A test device, method and system for testing shale properties

Abstract

The present invention provides a test device, method and system for testing shale characteristics, the method comprising: applying a preset normal stress to a test sample in a core groove of a U-shaped test fixture, applying a horizontal stress to a flat test fixture, making the flat test fixture have a preset loading speed, and performing a shear friction operation on the test sample; determining the composition of the test sample according to the sample rock cuttings of the shear friction operation; determining the shale characteristics according to the composition of the test sample, the preset normal stress and the preset loading speed. The test device, method and system for testing shale characteristics provided by the present invention can truly reflect the mechanical properties of shale, and by changing the stress magnitude, more efficiently and conveniently realizes the shale characteristic test analysis under different stress states.

Description

Technical Field

[0001] The present invention relates to the technical field of rock properties in shale oil and gas storage, and in particular to a test device, method and system for testing shale properties. Background Art

[0002] Shale oil and gas is an unconventional resource with great potential. It has been successfully developed in North America and my country, becoming a new field of global oil and gas exploration. Horizontal well volume transformation has become the main mode of shale oil and gas development. This mode requires in-depth analysis and research on the mechanical properties of shale rock. For horizontal well volume transformation, shale fracturing is a key parameter for evaluating whether shale oil and gas reservoirs can be effectively fractured.

[0003] Regarding the steady-state and non-steady-state characteristics of shale oil and gas reservoirs, although some foreign scholars have conducted qualitative evaluations of the non-steady-state crack expansion of highly brittle shales by monitoring microseismic signals during fracturing operations, and scholars in the seismic industry have conducted indoor experiments and used the velocity-state constitutive equation to quantitatively evaluate the steady-state and non-steady-state characteristics of fault mud, there has been no comprehensive experimental research and analysis conducted at home and abroad on the steady-state and non-steady-state characteristics of shale oil and gas reservoirs. Due to the large variation in mineral components of different shale reservoirs, it is troublesome to artificially synthesize rock samples similar to fault mud, and the authenticity of the mineral components is lost. At the same time, no evaluation and analysis of the steady-state and non-steady-state characteristics of shale under different stresses and confining pressures has been conducted at home and abroad. Therefore, in order to more comprehensively evaluate the brittleness of shale, to help better select the sweet spot of fracturing engineering, to improve the effect of fracturing operations, and to achieve an increase in the production of shale oil and gas single wells, there is an urgent need for an experimental test and analysis method suitable for shale characteristics. Summary of the invention

[0004] In order to more comprehensively evaluate the brittleness of shale, so as to help better select the sweet spots of fracturing engineering, improve the effect of fracturing operations, and achieve an increase in the production of shale oil and gas wells, the present invention provides a test device, method and system for testing shale characteristics.

[0005] In a first aspect, the present invention provides a test device for testing shale properties, the test device comprising:

[0006] U-shaped test fixture and flat plate test fixture;

[0007] The two opposite side walls of the U-shaped test fixture are respectively provided with core grooves, and the flat plate test fixture has a core groove, and the core groove is arranged in the U-shaped groove of the U-shaped test fixture.

[0008] In a second aspect, the present invention provides a method for testing shale properties, wherein the method uses the aforementioned device to perform a shear friction test to determine the shale properties, and the method comprises:

[0009] Applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, and applying a horizontal stress to the flat test fixture, so that the flat test fixture has a preset loading speed, and performing a shear friction operation on the test sample;

[0010] Determining the composition of the test sample based on the sample cuttings from the shear friction operation;

[0011] The shale characteristics are determined based on the composition of the test sample, the preset normal stress and the preset loading speed.

[0012] In a third aspect, the present invention provides a system for testing shale properties, the system comprising: a test device for testing shale properties and a shale property determination device; wherein the test device comprises:

[0013] U-shaped test fixture and flat plate test fixture;

[0014] The two opposite side walls of the U-shaped test fixture are respectively provided with core grooves, and the flat plate test fixture is provided with a core groove, and the core groove is arranged in the U-shaped groove of the U-shaped test fixture;

[0015] Applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture through the test device, and applying a horizontal stress to the flat test fixture, so that the flat test fixture has a preset loading speed, and performing a shear friction operation on the test sample;

[0016] The shale property determination device comprises:

[0017] A component determination module, used to determine the component of the test sample based on the sample cuttings of the shear friction operation;

[0018] The shale property determination module determines the shale property according to the composition of the test sample, the preset normal stress and the preset loading speed.

[0019] The present invention provides a test device, method and system for testing shale properties, which can truly reflect the mechanical properties of shale and more efficiently and conveniently realize shale property test analysis under different stress states by changing the stress magnitude.

[0020] In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the structure of a U-shaped test fixture and a flat plate test fixture provided in an embodiment of the present invention;

[0023] Figure 2 A schematic diagram of the structure of a test device for testing shale properties provided in an embodiment of the present invention;

[0024] Figure 3 A schematic diagram of a process for testing shale characteristics provided by an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of a test state of a test sample provided by an embodiment of the present invention;

[0026] Figure 5 A schematic diagram of a τ-t curve for a shale property test provided in an embodiment of the present invention;

[0027] Figure 6 A schematic diagram of the average value of steady-state velocity-dependent parameters of the same test sample under different normal stresses provided by an embodiment of the present invention;

[0028] Figure 7 A schematic diagram of shale characteristics under different normal stresses of different test samples provided in an embodiment of the present invention;

[0029] Figure 8 A schematic diagram of a τ-t curve for another shale property test provided by an embodiment of the present invention;

[0030] Fig. 9 A schematic diagram of the average value of steady-state velocity-dependent parameters of another test sample under different normal stresses provided by an embodiment of the present invention;

[0031] Fig.10 A schematic diagram of shale characteristics under different normal stresses of another different test sample provided by an embodiment of the present invention;

[0032] Fig.11 A system diagram for testing shale properties provided by an embodiment of the present invention;

[0033] Fig.12 A block diagram of a shale property determination device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In recent years, for horizontal well volume transformation, shale compressibility is a key parameter for evaluating whether shale oil and gas reservoirs can be effectively fractured. In the existing research on the steady-state and non-steady-state characteristics of shale oil and gas reservoirs, due to the large variation of mineral components in different shale reservoirs, it is troublesome to artificially synthesize rock samples similar to fault mud, and the authenticity of mineral components is lost. Therefore, no evaluation and analysis of shale steady-state and non-steady-state characteristics under different stresses and confining pressures has been carried out at home and abroad.

[0036] In order to solve the above problems of the prior art, the embodiments of the present invention provide a test device, method and system for testing shale characteristics. The inventive concept is: applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, and applying a horizontal stress to the flat test fixture, so that the flat test fixture has a preset loading speed, and performing a shear friction operation on the test sample; determining the composition of the test sample according to the sample rock cuttings of the shear friction operation; determining the shale characteristics according to the composition of the test sample, the preset normal stress and the preset loading speed. The test device, method and system for testing shale characteristics provided by the embodiments of the present invention can truly reflect the mechanical properties of shale, and by changing the stress magnitude, more efficiently and conveniently realize the shale characteristic test analysis under different stress states.

[0037] Figure 1 A schematic diagram of the structure of a U-shaped test fixture and a flat test fixture provided in an embodiment of the present invention, Figure 2 A schematic diagram of the structure of a test device for testing shale properties provided in an embodiment of the present invention, as shown in FIG. Figure 1 , Figure 2 As shown, the device includes: a U-shaped test fixture 104 and a flat test fixture 105, three test samples 101, 102, 103, an upper core groove 106 and a lower core groove 108 of the U-shaped test fixture 104, a core groove 109 of the flat test fixture 105, a screw locking device 110, and a fixing device 111.

[0038] Specifically, three test samples 101, 102, and 103 are processed and manufactured at the same position by wire cutting using coring or surface outcropping, and the test samples are of the same size and are all rectangular, and each end surface must be smooth and flat. Two of the test samples 101 and 103 are installed in the upper core groove 106 and the lower core groove 108 of the fixed U-shaped test fixture 104, and the third test sample 102 is installed in the core groove 109 of the movable flat plate test fixture 105. The height of the upper core groove 106 of the U-shaped test fixture 104 for loading the test sample should be 1mm-2mm less than the height of the test sample 101. The test sample 101 is installed in the upper core groove 106. The lower end of the test sample 101 is exposed in the U-shaped groove 107 of the U-shaped test fixture at a height of about 2mm-4mm. There is a blank area of ​​about 1-2mm in height on the upper part of the upper core groove 106. The height of the lower core groove 108 of the U-shaped test fixture 104 for loading the test sample 103 should be 2mm-4mm less than the height of the test sample 103. The test sample 103 is installed in the lower core groove 108. In the figure, the lower end of the test sample 103 is flush with the bottom surface of the lower core groove 108, and the upper end of the test sample 103 is exposed in the U-shaped groove 107 of the U-shaped test fixture 104 at a height of about 2mm-4mm. The height of the core groove 109 of the flat test fixture 105 is 2mm-4mm less than the height of the test sample 102. The test sample 102 is fixedly installed in the core groove 109 of the flat test fixture 105 by using the screw locking device 110 on one side of the flat test fixture 105. Both the upper and lower ends of the test sample 102 are exposed to the air at a height of about 1mm-2mm.

[0039] The flat test fixture 105 with the test sample 102 installed is placed centrally in the U-shaped groove 107 of the U-shaped test fixture 104 with the test samples 101 and 103 installed. The upper end surface of the test sample 102 in the flat test fixture 105 is completely aligned and in contact with the lower end surface of the test sample 101 in the upper core groove 106 of the U-shaped test fixture 104, and the lower end surface of the test sample 102 in the flat test fixture 105 is completely aligned and in contact with the upper end surface of the test sample 103 in the lower core groove 108 of the U-shaped test fixture 104.

[0040] The test fixtures 104 and 105 with the test samples 101, 102, and 103 installed are placed on the test platform, and the U-shaped test fixture 104 is limited and fixed 111. The embodiment of the present invention does not specifically limit the millimeter height of the samples and devices involved.

[0041] The embodiment of the present invention can better uniformly rub the shale sample by configuring a test device for testing shale characteristics, so that the test results are more accurate.

[0042] According to another aspect of the present invention, an embodiment of the present invention also provides a method for testing shale properties, such as Figure 3 As shown, Figure 3 A schematic flow chart of a method for testing shale characteristics provided in an embodiment of the present invention, the method comprising:

[0043] S301, applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, and applying a horizontal stress to the flat test fixture, so that the flat test fixture has a preset loading speed, and performing a shear friction operation on the test sample.

[0044] Specifically, Figure 4 As shown, Figure 4 A schematic diagram of the test state of a test sample provided in an embodiment of the present invention, in which a normal stress σ is applied to a blank area at the upper height of the core groove on a U-shaped test fixture, and a horizontal stress τ is applied to an outer end of a flat test fixture, so that when the normal stress σ and the horizontal stress τ are applied, the initial loading speed of the horizontal stress is v, and shear friction is performed on the test sample with the applied normal stress σ and the horizontal stress τ.

[0045] S302, determining the composition of the test sample based on the sample rock cuttings obtained from the shear friction operation.

[0046] Specifically, sufficient rock cuttings are taken from the contact surface of the test sample to conduct XRD diffraction tests on whole-rock minerals and clay mineral components.

[0047] S303, determining shale characteristics according to the composition of the test sample, the preset normal stress and the preset loading speed.

[0048] Specifically, according to the different normal stresses, different horizontal stresses and different loading speeds applied to different groups of test samples, the steady-state velocity dependence parameters under different groups are obtained, and then XRD diffraction is performed on different groups of test samples to obtain the percentage of mineral and clay mineral composition, and then the shale characteristic plate is obtained in the coordinate axis.

[0049] The embodiment of the present invention can efficiently and conveniently realize the friction coefficient under different stress states by changing the stress magnitude, can truly reflect the mechanical properties of shale, and is convenient for researchers to carry out extensive experimental research.

[0050] Based on the content of the above embodiment, as an optional embodiment: applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, and applying a horizontal stress to the flat test fixture so that the flat test fixture has a preset loading speed, before performing the shear friction operation, it also includes:

[0051] The height of the test samples in the core grooves on both sides of the U-shaped test fixture is set to be higher than the height of the core grooves on both sides of the U-shaped test fixture.

[0052] Specifically, the height of the upper core groove of the U-shaped test fixture for loading the test sample should be 1mm-2mm smaller than the height of the test sample. The test sample is installed in the upper core groove, and the lower end of the test sample is exposed in the U-shaped groove of the U-shaped test fixture at a height of about 2mm-4mm. There is a blank area of ​​about 1-2mm in height on the upper part of the upper core groove.

[0053] The height of the test sample in the core groove of the flat plate test fixture is set to be higher than the height of the core groove of the flat plate test fixture.

[0054] Specifically, the height of the core groove of the flat test fixture should be 2mm-4mm smaller than the height of the test sample. The test sample is fixed in the center of the core groove of the flat test fixture using the screw locking device on one side of the flat test fixture. Both the upper and lower ends of the test sample are exposed to the air at a height of about 1mm-2mm.

[0055] The two end faces of the test sample in the core groove of the flat test fixture are respectively aligned with the end faces of the test sample in the core grooves of the two side walls of the U-shaped test fixture.

[0056] Specifically, the height of the lower core groove of the U-shaped test fixture for loading the test sample should be 2mm-4mm less than the height of the test sample. The test sample is installed in the lower core groove, the lower end of the test sample is flush with the bottom surface of the lower core groove, and the upper end of the test sample is exposed in the U-shaped groove of the U-shaped test fixture at a height of about 2mm-4mm. The flat test fixture with the test sample installed is placed centrally in the U-shaped groove of the U-shaped test fixture with the test sample already installed. The upper end face of the test sample in the flat test fixture is completely aligned and in contact with the lower end face of the test sample in the upper core groove of the U-shaped test fixture, and the lower end face of the test sample in the flat test fixture is completely aligned and in contact with the upper end face of the test sample in the lower core groove of the U-shaped test fixture. Among them, the embodiments of the present invention do not specifically limit the millimeter height of the samples and devices involved.

[0057] In the embodiment of the present invention, the friction surface is adjusted and increased by setting the height of the test sample in the core grooves on both sides of the U-shaped test fixture and the height of the test sample in the core groove of the flat test fixture.

[0058] Based on the content of the above embodiment, as an optional embodiment: applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, and applying a horizontal stress to the flat test fixture, so that the flat test fixture has a preset loading speed, before performing a shear friction operation on the test sample, it also includes:

[0059] The test sample is rubbed with a maximum normal stress greater than a preset maximum normal stress and a preset maximum horizontal stress loading speed, and the rubbed test sample is restored to an initial state before friction; wherein the preset maximum normal stress is the maximum value of multiple preset normal stresses applied in the shear friction operation, and the preset maximum horizontal stress loading speed is the maximum value of multiple preset horizontal stress loading speeds in the shear friction operation.

[0060] Specifically, before the shear friction test of the test sample, a normal stress higher than the maximum value σ in the test scheme is first selected. max A normal stress σ′ is selected, and the loading speed v is selected to be higher than the maximum horizontal stress in the test scheme. max At a certain horizontal stress loading speed v', the test rock sample is rubbed to reduce the roughness of the contact surface of the test sample. According to the processing conditions of the test sample, the friction can be repeated 1-2 times. Each time the test sample is rubbed again, the test sample must be restored to the initial state. For example, in a group of test schemes, the selected normal stress values ​​are 10MPa, 20MPa, and 30MPa, respectively. Then, at this time, in the normal stress data of this group of test schemes, 30MPa is the maximum value. Then a normal stress higher than 30MPa, such as 35MPa, is selected as the normal stress value for rubbing the test sample. In a group of test schemes, the selected horizontal stress loading speeds are 20μm / s, 30μm / s, and 40μm / s. Then a horizontal stress loading speed higher than 40μm / s is selected as the horizontal stress loading speed for rubbing the test sample, such as 45μm / s.

[0061] The embodiment of the present invention performs friction pretreatment on the test sample before the shear friction test, which is beneficial to reducing the contact surface roughness of the test sample and ensuring that the end surface is smooth and flat, so as to improve the accuracy of the test calculation.

[0062] Based on the content of the above embodiment, as an optional embodiment: determining the composition of the test sample according to the sample rock cuttings of the shear friction operation includes:

[0063] XRD diffraction is performed on the sample cuttings of the shear friction operation to determine the composition of the test sample.

[0064] Specifically, the embodiment of the present invention performs XRD diffraction on the rock cuttings obtained after shearing and friction, and obtains the composition of the test sample according to the XRD spectrum.

[0065] The embodiments of the present invention can better study and analyze the mineral components of different shale reservoirs according to the composition of shale.

[0066] Based on the content of the above embodiment, as an optional embodiment: applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, and applying a horizontal stress to the flat test fixture, so that the flat test fixture has a preset loading speed, and performing a shear friction operation on the test sample, including:

[0067] A normal stress of a preset magnitude is applied to the test sample in the core groove of the U-shaped test fixture, and different horizontal stresses are applied to the flat plate test fixture, so that the flat plate test fixture has preset horizontal stress loading speeds of different magnitudes.

[0068] Specifically, the test samples were subjected to shear friction tests under the same normal stress and different horizontal stress loading speeds. The normal stress applied was σ1, and the initial horizontal stress loading speed was v1. Figure 5 The experimental curve shown is Figure 5 This is a schematic diagram of the τ-t curve of the shale property test provided by the embodiment of the present invention. In the figure, the horizontal stress increases with the increase of the loading displacement. When the horizontal stress reaches τ r When the maximum static friction between the test samples is completely overcome, the middle test sample begins to slide, and the normal stress σ1 is always maintained unchanged. When the sliding is in a stable state, the horizontal loading speed v1 is changed to v2. After sliding a distance of ΔL, the horizontal loading speed v2 is changed to v3. After sliding a distance of ΔL, the horizontal loading speed v3 is changed to v1. Repeat this loading method for 1-2 cycles.

[0069] In the embodiment of the present invention, the test sample is subjected to the same normal stress and different horizontal stress loading speeds to obtain a curve graph of the test sample at different horizontal stress loading speeds.

[0070] Based on the content of the above embodiment, as an optional embodiment: determining the shale characteristics according to the composition of the test sample, the preset normal stress and the preset loading speed includes:

[0071] Step A1, according to a normal stress of a preset magnitude and different horizontal stresses, determining the friction coefficient of the rock sample when different horizontal stresses are applied under the current normal stress.

[0072] Specifically, when the normal stress σ is determined, different horizontal stresses are applied to the test sample, and the friction coefficient is calculated according to the formula The friction coefficient μ is obtained. Where τ is the horizontal stress and σ is the normal stress.

[0073] Step A2, determining the steady-state velocity dependence parameters of the test sample under the current normal stress according to the rock sample friction coefficient and the stress loading speeds at different levels.

[0074] like Figure 6As shown, Figure 6 A schematic diagram of the average value of steady-state velocity-dependent parameters of the same test sample under different normal stresses provided in an embodiment of the present invention.

[0075] Specifically, the embodiment of the present invention adopts the velocity-state constitutive equation The test data are analyzed, where the ab value is a steady-state speed-dependent parameter. When ab is a positive value, it has a rate-enhancing characteristic, and when ab is a negative value, it has a rate-weakening characteristic.

[0076] According to the velocity constitutive equation, under the same test sample, the normal stress σ is obtained i The steady-state velocity-dependent parameters of , the velocity constitutive equation is as follows:

[0077]

[0078] Where, 1≤i≤n, n is a natural number, i is the i-th normal stress; a is the constitutive parameter of the direct rate effect; b is the strong and weak local constitutive parameter of the transition process; v i is the initial velocity of horizontal stress, when the same normal stress σ is applied i The corresponding friction coefficient is μ i ;v j For i The loading speed obtained when the load is stably slid for a certain distance is μ j ; Δμ is μ j -μ i .

[0079] For example, under normal stress σ1, the horizontal stress loading speed changes from horizontal loading speed v1 to v2, and then from horizontal loading speed v2 to v3. At this time, the steady-state velocity dependence parameters α1 and α2 under normal stress σ1 are:

[0080]

[0081] Step A3, applying different preset normal stresses to the test sample to determine the average value of the steady-state velocity dependence parameter of the test sample under different normal stresses; repeating steps A1, A2 and A3 to determine the steady-state velocity dependence parameter M of different test samples under different normal stresses. ji ; Wherein, 1≤i≤n, 1≤j≤n, n is a natural number, j is the jth test sample, and i is the i-th normal stress.

[0082] Specifically, here, M 1iis the average value of the steady-state velocity-dependent parameter of the first test sample under different normal stresses. As described in the above embodiment, when the normal stress is σ1, the steady-state velocity-dependent parameters α1 and α2 are respectively:

[0083] At this time,

[0084] Therefore, after executing step 2, the test sample is restored to the initial state, and then normal stresses σ2, σ3, σ4, ..., σ n , calculate the steady-state velocity-dependent parameters under different normal stress conditions. Finally, replace different groups of test samples and conduct tests according to the above steps in turn to obtain M ji .

[0085] According to the composition of each test sample and the average value of the steady-state velocity-dependent parameter M under different normal stresses, ji Determine the shale properties of different test samples.

[0086] Specifically, Figure 7 As shown, Figure 7 Schematic diagram of shale property chart under different normal stresses of different test samples provided in an embodiment of the present invention. After obtaining the components of different test samples, shale property charts under different clay mineral components and different normal stresses are established according to the percentage of mineral component content of different groups of test samples.

[0087] The embodiment of the present invention obtains a more accurate shale property map by subjecting different test samples to different normal stresses and different horizontal stress loading speeds.

[0088] Based on the content of the above embodiment, as an optional embodiment: applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, and applying a horizontal stress to the flat test fixture, so that the flat test fixture has a preset loading speed, and performing a shear friction operation on the test sample, including:

[0089] The test sample in the core groove of the U-shaped test fixture is applied with preset normal stresses of different magnitudes, and the same horizontal stress is applied to the flat plate test fixture, so that the flat plate test fixture has a preset horizontal stress loading speed.

[0090] Specifically, the normal stress applied is σ1, and the initial loading speed of the horizontal stress is v1, such as Figure 8 The experimental curve shown is Figure 8 A schematic diagram of a τ-t curve for another shale property test provided by an embodiment of the present invention, in which the horizontal stress increases with the increase of loading displacement. When the horizontal stress reaches τ rWhen the maximum static friction between the test samples is completely overcome, the middle test sample begins to slide, and the normal stress σ1 is always maintained unchanged. When the sliding is in a stable state, the horizontal loading speed v1 is changed to v2. After sliding a distance of ΔL, the horizontal loading speed v2 is changed to v3. After sliding a distance of ΔL, the horizontal loading speed v3 is changed to v1. Repeat this loading method for 1-2 cycles.

[0091] Based on the content of the above embodiment, as an optional embodiment: determining the shale characteristics according to the composition of the test sample, the preset normal stress and the preset loading speed includes:

[0092] Step B1, according to a preset horizontal stress and different normal stresses, determining the friction coefficient of the rock sample when different normal stresses are applied under the current horizontal stress.

[0093] Specifically, when the horizontal stress τ is determined, different normal stresses are applied to the test sample, and the friction coefficient is calculated according to the formula The friction coefficient μ is obtained. Where τ is the horizontal stress and σ is the normal stress.

[0094] Step B2, determining the steady-state velocity dependence parameters of the test sample under the current normal stress according to the rock sample friction coefficient and the stress loading speeds at different levels.

[0095] like Fig. 9 As shown, Fig. 9 This is another example of the present invention providing a diagram of the average value of the steady-state velocity-dependent parameters of the same test sample under different normal stresses. Specifically, when the horizontal stress loading speed is v1, the friction coefficient calculation formula is used: Get σ1, σ2, σ3, σ4,…,σ n Friction coefficient under normal stress μ 11 ,μ 12 ,μ 13 ,...,μ 1n According to this step, the friction coefficient μ under different normal stresses at horizontal stress loading speed v2 is calculated in sequence. 21 ,μ 22 ,μ 23 ,...,μ 2n , friction coefficient μ under different normal stresses at horizontal stress loading speed v3 31 ,μ 32 ,μ 33 ,...,μ 3n . Combined μ 11 , μ 21 , μ 31 , using the velocity-state constitutive equation Calculate the steady-state velocity-dependent parameters at different horizontal stress loading speeds under the current normal stress. i Under the same condition, different normal stresses σ1, σ2, ...., σ n , and then get the corresponding μ i1 ,μ i2 ,....,μ in , at the horizontal stress loading speed v j Under the same condition, the corresponding μ j1 ,μ j2 ,....,μ jn , at this time, under normal stress σ1, Δμ=μ j1 -μ i1 .

[0096] For example: when the normal stress is calculated to be σ1, the steady-state velocity-dependent parameters when the horizontal stress loading speed changes from the horizontal loading speed v1 to v2, and then from the horizontal loading speed v2 to v3 are:

[0097] From the above, we can see that when the normal stress is σ1 and the horizontal loading speed is v1, the corresponding friction coefficient is μ 11 , when the horizontal loading speed is v2, the corresponding friction coefficient is μ 21 , when the horizontal loading speed is v3, the corresponding friction coefficient is μ 31 , so when the normal stress is calculated as σ1, the steady-state velocity-dependent parameters α1 and α2 at different horizontal stress loading speeds are:

[0098]

[0099] Among them, the horizontal stress loading speed v i Under the same condition, different normal stresses σ1, σ2, ...., σ n , and then get the corresponding μ i1 ,μ i2 ,....,μ in , at the horizontal stress loading speed v j Under the same condition, the corresponding μ j1 ,μ j2 ,....,μ jn , at this time, under normal stress σ1, Δμ=μ j1 -μ i1 .

[0100] Step B3, applying different preset normal stresses to the test sample to determine the average value of the steady-state velocity-dependent parameters of the test sample under different normal stresses; repeating steps B1, B2 and B3 to determine the average value M′ of the steady-state velocity-dependent parameters of different test samples under different normal stresses ji ; Wherein, 1≤i≤n, 1≤j≤n, n is a natural number, j is the jth test sample, and i is the i-th normal stress.

[0101] Specifically, here, M' 1i is the average value of the steady-state velocity-dependent parameter of the test sample under different normal stresses. As described in the above embodiment, when the normal stress is σ1, the steady-state velocity-dependent parameters α1 and α2 are respectively:

[0102] At this time,

[0103] Therefore, after executing step 2, the test sample is restored to the initial state, and then normal stresses σ2, σ3, σ4, ..., σ n , calculate the steady-state velocity-dependent parameters under different normal stress conditions. Finally, replace different groups of test samples and conduct tests according to the above steps in turn to obtain M′ ji .

[0104] According to the composition of each test sample and the average value of the steady-state velocity-dependent parameter M′ under different normal stresses ji Determine the shale properties of different test samples.

[0105] Specifically, Fig.10 As shown, Fig.10 Another schematic diagram of shale property diagrams under different normal stresses for different test samples provided by an embodiment of the present invention. After obtaining the components of different test samples, shale property diagrams under different clay mineral components and different normal stresses are established according to the percentage of mineral component content of different groups of test samples.

[0106] The embodiment of the present invention obtains a more accurate shale property map by subjecting different test samples to different normal stresses and different horizontal stress loading speeds.

[0107] According to another aspect of the present invention, an embodiment of the present invention further provides a system for testing shale properties. Fig.11 , Fig.11 A diagram of a system for testing shale properties provided in an embodiment of the present invention. The system is used to determine the method for testing shale properties in the aforementioned embodiments. Therefore, the description and definition of the method for testing shale properties in the aforementioned embodiments can be used to understand the various execution devices in the embodiments of the present invention.

[0108] like Fig.11 As shown, the system includes: a test device 1101 for testing shale properties and a shale property determination device 1102; wherein the test device 1101 includes:

[0109] U-shaped test fixture and flat plate test fixture;

[0110] Two opposite side walls of the U-shaped test fixture are respectively provided with core grooves, and the flat plate test fixture is provided with a core groove, and the core groove is arranged in the U-shaped groove of the U-shaped test fixture;

[0111] Apply a preset normal stress to the test sample in the core groove of the U-shaped test fixture through the test device, and apply a horizontal stress to the flat test fixture, so that the flat test fixture has a preset loading speed, and perform a shear friction operation on the test sample;

[0112] like Fig.12 As shown, Fig.12 A block diagram of a shale characteristic determination device provided in an embodiment of the present invention. In the figure, the shale characteristic determination device 1102 includes:

[0113] The component determination module 1201 is used to determine the components of the test sample according to the sample cuttings of the shear friction operation;

[0114] The shale property determination module 1202 determines the shale property according to the composition of the test sample, the preset normal stress and the preset loading speed.

[0115] Specifically, those skilled in the art can understand the implementation of the system for testing shale characteristics in the embodiments of the present invention based on the above description of the embodiments of the device and the method, and therefore, they will not be described in detail here.

[0116] Based on the content of the above embodiment, as an optional embodiment: applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, and applying a horizontal stress to the flat test fixture, so that the flat test fixture has a preset loading speed, and performing a shear friction operation on the test sample, including:

[0117] A preset normal stress is applied to the test sample in the core groove of the U-shaped test fixture, and different horizontal stresses are applied to the flat plate test fixture, so that the flat plate test fixture has preset horizontal stress loading speeds of different sizes.

[0118] Specifically, those skilled in the art can know the implementation method of the system for testing shale characteristics in the embodiment of the present invention based on the above description of the embodiment of the method, so it will not be described in detail here.

[0119] Based on the content of the above embodiment, as an optional embodiment: the shale property determination module determines the shale property according to the composition of the test sample, the preset normal stress and the preset loading speed, specifically including:

[0120] Step A1, determining the friction coefficient of the rock sample when different horizontal stresses are applied under the current normal stress according to a preset normal stress and different horizontal stresses;

[0121] Step A2, determining the steady-state velocity-dependent parameters of the test sample under the current normal stress according to the rock sample friction coefficient and the stress loading speeds at different levels;

[0122] Step A3, applying different preset normal stresses to the test sample to determine the average value of the steady-state velocity-dependent parameters of the test sample under different normal stresses; repeating steps A1, A2 and A3 to determine the average value M of the steady-state velocity-dependent parameters of different test samples under different normal stresses. ji ; Wherein, 1≤i≤n, 1≤j≤n, n is a natural number, j is the jth test sample, and i is the i-th normal stress;

[0123] According to the composition of each test sample and the average value of the steady-state velocity-dependent parameter M under different normal stresses, ji Determine the shale properties of different test samples.

[0124] Specifically, those skilled in the art can know the implementation method of the system for testing shale characteristics in the embodiment of the present invention based on the above description of the embodiment of the method, so it will not be described in detail here.

[0125] Based on the content of the above embodiment, as an optional embodiment: applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, applying a horizontal stress to the flat test fixture, so that the flat test fixture has a preset loading speed, and performing a shear friction operation on the test sample, including:

[0126] Preset normal stresses of different magnitudes are applied to the test sample in the core groove of the U-shaped test fixture, and the same horizontal stress is applied to the flat plate test fixture, so that the flat plate test fixture has a preset horizontal stress loading speed.

[0127] Specifically, those skilled in the art can understand the implementation of the system for testing shale characteristics in the embodiments of the present invention based on the above description of the embodiments of the device and the method, and therefore, they will not be described in detail here.

[0128] Based on the content of the above embodiment, as an optional embodiment: the shale property determination module determines the shale property according to the composition of the test sample, the preset normal stress and the preset loading speed, including:

[0129] Step B1, determining the friction coefficient of the rock sample when different normal stresses are applied under the current horizontal stress according to a preset horizontal stress and different normal stresses;

[0130] Step B2, determining the steady-state velocity dependence parameters of the test sample under the current normal stress according to the friction coefficient of the rock sample and the stress loading speeds at different levels;

[0131] Step B3, applying different preset normal stresses to the test sample to determine the average value of the steady-state velocity-dependent parameters of the test sample under different normal stresses; repeating steps B1, B2 and B3 to determine the average value M′ of the steady-state velocity-dependent parameters of different test samples under different normal stresses ji ; Wherein, 1≤i≤n, 1≤j≤n, n is a natural number, j is the jth test sample, and i is the i-th normal stress;

[0132] According to the composition of each test sample and the average value of the steady-state velocity-dependent parameter M′ under different normal stresses ji Determine the shale properties of different test samples.

[0133] Specifically, those skilled in the art can know the implementation method of the system for testing shale characteristics in the embodiment of the present invention based on the above description of the embodiment of the method, so it will not be described in detail here.

[0134] The embodiment of the present invention is a system for testing shale properties, which is composed of a test device for testing shale properties and a shale property determination device. The system operates a test sample in a shear friction module, and then confirms the components of the sample rock cuttings after the shear friction operation in a component determination module, and then determines the shale properties in the shale property determination module according to the components of the test sample, a preset normal stress, and a preset loading speed. In this way, the mechanical properties of shale can be truly reflected, and by changing the stress size, the shale property test and analysis under different stress states can be more efficiently and conveniently achieved.

[0135] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A test device for testing shale properties, characterized in that: The test device comprises: U-shaped test fixture and flat plate test fixture; The two opposite side walls of the U-shaped test fixture are respectively provided with core grooves, the flat plate test fixture is provided with a core groove, and the core groove of the flat plate test fixture is arranged in the U-shaped groove of the U-shaped test fixture; Wherein, the flat test fixture comprises: a locking component for locking the test sample in the core groove of the flat test fixture; the U-shaped test fixture comprises: a fixing component for limiting and fixing the U-shaped test fixture; The shale properties are determined based on the composition of the test sample, the preset normal stress and the preset loading speed.

2. A method for testing shale properties, characterized in that: The method uses the device of claim 1 to perform a shear friction test to determine shale properties, and the method comprises: Applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, and applying a horizontal stress to the flat test fixture, so that the flat test fixture has a preset loading speed, and performing a shear friction operation on the test sample; Determining the composition of the test sample based on the sample rock cuttings after the shear friction operation; The shale characteristics are determined based on the composition of the test sample, the preset normal stress and the preset loading speed.

3. The method according to claim 2, characterized in that The method further comprises: applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, applying a horizontal stress to the flat plate test fixture so that the flat plate test fixture has a preset loading speed, and performing the shear friction operation. The height of the test samples in the core grooves on both sides of the U-shaped test fixture is set to be higher than the height of the core grooves on both sides of the U-shaped test fixture; Setting the height of the test sample in the core groove of the flat plate test fixture to be higher than the height of the core groove of the flat plate test fixture; The two end faces of the test sample in the core groove of the flat test fixture are respectively aligned with the end faces of the test sample in the core grooves on both side walls of the U-shaped test fixture.

4. The method according to claim 2, characterized in that: The method further comprises: applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, applying a horizontal stress to the flat test fixture so that the flat test fixture has a preset loading speed, and performing a shear friction operation on the test sample. The test sample is rubbed at a maximum normal stress greater than a preset maximum horizontal loading speed, and the rubbed test sample is restored to an initial state before rubbing; wherein, The preset maximum normal stress is the maximum value of multiple preset normal stresses applied in the shear friction operation, and the preset maximum horizontal loading speed is the maximum value of multiple preset horizontal loading speeds in the shear friction operation.

5. The method according to claim 2, characterized in that: Determining the composition of the test sample based on the sample rock cuttings of the shear friction operation includes: XRD diffraction is performed on the sample cuttings of the shear friction operation to determine the composition of the test sample.

6. The method according to claim 2, characterized in that Applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, applying a horizontal stress to the flat test fixture, making the flat test fixture have a preset loading speed, and performing a shear friction operation on the test sample, including: A normal stress of a preset magnitude is applied to the test sample in the core groove of the U-shaped test fixture, and different horizontal stresses are applied to the flat plate test fixture, so that the flat plate test fixture has preset horizontal stress loading speeds of different magnitudes.

7. The method according to claim 6, characterized in that The determining of shale characteristics according to the composition of the test sample, the preset normal stress and the preset loading speed includes: Step A1, determining the friction coefficient of the rock sample when different horizontal stresses are applied under the current normal stress according to a normal stress of a preset magnitude and different horizontal stresses; Step A2, determining the steady-state velocity-dependent parameters of the test sample under the current normal stress according to the rock sample friction coefficient and different horizontal stress loading speeds; Step A3, applying different preset normal stresses to the test sample to determine the average value of the steady-state velocity-dependent parameters of the test sample under different normal stresses; repeating steps A1, A2 and A3 to determine the average value M of the steady-state velocity-dependent parameters of different test samples under different normal stresses. ji ; Wherein, 1≤i≤n, 1≤j≤n, n is a natural number, j is the jth test sample, and i is the i-th normal stress; According to the composition of each test sample and the average value of the steady-state velocity-dependent parameter M under different normal stresses, ji Determine the shale properties of different test samples.

8. The method according to claim 2, characterized in that: Applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, applying a horizontal stress to the flat test fixture, making the flat test fixture have a preset loading speed, and performing a shear friction operation on the test sample, including: The test sample in the core groove of the U-shaped test fixture is applied with preset normal stresses of different magnitudes, and the same horizontal stress is applied to the flat plate test fixture, so that the flat plate test fixture has a preset horizontal stress loading speed.

9. The method according to claim 8, characterized in that The determining of shale characteristics according to the composition of the test sample, the preset normal stress and the preset loading speed includes: Step B1, determining the friction coefficient of the rock sample when different normal stresses are applied under the current horizontal stress according to a preset horizontal stress and different normal stresses; Step B2, determining the steady-state velocity dependence parameters of the test sample under the current normal stress according to the rock sample friction coefficient and the stress loading speeds at different levels; Step B3, applying different preset normal stresses to the test sample to determine the average value of the steady-state velocity-dependent parameters of the test sample under different normal stresses; repeating steps B1, B2 and B3 to determine the average value M′ of the steady-state velocity-dependent parameters of different test samples under different normal stresses ji ; Wherein, 1≤i≤n, 1≤j≤n, n is a natural number, j is the jth test sample, and i is the i-th normal stress; According to the composition of each test sample and the average value of the steady-state velocity-dependent parameter M′ under different normal stresses ji Determine the shale properties of different test samples.

10. A system for testing shale properties, characterized in that: The system comprises: the test device for testing shale properties and the shale property determination device according to claim 1; wherein the test device comprises: U-shaped test fixture and flat plate test fixture; The two opposite side walls of the U-shaped test fixture are respectively provided with core grooves, the flat plate test fixture is provided with a core groove, and the core groove of the flat plate test fixture is arranged in the U-shaped groove of the U-shaped test fixture; Applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture through the test device, and applying a horizontal stress to the flat test fixture, so that the flat test fixture has a preset loading speed, and performing a shear friction operation on the test sample; The shale property determination device comprises: A component determination module, used to determine the component of the test sample based on the sample cuttings of the shear friction operation; The shale property determination module determines the shale property according to the composition of the test sample, the preset normal stress and the preset loading speed.

11. The system according to claim 10, characterized in that Applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, applying a horizontal stress to the flat test fixture, making the flat test fixture have a preset loading speed, and performing a shear friction operation on the test sample, including: A normal stress of a preset magnitude is applied to the test sample in the core groove of the U-shaped test fixture, and different horizontal stresses are applied to the flat plate test fixture, so that the flat plate test fixture has preset horizontal stress loading speeds of different magnitudes.

12. The system according to claim 11, characterized in that The shale property determination module determines the shale property according to the composition of the test sample, the preset normal stress and the preset loading speed, and specifically includes: Step A1, determining the friction coefficient of the rock sample when different horizontal stresses are applied under the current normal stress according to a normal stress of a preset magnitude and different horizontal stresses; Step A2, determining the steady-state velocity-dependent parameters of the test sample under the current normal stress according to the rock sample friction coefficient and different horizontal stress loading speeds; Step A3, applying different preset normal stresses to the test sample to determine the average value of the steady-state velocity-dependent parameters of the test sample under different normal stresses; repeating steps A1, A2 and A3 to determine the average value M of the steady-state velocity-dependent parameters of different test samples under different normal stresses. ji ; Wherein, 1≤i≤n, 1≤j≤n, n is a natural number, j is the jth test sample, and i is the i-th normal stress; According to the composition of each test sample and the average value of the steady-state velocity-dependent parameter M under different normal stresses, ji Determine the shale properties of different test samples.

13. The system according to claim 10, characterized in that Applying a preset normal stress to the test sample in the core groove of the U-shaped test fixture, applying a horizontal stress to the flat test fixture, making the flat test fixture have a preset loading speed, and performing a shear friction operation on the test sample, including: The test sample in the core groove of the U-shaped test fixture is applied with preset normal stresses of different magnitudes, and the same horizontal stress is applied to the flat plate test fixture, so that the flat plate test fixture has a preset horizontal stress loading speed.

14. The system according to claim 13, characterized in that The shale property determination module determines the shale property according to the composition of the test sample, the preset normal stress and the preset loading speed, including: Step B1, determining the friction coefficient of the rock sample when different normal stresses are applied under the current horizontal stress according to a preset horizontal stress and different normal stresses; Step B2, determining the steady-state velocity dependence parameters of the test sample under the current normal stress according to the rock sample friction coefficient and the stress loading speeds at different levels; Step B3, applying different preset normal stresses to the test sample to determine the average value of the steady-state velocity-dependent parameters of the test sample under different normal stresses; repeating steps B1, B2 and B3 to determine the average value M′ of the steady-state velocity-dependent parameters of different test samples under different normal stresses ji ; Wherein, 1≤i≤n, 1≤j≤n, n is a natural number, j is the jth test sample, and i is the i-th normal stress; According to the composition of each test sample and the average value of the steady-state velocity-dependent parameter M′ under different normal stresses ji Determine the shale properties of different test samples.

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