact angle θ3 (oil) of the water droplets and oil droplets after competition are measured. In this way, the displacement and coexistence process of oil and water in the narrow space can be simulated, and it is possible to directly observe which fluid occupies a dominant position.

[0063] The method for detecting the oil, gas, and water storage capacity of shale surfaces provided in this application employs a more rational processing method to manufacture a standardized test surface that retains its original components and has controllable roughness, eliminating the influence of morphology interference on contact angle measurements. It provides angle measurement scenarios for planes and inclined walls, allowing for the measurement of first and second contact angle data. This yields individual storage capacity indices for water droplets, oil, and the competitive storage capacity index between oil and liquid droplets, comprehensively simulating the storage behavior of oil, gas, and water in shale in horizontal, inclined, and fractured spaces. Furthermore, it establishes a storage capacity index system based on contact angle changes, improving the comparability and engineering applicability of the results. Thus, through standardized sample preparation, multi-scenario contact angle measurement, and storage capacity index calculation, a reliable technical means is provided for the efficient and quantitative evaluation of shale oil, gas, and water storage capacity, which can be widely applied in reservoir evaluation, fracturing scheme design, and development strategy optimization.

[0064] In some embodiments, preparing a grooved shale sample 200 includes: cutting the shale to obtain a cut body; rough machining the cut body; fine machining the rough-machined cut body to give it a test surface; and machining grooves on the test surface to obtain the shale sample 200. The cut body is blocky in shape and has a uniform size; exemplaryly, it can be a 10mm × 10mm or 5mm × 5mm block, but is not limited to these.

[0065] The preparation of grooved shale samples 200 is to prepare for subsequent tests on the oil, gas, and water storage capacity of the shale surface. Therefore, the cutting method for shale sample 200 must ensure a smooth cut surface, free from stress damage, and with high dimensional accuracy. Shale sample 200 cutting methods include diamond saw blade cutting, diamond wire cutting, and electrical discharge wire cutting. Diamond saw blade cutting uses a circular saw blade made of sintered diamond particles to grind the shale at high speed, with cooling water used to lower the cutting temperature and remove debris, preventing the shale from cracking due to thermal stress. Diamond wire cutting uses diamond micropowder fixed on a steel wire to create a cutting wire. The wire's reciprocating or circular motion achieves shale cutting through grinding, with no significant mechanical impact throughout the process, resulting in high-precision, damage-free cutting.

[0066] The process of first roughing and then finishing the cutting surface balances processing efficiency and high precision, while protecting the original performance of the cutting surface and reducing equipment wear. Roughing methods include rough cutting and rough polishing. Rough cutting includes low-grit diamond saw blade cutting, hydraulic pliers splitting cutting, and coarse grinding wheel grinding; rough polishing can be done with diamond grinding wheels. Finishing includes fine cutting and fine polishing. Fine cutting includes high-grit diamond saw blade precision cutting, high-precision diamond wire cutting, and electrical discharge machining (EDM), with diamond wire cutting being the primary choice for high-precision cutting. Fine polishing includes primary polishing, secondary polishing, and tertiary polishing. Primary polishing removes cutting damage from the test surface, secondary polishing improves flatness, and tertiary polishing achieves a uniform mirror reflection on the test surface.

[0067] Furthermore, grooves are machined on the test surface. The machining methods for these grooves include roughing and finishing methods. Roughing methods include V-shaped diamond milling and grinding wheel combination grooving, while finishing methods include diamond wire cutting and laser etching, among others.

[0068] Therefore, following the above processing steps, a shale sample 200 with grooves was prepared. Such a shale sample meets the experimental requirements for detecting the oil, gas and water storage capacity of the shale surface.

[0069] In some embodiments, cutting shale includes: cutting shale along a predetermined direction of the shale core, wherein the predetermined direction is parallel to or perpendicular to the bedding plane of the shale.

[0070] Shale cores refer to columnar rock samples obtained directly from underground shale strata using core drilling technology, preserving the original stratigraphic occurrence and structural characteristics. Shale bedding planes are parallel or near-parallel primary weak surfaces formed during the formation of sedimentary rocks like shale due to periodic variations in sediment composition, grain size, and structure, as well as compaction and cementation during diagenesis. Essentially, they are the interlayer interfaces within the shale.

[0071] Cutting parallel to the bedding planes of shale can completely preserve the interlayer pores and microfracture network developed on the bedding planes, which are the main storage spaces and migration channels for shale oil, gas, and water. Understandably, about 60%–80% of the free oil, gas, and water in shale is stored in the interlayer pores and bedding-parallel microfractures between bedding planes. Cutting parallel to the bedding planes of shale can completely expose the storage spaces of oil, gas, and water, improving the accuracy of testing. Cutting parallel to the bedding planes of shale can simulate the actual migration paths of oil, gas, and water, obtaining horizontal permeability data. Furthermore, cutting parallel to the bedding planes of shale can reduce damage to the shale and minimize experimental errors.

[0072] Among these methods, cutting perpendicular to the bedding planes of shale can visually characterize the vertical differences in the occurrence of oil, gas and water, and study interlayer heterogeneity; measure vertical permeability to evaluate the difficulty of interlayer migration; and simulate the propagation of fracturing fractures across layers to optimize fracturing parameters.

[0073] Therefore, cutting along bedding planes parallel to or perpendicular to shale can provide a more comprehensive understanding of the occurrence and migration characteristics of shale oil, gas and water, and obtain real and targeted experimental data.

[0074] In some embodiments, rough machining of the cutting body includes: defining a machining area; and leveling the machining area using an inert liquid as the machining cooling medium. The inert liquid may be an alcohol cooled by liquid nitrogen. Understandably, liquid nitrogen can lower the temperature of the alcohol, enhancing its cooling effect; the alcohol includes anhydrous ethanol and isopropanol, among others, with anhydrous ethanol playing the primary role as the machining cooling medium.

[0075] The processing area can be a relatively flat surface; and perpendicular to this flat surface, there should be sufficient dimensions to process the grooves mentioned above. This improves processing efficiency and reduces processing costs. The purpose of the flattening process is to eliminate surface scratches, chipping, unevenness, and other defects left during the cutting process, obtaining a flat surface that meets the accuracy requirements for shale surface oil, gas, and water storage capacity testing.

[0076] Therefore, selecting a suitable processing area for the cutting body first can save processing costs and improve processing efficiency; then, the processing area is flattened to obtain the flat surface required for the experiment; during the processing, using an inert liquid as the cooling medium can minimize thermal damage and chemical corrosion to the cutting body. In this way, the initial rough processing of the cutting body is completed.

[0077] In some embodiments, the rough-machined cut body is finished to give it a test surface. The finishing of the cut body includes multiple polishing of the planarized machined area, wherein the roughness of the polishing pads used in the multiple polishings decreases.

[0078] The roughness reduction of the polishing pad must be synchronized with the grit reduction of the polishing paste, and the roughness gradient between adjacent polishing pads should not be too large; otherwise, the scratches left by the previous polishing stage cannot be completely covered by the subsequent polishing stage. The polishing paste can be diamond polishing paste or alumina polishing paste.

[0079] The multiple polishing processes can be the first-stage, second-stage, and third-stage polishing mentioned above. For example, the first-stage polishing uses a short-fiber velvet polishing pad with 2000-mesh diamond polishing paste, resulting in a surface roughness of less than 1.5 μm on the polished test surface; the second-stage polishing uses a dense nylon polishing pad with 5000-mesh diamond polishing paste, resulting in a surface roughness of less than 0.8 μm on the polished test surface; and the third-stage polishing uses a porous polyurethane polishing pad with 10000-mesh diamond polishing paste, resulting in a surface roughness of less than 0.6 μm on the polished test surface.

[0080] The processed area was finely polished using a suspension to obtain a test surface, which exhibits specular reflection under a microscope. The surface roughness at this point is less than or equal to 0.05 μm, with clear edges of micropores and no embedded polishing paste particles.

[0081] The suspensions include diamond nano-suspension, alumina nano-suspension, and colloidal silica suspension. Among them, diamond nano-suspension can achieve ultra-high precision polishing; alumina nano-suspension is suitable as a semi-precision polishing process before diamond nano-suspension, or for polishing of shale surfaces with slightly lower precision requirements for testing oil, gas and water storage capacity; the fine polishing of colloidal silica suspension combines chemical action and mechanical cutting, and with the use of ethanol-based processing cooling media, damage to the test surface can be avoided.

[0082] Therefore, the rough-machined cut body is then fine-machined, that is, polished multiple times, so that the test surface exhibits a mirror-like reflection under a microscope, eliminating the influence of morphology interference on the contact angle measurement, and making it a test surface that meets the experimental requirements.

[0083] In some embodiments, the suspension includes an alumina suspension or a colloidal silica suspension. The alumina suspension may be the alumina nano-suspension discussed above. The colloidal silica suspension is suitable for polishing ultra-high precision test surfaces and can achieve specular reflection under a microscope.

[0084] To balance cost and accuracy, a combined process of semi-finish polishing with alumina suspension and mirror polishing with colloidal silica suspension can be used. For example, first, polishing with a 0.5μm alumina ethanol suspension and a nylon pad reduces the surface roughness to below 0.8μm; then, ultrasonic cleaning with anhydrous ethanol for 15 minutes thoroughly removes any alumina residue; finally, polishing with a 20nm colloidal silica ethanol suspension and a silk pad reduces the roughness to below 0.05μm, achieving a mirror-like reflection effect. Here, the 0.5μm alumina ethanol suspension refers to a suspension containing 0.5μm alumina abrasive particles in ethanol; the 20nm colloidal silica ethanol suspension refers to a suspension containing 20nm colloidal silica abrasive particles in ethanol.

[0085] Thus, the test surface obtained by fine polishing the processing area using alumina suspension or colloidal silica suspension can balance low cost and ultra-high precision.

[0086] In some embodiments, grooves are machined on the test surface, including: machining the test surface using an ultra-precision CNC machine tool with a single-crystal diamond tool or a focused ion beam to obtain the grooves; purging the test surface with a high-purity inert gas to remove machining debris. The high-purity inert gas can be high-purity nitrogen or argon. The use of any solvent for ultrasonic or immersion cleaning of the test surface is strictly prohibited to ensure that the wettability of the original organic matter and minerals on the test surface is fully preserved.

[0087] Among them, single-crystal diamond tools are special tools adapted to high-precision cutting requirements. They have extremely high hardness and cutting edge sharpness down to the nanometer level, effectively solving the processing pain points of shale's high brittleness and easy edge chipping due to its well-developed bedding. They are also suitable for preparing high-precision shale samples for detecting oil, gas, and water storage capacity. Focused ion beam (FIP) uses a focused gallium ion (Ga⁺) beam to perform targeted cutting and etching on shale samples, which can prepare stress-damage-free nanoscale flakes or three-dimensional microstructures. Combined with scanning electron microscopy (SEM) and transmission electron microscopy (TEM), in-situ observation of the oil, gas, and water storage space on the shale surface can be achieved.

[0088] The surface roughness Ra of the first inclined wall 23 and the second inclined wall 24 of the groove must be less than 1 μm. First, the test surface is processed using an ultra-precision CNC machine tool with a single crystal diamond tool or a focused ion beam. Then, it is verified by an atomic force microscope. If the surface roughness Ra does not meet the requirements, the finishing process continues until the surface roughness Ra of the first inclined wall 23 and the second inclined wall 24 of the groove is less than 1 μm, thus obtaining a groove that meets the standard.

[0089] Therefore, by using an ultra-precision CNC machine tool with a single-crystal diamond tool or a focused ion beam to process the test surface, the above-mentioned grooves can be obtained. The grooves have nanoscale sharp edges and minimize the surface chemical changes caused by processing. Using high-purity inert gas to purge the test surface can preserve the original organic matter and wettability of the test surface.

[0090] In some embodiments, the included angle between the first inclined wall 23 and the second inclined wall 24 is 60°-120°, for example, 60°, 70°, 80°, 90°, 100°, 110° and 120°, but is not limited thereto.

[0091] The angle between the first inclined wall 23 and the second inclined wall 24 is 60°-90°, for example, 60°, 65°, 70°, 75°, 80°, 85° and 90°, but not limited to these. This range of angles constitutes a relatively steep V-shaped groove, used to simulate the steep inclined walls of shale, and can accurately expose the cross-layer fractures and the vertical differentiation interface of oil, gas and water. Understandably, the first inclined wall 23 and the second inclined wall 24 can be perpendicular to the bedding plane, exposing the cross-layer fractures, allowing direct observation of the occurrence state of oil, gas and water in the cross-layer channel. Due to the density difference between oil, gas and water, vertical gravity differentiation occurs, i.e., oil is on top and water is below. The relatively steep V-shaped groove can clearly present the geometric shape of the differentiation interface, quantify the oil saturation gradient and water saturation gradient at different depths, and provide direct data for oil and gas recovery simulation.

[0092] The angle between the first inclined wall 23 and the second inclined wall 24 is 90°-120°, for example, 90°, 95°, 100°, 105°, 110°, 115° and 120°, but not limited to these. This range of angles belongs to a wide-mouth V-groove, which is suitable for the composite occurrence system of large-scale fractures and dense matrix. Understandably, the wide-mouth V-groove can cover the large fractures in the horizontal direction and the matrix areas on both sides, avoiding the limitation of the observation range caused by the narrow groove opening. It can simultaneously observe the oil, gas and water filling state of the large fractures and the distribution of adsorbed oil and gas in the matrix pores, revealing the oil and gas migration coupling mechanism between the fractures and the matrix. The processing depth of the wide-mouth V-groove is more uniform, and the stress concentration is lower than that of the narrow groove. It can effectively avoid the collapse of nanopores in the dense matrix. For the detection of the low porosity oil, gas and water occurrence capacity, it preserves the original morphology of the matrix pores to the greatest extent and ensures the accuracy of the determination of adsorbed oil and gas content.

[0093] Therefore, by providing the included angle range of the first inclined wall 23 and the second inclined wall 24, multi-angle and multi-scale collaborative detection can be achieved. It can simulate and detect the oil, gas and water occurrence characteristics of cross-layer fractures, horizontal bedding fractures and matrix pores respectively, and establish a full-scale occurrence capacity detection model.

[0094] In some embodiments, water droplets are added to the first plane 21, oil droplets are added to the second plane 22, water droplets are added to the first inclined wall 23, and oil droplets are added to the second inclined wall 24. This provides occurrence scenarios on both planes and inclined walls, comprehensively simulating the occurrence behavior of oil, gas, and water in shale in horizontal, inclined, and slotted spaces.

[0095] The volumes of water and oil droplets range from 2 μL to 10 μL, for example, 2 μL, 3 μL, 4 μL, 5 μL, 6 μL, 7 μL, 8 μL, 9 μL, and 10 μL, but are not limited to these. Providing a range of water and oil droplet volumes allows them to form stable water and oil contact interfaces on the first inclined wall 23 and the second inclined wall 24, respectively. This balances surface tension with gravity, allowing gravity to drive the water and oil droplets to slowly penetrate the pores, ensuring that both nanoscale pores and micron-scale cracks are wetted by the water and oil droplets.

[0096] For example, if the volume of water and oil droplets is greater than 10 μL, under the influence of gravity, they will quickly flow downwards, unable to penetrate the exposed pores and cracks of the first inclined wall 23 and the second inclined wall 24, and will cover the observation area, obscuring the true occurrence of oil, gas, and water within the pores. If the volume of water and oil droplets is less than 2 μL, they are easily intercepted by the tiny protrusions on the surfaces of the first inclined wall 23 and the second inclined wall 24, and the edges of the pore inlets, unable to penetrate along the slope of the first inclined wall 23 and the second inclined wall 24, resulting in the droplets not contacting the deep pores.

[0097] The dropping rates of water and oil droplets are 0.2 μL / s to 2 μL / s, for example, 0.2 μL / s, 0.4 μL / s, 0.6 μL / s, 0.8 μL / s, 1 μL / s, 1.4 μL / s, 1.8 μL / s and 2 μL / s, and of course, not limited to these.

[0098] Understandably, the infiltration rate of oil, gas and water in shale reservoirs is itself a low-speed level on the order of μL per second. The drip rate of water droplets and oil droplets is 0.2μL / s - 2μL / s, which can perfectly match the actual oil, gas and water migration and occurrence process in shale reservoirs.

[0099] The distance between water droplets and oil droplets and the test surface before they fall is 1mm-2mm, for example, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm and 2mm, and of course, it is not limited to these.

[0100] Understandably, the distance between water and oil droplets and the test surface before they fall is 1mm-2mm, and their drop rates are 0.2μL / s-2μL / s. These reasonable drop rates and distances can eliminate the influence of gravity and inertia on the oil and water droplets. The spreading, shrinking, adsorption, pore filling, and oil-water phase separation of the droplets are entirely determined by the shale's surface energy, pore structure, and mineral composition—a spontaneous occurrence process. This eliminates the influence of false occurrences and false wetting on the detection of oil, gas, and water storage capacity on the shale surface.

[0101] Thus, by providing titration scenarios on both flat and inclined walls, the occurrence behavior of oil, gas and water in shale can be fully simulated in horizontal, inclined and narrow spaces; by providing the volume range, drop rate range and distance range between water droplets and oil droplets and the test surface before dripping, the occurrence behavior of oil, gas and water on the shale surface can be realistically simulated, thereby ensuring the accuracy of the test.

[0102] Combination Figure 3 In some embodiments, the first contact angle data of the water droplet on the first plane 21 and the first inclined wall 23 are obtained, and the single-item retention capacity index of the water droplet is determined based on the first contact angle data. The first contact angle data includes the first static contact angle θ0 (water) of the water droplet on the first plane 21, the first upper contact angle θ1 (water) and the first lower contact angle θ2 (water) of the water droplet on the first inclined wall 23, and the first competitive contact angle θ3 (water) between the water droplet and the oil droplet.

[0103] Wherein, the first static contact angle θ0 (water) refers to the angle between the tangent at the three-phase contact point on either side of the water droplet and the first plane 21, wherein the water droplet is deposited above the first plane 21; the first upper contact angle θ1 (water) refers to the angle between the tangent at the upper edge of the three-phase contact point of the water droplet and the first inclined wall 23; the first lower contact angle θ2 (water) refers to the angle between the tangent at the lower edge of the three-phase contact point of the water droplet and the first inclined wall 23, wherein the water droplet is deposited at the middle position on the surface of the first inclined wall 23; the first competing contact angle θ3 (water) between the water droplet and the oil droplet refers to the angle between the tangent at the upper edge of the three-phase contact point of the water droplet and the first inclined wall 23, wherein the water droplet is deposited on the surface of the first inclined wall 23 biased towards the contact end, wherein the contact end refers to the position where the first inclined wall 23 contacts the second inclined wall 24.

[0104] Understandably, the three-phase contact point of the water droplet refers to the junction where the shale, water droplet, and air meet; where the upper edge of the water droplet refers to the upper half of the water droplet on the first inclined wall 23; and the lower edge of the water droplet refers to the lower half of the water droplet on the first inclined wall 23.

[0105] The single-item endowment capacity index S (water) of a water droplet is:

[0106] ;

[0107] When the value of |S(water)| approaches 0, it indicates that: θ2(water) = θ0(water), that is, the shape of the water droplet on the first inclined wall 23 is almost the same as the shape on the first plane 21, which has a very strong ability to resist gravity and slide down, and has a very strong ability to survive.

[0108] When the value of |S(water)| is between 0 and 1, the smaller the value of S(water), the smaller the change in the shape of the water droplet on the first inclined wall 23 and the shape on the first plane 21, and the stronger the retention capacity.

[0109] When the value of |S(water)| approaches 1, it indicates that the value of θ2(water) approaches 0°, meaning that water droplets can hardly stay on the first inclined wall 23, and their retention capacity is extremely weak.

[0110] Optionally, based on experimental data, a threshold range can be set, such as defining |S(water)| < 0.3 as strong memory, 0.3 ≤ |S(water)| ≤ 0.7 as medium memory, and |S(water)| > 0.7 as weak memory.

[0111] The second contact angle data of the oil droplet on the second plane 22 and the second inclined wall 24 are obtained, and the single-item retention capacity index of the oil droplet is determined based on the second contact angle data. The second contact angle data includes the second static contact angle θ0 (oil) of the oil droplet on the second plane 22, the second upper contact angle θ1 (oil) and the second lower contact angle θ2 (oil) of the oil droplet on the second inclined wall 24, and the second competitive contact angle θ3 (oil) of the oil droplet and the water droplet.

[0112] The second static contact angle θ0 (oil) refers to the angle between the tangent at the three-phase contact point on either side of the oil droplet and the second plane 22, wherein the oil droplet is deposited above the second plane 22; the second upper contact angle θ1 (oil) refers to the angle between the tangent at the upper edge of the three-phase contact point of the oil droplet and the second inclined wall 24; the second lower contact angle θ2 (oil) refers to the angle between the tangent at the lower edge of the three-phase contact point of the oil droplet and the second inclined wall 24, wherein the oil droplet is deposited at the middle position on the surface of the second inclined wall 24; the second competing contact angle θ3 (oil) between the oil droplet and the water droplet refers to the angle between the tangent at the upper edge of the three-phase contact point of the oil droplet and the second inclined wall 24, wherein the oil droplet is deposited on the surface of the second inclined wall 24 biased towards the contact end, wherein the contact end refers to the position where the first inclined wall 23 and the second inclined wall 24 are in contact.

[0113] Understandably, the three-phase contact point of the oil droplet refers to the junction where the shale, oil droplet, and air meet. The upper edge of the oil droplet refers to the upper half of the oil droplet on the second inclined wall 24, and the lower edge of the oil droplet refers to the lower half of the oil droplet on the second inclined wall 24.

[0114] The single-item retention capacity index S (oil) of an oil droplet is:

[0115] ;

[0116] When the value of |S(oil)| approaches 0, it indicates that: θ2(oil) = θ0(oil), that is, the shape of the oil droplet on the second inclined wall 24 is almost the same as the shape on the second plane 22, which has a very strong ability to resist gravity and slide down, and has a very strong ability to survive.

[0117] When the value of |S(oil)| is between 0 and 1, the smaller the value of S(oil), the smaller the change in the shape of the oil droplet on the second inclined wall 24 and the shape on the second plane 22, and the stronger the storage ability.

[0118] When the value of |S(oil)| approaches 1, it indicates that the value of θ2(oil) approaches 0°, meaning that oil droplets can hardly stay on the second inclined wall 24, and their retention capacity is extremely weak.

[0119] Optionally, based on experimental data, a threshold range can be set, such as defining |S(oil)| < 0.3 as strong memory, 0.3 ≤ |S(oil)| ≤ 0.7 as medium memory, and |S(oil)| > 0.7 as weak memory.

[0120] The oil droplet and water droplet compete for the index of survival capability based on the first contact angle data and the second contact angle data.

[0121] The competitive endowment capability index is:

[0122] in, , .

[0123] To ensure the applicability of the formula in extreme cases, it is stipulated that C = 0.5 when both Δθ (oil) and Δθ (water) are zero.

[0124] When C > 0.5, it indicates that in the competition process, Δθ (water) > Δθ (oil). This can be understood as the change in the contact angle of the water droplet being greater than the change in the contact angle of the oil droplet. In other words, the existence state of the water droplet is more disturbed, and the oil droplet has the advantage in the competition, with a stronger competitive existence ability.

[0125] When C < 0.5, it indicates that during the competition, Δθ (water) < Δθ (oil). This can be understood as the change in the contact angle of the water droplet being less than the change in the contact angle of the oil droplet. In other words, the state of the oil droplet is more disturbed, and the water droplet has the advantage in the competition, making it more competitive.

[0126] When C = 0.5, it indicates that during the competition, Δθ (water) = Δθ (oil), which can be understood as the change in the contact angle of the water droplet being equal to the change in the contact angle of the oil droplet, meaning that the competitive survival capabilities of the water droplet and the oil droplet are comparable.

[0127] Thus, by measuring the contact angle in various scenarios such as planes and inclined walls, the single-item occurrence capacity index of water droplets, the single-item occurrence capacity index of oil droplets, and the competitive occurrence capacity index of oil droplets and water droplets are calculated, thereby achieving a rapid and standardized evaluation of the occurrence priority of oil, gas and water in shale reservoirs. This solves the limitation of traditional contact angle measurement in a single plane scenario and addresses the evaluation bias caused by surface heterogeneity, insufficient measurement scenarios, and lack of quantitative methods in existing technologies.

[0128] Secondly, this application provides a testing apparatus 100 for assessing the oil, gas, and water storage capacity on a shale surface, used to perform any of the aforementioned methods for detecting the oil, gas, and water storage capacity on a shale surface. Combined with... Figure 2 The testing device 100 for the oil, gas and water storage capacity of shale surfaces includes: a base 1, a stage 2, a support frame 3, a fluid competition control baffle 4, a titration mechanism 5, a camera unit 6, and a control unit 7. The support frame 3 is mounted on the base 1, and the base 1 supports the support frame 3.

[0129] The stage 2 is mounted on the base 1 and is used to place the shale sample 200 to be tested. The test surface is located on the side of the shale sample 200 facing away from the stage 2. This can be understood as follows: the stage 2 is located above the base 1, and the lower bottom surface of the stage 2 is in direct contact with the upper surface of the base 1; the lower bottom surface of the shale sample 200 is in direct contact with the upper surface of the stage 2; the upper surface of the shale sample 200 is the test surface.

[0130] A fluid competition control baffle 4 is vertically mounted on the support frame 3. The fluid competition control baffle 4 is vertically aligned with the intersection of the first inclined wall 23 and the second inclined wall 24 of the groove in the shale sample 200. When the fluid competition control baffle 4 comes into contact with the intersection, it separates the water droplets on the first inclined wall 23 and the oil droplets on the second inclined wall 24. This can be understood as follows: the support frame 3 is perpendicular to the base 1 and extends vertically; the fluid competition control baffle 4 is mounted on the support frame 3 and can move vertically; the fluid competition control baffle 4 is perpendicular to the stage 2 and comes into contact with the intersection of the first inclined wall 23 and the second inclined wall 24, separating the water droplets on the first inclined wall 23 and the oil droplets on the second inclined wall 24.

[0131] The titration mechanism 5 includes a first titration unit 51 and a second titration unit 52. The first titration unit 51 is used to titrate water droplets onto the first plane 21 and the first inclined wall 23 of the test surface, and the second titration unit 52 is used to titrate oil droplets onto the second plane 22 and the second inclined wall 24 of the test surface.

[0132] Camera unit 6 is used to acquire the first contact angle data of water droplets and the second contact angle data of oil droplets. Camera unit 6 is located in front of shale sample 200, enabling clear imaging of the entire process of water and oil droplet deposition on the trench; support frame 3 is located behind the shale sample, such as... Figure 2 As shown. The acquired first contact angle data and second contact angle data can be used to calculate the single-item memory capability index and the competitive memory capability index. The camera unit 6 can be a high-speed camera equipped with a macro lens, thus enabling the capture of side-view contour images of water droplets and oil droplets.

[0133] The control unit 7 is electrically connected to the camera unit 6. The control unit 7 is configured to determine the single-item retention capacity index of the water droplet based on the first contact angle data, and to determine the single-item retention capacity index of the oil droplet based on the second contact angle data, and to determine the competitive retention capacity index of the oil droplet and the water droplet based on the first contact angle data and the second contact angle data.

[0134] The control unit 7 is electrically connected to the camera unit 6. The control unit 7 acquires an image with first contact angle data and second contact angle data from the camera unit 6, and imports the image into professional contact angle analysis software to fit the Young-Laplace equation, thereby calculating the single-term retention capacity index of the water droplet, the single-term retention capacity index of the oil droplet, and the competitive retention capacity index between the oil droplet and the water droplet. The contact angle analysis software can be ImageJ.

[0135] The shale surface oil, gas and water storage capacity testing device 100 provided in this application automates the experimental process. It integrates a base 1, a stage 2, a support frame 3, a fluid competition control baffle 4, a titration mechanism 5, a camera unit 6, and a control unit 7, enabling precise control of the shale sample tilt angle 200°, standardization of droplet deposition parameters, and high-precision capture of the dynamic process. The camera unit 6 can capture side-view contour images of oil droplets and water droplets. The control unit 7 is electrically connected to the camera unit 6. The control unit 7 imports the images from the camera unit 6 into professional contact angle analysis software and fits the Young-Laplace equation to calculate the individual storage capacity index of water droplets, the individual storage capacity index of oil droplets, and the competitive storage capacity index of oil droplets and liquid droplets, thus achieving standardized data processing.

[0136] Combination Figure 2In some embodiments, the testing device 100 for the oil, gas and water storage capacity of shale surfaces further includes a lifting mechanism 8. The lifting mechanism 8 is vertically mounted on the support frame 3, and a fluid competition control baffle 4 is mounted on the lifting mechanism 8. The lifting mechanism 8 is a mechanism that can move up and down along the vertical direction of the support frame 3.

[0137] Understandably, the fluid competition control baffle 4 is mounted on the lifting mechanism 8 and is biased toward one side of the shale sample 200; the fluid competition control baffle 4 can move up or down along the vertical direction of the support frame 3 along with the lifting mechanism 8.

[0138] Specifically, when measuring the first competitive contact angle θ3 (water) between water droplets and oil droplets, and the second competitive contact angle θ3 (oil) between oil droplets and water droplets, the control unit 7 can control the fluid competition control baffle 4 to descend to the intersection of the first inclined wall 23 and the second inclined wall 24, or control the fluid competition control baffle 4 to rapidly rise in the vertical direction within milliseconds.

[0139] Thus, the lifting mechanism 8 and the support frame 3 are used to lift the fluid competition control baffle 4, complete the test of the competitive survival ability of oil droplets and water droplets, and then realize the measurement of the first competitive contact angle θ3 (water) and the second competitive contact angle θ3 (oil).

[0140] Combination Figure 2 In some embodiments, the first titration unit 51 includes a first mounting bracket 51a and a first titrator 51b. The first mounting bracket 51a is located on one side of the first plane 21 of the base 1, meaning it is mounted on the upper surface of the base 1 and positioned towards the side of the first plane 21. The first titrator 51b is located on the first mounting bracket 51a and is used to titrate water droplets onto the first plane 21 and the first inclined wall 23. The first titrator 51b can be a micro-injection pump. The first mounting bracket 51a has an L-shaped structure and can be made of stainless steel, but is not limited to this. The mounting state of the first mounting bracket 51a is as follows: Figure 2 As shown.

[0141] The second titration unit 52 includes a second mounting bracket 52a and a second titrator 52b. The second mounting bracket 52a is located on one side of the second plane 22 of the base 1; that is, the second mounting bracket 52a is mounted on the upper surface of the base 1 and located on the side biased towards the second plane 22. The second titrator 52b is located on the second mounting bracket 52a and is used to titrate oil droplets onto the second plane 22 and the second inclined wall 24. The second titrator 52b can be a micro-injection pump. The second mounting bracket 52a has an L-shaped structure and can be made of stainless steel, but is not limited to this. The mounting state of the second mounting bracket 52a is as follows: Figure 2 As shown.

[0142] The first mounting bracket 51a includes a first clamp; the second mounting bracket 52a includes a second clamp. Both the first clamp and the second clamp are telescopic, thereby enabling the clamping function of the first titrator 51b and the second titrator 52b.

[0143] Therefore, the first mounting bracket 51a of the first titration unit 51 can clamp the first titrator 51b, and the first titrator 51b can titrate water droplets on the first plane 21 and the first inclined wall 23; the second mounting bracket 52a of the second titration unit 52 can clamp the second titrator 52b, and the second titrator 52b can titrate oil droplets on the second plane 22 and the second inclined wall 24.

[0144] Combination Figure 2 In some embodiments, the testing device 100 for the oil, gas, and water storage capacity of the shale surface further includes a first light source 9 and a second light source 10. The first light source 9 is mounted on a first mounting frame 51a and is used to emit light onto the first plane 21 and the first inclined wall 23; the second light source 10 is mounted on a second mounting frame 52a and is used to emit light onto the second plane 22 and the second inclined wall 24. Figure 2 For illustrative purposes only, the positions of the first light source 9 and the second light source 10 are not limited to this. This provides illumination to the surfaces of the first plane 21, the second plane 22, the first inclined wall 23, and the second inclined wall 24, facilitating observation of the formation process of oil and water droplets and reducing detection errors in assessing the oil, gas, and water formation capacity of the shale surface.

[0145] The first light source 9 and the second light source 10 can be visible light sources, ultraviolet light sources, infrared light sources, X-ray light sources, and laser light sources, etc. Among these, visible light sources have wavelengths covering the range visible to the human eye, their intensity is easily adjustable, and the equipment cost is low. They are suitable for contact angle measurement, dynamic observation of water and oil droplet adsorption, and morphological characterization of shale surfaces.

[0146] Thus, the first light source 9 can emit light onto the first plane 21 and the first inclined wall 23, thereby providing illumination to the first plane 21 and the first inclined wall 23; the second light source 10 can emit light onto the second plane 22 and the second inclined wall 24, thereby providing illumination to the second plane 22 and the second inclined wall 24. In this way, the occurrence process of oil and water droplets can be observed more intuitively and clearly, reducing the detection error of the oil, gas and water occurrence capacity on the shale surface.

[0147] To further explain, the control unit 7 can be electrically connected to the support frame 3, the camera unit 6, the first light source 9, and the second light source 10. Specifically, the control unit 7 controls the camera unit 6 to automatically capture the entire process of water and oil droplet accumulation on the test surface; the control unit 7 can control the first light source 9 and the second light source 10 to automatically provide light to the test surface; and the control unit 7 controls the support frame 3 to vertically raise and lower the lifting mechanism 8 on the support frame 3, thereby automating the raising and lowering of the fluid competition control baffle 4. In this way, the automation level of the testing device 100 for the oil, gas, and water accumulation capacity of shale surfaces is significantly improved.

[0148] The following is a detailed description of the experimental procedure for testing the oil, gas, and water storage capacity of shale surfaces, such as... Figure 1 As shown.

[0149] First, directional sampling is performed on the shale core.

[0150] Step 1 involves the standardized preparation of shale samples to create grooved shale samples. Specifically, the shale core is first cut to obtain a cut body; then, the cut body undergoes roughing and finishing processes to obtain a qualified test surface; subsequently, the test surface is further processed to create grooves, maintaining a surface roughness Ra of less than 1 μm, i.e., the surface roughness Ra of the first plane 21, the second plane 22, the first inclined wall 23, and the second inclined wall 24 are all less than 1 μm.

[0151] Step 2, Test surface, capable of providing contact angle measurements for multiple scenarios. Camera unit 6 acquires images with first contact angle data and second contact angle data. Specifically, the first static contact angle θ0 (water) is acquired from the first plane 21, and the second static contact angle θ0 (oil) is acquired from the second plane 22; the first upper contact angle θ1 (water) and the first lower contact angle θ2 (water) are acquired from the first inclined wall 23, and the second upper contact angle θ1 (oil) and the second lower contact angle θ2 (oil) are acquired from the second inclined wall 24; the first competing contact angle θ3 (water) and the second competing contact angle θ3 (oil) between water droplets and oil droplets are acquired from the center of the V-groove.

[0152] Step 3: The control unit 7 is electrically connected to the camera unit 6. The control unit 7 acquires an image with first contact angle data and second contact angle data from the camera unit 6, imports it into the contact angle analysis software in the control unit 7, and calculates the first contact angle data and second contact angle data mentioned above.

[0153] Step 4: Calculate the single-element retention capacity index S(water) and the single-element retention capacity index of the oil droplet using the formulas above. .

[0154] Step 5: Calculate the competitive survival ability index of oil droplets and water droplets according to the formula.

[0155] Step 6, the single-item retention capacity index S (water) of the water droplet and the single-item retention capacity index of the oil droplet mentioned above. The system uses oil droplets and water droplets to compete for the survival capacity index, outputting a comprehensive evaluation report to provide guidance for the classification of wettability and survival capacity.

[0156] Finally, it should be noted that other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and alterations may be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for detecting the oil, gas, and water storage capacity of shale surfaces, characterized in that, include: A shale sample with grooves is prepared. The shale sample includes a test surface, the grooves are disposed on the test surface, the grooves have opposing first and second inclined walls, the roughness of the first and second inclined walls is less than 1 μm, and the test surface further includes a first plane located on one side of the first inclined wall and a second plane located on one side of the second inclined wall, the roughness of the first and second planes is less than 1 μm. Add a drop of water to the first plane and a drop of oil to the second plane; Add water droplets to the first inclined wall and oil droplets to the second inclined wall; Acquire first contact angle data of water droplets on the first plane and the first inclined wall, determine the single-item retention capacity index of water droplets based on the first contact angle data, acquire second contact angle data of oil droplets on the second plane and the second inclined wall, determine the single-item retention capacity index of oil droplets based on the second contact angle data, and determine the competitive retention capacity index of oil droplets and water droplets based on the first contact angle data and the second contact angle data.

2. The method for detecting the oil, gas, and water storage capacity on the shale surface according to claim 1, characterized in that, The preparation of the grooved shale sample includes: The shale is cut to obtain the cut body; The cut body is rough-machined; The cut body after rough machining is then finely machined to give it a test surface. The grooves are machined into the test surface to obtain the shale sample.

3. The method for detecting the oil, gas, and water storage capacity on the shale surface according to claim 2, characterized in that, The cutting of shale includes: The shale is cut along a predetermined direction from the shale core, the predetermined direction being parallel to or perpendicular to the bedding planes of the shale.

4. The method for detecting the oil, gas, and water storage capacity on the shale surface according to claim 2, characterized in that, Rough machining of the cut body includes: Determine the processing area; The processing area is leveled using an inert liquid as the processing cooling medium.

5. The method for detecting the oil, gas, and water storage capacity on the shale surface according to claim 4, characterized in that, The finishing process of the rough-machined cut body to give it a test surface includes: The processed area after leveling is polished multiple times, and the roughness of the polishing pads used in the multiple polishings decreases. The processing area is finely polished using a suspension to obtain the test surface, wherein the test surface exhibits specular reflection under a microscope.

6. The method for detecting the oil, gas, and water storage capacity on the shale surface according to claim 5, characterized in that, The suspension includes an alumina suspension or a colloidal silica suspension.

7. The method for detecting the oil, gas, and water storage capacity on the shale surface according to claim 2, characterized in that, The grooves are machined on the test surface, including: The test surface is machined using an ultra-precision CNC machine tool with a single-crystal diamond tool or a focused ion beam to obtain the groove; The test surface was purged with high-purity inert gas to remove machining debris.

8. The method for detecting the oil, gas, and water storage capacity on the shale surface according to claim 7, characterized in that, The angle between the first inclined wall and the second inclined wall is 60°-120°.

9. The method for detecting the oil, gas, and water storage capacity on the shale surface according to claim 1, characterized in that, Adding water droplets to the first plane, adding oil droplets to the second plane, and adding water droplets to the first inclined wall and adding oil droplets to the second inclined wall all include: The volume of water and oil droplets is 2 μL - 10 μL; and / or, The dropping rates of water and oil droplets are 0.2 μL / s - 2 μL / s; and / or, The distance between the water droplets and oil droplets and the test surface before they fall is 1mm-2mm.

10. The method for detecting the oil, gas, and water storage capacity on the shale surface according to claim 1, characterized in that, The step of acquiring the first contact angle data of the water droplet on the first plane and the first inclined wall, and determining the single-item retention capacity index of the water droplet based on the first contact angle data, includes: The first contact angle data includes the first static contact angle θ0 (water) of the water droplet on the first plane, the first upper contact angle θ1 (water) and the first lower contact angle θ2 (water) of the water droplet on the first inclined wall, the first competing contact angle θ3 (water) between the water droplet and the oil droplet, and the single-item retention capacity index of the water droplet. for: ； The step of acquiring the second contact angle data of the oil droplet on the second plane and the second inclined wall, and determining the single-item retention capacity index of the oil droplet based on the second contact angle data, includes: The second contact angle data includes the second static contact angle θ0 (oil) of the oil droplet on the second plane, the second upper contact angle θ1 (oil) and the second lower contact angle θ2 (oil) of the oil droplet on the second inclined wall, the second competing contact angle θ3 (oil) of the oil droplet and the water droplet, and the single-item retention capacity index of the oil droplet. for: ； The competitive retention capacity index of oil droplets and water droplets is determined based on the first contact angle data and the second contact angle data, including: The competitive endowment capability index is: in, , .

11. A testing device for the oil, gas, and water storage capacity of shale surfaces, used to perform the testing method for the oil, gas, and water storage capacity of shale surfaces according to any one of claims 1-10, characterized in that, include: Base; A stage is provided on the base, the stage is used to place the shale sample to be tested, and the test surface is located on the side of the shale sample facing away from the stage; A support frame is provided on the base; A fluid competition control baffle is vertically mounted on the support frame. The fluid competition control baffle is vertically opposite to the intersection of the first and second inclined walls of the groove of the shale sample. When the fluid competition control baffle abuts against the intersection, it separates the water droplets on the first inclined wall and the oil droplets on the second inclined wall. The titration mechanism includes: a first titration unit and a second titration unit, wherein the first titration unit is used to titrate water droplets onto a first plane and a first inclined wall of the test surface, and the second titration unit is used to titrate oil droplets onto a second plane and a second inclined wall of the test surface; The camera unit is used to acquire the first contact angle data of the water droplet and the second contact angle data of the oil droplet; A control unit, electrically connected to the camera unit, is configured to determine the single-item retention capacity index of a water droplet based on the first contact angle data, and to determine the single-item retention capacity index of an oil droplet based on the second contact angle data, and to determine the competitive retention capacity index between oil droplets and water droplets based on the first contact angle data and the second contact angle data.

12. The testing device for the oil, gas and water storage capacity of shale surfaces according to claim 11, characterized in that, Also includes: A lifting mechanism is movably mounted on the support frame, and the fluid competition control baffle is mounted on the lifting mechanism.

13. The testing device for the oil, gas and water storage capacity of shale surfaces according to claim 11, characterized in that, The first titration unit includes: A first mounting bracket is disposed on one side of the first plane of the base; A first titrator is disposed on the first mounting bracket, and the first titrator is used to titrate water droplets onto the first plane and the first inclined wall; The second titration unit includes: The second mounting bracket is disposed on one side of the second plane of the base; A second titrator is disposed on the second mounting bracket, and the second titrator is used to titrate oil droplets onto the second plane and the second inclined wall.

14. The testing device for the oil, gas and water storage capacity of shale surfaces according to claim 13, characterized in that, Also includes: A first light source is disposed on the first mounting bracket and is used to emit light onto the first plane and the first inclined wall; A second light source, located on the second mounting bracket, is used to emit light onto the second plane and the second inclined wall.

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