Electrodeless anisotropic permeability tensor testing device and method

Abstract

The invention discloses an electrodeless anisotropic permeability tensor testing device and method, and relates to the technical field of rock core testing devices. The device comprises a rock core holder and a spherical rock core and is provided with a simulation shaft penetrating through the spherical rock core, the spherical rock core can rotate along with the simulation shaft, and the rock core holder is further provided with a flow guide pipe and a plurality of liquid flow channels. When in use, the non-polar anisotropy measurement of the core permeability can be realized by rotating the spherical core and changing the liquid flow channel, so that the measurement of the core permeability tensor is completed.

Description

Technical Field

[0001] The invention relates to the technical field of core testing devices, in particular to a non-polar anisotropic permeability tensor testing device and method. Background Art

[0002] Since rock particles have directionality during the deposition process, anisotropy caused by the arrangement of rock particle pores is common. Permeability anisotropy is a basic characteristic of rock permeability. Almost all rocks have a certain degree of anisotropy, but the degree of anisotropy varies. This anisotropy has a significant impact on oil and gas flow. During the development and production of oil and gas fields, changes in permeability can cause fluctuations in production capacity. Therefore, accurately determining the permeability tensor of rocks is of great significance to exploration and development as well as oil well production research.

[0003] At present, the commonly used permeability tensor testing methods at home and abroad are to apply a displacement pressure difference on the end face of a cylindrical rock sample in a mold cavity of a specific shape, inject fluid at a constant rate, measure the pressure drop through a pressure sensor, and calculate the permeability tensor using the Darcy formula. At present, there are many studies on two-dimensional permeability tensors, and there are also a few discussions and analyses on three-dimensional permeability tensors. However, these traditional testing methods are often limited to permeability tests in a single direction, and it is difficult to obtain anisotropic permeability tensors comprehensively and accurately. Therefore, it is of great significance to develop a non-polar anisotropic permeability tensor testing device and testing method. Summary of the invention

[0004] In order to solve at least one of the above problems, the present invention proposes a non-polar anisotropic permeability tensor testing device.

[0005] The technical solution of the present invention is: a non-polar anisotropic permeability tensor testing device, comprising: A spherical core, wherein a rubber sleeve is provided on the outside of the spherical core and a simulated well wall is provided inside the spherical core; A core holder, the core holder is composed of a shell of at least two parts, and a pressure chamber is provided inside the core holder, the spherical core is arranged inside the pressure chamber, and a gap is provided between the spherical core and the inner wall of the core holder; the core holder is also provided with a simulated wellbore, one end of the simulated wellbore is arranged inside the simulated well wall, and the other end is arranged outside the core holder, when the simulated wellbore rotates, the spherical core is driven to rotate; the core holder is also provided with a plurality of liquid flow channels and a confining pressure channel, a flow guide tube is provided in the liquid flow channel, and one end of the flow guide tube is arranged inside the rubber sleeve; The injection-production system comprises an injection pump, a confining pressure pump and a meter, wherein the output end of the injection pump is connected to a first pressure gauge and a simulated wellbore in sequence, the output end of the confining pressure pump is connected to the confining pressure channel, and the meter is connected to a second pressure gauge and a flow guide pipe in sequence.

[0006] An implementation manner of the present invention is that the core holder is composed of two hemispherical shells, and the pressure chamber is spherical.

[0007] Furthermore, an annular rotating disk is provided between the two shells, and one end of the simulated wellbore passes through the rotating disk and is provided inside the simulated wellbore wall.

[0008] Preferably, the rotating disk is provided with a plurality of positioning blocks, and the housing is provided with an annular positioning groove matching the positioning blocks.

[0009] An implementation manner of the present invention is that a rubber sealing strip is provided between two adjacent shells of the core clamp, and the core clamp is also provided with at least one clamping band for fastening the shells.

[0010] An implementation manner of the present invention is that a plurality of liquid flow channels are provided on multiple parts of the core holder, and any of the liquid flow channels is provided with a sealing plug.

[0011] Another object of the present invention is to disclose a method for testing a non-polar anisotropic permeability tensor, using any of the above-mentioned devices, comprising the following steps: S1. Cut a hole in the rubber sleeve so that the guide tube extends into the rubber sleeve, and use a sealant to seal the guide tube and the rubber sleeve. After the sealing is completed, install the equipment; S2, applying confining pressure to the pressure chamber using a confining pressure pump, injecting fluid into the spherical core at a constant rate using an injection pump, measuring the produced fluid from the flow guide tube using a meter, and recording the pressure changes at the inlet and outlet of the spherical core during the experiment using a first pressure gauge and a second pressure gauge. After the experiment, the pressure chamber is depressurized; S3, remove the core holder and sealant, seal the hole on the rubber sleeve, then rotate the simulated wellbore, and repeat the operations of S1 and S2 until the permeability within the circumference of the hole is measured; S4, replace a new liquid flow channel, repeat S1-S3, and complete the non-polar permeability measurement of the spherical core; S5. Calculate the permeability tensor: , where K xx , K yy , K zz There are three main permeability coefficients on the diagonal line, representing the degree of fluid penetration in the x, y, and z directions respectively, and are obtained by measuring the x, y, and z directions using test equipment; Kxy , K xz , K yx , K yz , K zx , K zy represents the cross permeability coefficient between different directions. Since the permeability tensor has symmetry, K xy =K yx , K xz =K zx , K yz =K zy ; According to Darcy's law and matrix multiplication, the seepage velocity equation in each direction is obtained. According to the seepage velocity equation, K is obtained by solving it. xy , K xz and K yz : , In the formula, , , They are the pressure gradients in the X, Y, and Z directions. Under the premise of constant displacement, after the fluid flow rate stabilizes, we can get , , ; is the fluid viscosity; V x 、V y 、V z Represent the seepage velocity components along the X, Y, and Z axes respectively.

[0012] Beneficial effect: The above-mentioned non-polar anisotropic permeability tensor testing device provided by the present invention first needs to grind the rock sample into a spherical core, then install the rubber sleeve, and obtain the measured fluid flow, seepage velocity and permeability on three main axes through the joint action of the core holder and the injection and production system, and finally solve the permeability tensor of the spherical core using the permeability tensor formula. The device is simple in equipment, easy to operate, and has strong applicability.

[0013] In addition, the present invention also provides a corresponding testing method for a non-polar anisotropic permeability tensor testing device, further making the above permeability tensor testing device more practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the overall structure of the device of Example 1; Figure 2 It is a cross-sectional view of the core holder of Example 1 when no rotating disk is provided; Figure 3 It is a cross-sectional view of the core holder of Example 1 when a rotating disk is provided; Figure 4 This is a schematic structural diagram of the hemispherical shell of the core holder of Example 1 when a rotating disk is provided.

[0015] In the figure, 1 is a core holder, 101 is a shell, 2 is a simulated wellbore, 3 is a liquid flow channel, 4 is a first pressure gauge, 5 is an injection pump, 6 is a confining pressure pump, 7 is a meter, 8 is a clamp belt, 9 is a confining pressure channel, 10 is a pressure chamber, 11 is a rubber sleeve, 12 is a spherical core, 13 is a simulated wellbore wall, 14 is a rotating disk, 15 is a positioning block, 16 is a sealing plug, 17 is a guide tube, 18 is a second pressure gauge, 19 is a rubber sealing strip, and 20 is an annular positioning groove. DETAILED DESCRIPTION

[0016] The specific implementation modes of the present invention will be described clearly and completely below in conjunction with examples and drawings. Obviously, the described examples are only some embodiments of the present invention, rather than all embodiments.

[0017] Example 1: Figure 1-Figure 4 As shown, a non-polar anisotropic permeability tensor testing device comprises: A spherical core 12, wherein a rubber sleeve 11 is disposed outside the spherical core 12, and a simulated well wall 13 is disposed inside the spherical core 12; A core holder 1, the core holder 1 is composed of a shell 101 of at least two parts, and a pressure chamber 10 is provided inside the core holder 1, the spherical core 12 is arranged inside the pressure chamber 10, and a gap is provided between the spherical core 12 and the inner wall of the core holder 1; the core holder 1 is also provided with a simulated wellbore 2, one end of the simulated wellbore 2 is arranged inside the simulated well wall 13, and the other end is arranged outside the core holder 1, when the simulated wellbore 2 rotates, the spherical core 12 is driven to rotate; the core holder 1 is also provided with a plurality of liquid flow channels 3 and a confining pressure channel 9, a guide tube 17 is provided in the liquid flow channel 3, and one end of the guide tube 17 is arranged inside the rubber sleeve 11; The injection-production system includes an injection pump 5, a confining pressure pump 6 and a meter 7. The output end of the injection pump 5 is connected to the first pressure gauge 4 and the simulated wellbore 2 in sequence. The output end of the confining pressure pump 6 is connected to the confining pressure channel 9. The meter 7 is connected to the second pressure gauge 18 and the guide tube 17 in sequence.

[0018] Specifically, in this embodiment, when making the spherical core 12, a rock block with uniform texture, no obvious cracks and impurities should be selected, and then it should be cut and polished to a suitable size. Generally speaking, considering the subsequent experimental operation, the size of the spherical core 12 is generally more than ten centimeters to tens of centimeters. Those skilled in the art can select a spherical core 12 of a suitable size according to actual conditions.

[0019] For the simulated well wall 13 in the spherical core 12, it is usually set along the diameter direction of the spherical core 12, and one end of the simulated well wall 13 is usually set at the center of the spherical core 12, the same as the conventional well wall, and the other end of the simulated well wall 13 is on the surface of the spherical core 12.

[0020] As for the rubber sleeve 11, its function is to separate the spherical core 12 and the confining pressure oil in the pressure chamber 10, which is the same as the function of conventional rubber sleeves in the art, so the commonly used rubber sleeves in the art can be used.

[0021] For the core holder 1, it is composed of at least two parts of the shell 101, such as 2 parts, 3 parts, etc., but considering the actual operation, it is set as two hemispherical shells 101 with hemispherical grooves inside in this embodiment. When the two hemispherical shells 101 are combined, the two hemispherical grooves are combined into a relatively sealed pressure chamber 10. Of course, those skilled in the art can also use shells and grooves of other shapes, such as square shells and square grooves, but since it is relatively difficult to calculate the angle of the square shell, those skilled in the art can choose according to the actual situation. At the same time, those skilled in the art know that in order to make the sealing performance of the core holder 1 composed of the two parts of the shell 101 better, a corresponding rubber sealing strip 19 can be set between the shells 101, and a clamp band 8 for fastening the shell 101 can be set outside the shell 101. Of course, those skilled in the art can also use other components that can be used to fasten the shell 101, such as setting corresponding ears and bolts on the shell 101. Those skilled in the art can choose a suitable fastening method according to the actual situation.

[0022] For the simulated wellbore 2, its outer diameter is the same as the inner diameter of the simulated well wall 13, and a material with greater friction resistance, such as a rubber layer, is provided on the outer wall of the simulated wellbore 2. When the simulated wellbore 2 rotates, the spherical core 12 can be driven to rotate. At the same time, since one end of the simulated wellbore 2 needs to pass through the rubber sleeve 11 and be arranged inside the simulated well wall 13, when installing the equipment, it is necessary to apply a corresponding sealant to the connection between the simulated wellbore 2 and the rubber sleeve 11 for sealing. The sealant used can be a two-component polysulfide sealing paste, and those skilled in the art can select a suitable sealant according to actual conditions.

[0023] As for the liquid flow channel 3, its main function is to extract the fluid injected into the spherical core 12 by the injection pump 5. Therefore, we set a guide tube 17 inside the liquid flow channel 3, and at the same time, one end of the guide tube 17 is set inside the rubber sleeve 11. In order to ensure the sealing of the rubber sleeve 11, it is usually necessary to perform the following operations before installing the core clamp 1: cutting and drilling on the rubber sleeve 11, then inserting the guide tube 17 into the rubber sleeve 11, and then using a sealant to seal the gap between the guide tube 17 and the rubber sleeve 11. Finally, the core clamp 1 is installed, and one end of the guide tube 17 is set outside the core clamp 1 through the liquid flow channel 3. In order to prevent the gap between the guide tube 17 and the liquid flow channel 3 from leaking, it is also necessary to seal it. There are many ways to seal it, such as setting a sealant or setting a corresponding sealing ring, which belongs to conventional means in the field, so its specific operation will not be repeated here. Likewise, in this step, the sealant used may also be a two-component polysulfide sealing paste, or other sealants in the art.

[0024] Meanwhile, when setting the liquid flow channel 3, we can set a plurality of liquid flow channels 3 on the housing 101 in advance according to actual conditions, with the intersection of any diameter of the spherical core 12 and the surface of the spherical core 12 as the pole (equivalent to the South Pole and the North Pole of the earth), and the intersections of the plurality of liquid flow channels 3 and the spherical core 12 are set at different latitudes of the spherical core 12. When there are even a plurality of liquid flow channels 3 in advance, a sealing plug 16 is set on each liquid flow channel 3, and when the liquid flow channel 3 is not used, it is blocked by the sealing plug 16.

[0025] In other cases, in order to test the spherical core 12 from more angles and reduce the number of liquid flow channels 3, an annular rotating disk 14 is further provided between the two housings 101, and one end of the simulated wellbore 2 passes through the rotating disk 14 and is arranged inside the simulated well wall 13. The outer diameter of the rotating disk 14 is the same as the outer diameter of the housing 101, and the inner diameter of the rotating disk 14 is the same as the diameter of the pressure chamber 10. At the same time, a corresponding through hole is provided on the rotating disk 14, and one end of the simulated wellbore 2 can pass through the through hole and be arranged inside the simulated well wall 13. In this case, when the rotating disk 14 rotates, even if the position of the liquid flow channel 3 is not changed, the circumference on the spherical core 12 corresponding to the liquid flow channel 3 can be changed, and its permeability and conductivity can be tested from multiple angles and directions. Preferably, in order to facilitate the installation of the rotating disk 14, a plurality of positioning blocks 15 are provided on the rotating disk 14, and an annular positioning groove 20 matching the positioning blocks 15 is provided on the housing 101. During installation, the rotating disk 14 and the housing 101 can be installed through the positioning blocks 15 and the annular positioning groove 20. As for the confining pressure channel 9, its main function is to allow the confining pressure oil output by the confining pressure pump 6 to enter the pressure chamber 10 to apply confining pressure to the spherical core 12, which is a conventional setting.

[0026] The injection-production system is a conventional system in this field, and its specific structure will not be described in detail here.

[0027] Embodiment 2: A method for testing anisotropic permeability tensor without polarity, using the device of embodiment 1, the method comprising the following steps: S1, cutting a hole in the rubber sleeve 11 so that the guide tube 17 extends into the rubber sleeve 11, using a sealant to seal the guide tube 17 and the rubber sleeve 11, and after the sealing is completed, installing the equipment; S2, applying confining pressure to the pressure chamber 10 by the confining pressure pump 6, injecting fluid into the spherical core 12 at a constant speed by the injection pump 5, measuring the produced fluid of the flow guide tube 17 by the meter 7, and recording the pressure changes at the inlet and outlet of the spherical core during the experiment by the first pressure gauge 4 and the second pressure gauge 18. After the experiment, the pressure chamber 10 is depressurized; S3, remove the core holder 1 and the sealant, seal the hole on the rubber sleeve 11, then rotate the simulated wellbore 2, and repeat the operations of S1 and S2 until the permeability within the circumference of the hole is measured; in this process, the hole on the rubber sleeve 11 can be sealed with a currently commonly used rubber sealant, such as an acrylic sealant, and those skilled in the art can also use other sealing agents; S4, replace the new liquid flow channel 3, repeat S1-S3, and complete the non-polar permeability measurement of the core; S5. Calculate the permeability tensor: , where K xx , K yy , K zz There are three main permeability coefficients on the diagonal line, representing the degree of fluid penetration in the x, y, and z directions respectively, and are obtained by measuring the x, y, and z directions using test equipment; K xy , K xz , K yx , K yz , K zx , K zy represents the cross permeability coefficient between different directions. Since the permeability tensor has symmetry, K xy =K yx , K xz =K zx , K yz =K zy ; According to Darcy's law and matrix multiplication, the seepage velocity equation in each direction is obtained. According to the seepage velocity equation, K is obtained by solving it.xy , K xz and K yz : , In the formula, , , They are the pressure gradients in the X, Y, and Z directions. Under the premise of constant displacement, after the fluid flow rate stabilizes, we can get , , , the method of obtaining it is common knowledge in this field; is the fluid viscosity; V x 、V y 、V z They represent the seepage velocity components along the X, Y, and Z axes respectively, and can be obtained under the premise of constant pressure displacement. The solution is common knowledge in this field.

[0028] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A non-polar anisotropic permeability tensor testing device, characterized in that: include: A spherical core, wherein a rubber sleeve is provided on the outside of the spherical core and a simulated well wall is provided inside the spherical core; A core holder, the core holder is composed of a shell of at least two parts, and a pressure chamber is provided inside the core holder, the spherical core is arranged inside the pressure chamber, and a gap is provided between the spherical core and the inner wall of the core holder; the core holder is also provided with a simulated wellbore, one end of the simulated wellbore is arranged inside the simulated well wall, and the other end is arranged outside the core holder, when the simulated wellbore rotates, the spherical core is driven to rotate; the core holder is also provided with a plurality of liquid flow channels and a confining pressure channel, a flow guide tube is provided in the liquid flow channel, and one end of the flow guide tube is arranged inside the rubber sleeve; The injection-production system comprises an injection pump, a confining pressure pump and a meter, wherein the output end of the injection pump is connected to a first pressure gauge and a simulated wellbore in sequence, the output end of the confining pressure pump is connected to the confining pressure channel, and the meter is connected to a second pressure gauge and a flow guide pipe in sequence.

2. The device according to claim 1, characterized in that The core holder is composed of two hemispherical shells, and the pressure chamber is spherical.

3. The device according to claim 2, characterized in that An annular rotating disk is also arranged between the two shells, and one end of the simulated wellbore passes through the rotating disk and is arranged inside the simulated well wall.

4. The device according to claim 3, characterized in that The rotating disk is provided with a plurality of positioning blocks, and the shell is provided with an annular positioning groove matching with the positioning blocks.

5. The device according to claim 1, characterized in that A rubber sealing strip is arranged between two adjacent shells of the core clamp, and at least one clamping band for fastening the shells is also arranged on the core clamp.

6. The device according to claim 1, characterized in that A plurality of liquid flow channels are arranged on the multiple parts of the core holder, and any of the liquid flow channels is provided with a sealing plug.

7. A method for testing anisotropic permeability tensor without polarity, using the device of claim 1, comprising the following steps: S1. Cut a hole in the rubber sleeve so that the guide tube extends into the rubber sleeve, and seal the guide tube and the rubber sleeve with a sealant. After the sealing is completed, install the equipment; S2, applying confining pressure to the pressure chamber using a confining pressure pump, injecting fluid into the spherical core at a constant rate using an injection pump, measuring the produced fluid from the flow guide tube using a meter, and recording the pressure changes at the inlet and outlet of the spherical core during the experiment using a first pressure gauge and a second pressure gauge. After the experiment, the pressure chamber is depressurized; S3, remove the core holder and sealant, seal the hole on the rubber sleeve, then rotate the simulated wellbore, and repeat the operations of S1 and S2 until the permeability within the circumference of the hole is measured; S4, replace a new liquid flow channel, repeat S1-S3, and complete the non-polar permeability measurement of the spherical core; S5. Calculate the permeability tensor: , where K xx , K yy , K zz are the three main permeability coefficients on the diagonal line, representing the degree of fluid penetration in the x, y, and z directions respectively; K xy , K xz , K yx , K yz , K zx , K zy represents the cross permeability coefficient between different directions. Since the permeability tensor has symmetry, K xy =K yx , K xz =K zx , K yz =K zy ; According to Darcy's law and matrix multiplication, the seepage velocity equation in each direction is obtained. According to the seepage velocity equation, K is obtained by solving it. xy , K xz and K yz : ， In the formula, , , They are the pressure gradients in the X, Y, and Z directions. Under the premise of constant displacement, after the fluid flow rate stabilizes, we can get , , ; is the fluid viscosity; V x 、V y 、V z Represent the seepage velocity components along the X, Y, and Z axes respectively.

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