Fracture conductivity measuring system and fracture conductivity measuring method

Abstract

The invention relates to a fracture conductivity measuring system and a fracture conductivity measuring method, a shale self-supporting fracture morphology colloid block under each confining pressure is obtained by splitting a plunger core and injecting glue, the colloid block is uniformly scanned by using a three-dimensional digital scanner after the measurement is finished, the width of a self-supporting fracture is obtained through numerical calculation, and the thickness of the self-supporting fracture is measured. The fracture permeability is measured through the displacement fluid, finally, the fracture conductivity is calculated according to the fracture width and the permeability, the result is accurate and reliable, and therefore whether the stratum is suitable for fracturing exploitation or not is judged according to the fracture conductivity.

Description

Technical Field

[0001] This specification relates to the field of oil and gas exploration, and in particular to a fracture conductivity measurement system and method. Background Technology

[0002] The fracture conductivity of a rock sample can characterize whether the strata where the rock sample is located are suitable for hydraulic fracturing. Currently, when measuring fracture conductivity, self-supporting fractures are prone to deformation under high closure pressure due to the lack of proppant, making it difficult to accurately measure fracture parameters.

[0003] Currently, there are three main methods for measuring fracture conductivity. The first method involves drying the sample after each confining pressure test and then scanning the entire rock sample using a large CT scanner to obtain fracture patterns. This method is not only discontinuous in its testing process, time-consuming, and expensive, but the fracture morphology may also change after the sample dries, affecting measurement accuracy. The second method is estimation, typically using several 24# (0.55mm diameter) or 25# (0.5mm diameter) iron wires inserted side-by-side into the fracture, roughly estimating the fracture width based on the number of wires inserted. This method is not only prone to large errors but also fails to accurately characterize the internal fracture morphology of the sample. The third method involves modifying the conductivity calculation formula and using other easily measurable values ​​to estimate the average fracture width. This is generally done by calculating shear slip or setting slip values, and then estimating the equivalent fracture width using empirical formulas. This method is not only limited in experimental design but also fails to intuitively reflect the impact of changes in the width of self-supporting fractures on the conductivity of self-supporting fractures.

[0004] Accurately measuring the conductivity of cracks is currently a problem that urgently needs to be solved. Summary of the Invention

[0005] To address the problems existing in the prior art, this specification provides a fracture conductivity measurement system and method. The system involves splitting a plunger core and injecting adhesive to obtain colloidal blocks of the morphology of self-supporting shale fractures under confining pressure. After measurement, a three-dimensional digital scanner is used to uniformly scan the colloidal blocks. The width of the self-supporting fracture is obtained through numerical calculation, and the permeability of the fracture is measured using a displacement fluid. Finally, the conductivity of the fracture is calculated based on the fracture width and permeability. The results are accurate and reliable, allowing for the determination of whether the formation is suitable for fracturing based on the fracture conductivity.

[0006] To solve any of the above-mentioned technical problems, the specific technical solution in this specification is as follows:

[0007] This specification provides an embodiment of a crack conductivity measurement system, comprising:

[0008] The adhesive injection unit is used to inject adhesive into the cracks of a rock sample taken from a target stratum, the cracks being pre-formed on the extracted rock sample.

[0009] A rock sample holder is used to hold a rock sample that has been injected with colloid within the sealed space of the rock sample holder.

[0010] A confining pressure pump is used to apply a predetermined confining pressure to the sealed space of the rock sample holder to shape the colloid into a colloid block.

[0011] The colloidal block measuring unit is used to measure the average width of the removed colloidal block after it has been removed. The rock sample holder is further used to hold the rock sample again in the sealed space of the rock sample holder after the colloidal block has been removed. The confining pressure pump is further used to apply the predetermined confining pressure again to the sealed space of the rock sample holder.

[0012] A plunger pump is used to inject displacement fluid into the cracks of the rock sample after the colloidal block has been removed;

[0013] A flow measurement unit is used to measure the flow rate of the displacing fluid flowing out of the crack;

[0014] The pressure difference measurement unit is used to measure the pressure difference between the inflow end and the outflow end of the displacement fluid in the fracture after the flow rate of the displacement fluid flowing out of the rock sample has stabilized.

[0015] A permeability calculation unit is used to calculate the permeability of the crack based on the pressure difference and the flow rate;

[0016] A flow capacity calculation unit is used to calculate the flow capacity of the fracture based on the permeability and the average width, so as to guide the mining of the target formation based on the flow capacity.

[0017] Furthermore, the rock sample holder is provided with a displacement fluid inlet and a displacement fluid outlet;

[0018] The plunger pump is further used to inject the displacing fluid into the displacing fluid inlet so that the displacing fluid flows into the crack and flows out from the displacing fluid outlet.

[0019] Furthermore, the pressure difference measurement unit includes:

[0020] A first pressure gauge is installed at the inlet of the displacing fluid to measure the inlet pressure;

[0021] A second pressure gauge is installed at the outlet of the displacing fluid to measure the outlet pressure;

[0022] The pressure difference calculation module is used to calculate the difference between the inlet pressure and the outlet pressure to obtain the pressure difference.

[0023] Furthermore, the flow measurement unit includes:

[0024] A displacement fluid mass measurement module is installed at the displacement fluid outlet to measure the mass of the displacement fluid flowing out of the crack;

[0025] A flow calculation unit is used to calculate the flow rate of the displacing fluid based on the mass of the displacing fluid and the time it takes for the plunger pump to inject the displacing fluid.

[0026] Furthermore, the colloidal block measuring unit includes:

[0027] A colloidal block volume measurement module is used to measure the volume of the colloidal block;

[0028] A colloidal block average area measurement module is used to measure the average area of ​​the colloidal block;

[0029] The average width calculation module for the colloidal block is used to calculate the average width of the colloidal block based on its volume and average area.

[0030] Furthermore, the fracture conductivity measurement system also includes a saturation unit, used to saturate the rock sample according to a predetermined saturation degree after the fracture is formed on the extracted rock sample.

[0031] Based on the same inventive concept, embodiments of this specification also provide a method for measuring fracture conductivity, applied to the aforementioned fracture conductivity measurement system, comprising:

[0032] The injection of adhesive into the cracks of a rock sample taken from a target stratum is controlled by a colloid injection unit box. The cracks are pre-formed on the rock sample after it has been taken out.

[0033] The rock sample, after being injected with colloid, is placed in the sealed space of the rock sample holder, and the rock sample holder is controlled to hold the rock sample.

[0034] The confining pressure pump is controlled to apply a predetermined confining pressure to the sealed space of the rock sample holder, so as to shape the colloid into a colloid block;

[0035] Remove the colloidal block and control the colloidal block measuring unit to measure the average width of the colloidal block;

[0036] After removing the colloidal block, the rock sample is placed back into the sealed space of the rock sample holder. The rock sample holder is controlled to clamp the rock sample again, and the confining pressure pump is controlled to apply the predetermined confining pressure to the sealed space of the rock sample holder again.

[0037] The plunger pump is controlled to inject displacement fluid into the cracks of the rock sample after the colloidal block is removed, and the flow measurement unit is controlled to measure the flow rate of the displacement fluid flowing out of the cracks. After the flow rate of the displacement fluid flowing out of the rock sample stabilizes, the pressure difference measurement unit is controlled to measure the pressure difference between the inlet end and the outlet end of the displacement fluid in the cracks.

[0038] The permeability of the fracture is calculated by the permeability calculation unit based on the pressure difference and the flow rate, and the flow capacity of the fracture is calculated by the flow capacity calculation unit based on the permeability and the average width, so as to guide the mining of the target formation based on the flow capacity.

[0039] Further, measuring the average width of the colloidal block includes:

[0040] The colloidal block was scanned using a 3D digital scanner to obtain point cloud data of the upper and lower surfaces of the colloidal block.

[0041] The average area of ​​the colloidal block is calculated based on the point cloud data of the upper and lower surfaces of the colloidal block.

[0042] The volume of the colloidal block was measured by the water displacement method;

[0043] The average width of the colloidal block is obtained by calculating the ratio of its volume to its average area.

[0044] Furthermore, before controlling the injection of adhesive into the cracks of the rock sample in the adhesive injection unit box, the method further includes:

[0045] The saturation control unit saturates the rock sample according to a predetermined saturation level.

[0046] Furthermore, when measuring the conductivity of the same rock sample under multiple different confining pressures, the method further includes:

[0047] Sort the different confining pressures in ascending order;

[0048] The injection unit injects colloid into the cracks of the rock sample. The rock sample with colloid injected is placed in the sealed space of the rock sample holder, and the rock sample holder is controlled to hold the rock sample. The confining pressure pump is controlled to apply the first confining pressure in the sealed space of the rock sample holder to obtain the colloid block corresponding to the first confining pressure. The colloid block corresponding to the first confining pressure is taken out, and the colloid block measuring unit is controlled to measure the average width of the colloid block corresponding to the first confining pressure and measure the permeability of the crack corresponding to the first confining pressure. The conductivity of the crack corresponding to the first confining pressure is calculated based on the permeability and average width.

[0049] The injection unit is controlled to inject colloid into the cracks of the rock sample again. The rock sample with colloid injected is placed in the sealed space of the rock sample holder, and the rock sample holder is controlled to hold the rock sample. The confining pressure pump is controlled to apply a second confining pressure, which is ordered after the first confining pressure, to the sealed space of the rock sample holder to obtain a colloid block corresponding to the second confining pressure. The colloid block corresponding to the second confining pressure is taken out, and the colloid block measuring unit is controlled to measure the average width of the colloid block corresponding to the second confining pressure and measure the permeability of the crack corresponding to the second confining pressure. The conductivity of the crack corresponding to the second confining pressure is calculated based on the permeability and the average width.

[0050] Repeat the above steps to obtain the conductivity corresponding to multiple different confining pressures, so as to guide the mining of the target formation based on the conductivity corresponding to multiple different confining pressures.

[0051] Using the embodiments of this specification, colloidal blocks of shale self-supporting fractures under different measurement conditions are obtained by fracture grouting and injection. The average width of the colloidal blocks is measured using a colloidal block measurement unit. Then, the permeability of the fractures is measured by injecting a displacement fluid into the fractures of the rock sample from which the colloidal blocks were extracted. Finally, the conductivity of the fractures is calculated based on the average width and permeability. The fracture conductivity measurement system of this specification solves the problem of difficulty in measuring fracture width in current measurement methods. Compared to methods using large CT scans, the measurement method of this specification is low-cost, has a simple and continuous operation process, and a short measurement time. Compared to traditional estimation methods, the measurement results of the method of this specification are more accurate. Compared to variable substitution methods, the fracture conductivity measurement system of this specification is more flexible and can intuitively reflect the influence of self-supporting fracture width on the conductivity of self-supporting fractures. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 The diagram shown is a structural schematic of a crack conductivity measurement system according to an embodiment of this specification.

[0054] Figure 2 The diagram shown is a flowchart illustrating a method for measuring the conductivity of a crack according to an embodiment of this specification.

[0055] Figure 3The diagram shown is a structural schematic of a crack conductivity measurement system including saturation units in an embodiment of this specification.

[0056] Figure 4 The diagram shown is a flowchart illustrating the process of measuring the average width of the colloidal block according to an embodiment of this specification.

[0057] Figure 5 The diagram shown is a first detailed structural schematic of the crack conductivity measurement system in an embodiment of this specification.

[0058] Figure 6 The diagram shown is a second detailed structural schematic of the crack conductivity measurement system in an embodiment of this specification.

[0059] Figure 7 The figure shows the measurement results of the conductivity of self-supporting fractures in rock samples under different confining pressures in the embodiments of this specification;

[0060] Figure 8 The diagram shown is a structural schematic of the computer device in an embodiment of this specification.

[0061] [Explanation of Figure Markers]:

[0062] 101. Glue dispensing unit;

[0063] 102. Rock sample holder;

[0064] 1021. Import of displacement fluid;

[0065] 1022, Displacement fluid outlet;

[0066] 103. Confining pressure pump;

[0067] 104. Colloidal block measurement unit;

[0068] 105. Plunger pump;

[0069] 106. Flow measurement unit;

[0070] 1061. Displacement fluid mass measurement module;

[0071] 1062. Flow calculation unit;

[0072] 107. Pressure differential measurement unit;

[0073] 1071. First pressure gauge;

[0074] 1072. Second pressure gauge;

[0075] 1073. Pressure Difference Calculation Module;

[0076] 108. Permeability Calculation Unit;

[0077] 109. Flow diversion capacity calculation unit;

[0078] 110. Saturated unit;

[0079] 802. Computer equipment;

[0080] 804. Processing equipment;

[0081] 806. Storage resources;

[0082] 808. Drive mechanism;

[0083] 810. Input / Output Module;

[0084] 812. Input devices;

[0085] 814. Output devices;

[0086] 816. Presentation equipment;

[0087] 818. Graphical User Interface;

[0088] 820. Network interface;

[0089] 822. Communication link;

[0090] 824. Communication bus. Detailed Implementation

[0091] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this specification.

[0092] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, apparatus, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0093] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0094] It should be noted that the acquisition, storage, use, and processing of data in the technical solution of this application all comply with the relevant provisions of relevant laws and regulations.

[0095] like Figure 1 The diagram shown is a structural schematic of a crack conductivity measurement system according to an embodiment of this specification, including:

[0096] The adhesive injection unit 101 is used to inject adhesive into the cracks of a rock sample taken from a target stratum, and the cracks are formed in advance on the rock sample after it has been taken out.

[0097] Rock sample holder 102 is used to hold a rock sample that has been injected with colloid within the sealed space of the rock sample holder 102;

[0098] The confining pressure pump 103 is used to apply a predetermined confining pressure to the sealed space of the rock sample holder 102 to shape the colloid into a colloid block.

[0099] The colloidal block measuring unit 104 is used to measure the average width of the colloidal block after it is removed. The rock sample holder 102 is further used to hold the rock sample again in the sealed space of the rock sample holder 102 after the colloidal block is removed. The confining pressure pump 103 is further used to apply the predetermined confining pressure again to the sealed space of the rock sample holder.

[0100] A plunger pump 105 is used to inject displacement fluid into the cracks of the rock sample after the colloidal block has been removed;

[0101] The flow measurement unit 106 is used to measure the flow rate of the displacing fluid flowing out of the crack;

[0102] The pressure difference measurement unit 107 is used to measure the pressure difference between the inflow end and the outflow end of the displacement fluid in the fracture after the flow rate of the displacement fluid flowing out of the rock sample has stabilized.

[0103] The permeability calculation unit 108 is used to calculate the permeability of the crack based on the pressure difference and the flow rate;

[0104] The conductivity calculation unit 109 is used to calculate the conductivity of the fracture based on the permeability and the average width, so as to guide the mining of the target formation based on the conductivity.

[0105] Using the embodiments of this specification, colloidal blocks of shale self-supporting fractures under different measurement conditions are obtained by fracture grouting and injection. The average width of the colloidal blocks is measured using a colloidal block measurement unit. Then, the permeability of the fractures is measured by injecting a displacement fluid into the fractures of the rock sample from which the colloidal blocks were extracted. Finally, the conductivity of the fractures is calculated based on the average width and permeability. The fracture conductivity measurement system of this specification solves the problem of difficulty in measuring fracture width in current measurement methods. Compared to methods using large CT scans, the measurement method of this specification is low-cost, has a simple and continuous operation process, and a short measurement time. Compared to traditional estimation methods, the measurement results of the method of this specification are more accurate. Compared to variable substitution methods, the fracture conductivity measurement system of this specification is more flexible and can intuitively reflect the influence of self-supporting fracture width on the conductivity of self-supporting fractures.

[0106] Based on the same inventive concept, embodiments of this specification also provide a method for measuring the conductivity of a fracture, such as... Figure 2 As shown, it includes:

[0107] Step 201: Control the injection of colloid into the cracks of the rock sample in the injection unit box. The rock sample is taken from the target stratum, and the cracks are formed in advance on the rock sample after it is taken out.

[0108] Step 202: Place the rock sample after it has been injected with colloid into the sealed space of the rock sample holder, and control the rock sample holder to hold the rock sample;

[0109] Step 203: Control the confining pressure pump to apply a predetermined confining pressure to the sealed space of the rock sample holder to shape the colloid into a colloid block;

[0110] Step 204: Remove the colloidal block and control the colloidal block measuring unit to measure the average width of the colloidal block;

[0111] Step 205: Place the rock sample after removing the colloidal block back into the sealed space of the rock sample holder, control the rock sample holder to hold the rock sample again, and control the confining pressure pump to apply the predetermined confining pressure to the sealed space of the rock sample holder again;

[0112] Step 206: Control the plunger pump to inject the displacement fluid into the crack of the rock sample after the colloidal block is removed, and control the flow measurement unit to measure the flow rate of the displacement fluid flowing out of the crack. After the flow rate of the displacement fluid flowing out of the rock sample stabilizes, control the pressure difference measurement unit to measure the pressure difference between the inlet end and the outlet end of the displacement fluid in the crack.

[0113] Step 207: The permeability of the fracture is calculated by the permeability calculation unit based on the pressure difference and the flow rate, and the flow capacity of the fracture is calculated by the flow capacity calculation unit based on the permeability and the average width, so as to guide the mining of the target formation based on the flow capacity.

[0114] In the embodiments of this specification, if the measured conductivity does not exceed a predetermined threshold, it indicates that the target formation is not suitable for fracturing. In addition, other methods in the art can be used to guide the mining of target formations based on conductivity, and the embodiments of this specification do not impose limitations.

[0115] In the embodiments of this specification, the first step is to prepare an artificial rock sample. The rock sample is a rock sample taken from the target stratum. The target stratum can be an unfractured stratum, so the extracted rock sample will not have cracks. If there are cracks, it will be impossible to extract the rock sample intact while ensuring the crack morphology.

[0116] For example, according to measurement requirements, several standard plunger cores with a diameter of 25 mm and a length of 50 mm are drilled along the bedding direction.

[0117] Each standard plunger core was cut into two sections with a diameter of 25 mm ± 0.2 mm and a length of 24 mm ± 0.2 mm using a programmable rock slicer.

[0118] The end faces of the core sample were ground flat using a double-end grinding machine to ensure that the parallelism between the upper and lower end faces of the sample was less than ±0.02 mm, in preparation for further fine processing of the core sample.

[0119] Then, artificial fractures are created on the extracted rock samples. For example, artificial fractures are pre-created by splitting the core sample using Brazilian fracturing to simulate the morphology of self-supporting fractures in shale after hydraulic fracturing. The specific method is as follows:

[0120] Pre-drill cross-shaped incisions along the bedding planes on the rock sample. Induce the sample to split perpendicular to the bedding planes, aiming to make the fractures penetrate the center of the rock sample as much as possible, so that the test fluid can come into contact with as much of the shale bedding plane as possible;

[0121] The rock sample was placed in a high-temperature steam heating vessel, and a prestress of 0.1 kN was applied to both ends of the sample by a press.

[0122] Start the high-temperature steam generator and activate the temperature measurement system. Heat the rock sample to 200℃-300℃. After reaching the target temperature, maintain the temperature for 2 hours to ensure uniform heating throughout the rock sample.

[0123] The pressure machine was controlled to apply a load at a constant rate of 0.002 mm / s, and the instrument was stopped after the rock sample split.

[0124] After the rock sample cools to room temperature, remove it from the heating vessel and check its splitting condition.

[0125] The preferred and qualified sample requirements are as follows: both parts of the sample must be intact, with no obvious breakage. The sample must have only one through-type main crack, with no other secondary cracks. The maximum deviation of the crack diameter after splitting should not exceed 2 mm. If there are too many secondary cracks, the temperature inside the heating vessel can be increased; if the crack deviation is too large, the load application rate can be appropriately increased; if the rock is broken, the temperature inside the heating vessel can be increased or decreased based on experience.

[0126] The qualified rock sample was set with a misalignment amount according to the measurement plan. The two ends of the misaligned rock sample were ground flat using a double-end grinding machine, so that the parallelism of the upper and lower end faces of the rock sample was less than ±0.02mm. The rock sample was then fixed and sealed with tape.

[0127] The sealed rock samples were numbered sequentially as sample 1, 2, ..., m. The diameter and length of each sample were then measured using calipers.

[0128] As a preferred method, to ensure measurement accuracy, the entire rock sample is divided into three sections along its length, and the diameter is measured at the midpoint of each section; the entire rock sample is also divided into three sections along its circumference, each section being 120°, and the length is measured at the midpoint of each section. The diameter R of each rock sample is measured at three different locations using vernier calipers. m1 R m2 R m3 and length L m1 L m2 L m3 And calculate the average diameter average length Average cross-sectional area Where m is the rock sample number.

[0129]

[0130] Among them, R m is the average diameter of the m-th rock sample, in mm; is the average length of the m-th rock sample, in mm; It is the average cross-sectional area of ​​the m-th rock sample, in mm. 2 .

[0131] According to one embodiment of this specification, such as Figure 3 As shown, the fracture conductivity measurement system also includes a saturation unit 110, which is used to saturate the rock sample according to a predetermined saturation degree after the fracture is formed on the extracted rock sample.

[0132] Specifically, rock samples are placed in a constant temperature chamber, the temperature is adjusted to 60°C, and dried for more than 24 hours to reduce the influence of liquid in the pores on the conductivity measurement. The embodiments in this manual can study the effects of shale hydration and different fracturing fluids on the conductivity of self-supporting fractures during the well-shutting stage after fracturing. A rock sample saturation process has been added to the original self-supporting fracture conductivity measurement procedure, and the specific optimization scheme is shown below:

[0133] ① Place the rock sample in a constant temperature oven, adjust the temperature to 60℃, and dry for at least 24 hours. Measure the dry weight (m) of the rock sample using an electronic balance. 干 ;

[0134] ②According to Boyle's law, the porosity φ of the rock sample is measured using a porosity measuring instrument. m ;

[0135] ③ Place the rock sample into the metal piston container, close the valve, and seal the container;

[0136] ④ Connect the vacuum pump to the vent valve of the piston container and pump air for more than 24 hours to create a negative pressure environment inside the container;

[0137] ⑤ Close the exhaust valve. According to the measurement plan, connect the intake valve to the beaker containing formation water or fracturing fluid via a hose, ensuring the hose is always submerged. Open the intake valve to allow the formation water or fracturing fluid to enter the container through the hose. Once the liquid fills the piston container to the point where no more liquid can enter, close the intake valve.

[0138] ⑥ Pressurize the piston container to 20 MPa using a pressure pump and allow it to stand for at least 24 hours. Remove the rock sample, dry its surface, and then measure its mass (m) using an electronic balance. 湿 The liquid saturation S of the rock sample is calculated using the following formula:

[0139]

[0140] In the formula, S is the liquid saturation of the rock sample, which is dimensionless; ρ b This is the density of the saturated liquid, expressed in g / cm³. 3 m 干 m 湿 These are the dry weight and saturated mass of the rock sample, respectively, in grams; φ m It is the porosity of the rock sample, dimensionless;

[0141] ⑦ Repeat steps ③ to ⑥ until the rock sample reaches the target liquid saturation;

[0142] ⑧ Repeat the above steps to saturate all rock samples.

[0143] In the embodiments described in this specification, the saturation can be set according to the saturation of the actual formation, so that the measurement environment is closer to the actual formation.

[0144] As a preferred approach: According to the measurement scheme, if the study aims to investigate the impact of shale hydration on the conductivity of self-supporting fractures in the post-fracturing well-closing stage, the control group should reach the original formation's average water saturation, while the measurement group should reach a high water saturation of over 80%. If the study aims to investigate the impact of different fracturing fluids on the conductivity of self-supporting fractures in shale, all measured rock samples must reach a high saturation of over 80%.

[0145] Then the injection unit injects colloid into the cracks of the rock sample.

[0146] Specifically, after opening the saturated rock sample sealant, apply the adhesive evenly to the crack surface of the rock sample, close the rock sample, seal the top of the rock sample with tape, let it stand for 20 minutes, scrape off the overflowing adhesive, and use tape to seal the entire rock sample.

[0147] The preferred colloid possesses the following properties: it exhibits a gel-like fluid at room temperature and pressure, and automatically fills nearby fracture spaces as the rock sample closes. Under high temperature and pressure, the colloid slowly hardens and deforms; once fully plasticized, it does not deform upon returning to room temperature and pressure. The examples in this specification use a laboratory-prepared composite hydrogel temporary plugging agent. In actual implementation, a colloid with similar properties can be selected based on available resources.

[0148] Then check the airtightness of the sealing space of the rock sample holder, and control the rock sample holder to hold the rock sample with injected colloid within the sealing space of the rock sample holder. Then check the airtightness of the sealing space.

[0149] The conductivity of the same rock can be measured under multiple different confining pressures. First, the multiple different confining pressures are sorted in ascending order.

[0150] The injection unit injects colloid into the cracks of the rock sample. The rock sample with colloid injected is placed in the sealed space of the rock sample holder, and the rock sample holder is controlled to hold the rock sample. The confining pressure pump is controlled to apply the first confining pressure in the sealed space of the rock sample holder to obtain the colloid block corresponding to the first confining pressure. The colloid block corresponding to the first confining pressure is taken out, and the colloid block measuring unit is controlled to measure the average width of the colloid block corresponding to the first confining pressure and measure the permeability of the crack corresponding to the first confining pressure. The conductivity of the crack corresponding to the first confining pressure is calculated based on the permeability and average width.

[0151] The injection unit is controlled to inject colloid into the cracks of the rock sample again. The rock sample with colloid injected is placed in the sealed space of the rock sample holder, and the rock sample holder is controlled to hold the rock sample. The confining pressure pump is controlled to apply a second confining pressure, which is ordered after the first confining pressure, to the sealed space of the rock sample holder to obtain a colloid block corresponding to the second confining pressure. The colloid block corresponding to the second confining pressure is taken out, and the colloid block measuring unit is controlled to measure the average width of the colloid block corresponding to the second confining pressure and measure the permeability of the crack corresponding to the second confining pressure. The conductivity of the crack corresponding to the second confining pressure is calculated based on the permeability and the average width.

[0152] Repeat the above steps to obtain the conductivity corresponding to multiple different confining pressures, so as to guide the mining of the target formation based on the conductivity corresponding to multiple different confining pressures.

[0153] When measuring the conductivity of the m-th rock sample under the nth confining pressure, the prepared rock sample is placed into the rock sample holder. The confining pressure pump is controlled to apply a predetermined confining pressure to the sealed space of the rock sample holder, and the pressure is stabilized for at least 2 hours to allow the colloid to be completely molded and form a colloidal block.

[0154] The colloidal block is then removed, and the colloidal block measuring unit measures the average width of the removed colloidal block.

[0155] Specifically, the colloidal block measuring unit includes:

[0156] A colloidal block volume measurement module is used to measure the volume of the colloidal block;

[0157] A colloidal block average area measurement module is used to measure the average area of ​​the colloidal block;

[0158] The average width calculation module for the colloidal block is used to calculate the average width of the colloidal block based on its volume and average area.

[0159] like Figure 4 As shown, measuring the average width of the colloidal block includes:

[0160] Step 401: Scan the colloidal block using a 3D digital scanner to obtain point cloud data of the upper and lower surfaces of the colloidal block;

[0161] Step 402: Calculate the average area of ​​the colloidal block based on the point cloud data of the upper and lower surfaces of the colloidal block;

[0162] Step 403: Measure the volume of the colloidal block using the water displacement method;

[0163] Step 404: Calculate the ratio of the volume to the average area of ​​the colloidal block to obtain the average width of the colloidal block.

[0164] For example, a 3D digital scanner is used to examine the fracture morphology of colloidal block D of the m-th rock sample under the n-th confining pressure. mn The upper and lower surfaces were scanned with a scanning accuracy of 0.02 mm. Point cloud data of the upper and lower surfaces were obtained respectively.

[0165] After the scan is complete, output D. mn The colloidal block's topographic point cloud data was scanned from the upper and lower surfaces, and D was calculated using the following formula. mn The area of ​​one surface of the colloidal block:

[0166]

[0167] Among them, A f The area is the area being calculated, and x, y, and z are the x, y, and z coordinates of the point cloud data.

[0168] Calculate D using formula (3) respectively mn The area A of the upper surface of the colloidal block fmn上 and lower surface A fmn下 The area.

[0169] Then calculate D. mn Average area of ​​colloidal block The unit is cm 2 :

[0170]

[0171] D mn The colloidal block is placed in a beaker filled with water. The displaced liquid is collected in an empty beaker, and the mass m of the displaced water is measured using a precision balance. mn水 The volume V of the colloidal block is calculated using the following formula. mn :

[0172]

[0173] In the formula: V mn This refers to the volume of the colloidal block, in cm³. 3 .

[0174] Repeat the above steps until all cracked colloidal blocks have been measured, and obtain the average area of ​​any colloidal block. and volume V mn .

[0175] Then, the average width of the crack is calculated using formula (6):

[0176]

[0177] in, The average width of the self-supporting crack in the m-th rock sample under the n-th confining pressure is expressed in cm.

[0178] Then, the plunger pump is controlled to inject displacement fluid into the cracks of the rock sample after the colloidal block has been removed.

[0179] Specifically, first record the ambient temperature T. mn The displacement solution at temperature T was obtained by referring to a table. mn Viscosity μ at temperature mn .

[0180] As a preferred option: given that shale contains a large amount of clay minerals, when measuring the conductivity of liquids, in order to prevent the clay minerals from expanding and affecting the measurement accuracy, a prepared 2% KCl solution is used as the displacement fluid.

[0181] According to one embodiment of this specification, such as Figure 5 As shown, the rock sample holder 102 is provided with a displacement fluid inlet 1021 and a displacement fluid outlet 1022;

[0182] The plunger pump is further used to inject the displacing fluid into the displacing fluid inlet 1021 so that the displacing fluid flows into the crack and flows out from the displacing fluid outlet 1022.

[0183] Continue as Figure 5 As shown, the pressure difference measurement unit 107 includes:

[0184] A first pressure gauge 1071 is installed at the displacing fluid inlet 1021 to measure the inlet pressure;

[0185] The second pressure gauge 1072 is installed at the displacing fluid outlet 1022 and is used to measure the outlet pressure;

[0186] The pressure difference calculation module 1073 is used to calculate the difference between the inlet pressure and the outlet pressure to obtain the pressure difference.

[0187] Furthermore, such as Figure 6 As shown, the flow measurement unit 106 includes:

[0188] Displacement fluid mass measurement module 1061 is installed at the displacement fluid outlet 1022 and is used to measure the mass of the displacement fluid flowing out of the crack.

[0189] The flow calculation unit 1062 is used to calculate the flow rate of the displacement fluid based on the mass of the displacement fluid and the time when the plunger pump 105 injects the displacement fluid.

[0190] Specifically, the displacing fluid needs a certain amount of time to flow out of the fracture. Therefore, it is necessary to control the plunger pump to inject the displacing fluid into the fracture for a period of time, such as 10 seconds, and collect the mass of the displacing fluid flowing out of the displacing fluid outlet 1022, for example, by measuring the mass Δm of the displacing fluid using an electronic balance.mn .

[0191] Simultaneously, the inlet pressure P is measured using the first pressure gauge. mn进 The outlet pressure P is measured using a second pressure gauge. mn out.

[0192] Then the pressure difference is calculated using formula (7):

[0193] ΔP mn =P mn进 - P mn出 (7)

[0194] Where, ΔP mn It is the pressure difference of the m-th rock sample under the n-th confining pressure, in MPa.

[0195] The flow rate of the displacing fluid is calculated using formula (8):

[0196] Q mn =Δm mn / 10ρ 液 (8)

[0197] Among them, Q mn It is the flow rate of the m-th rock sample under the n-th confining pressure, in cm³. 3 / s;ρ 液 This is the density of the displacing solution, expressed in g / cm³. 3 .

[0198] Then the permeability of the crack is calculated using formula (9):

[0199]

[0200] Among them, K mn It is the permeability of the self-supporting fracture of the m-th rock sample under the n-th confining pressure, expressed in mD.

[0201] Then the conductivity of the crack is calculated using formula (10):

[0202]

[0203] Among them, F mn It represents the conductivity of the self-supporting fracture of the m-th rock sample under the n-th confining pressure, expressed in mD·cm.

[0204] Then, following the above procedure, the conductivity of the m-th rock sample under the (n+1)-th confining pressure is calculated, until the conductivity of all rock samples under all confining pressures is calculated. This is to guide the fracturing and mining of the target formation based on the conductivity of all rock samples.

[0205] For example, to understand the variation of the conductivity of self-supporting fractures in a certain production block with closing stress, a damage mathematical model of the conductivity of self-supporting fractures in this production block needs to be established. Basic data on the variation of the conductivity of self-supporting fractures with closing stress needs to be obtained through laboratory measurements. The method provided in the embodiments of this specification is used to measure the conductivity of self-supporting fractures in samples at 30 MPa, 40 MPa, and 50 MPa. The specific steps are as follows:

[0206] S1. Preparation of artificial rock samples;

[0207] S11. According to the measurement requirements, drill two standard downhole plunger core samples along the bedding direction from the target deep shale gas well. The core samples should be 25 mm in diameter and 50 mm in length.

[0208] S12. Each standard plunger core was cut into two sections using a programmable rock slicer, resulting in a total of 4 samples with a diameter of 25 mm ± 0.2 mm and a length of 24 mm ± 0.2 mm.

[0209] S13. Use a double-end grinding machine to grind the end faces of the core sample flat, so that the parallelism between the upper and lower end faces of the rock sample is less than ±0.02mm, in preparation for further fine processing of the core sample;

[0210] S14. Brazilian splitting was used to prefabricate artificial cracks in four rock samples to simulate the morphology of self-supporting cracks in shale after acid fracturing.

[0211] The specific method is as follows:

[0212] ① Make cross-shaped scratches along the bedding planes on 4 rock samples;

[0213] ② Place the rock sample in a high-temperature steam heating kettle and control the press to apply a prestress of 0.1 kN to both ends of the sample;

[0214] ③ Start the high-temperature steam generator and activate the temperature measurement system. Heat the rock sample to 260℃. After reaching the target temperature, maintain the temperature for 2 hours.

[0215] ④ Control the press to apply load at a constant rate of 0.002 mm / s, and stop the instrument after the rock sample splits;

[0216] ⑤ After the rock samples cooled to room temperature, they were removed from the heating vessel. Following a conformity check, the second rock sample showed a maximum deviation of over 2 mm in diameter from the splitting crack. The load application rate was increased to 0.003 mm / s, and subsequent splitting of the rock samples all passed the test. Three qualified rock samples were obtained.

[0217] S15. After setting a 1mm misalignment allowance for 3 qualified rock samples according to the measurement plan, use a double-end grinding machine to grind the two ends of the misaligned rock samples flat, so that the parallelism of the upper and lower end faces of the rock samples is less than ±0.02mm. Use tape to fix and seal the rock samples as a whole.

[0218] S2. Preliminary preparations;

[0219] S21. Number the sealed rock samples as Rock Sample 1, 2, and 3 in sequence. Measure the diameter and length of each rock sample using calipers. Calculate the average diameter, length, and cross-sectional area of ​​each rock sample using formula (1); the specific data are shown in the table below:

[0220] As a preferred method: Divide the entire rock sample along its length into 3 sections, and measure the diameter of the rock sample at the midpoint of each section. Divide the entire rock sample along its circumference into 3 sections, each section being 120°, and measure the length of the rock sample at the midpoint of each section.

[0221] Table 1. Rock Sample Dimensions (Unit: mm)

[0222]

[0223] S22. This scheme preliminarily studies the impact of shale hydration on the self-supporting conductivity of shale during the well-closing stage after fracturing, and determines the impact of a certain regenerated fracturing fluid on the self-supporting conductivity of shale. A saturation process is added to the previous conductivity measurement procedure. The specific optimization scheme is as follows: Rock sample 3 serves as the control group, saturated with clean water to the original formation water saturation (approximately 26% for rock samples in this block; researchers need to adjust according to actual conditions); Rock sample 2 serves as measurement group 1, saturated with regenerated fracturing fluid to a high saturation state (above 80%); Rock sample 1 serves as measurement group 2, saturated with clean water to a high saturation state (above 80%). The density ρ of the regenerated fracturing fluid used in the examples in this specification is... b =1.3g / cm 3 The density of pure water is taken as 1 g / cm³. 3 .

[0224] The specific measurement procedure is as follows:

[0225] ① Place rock sample 1 in a constant temperature drying oven, adjust the temperature to 60℃, and dry for 24 hours. Measure the dry weight (m) of the rock sample using an electronic balance. 干 =57.13g;

[0226] ②According to Boyle's law, the porosity φ of rock sample 1 was measured using a core porosity meter. m It was 3.39%;

[0227] ③ Place rock sample 1 into a piston container (1000ml, pressure limit 40MPa), close the valve, and seal the container;

[0228] ④ Use a rotary vane vacuum pump connected to the outlet valve of the piston container to pump air for 24 hours to create a negative pressure environment inside the container;

[0229] ⑤ Close the outlet valve, connect the inlet valve to the beaker containing regenerated fracturing fluid through the hose and keep the hose submerged, open the inlet valve to allow the regenerated fracturing fluid to enter the container through the hose, and close the inlet valve when the liquid fills the piston container to the point where no more liquid can enter.

[0230] ⑥ Pressurize the piston container to 20 MPa using a pressure pump and let it stand for 60 hours. Remove the rock sample, dry the surface, and measure its mass (m) using an electronic balance. 湿 =57.46g, and the liquid saturation of the rock sample is calculated to be S = 82.08% according to Formula 2.

[0231] Once the requirements are met, resaturation is unnecessary.

[0232] ⑦ Repeat the above steps to saturate the three rock samples. The specific parameters are shown in the table below:

[0233] Table 2 Saturated Process Parameters

[0234] Rock sample number <![CDATA[m 干 / (g)]]> <![CDATA[m 湿 / (g)]]> <![CDATA[φ m / (%)]]> S / (％) 1 57.13 57.46 3.39 82.08 2 58.24 58.67 3.27 84.55 3 56.87 56.97 3.23 26.32

[0235] S3. Measurement of the conductivity of self-supporting cracks;

[0236] S31. Open the rock sample tape seal, apply the adhesive evenly to the crack surface of the rock sample, close the rock sample, seal the top of the rock sample with tape, let it stand for 20 minutes, scrape off the overflowing adhesive, and use tape to seal the entire rock sample.

[0237] S32. Connect the measurement system as described in the embodiment of the instruction manual;

[0238] A 2% KCl solution was used as the displacing fluid. After checking the airtightness of the apparatus, the first rock sample and the first confining pressure measurement were performed. The prepared rock sample was placed in the sample holder. The temperature was recorded as 21.3℃, and the viscosity of the displacing fluid was found to be 1.03 mPa·s from the table.

[0239] S33. According to the measurement requirements, use a confining pressure pump to apply confining pressure to 30MPa, stabilize the pressure for 2 hours, and remove the colloid block D after the colloid has been completely molded. 11 The rock sample was placed back into the sample holder, and the plunger pump was used to inject displacement fluid into the sample. The density of the displacement fluid was 1.01 g / cm³. 3 After the flow rate and pressure stabilize, record the pressure gauge readings P at the inlet and outlet of the rock sample clamping chamber. 11进 =1.66MPa, P 11出 =0.12MPa, record the increase in mass Δm of the electronic balance within 10 seconds. 11= 33.37g; and calculate the inlet and outlet pressure difference ΔP. 11 =1.54MPa and flow rate Q 11 =3.30cm 3 / s;

[0240] S34. Calculate the permeability K of the self-supporting fractures in the first rock sample under a confining pressure (30 MPa). 11 =107.02mD;

[0241] S35. Release the confining pressure and remove the rock sample from the rock sample holder;

[0242] S36. Repeat steps S31-S35 to measure the first rock sample and the second confining pressure, until all three confining pressure measurements required for the first rock sample are completed.

[0243] S37. Repeat steps S31-S36 to measure the second rock sample, until all three rock samples have been measured. Obtain the permeability K of the self-supporting fracture under any confining pressure for any rock sample. mn The specific data is shown below:

[0244] Table 3. Permeability of self-supporting cracks under various measurement conditions

[0245]

[0246] S38. Using a 3D digital scanner, analyze the fracture morphology of colloidal block D of the first rock sample under confining pressure. 11 The upper and lower surfaces are scanned with a scanning accuracy of 0.02 mm. The morphological data of the upper and lower surfaces are obtained respectively. After the scan is completed, D is output. 11 The colloidal block's top and bottom surface topography point cloud data were scanned and D was calculated. 11 Average area of ​​colloidal block 10.09cm 2 ;

[0247] S39. D mn The colloidal block is placed in a beaker filled with water. The displaced liquid is collected in an empty beaker, and the mass m of the displaced water is measured using a precision balance. 11水 =2.11g, and calculate the volume V of the colloidal block using the following formula. 11 =2.11cm 3 ;

[0248] S310. Repeat steps S38-S39 until the measurements of 9 cracked colloidal blocks are completed, and obtain the average area of ​​any colloidal block. and volume V mn The specific data is shown in the table below:

[0249] Table 4. Average area and volume of each colloidal block

[0250]

[0251] S4. Calculation of self-supporting flow guiding capacity;

[0252] Based on the calculation results in Table 4, the average width of the self-supporting crack in the first rock sample under the first confining pressure (30 MPa) was calculated. Combining the permeability data in Table 3, and based on the calculation of the conductivity F of the self-supporting fracture under the first confining pressure (30 MPa) of the first rock sample, 11 = 21.38 mD·cm. Repeating the above calculations, the width and conductivity of the self-supporting fractures under different confining pressures are shown in Table 5. The conductivity results of the self-supporting fractures in the rock samples measured under confining pressures of 30 MPa, 40 MPa, and 50 MPa are shown in the figure below. Figure 7 As shown.

[0253] Table 5. Details of self-supporting crack width and conductivity under different confining pressures.

[0254]

[0255] like Figure 8 The diagram shown is a structural schematic of a computer device according to an embodiment of this specification. The penetration rate calculation unit or diversion capacity calculation unit in this invention can be the computer device in this embodiment, executing the method of this invention described above. The computer device 802 may include one or more processing devices 804, such as one or more central processing units (CPUs), each processing unit may implement one or more hardware threads.

[0256] The computer device 802 may also include any storage resource 806 for storing any kind of information such as code, settings, data, etc.

[0257] Non-limiting, for example, storage resource 806 may include any one or more of the following: any type of RAM, any type of ROM, flash memory device, hard disk, optical disk, etc.

[0258] More generally, any storage resource can use any technology to store information.

[0259] Furthermore, any storage resource can provide volatile or non-volatile retention of information.

[0260] Furthermore, any storage resource can represent a fixed or removable component of the computer device 802.

[0261] In one scenario, when processing device 804 executes associated instructions stored in any storage resource or combination of storage resources, computer device 802 can perform any operation of the associated instructions. Computer device 802 also includes one or more drive mechanisms 808 for interacting with any storage resource, such as hard disk drive mechanisms, optical disk drive mechanisms, etc.

[0262] Computer device 802 may also include an input / output module 810 (I / O) for receiving various inputs (via input device 812) and providing various outputs (via output device 814). A specific output mechanism may include a presentation device 816 and an associated graphical user interface (GUI) 818. In other embodiments, the input / output module 810 (I / O), input device 812, and output device 814 may be omitted, and the device may function solely as a computer device within a network. Computer device 802 may also include one or more network interfaces 820 for exchanging data with other devices via one or more communication links 822. One or more communication buses 824 couple the components described above together.

[0263] Communication link 822 can be implemented in any way, such as via a local area network, a wide area network (e.g., the Internet), a point-to-point connection, or any combination thereof. Communication link 822 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc., governed by any protocol or combination of protocols.

[0264] This specification also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.

[0265] This specification also provides computer-readable instructions, wherein when a processor executes the instructions, the program therein causes the processor to perform the above-described method.

[0266] It should be understood that in the various embodiments of this specification, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this specification.

[0267] It should also be understood that, in the embodiments of this specification, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this specification generally indicates that the preceding and following related objects have an "or" relationship.

[0268] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed in this specification can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this specification.

[0269] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0270] In the several embodiments provided in this specification, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the couplings or direct couplings or communication connections shown or discussed may be indirect couplings or communication connections through some interfaces, devices, or units, or they may be electrical, mechanical, or other forms of connection.

[0271] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments described in this specification, depending on actual needs.

[0272] Furthermore, the functional units in the various embodiments of this specification can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0273] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this specification, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this specification. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0274] This specification uses specific embodiments to illustrate the principles and implementation methods of this specification. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this specification. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this specification. Therefore, the content of this specification should not be construed as a limitation of this specification.

Claims

1. A fracture conductivity measurement system, characterized in that, include: The adhesive injection unit is used to inject adhesive into the cracks of a rock sample taken from a target stratum, the cracks being pre-formed on the extracted rock sample. A rock sample holder is used to hold a rock sample that has been injected with colloid within the sealed space of the rock sample holder. A confining pressure pump is used to apply a predetermined confining pressure to the sealed space of the rock sample holder to shape the colloid into a colloid block. The colloidal block measuring unit is used to measure the average width of the removed colloidal block after it has been removed. The rock sample holder is further used to hold the rock sample again in the sealed space of the rock sample holder after the colloidal block has been removed. The confining pressure pump is further used to apply the predetermined confining pressure again to the sealed space of the rock sample holder. A plunger pump is used to inject displacement fluid into the cracks of the rock sample after the colloidal block has been removed; A flow measurement unit is used to measure the flow rate of the displacing fluid flowing out of the crack; The pressure difference measurement unit is used to measure the pressure difference between the inflow end and the outflow end of the displacement fluid in the fracture after the flow rate of the displacement fluid flowing out of the rock sample has stabilized. A permeability calculation unit is used to calculate the permeability of the crack based on the pressure difference and the flow rate; A flow capacity calculation unit is used to calculate the flow capacity of the fracture based on the permeability and the average width, so as to guide the mining of the target formation based on the flow capacity.

2. The fracture conductivity measurement system according to claim 1, characterized in that, The rock sample holder is equipped with a displacement fluid inlet and a displacement fluid outlet; The plunger pump is further used to inject the displacing fluid into the displacing fluid inlet so that the displacing fluid flows into the crack and flows out from the displacing fluid outlet.

3. The fracture conductivity measurement system according to claim 2, characterized in that, The pressure difference measurement unit includes: A first pressure gauge is installed at the inlet of the displacing fluid to measure the inlet pressure; A second pressure gauge is installed at the outlet of the displacing fluid to measure the outlet pressure; The pressure difference calculation module is used to calculate the difference between the inlet pressure and the outlet pressure to obtain the pressure difference.

4. The fracture conductivity measurement system according to claim 2, characterized in that, The flow measurement unit includes: A displacement fluid mass measurement module is installed at the displacement fluid outlet to measure the mass of the displacement fluid flowing out of the crack; A flow calculation unit is used to calculate the flow rate of the displacing fluid based on the mass of the displacing fluid and the time it takes for the plunger pump to inject the displacing fluid.

5. The fracture conductivity measurement system according to claim 1, characterized in that, The colloidal block measuring unit includes: A colloidal block volume measurement module is used to measure the volume of the colloidal block; A colloidal block average area measurement module is used to measure the average area of ​​the colloidal block; The average width calculation module for the colloidal block is used to calculate the average width of the colloidal block based on its volume and average area.

6. The fracture conductivity measurement system according to claim 1, characterized in that, The fracture conductivity measurement system also includes a saturation unit, which is used to saturate the rock sample according to a predetermined saturation degree after the fracture is formed on the extracted rock sample.

7. A method for measuring fracture conductivity, applied to the fracture conductivity measurement system according to any one of claims 1-6, characterized in that, include: The injection of adhesive into the cracks of a rock sample taken from a target stratum is controlled by a colloid injection unit box. The cracks are pre-formed on the rock sample after it has been taken out. The rock sample, after being injected with colloid, is placed in the sealed space of the rock sample holder, and the rock sample holder is controlled to hold the rock sample. The confining pressure pump is controlled to apply a predetermined confining pressure to the sealed space of the rock sample holder, so as to shape the colloid into a colloid block; Remove the colloidal block and control the colloidal block measuring unit to measure the average width of the colloidal block; After removing the colloidal block, the rock sample is placed back into the sealed space of the rock sample holder. The rock sample holder is controlled to clamp the rock sample again, and the confining pressure pump is controlled to apply the predetermined confining pressure to the sealed space of the rock sample holder again. The plunger pump is controlled to inject displacement fluid into the cracks of the rock sample after the colloidal block is removed, and the flow measurement unit is controlled to measure the flow rate of the displacement fluid flowing out of the cracks. After the flow rate of the displacement fluid flowing out of the rock sample stabilizes, the pressure difference measurement unit is controlled to measure the pressure difference between the inlet end and the outlet end of the displacement fluid in the cracks. The permeability of the fracture is calculated by the permeability calculation unit based on the pressure difference and the flow rate, and the flow capacity of the fracture is calculated by the flow capacity calculation unit based on the permeability and the average width, so as to guide the mining of the target formation based on the flow capacity.

8. The method according to claim 7, characterized in that, Measuring the average width of the colloidal block includes: The colloidal block was scanned using a 3D digital scanner to obtain point cloud data of the upper and lower surfaces of the colloidal block. The average area of ​​the colloidal block is calculated based on the point cloud data of the upper and lower surfaces of the colloidal block. The volume of the colloidal block was measured by the water displacement method; The average width of the colloidal block is obtained by calculating the ratio of its volume to its average area.

9. The method according to claim 7, characterized in that, Before injecting adhesive into the cracks of the rock sample in the controlled adhesive injection unit box, the method further includes: The saturation control unit saturates the rock sample according to a predetermined saturation level.

10. The method according to claim 7, characterized in that, When measuring the conductivity of the same rock sample under multiple different confining pressures, the method further includes: Sort the different confining pressures in ascending order; The injection unit injects colloid into the cracks of the rock sample. The rock sample with colloid injected is placed in the sealed space of the rock sample holder, and the rock sample holder is controlled to hold the rock sample. The confining pressure pump is controlled to apply the first confining pressure in the sealed space of the rock sample holder to obtain the colloid block corresponding to the first confining pressure. The colloid block corresponding to the first confining pressure is taken out, and the colloid block measuring unit is controlled to measure the average width of the colloid block corresponding to the first confining pressure and measure the permeability of the crack corresponding to the first confining pressure. The conductivity of the crack corresponding to the first confining pressure is calculated based on the permeability and average width. The injection unit is controlled to inject colloid into the cracks of the rock sample again. The rock sample with colloid injected is placed in the sealed space of the rock sample holder, and the rock sample holder is controlled to hold the rock sample. The confining pressure pump is controlled to apply a second confining pressure, which is ordered after the first confining pressure, to the sealed space of the rock sample holder to obtain a colloid block corresponding to the second confining pressure. The colloid block corresponding to the second confining pressure is taken out, and the colloid block measuring unit is controlled to measure the average width of the colloid block corresponding to the second confining pressure and measure the permeability of the crack corresponding to the second confining pressure. The conductivity of the crack corresponding to the second confining pressure is calculated based on the permeability and the average width. Repeat the above steps to obtain the conductivity corresponding to multiple different confining pressures, so as to guide the mining of the target formation based on the conductivity corresponding to multiple different confining pressures.

Images