Method and system for detecting stress sensitivity of reservoir

Abstract

The invention discloses a method and system for detecting the stress sensitivity of a reservoir, and the method comprises the steps: fixing a solid steel block in a holder, applying different overburden pressures to the holder, and obtaining the total volume of a holder rubber sleeve and the solid steel block under each overburden pressure, so as to obtain a correction volume for correcting a detection error caused by the deformation of the rubber sleeve; obtaining the pore volume of a rock sample from the reservoir to be researched under each overburden pressure according to the same pressure application mode as the solid steel block, and then obtaining corrected porosity by combining the corrected volume, so as to obtain first stress sensitivity according to the change of the corrected porosity along with the overburden pressure; the displacement pressure difference and the fracture-cavity characteristics of the rock sample under each overburden pressure are obtained, so that the second stress sensitivity and the third stress sensitivity are obtained according to the change of the displacement pressure difference and the fracture-cavity characteristics along with the overburden pressure, and the corresponding stress sensitivity detection result is obtained by combining the first stress sensitivity. According to the invention, accurate detection of the stress sensitivity of the reservoir is realized.

Description

Technical Field

[0001] The present invention belongs to the field of oilfield development, and particularly relates to a method and system for detecting reservoir stress sensitivity. Background Art

[0002] Currently, most industry standard tests for stress sensitivity analysis are based on directly measuring the sensitivity analysis of stress acting on the reservoir structure. Among them, the stress sensitivity caused by the deformation of the gripper rubber sleeve, which originally does not belong to rock stress sensitivity, is also classified as rock stress sensitivity, resulting in the inconsistency between the existing rock stress sensitivity detection results and the actual situation. Therefore, how to accurately detect reservoir stress sensitivity is an urgent problem to be solved at present. Summary of the Invention

[0003] To solve the above problems, an embodiment of the present invention provides a method for detecting reservoir stress sensitivity, including: fixing a solid steel block in a gripper and applying different overburden pressures thereto, and obtaining the total volume of the gripper rubber sleeve and the solid steel block under each overburden pressure to obtain a correction volume for correcting the detection error caused by the deformation of the rubber sleeve; obtaining the pore volume of the rock sample from the reservoir to be studied under each overburden pressure according to the same pressure application method as the solid steel block, and then combining the correction volume to obtain a corrected porosity, so as to obtain a first stress sensitivity according to the change of the corrected porosity with the overburden pressure; obtaining the displacement pressure difference and fracture-vug characteristics of the rock sample under each overburden pressure, and respectively obtaining a second stress sensitivity and a third stress sensitivity according to the changes of the displacement pressure difference and fracture-vug characteristics with the overburden pressure, and then combining the first stress sensitivity to obtain a corresponding stress sensitivity detection result.

[0004] Preferably, in the step of obtaining the correction volume for correcting the detection error caused by the deformation of the rubber sleeve, it includes: obtaining the original volume of the solid steel block before applying the overburden pressure, and respectively calculating the difference between the total volume corresponding to each overburden pressure and the original volume, so as to obtain the correction volume.

[0005] Preferably, in the step of obtaining the corrected porosity, it includes: grinding the rock sample into a regular rock sample with a preset size, and obtaining the total volume of the gripper rubber sleeve and the rock sample under each overburden pressure, and then calculating the corrected porosity by using the total volume of the gripper rubber sleeve and the rock sample, the correction volume, and the pore volume.

[0006] Preferably, the following expression is used to calculate the corrected porosity:

[0007]

[0008] Wherein, It represents the obtained calibrated porosity, V represents the pore volume, V c represents the calibrated volume, V p represents the total volume of the holder rubber sleeve and the rock sample.

[0009] Preferably, in the step of obtaining the displacement pressure difference of the rock sample under each overburden pressure, it includes: under each overburden pressure, displacing the rock sample according to a preset displacement flow rate and a preset flow pressure, and during the displacement process, gradually reducing the flow pressure inside the rock sample to the target flow pressure according to a preset flow pressure reduction method; obtaining the displacement pressure difference according to the displacement pressure under the preset flow pressure and the displacement pressure when the target flow pressure is reached.

[0010] Preferably, in the step of obtaining the third stress sensitivity according to the change of the fracture-vug characteristics with the overburden pressure, it includes: under each overburden pressure, obtaining the fracture-vug structure and scale of the rock sample during the displacement process, and taking the fracture-vug structure and scale before the start of the displacement and after the end of the displacement as the fracture-vug characteristics; respectively extracting the maximum fracture width and the minimum fracture width in the fracture-vug structure and scale before the start of the displacement and after the end of the displacement, so as to take the change of the fracture width with the overburden pressure as the change of the fracture-vug characteristics with the overburden pressure, and obtain the third stress sensitivity.

[0011] Preferably, after obtaining the stress sensitivity detection result, the method further includes: under each overburden pressure, obtaining the pressure difference between the displacement fluid input end and the displacement fluid output end of the rock sample during the displacement process, so as to determine the change of the seepage capacity of the fractures and fracture-vugs in the reservoir to be studied with the overburden pressure according to the change of the pressure difference with the overburden pressure, in order to obtain the correlation between the fracture closure degree and the stress in the reservoir to be studied.

[0012] Preferably, the method further includes: under each overburden pressure, obtaining the morphological change characteristics and aperture change characteristics of the fractures in the rock sample during the displacement process, so as to evaluate the surrounding rock protection ability of the fractures in the reservoir to be studied.

[0013] Preferably, the method further includes: under each overburden pressure, obtaining the permeability of the experimental steel block, in order to obtain the change of the rigidity of the rock skeleton in the reservoir to be studied with the overburden pressure, where the experimental steel block is a steel block with a fixed pore volume.

[0014] On the other hand, the present invention also provides a system for detecting reservoir stress sensitivity, which is used to execute the method for detecting reservoir stress sensitivity. Wherein, the system includes: a correction volume calculation unit, which is used to fix a solid steel block in a holder, apply different overburden pressures thereto, and obtain the total volume of the holder rubber sleeve and the solid steel block under each overburden pressure, so as to obtain a correction volume for correcting the detection error caused by the deformation of the rubber sleeve; a first detection unit, which is used to obtain the pore volume of the rock sample from the reservoir to be studied under each overburden pressure according to the same pressure application method as the solid steel block, and then combine the correction volume to obtain a corrected porosity, so as to obtain a first stress sensitivity according to the change of the corrected porosity with the overburden pressure; a second detection unit, which is used to obtain the displacement pressure difference and the fracture-vug characteristics of the rock sample under each overburden pressure, so as to obtain a second stress sensitivity and a third stress sensitivity respectively according to the changes of the displacement pressure difference and the fracture-vug characteristics with the overburden pressure, and further combine the first stress sensitivity to obtain the corresponding stress sensitivity detection result.

[0015] Compared with the prior art, one or more embodiments of the above solutions may have the following advantages or beneficial effects:

[0016] The present invention discloses a method and a system for detecting reservoir stress sensitivity. Based on the characteristic that the solid steel block does not deform under the action of the overburden pressure, a variety of overburden pressures are applied by fixing the solid steel block or the rock sample from the reservoir to be studied in the holder alone, so as to obtain a correction volume for correcting the detection error caused by the deformation of the rubber sleeve for different overburden pressures. Then, the corrected porosity is obtained according to the correction volume, and the first stress sensitivity is obtained according to the change of the corrected porosity with the overburden pressure. After that, the second stress sensitivity and the third stress sensitivity are obtained respectively according to the changes of the displacement pressure difference and the fracture-vug characteristics with the overburden pressure. Finally, by comprehensively analyzing and comparing each stress sensitivity, the corresponding stress sensitivity detection result is obtained. The present invention realizes the accurate detection of reservoir stress sensitivity and can more accurately and intuitively judge the corresponding stress sensitivity of reservoir rocks under the action of different overburden pressures.

[0017] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained by the structures specifically pointed out in the specification, the claims, and the drawings. Description of the Drawings

[0018] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0019] Figure 1 It is a step diagram of the method for detecting reservoir stress sensitivity according to the embodiments of the present application.

[0020] Figure 2 It is a schematic diagram of the overall structure of the system for detecting reservoir stress sensitivity according to the embodiments of the present application. Detailed implementation manners

[0021] The following will combine the accompanying drawings and embodiments to detail the implementation manners of the present invention, so as to fully understand how the present invention uses technical means to solve technical problems and achieve the implementation process of technical effects and implement accordingly. It should be noted that as long as there is no conflict, each embodiment in the present invention and each feature in each embodiment can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

[0022] In addition, the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that here.

[0023] Currently, most of the industry standard tests for stress sensitivity analysis are based on the sensitivity analysis of directly measuring the stress acting on the reservoir structure. Among them, the stress sensitivity caused by the deformation of the gripper rubber sleeve, which originally does not belong to the rock stress sensitivity, is also classified as the rock stress sensitivity, resulting in the inconsistency between the existing rock stress sensitivity detection results and the actual situation. Therefore, how to accurately detect reservoir stress sensitivity is an urgent problem to be solved at present.

[0024] Therefore, to solve the above problems, the embodiments of the present invention propose a method and system for detecting reservoir stress sensitivity. Based on the characteristic that a solid steel block does not deform under the action of overburden pressure, by separately fixing the solid steel block or rock samples from the reservoir to be studied in the gripper to apply various overburden pressures, a correction volume for correcting the detection error caused by the deformation of the rubber sleeve is obtained for different overburden pressures. Then, the corrected porosity is obtained according to the correction volume, and thus the first stress sensitivity is obtained according to the change of the corrected porosity with the overburden pressure. Subsequently, the second stress sensitivity and the third stress sensitivity are obtained respectively according to the change of the displacement pressure difference and the fracture-vug characteristics with the overburden pressure. Finally, by comprehensively analyzing and comparing each stress sensitivity, the corresponding stress sensitivity detection result is obtained. The present invention realizes the accurate detection of reservoir stress sensitivity and can more accurately and intuitively judge the stress sensitivity corresponding to reservoir rocks under the action of different overburden pressures.

[0025] Example 1

[0026] Before the exploitation of an oil (gas) reservoir, the reservoir rock can generally maintain a balanced state under the action of overlying formation stress, pore fluid pressure, and the supporting force of the rock skeleton itself. However, with the exploitation of formation fluids, the pore pressure continuously decreases, resulting in an increase in the net overlying stress borne by the rock skeleton, thereby causing the pore structure of the rock to change with the change of the net overlying stress. This property is the stress sensitivity of the rock.

[0027] Figure 1 This is a step diagram of the method for detecting the stress sensitivity of a reservoir in an embodiment of the present application. The following will refer to Figure 1 to illustrate each step of this method.

[0028] As Figure 1 shown, in step S110, a solid steel block is fixed in a holder to apply different overlying pressures to it, and the total volume of the holder rubber sleeve and the solid steel block under each overlying pressure is obtained to obtain a correction volume for correcting the detection error caused by the deformation of the rubber sleeve. Specifically, the solid steel block has the characteristic of not deforming under the action of the overlying pressure, while the holder rubber sleeve will deform under the action of different overlying pressures, resulting in a certain deviation between the finally obtained stress sensitivity detection result and the actual situation, which will thus affect the accuracy of the judgment of the stress sensitivity corresponding to the reservoir rock. Therefore, in this embodiment, the solid steel block is fixed in the holder, and then by adjusting the confining pressure in the holder, different overlying pressures are applied to the solid steel block to simulate the net overlying stress borne by the rock skeleton. And, the total volume of the holder rubber sleeve and the solid steel block under each overlying pressure is obtained, and multiple total volumes corresponding to different overlying pressures are obtained. Finally, based on each obtained total volume, a correction volume for correcting the detection error caused by the deformation of the rubber sleeve corresponding to each overlying pressure is obtained.

[0029] In the step of obtaining the correction volume for correcting the detection error caused by the deformation of the rubber sleeve, the original volume of the solid steel block before applying the overlying pressure is obtained, and the difference between the total volume corresponding to each overlying pressure and the original volume is calculated respectively, so as to obtain the correction volume. In an embodiment of the present application, before the solid steel block is placed in the holder, its original length and original diameter under normal pressure are measured, and the original volume of the solid steel block is obtained by calculation. Then, the difference between each total volume and the original volume is calculated respectively to obtain the deformation volume of the holder rubber sleeve under different overlying pressures, and the current deformation volume is used as the correction volume.

[0030] In an embodiment of the present application, the following expression is used to calculate the correction volume:

[0031] V c =V p1 -V 0 (1)

[0032] where, Vc Denote the corrected volume as V p1 Denote the total volume of the gripper sleeve and the solid steel block as V 0 Denote the original volume.

[0033] Further, in step S120, in the same way of applying pressure as that of the solid steel block, obtain the pore volume of the rock sample from the reservoir to be studied under each overburden pressure, and then combine it with the corrected volume to obtain the corrected porosity. Thus, according to the change of the corrected porosity with the overburden pressure, obtain the first stress sensitivity. Specifically, after obtaining the total volume of the gripper sleeve and the solid steel block under each overburden pressure, take out the solid steel block from the gripper, fix the rock sample from the reservoir to be studied in the gripper, and then by adjusting the confining pressure in the gripper, apply the same overburden pressure as that of the solid steel block to the rock sample so that the rock skeleton bears the corresponding net overburden stress, so as to obtain the pore volume of the rock sample corresponding to each overburden pressure. Among them, there is a specific correlation between the net overburden stress borne by the rock skeleton and the applied overburden pressure. After that, use the pore volume and the corrected volume to calculate the corrected porosity. Accordingly, based on the influence of the porosity on the permeability of the rock sample, the first stress sensitivity can be obtained according to the change of the corrected porosity with the overburden pressure.

[0034] In the step of obtaining the corrected porosity, grind the rock sample into a regular rock sample with a preset size, and obtain the total volume of the gripper sleeve and the rock sample under each overburden pressure, and then use the total volume of the gripper sleeve and the rock sample, the corrected volume, and the pore volume to calculate the corrected porosity. In the embodiment of the present application, for the convenience of calculation, grind the rock sample from the reservoir to be studied into a regular rock sample with a specific length and diameter, so as to obtain the total volume of the gripper sleeve and the rock sample for calculating the pore volume of the rock sample corresponding to each overburden pressure. After that, obtain the total volume of the gripper sleeve and the rock sample under each overburden pressure. In practical applications, during the process of increasing the net overburden stress of the reservoir rock, the deformation of the total volume of the rock is equal to the deformation of the pore volume of the rock, and the deformation of the gripper sleeve will also generate stress inside the reservoir rock and cause the volume of the reservoir rock to change. Therefore, in this embodiment, use the total volume of the gripper sleeve and the rock sample, the corrected volume, and the pore volume to calculate the corrected porosity.

[0035] In the embodiment of the present application, calculate the corrected porosity by using the following expression:

[0036]

[0037] Wherein, Denote obtaining the corrected porosity, V denotes the pore volume, V p Denote the total volume of the gripper sleeve and the rock sample.

[0038] Further, in step S130, the displacement pressure difference and fracture-vug characteristics of the rock sample under each overburden pressure are obtained. Thus, according to the changes of the displacement pressure difference and fracture-vug characteristics with the overburden pressure respectively, the second stress sensitivity and the third stress sensitivity are obtained. Furthermore, combined with the first stress sensitivity, the corresponding stress sensitivity detection result is obtained. In this embodiment, the rock sample is displaced under each overburden pressure, so as to test the influence of the reservoir flow capacity under different overburden pressures on the rock sample. During each displacement process, the displacement pressure difference and fracture-vug characteristics of the rock sample are obtained in real time. Then, for each displacement process, the displacement pressure difference and fracture-vug characteristics with the same displacement parameters are extracted respectively. Thus, based on the method of controlling variables, the changes of the displacement pressure difference and fracture-vug characteristics with the overburden pressure are obtained. Accordingly, based on the influence of the displacement pressure difference on the permeability of the rock sample, the second stress sensitivity can be obtained according to the changes of the displacement pressure difference and fracture-vug characteristics with the overburden pressure. And based on the influence of the fracture-vug characteristics on the permeability of the rock sample, the third stress sensitivity can be obtained according to the changes of the fracture-vug characteristics with the overburden pressure. Finally, according to the first stress sensitivity, the second stress sensitivity and the third stress sensitivity, through taking the average value or other data processing methods, the actual stress sensitivity is obtained and used as the corresponding stress sensitivity detection result.

[0039] Next, in the step of obtaining the displacement pressure difference of the rock sample under each overburden pressure, first, under each overburden pressure, the rock sample is displaced according to the preset displacement flow rate and preset flow pressure, and during the displacement process, the flow pressure inside the rock sample is gradually reduced to the target flow pressure according to the preset flow pressure reduction method; then, according to the displacement pressure at the preset flow pressure and the displacement pressure when the target flow pressure is reached, the displacement pressure difference is obtained. In each displacement process of this embodiment, the displacement process of the rock sample is started according to the preset displacement flow rate (constant displacement flow rate) and preset flow pressure. Then, during the displacement process, the flow pressure inside the rock sample is gradually reduced to the target flow pressure (and the current displacement process ends) according to the preset flow pressure (or pore pressure) reduction method, and the displacement pressure at the preset flow pressure and the displacement pressure when the target flow pressure is reached are measured respectively. Then, by calculating the difference between the displacement pressures before and after the flow pressure reduction, the displacement pressure difference is obtained.

[0040] In the step of obtaining the third stress sensitivity according to the changes of the fracture-vug characteristics with the overburden pressure, first, under each overburden pressure, the fracture-vug structure and scale of the rock sample during the displacement process are obtained, and the fracture-vug structure and scale before the start of the displacement and after the end of the displacement are used as the fracture-vug characteristics; then, the maximum fracture width and the minimum fracture width in the fracture-vug structure and scale before the start of the displacement and after the end of the displacement are extracted respectively, so that the change of the fracture width with the overburden pressure is used as the change of the fracture-vug characteristics with the overburden pressure, and the third stress sensitivity is obtained.

[0041] Specifically, in each displacement process of this embodiment, the CT scanning technology is used to scan and analyze the fracture-vug structure and scale before and after the displacement to obtain the fracture-vug characteristics. Then, the maximum fracture width and the minimum fracture width in the fracture-vug structure and scale before and after the displacement are extracted respectively. Subsequently, by calculating the difference between the maximum fracture widths before and after the displacement and the difference between the minimum fracture widths, the variation of the fracture width with the overburden pressure is obtained, thereby achieving the purpose of taking the variation of the fracture width with the overburden pressure as the variation of the fracture-vug characteristics with the overburden pressure and obtaining the third stress sensitivity.

[0042] Furthermore, after obtaining the stress sensitivity detection results, in this embodiment, the pressure difference between the displacement fluid input end and the displacement fluid output end of the rock sample during the displacement process is obtained under each overburden pressure, so as to determine the variation of the seepage capacity of the fractures and fracture-vugs in the reservoir to be studied with the overburden pressure according to the variation of the pressure difference with the overburden pressure, in order to obtain the correlation between the fracture closure degree and the stress in the reservoir to be studied. Specifically, in this embodiment, the pressure difference between the displacement fluid input end and the displacement fluid output end of the rock sample during the displacement process is obtained under each overburden pressure, and then the variation of the pressure difference of the fractures in the reservoir to be studied under the condition of reducing the internal pore pressure and changing the overburden pressure is obtained. Finally, the variation of the seepage capacity of the fractures and fracture-vugs in the reservoir to be studied with the overburden pressure is obtained, and the correlation between the fracture closure degree and the stress in the reservoir to be studied is analyzed. Accordingly, the accurate analysis of the variation of the fracture closure degree with the stress is realized.

[0043] Furthermore, in this embodiment, the morphological change characteristics and the aperture change characteristics of the fractures in the rock sample during the displacement process are obtained under each overburden pressure to evaluate the surrounding rock protection ability of the fractures in the reservoir to be studied. Specifically, based on the CT scanning technology, the morphological changes and aperture changes of the fractures in the rock sample are compared under the condition of reducing the internal pore pressure and increasing the overburden pressure difference, and the anti-overburden pressure situation of the fractures in the reservoir to be studied in the surrounding rock protection is clarified, thereby evaluating the surrounding rock protection ability of the fractures in the reservoir to be studied.

[0044] Furthermore, in this embodiment, the permeability of the experimental steel block is obtained under each overburden pressure to obtain the variation of the rigidity of the rock skeleton in the reservoir to be studied with the overburden pressure, where the experimental steel block is a steel block with a fixed pore volume. Specifically, in this embodiment, the same overburden pressure as that of the aforementioned solid steel block is applied to the steel block with a fixed pore volume to obtain the permeability of the experimental steel block, thereby determining the influence of the overburden pressure on the permeability of the reservoir to be studied, and then obtaining the variation of the rigidity of the rock skeleton in the reservoir to be studied with the overburden pressure.

[0045] Example 2

[0046] Based on the method for detecting reservoir stress sensitivity described in the above-mentioned Embodiment 1, the embodiment of the present invention further provides a system for detecting reservoir stress sensitivity. Figure 2 It is a schematic diagram of the overall structure of the system for detecting reservoir stress sensitivity according to the embodiment of the present application. The structure and functions of the system for detecting reservoir stress sensitivity will be described in detail below in conjunction with the embodiments of the present invention.

[0047] The system for detecting reservoir stress sensitivity according to the present invention at least includes: a correction volume calculation unit 21, a first detection unit 22, and a second detection unit 23. Specifically, the correction volume calculation unit 21 is used to fix a solid steel block in a holder and apply different overburden pressures thereto, and obtain the total volume of the holder rubber sleeve and the solid steel block under each overburden pressure, so as to obtain a correction volume for correcting the detection error caused by the deformation of the rubber sleeve. The first detection unit 22 is used to obtain the pore volume of the rock sample from the reservoir to be studied under each overburden pressure in the same pressure application manner as the solid steel block of the correction volume calculation unit 21, and then combine the correction volume to obtain a corrected porosity, and thus obtain a first stress sensitivity according to the change of the corrected porosity with the overburden pressure. The second detection unit 23 is used to obtain the displacement pressure difference and the fracture-vug characteristics of the rock sample under each overburden pressure, and thus obtain a second stress sensitivity and a third stress sensitivity respectively according to the changes of the displacement pressure difference and the fracture-vug characteristics with the overburden pressure, and further combine the first stress sensitivity obtained by the first detection unit 22 to obtain a corresponding stress sensitivity detection result.

[0048] The present invention proposes a method and a system for detecting reservoir stress sensitivity. Based on the characteristic that the solid steel block does not deform under the action of the overburden pressure, by separately fixing the solid steel block or the rock sample from the reservoir to be studied in the holder to apply a variety of overburden pressures, a correction volume for correcting the detection error caused by the deformation of the rubber sleeve for different overburden pressures is obtained, and then a corrected porosity is obtained according to the correction volume, and thus a first stress sensitivity is obtained according to the change of the corrected porosity with the overburden pressure. Then, a second stress sensitivity and a third stress sensitivity are obtained respectively according to the changes of the displacement pressure difference and the fracture-vug characteristics with the overburden pressure. Finally, by comprehensively analyzing and comparing each stress sensitivity, a corresponding stress sensitivity detection result is obtained. The present invention realizes the accurate detection of reservoir stress sensitivity, and can not only more accurately and intuitively judge the corresponding stress sensitivity of reservoir rocks under the action of different overburden pressures, but also be used to simulate the stress sensitivity of reservoir pores and fractures during the pressure reduction development process of the oil reservoir.

[0049] The above is only a specific implementation case of the present invention, and the protection scope of the present invention is not limited thereto. Any modification or replacement of the present invention by those skilled in the art within the technical specifications described in the present invention shall fall within the protection scope of the present invention.

[0050] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention. However, these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

[0051] Those skilled in the art should understand that the above-mentioned modules or steps of the present invention can be implemented by a general-purpose computing device. They can be concentrated on a single computing device or distributed on a network composed of multiple computing devices. Optionally, they can be implemented by program codes executable by the computing device. Thus, they can be stored in a storage device and executed by the computing device, or they can be separately fabricated into individual integrated circuit modules, or multiple modules or steps among them can be fabricated into a single integrated circuit module to be implemented. In this way, the present invention is not limited to any specific combination of hardware and software.

[0052] Although the disclosed embodiments of the present invention are as above, the content described above is only an embodiment adopted for the convenience of understanding the present invention and is not used to limit the present invention. Any person skilled in the art within the technical field to which the present invention pertains can make any modifications and changes in the form of implementation and details without departing from the spirit and scope disclosed by the present invention. However, the patent protection scope of the present invention shall still be subject to the scope defined by the appended claims.

Claims

1. A method for detecting reservoir stress sensitivity, characterized in that, it includes: Fix a solid steel block in a holder and apply different overburden pressures to it, and obtain the total volume of the holder rubber sleeve and the solid steel block under each overburden pressure to obtain a correction volume for correcting the detection error caused by the deformation of the rubber sleeve; According to the same pressure application method as the solid steel block, obtain the pore volume of the rock sample from the reservoir to be studied under each overburden pressure, and then combine the correction volume to obtain the corrected porosity, so as to obtain the first stress sensitivity according to the change of the corrected porosity with the overburden pressure; Obtain the displacement pressure difference and fracture-vug characteristics of the rock sample under each overburden pressure, so as to obtain the second stress sensitivity and the third stress sensitivity respectively according to the changes of the displacement pressure difference and fracture-vug characteristics with the overburden pressure, and then combine the first stress sensitivity to obtain the corresponding stress sensitivity detection result.

2. The method according to claim 1, characterized in that, In the step of obtaining the correction volume for correcting the detection error caused by the deformation of the rubber sleeve, it includes: Obtain the original volume of the solid steel block before applying the overburden pressure, and calculate the difference between the total volume corresponding to each overburden pressure and the original volume respectively, so as to obtain the correction volume.

3. The method according to claim 1 or 2, characterized in that, In the step of obtaining the corrected porosity, it includes: Grind the rock sample into a regular rock sample with a preset size, and obtain the total volume of the holder rubber sleeve and the rock sample under each overburden pressure, and then calculate the corrected porosity by using the total volume of the holder rubber sleeve and the rock sample, the correction volume, and the pore volume.

4. The method according to claim 3, characterized in that, The corrected porosity is calculated by using the following expression: Among them, represents the obtained corrected porosity, V represents the pore volume, V c represents the corrected volume, V p represents the total volume of the gripper rubber sleeve and the rock sample.

5. The method according to any one of claims 1 to 4, characterized in that, In the step of obtaining the displacement pressure difference of the rock sample under each overburden pressure, it includes: Under each overburden pressure, displace the rock sample at a preset displacement flow rate and a preset flowing pressure, and during the displacement process, gradually reduce the flowing pressure inside the rock sample to the target flowing pressure according to a preset flowing pressure reduction method; Obtain the displacement pressure difference according to the displacement pressure under the preset flowing pressure and the displacement pressure when the target flowing pressure is reached.

6. The method according to claim 5, characterized in that, In the step of obtaining the third stress sensitivity according to the change of the fracture-vug characteristics with the overburden pressure, it includes: Under each overburden pressure, obtain the fracture-vug structure and scale of the rock sample during the displacement process, and use the fracture-vug structure and scale before and after the displacement start as the fracture-vug characteristics; Extract the maximum fracture width and the minimum fracture width in the fracture-vug structure and scale before and after the displacement start respectively, so as to use the change of the fracture width with the overburden pressure as the change of the fracture-vug characteristics with the overburden pressure to obtain the third stress sensitivity.

7. The method according to claim 5 or 6, characterized in that, After obtaining the stress sensitivity detection result, the method further includes: Under each overburden pressure, obtain the pressure difference between the displacement fluid input end and the displacement fluid output end of the rock sample during the displacement process, so as to determine the change in the seepage capacity of fractures and fracture-vug units in the reservoir to be studied with the overburden pressure according to the change of the pressure difference with the overburden pressure, and obtain the correlation between the fracture closure degree and stress in the reservoir to be studied.

8. The method according to claim 7, wherein, the method further includes: Under each overburden pressure, obtain the morphological change characteristics and aperture change characteristics of the fractures in the rock sample during the displacement process to evaluate the surrounding rock protection ability of the fractures in the reservoir to be studied.

9. The method according to any one of claims 1 to 8, wherein, the method further includes: Under each overburden pressure, obtain the permeability of the experimental steel block to obtain the change in the rigidity of the rock skeleton in the reservoir to be studied with the overburden pressure, wherein the experimental steel block is a steel block with a fixed pore volume.

10. A system for detecting reservoir stress sensitivity, wherein, the system is used to execute the method according to any one of claims 1 to 9, and wherein the system includes: A correction volume calculation unit, which is used to fix a solid steel block in a clamp and apply different overburden pressures to it, and obtain the total volume of the clamp rubber sleeve and the solid steel block under each overburden pressure to obtain a correction volume for correcting the detection error caused by the deformation of the rubber sleeve; A first detection unit, which is used to obtain the pore volume of the rock sample from the reservoir to be studied under each overburden pressure in the same pressure application manner as the solid steel block, and then combine the correction volume to obtain a corrected porosity, so as to obtain a first stress sensitivity according to the change of the corrected porosity with the overburden pressure; A second detection unit, which is used to obtain the displacement pressure difference and fracture-vug characteristics of the rock sample under each overburden pressure, so as to obtain a second stress sensitivity and a third stress sensitivity respectively according to the change of the displacement pressure difference and fracture-vug characteristics with the overburden pressure, and then combine the first stress sensitivity to obtain a corresponding stress sensitivity detection result.

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