A non-polar anisotropic permeability tensor testing device and method

Abstract

The present invention discloses a non-polarized anisotropic permeability tensor measurement device and method, relating to the technical field of core testing devices. The device comprises a core holder and a spherical core. A simulated wellbore is provided through the spherical core, which can rotate with the simulated wellbore. The core holder is also provided with a flow guide tube and multiple fluid flow channels. During use, the non-polarized anisotropic permeability measurement of the core can be achieved by rotating the spherical core and changing the fluid flow channels, thereby completing the measurement of the core permeability tensor.

Description

Technical Field

[0001] The present 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] Because rock particles exhibit directional characteristics during deposition, anisotropy caused by the arrangement of their pores is ubiquitous. Permeability anisotropy is a fundamental characteristic of rock permeability. Almost all rocks exhibit some degree of anisotropy, albeit to varying degrees. This anisotropy significantly impacts oil and gas flow. During oil and gas field development and production, permeability fluctuations can cause production fluctuations. Therefore, accurately measuring the rock permeability tensor is crucial for exploration and development, as well as for studying oil well yields.

[0003] Currently, the most commonly used permeability tensor testing methods, both domestically and internationally, involve applying a displacement pressure differential across the end face of a cylindrical rock sample within a specifically shaped mold cavity, injecting fluid at a constant rate, measuring the pressure drop with a pressure sensor, and calculating the permeability tensor using the Darcy equation. Currently, much research has focused on two-dimensional permeability tensors, with a limited focus on three-dimensional permeability tensors. However, these traditional testing methods are often limited to permeability testing in a single direction, making it difficult to comprehensively and accurately obtain anisotropic permeability tensors. Therefore, the development of a non-polarized anisotropic permeability tensor testing device and method is of great significance. Summary of the Invention

[0004] 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:

[0006] A spherical core, wherein a rubber sleeve is provided on the outside of the spherical core and a simulated well wall is provided on the inside of the spherical core;

[0007] A core holder, the core holder being composed of a shell having at least two parts, and a pressure chamber being provided inside the core holder, the spherical core being disposed inside the pressure chamber, and a gap being provided between the spherical core and the inner wall of the core holder; the core holder also being provided with a simulated wellbore, one end of which is disposed inside the simulated wellbore wall and the other end of which is disposed outside the core holder, and when the simulated wellbore rotates, the spherical core is driven to rotate; the core holder also being provided with a plurality of liquid flow channels and a confining pressure channel, a flow guide tube being provided in the liquid flow channel, one end of which is disposed inside the rubber sleeve;

[0008] The injection-production system includes an injection pump, a confining pressure pump and a meter. 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. The meter is connected to a second pressure gauge and a flow guide pipe in sequence.

[0009] In one embodiment of the present invention, the core holder is composed of two hemispherical shells, and the pressure chamber is spherical.

[0010] 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 well wall.

[0011] 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.

[0012] In one embodiment of the present invention, a rubber sealing strip is provided between two adjacent shells of the core holder, and the core holder is further provided with at least one clamping band for fastening the shells.

[0013] In one embodiment of the present invention, 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.

[0014] Another object of the present invention is to disclose a method for measuring anisotropic permeability tensor without polarity, using any of the above-mentioned devices, comprising the following steps:

[0015] 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 sealing, install the equipment.

[0016] S2. Apply confining pressure to the pressure chamber using a confining pressure pump, inject fluid into the spherical core at a constant rate using an injection pump, measure the produced fluid from the flow tube using a meter, and simultaneously record 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, depressurize the pressure chamber;

[0017] 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;

[0018] S4, replace the new liquid flow channel and repeat S1-S3 to complete the stepless permeability measurement of the spherical core;

[0019] S5. Calculate the permeability tensor: , where K xx , K yy , K zzThe three main permeability coefficients on the diagonal line represent 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 ;

[0020] 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 :

[0021] ,

[0022] Where, , , 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 They represent the seepage velocity components along the X, Y, and Z axes respectively.

[0023] Beneficial Effects: The non-polarized anisotropic permeability tensor testing device provided by the present invention first requires grinding a rock sample into a spherical core, then installing a rubber sleeve. Through the combined action of a core holder and an injection-production system, the fluid flow rate, seepage velocity, and permeability along three principal axes are measured. Finally, the permeability tensor formula is used to calculate the permeability tensor of the spherical core. The device is simple, easy to operate, and highly applicable.

[0024] 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

[0025] Figure 1 Schematic diagram of the overall structure of the device of Example 1;

[0026] Figure 2 This is a cross-sectional view of the core holder of Example 1 when no rotating disk is provided;

[0027] Figure 3 This is a cross-sectional view of the core holder of Example 1 when a rotating disk is provided;

[0028] 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.

[0029] 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 well wall, 14 is a rotating disk, 15 is a positioning block, 16 is a sealing plug, 17 is a flow guide tube, 18 is a second pressure gauge, 19 is a rubber sealing strip, and 20 is an annular positioning groove. DETAILED DESCRIPTION

[0030] The specific implementation methods of the present invention will be clearly and completely described below with reference to examples and drawings. Obviously, the described examples are only some embodiments of the present invention, rather than all embodiments.

[0031] Example 1: Figure 1-Figure 4 As shown, a non-polar anisotropic permeability tensor testing device comprises:

[0032] A spherical core 12, wherein a rubber sleeve 11 is provided on the outside of the spherical core 12 and a simulated wellbore wall 13 is provided inside the spherical core 12;

[0033] A core holder 1 is composed of a shell 101 having at least two parts, and a pressure chamber 10 is provided inside the core holder 1. The spherical core 12 is disposed 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 which is disposed inside the simulated wellbore wall 13 and the other end is disposed 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 multiple 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 disposed inside the rubber sleeve 11.

[0034] 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 diversion pipe 17 in sequence.

[0035] Specifically, in this embodiment, when preparing the spherical core 12, a rock block with a uniform texture and no obvious cracks or impurities should be selected, and then cut and polished to an appropriate size. Generally speaking, considering subsequent experimental operations, the size of the spherical core 12 is generally from a few dozen centimeters to several dozen centimeters. Those skilled in the art can select the appropriate size of the spherical core 12 based on actual conditions.

[0036] As 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.

[0037] 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 field, so the rubber sleeves commonly used in the field can be used.

[0038] The core holder 1 is composed of at least two shells 101, such as two or three parts. However, considering practical operation, in this embodiment, two hemispherical shells 101 are provided with hemispherical grooves therein. When the two hemispherical shells 101 are combined, the two hemispherical grooves form a relatively sealed pressure chamber 10. Of course, those skilled in the art may also use shells and grooves of other shapes, such as a square shell and a square groove. However, since calculating angles for a square shell is relatively difficult, those skilled in the art may choose a suitable method based on practical needs. Furthermore, those skilled in the art will appreciate that, to enhance the sealing performance of the core holder 1 composed of two shells 101, a corresponding rubber sealing strip 19 may be provided between the shells 101, and a clamping band 8 may be provided on the exterior of the shells 101 to secure the shells 101. Of course, those skilled in the art may also use other components capable of securing the shells 101, such as tabs and bolts provided on the shells 101. Those skilled in the art may select an appropriate fastening method based on practical needs.

[0039] The outer diameter of the simulated wellbore 2 is the same as the inner diameter of the simulated wellbore wall 13, and a material with high 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, because one end of the simulated wellbore 2 needs to pass through the rubber sleeve 11 and be located inside the simulated wellbore 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. Those skilled in the art can select a suitable sealant based on actual conditions.

[0040] 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: cut and drill a hole on the rubber sleeve 11, then insert the guide tube 17 into the rubber sleeve 11, and then use a sealant to seal the gap between the guide tube 17 and the rubber sleeve 11. Finally, install the core clamp 1 and make one end of the guide tube 17 be 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. It is a conventional method in this field, so its specific operation will not be described in detail here. Likewise, in this step, the sealant used may also be a two-component polysulfide sealing paste, or other sealants in the art.

[0041] Furthermore, when providing the liquid flow channels 3, multiple liquid flow channels 3 can be pre-installed on the housing 101 based on practical circumstances, with the intersection of any diameter of the spherical core 12 and the surface of the spherical core 12 serving as the pole (equivalent to the South Pole and the North Pole of the Earth). The intersections of the multiple liquid flow channels 3 with the spherical core 12 are located at different latitudes of the spherical core 12. When multiple liquid flow channels 3 are pre-installed, a sealing plug 16 is provided on each liquid flow channel 3. When the liquid flow channel 3 is not in use, the sealing plug 16 is used to block it.

[0042] In other cases, in order to test the spherical core 12 from more angles while reducing the number of fluid flow channels 3, an annular rotating disk 14 is further provided between the two housings 101. One end of the simulated wellbore 2 passes through the rotating disk 14 and is located within the simulated wellbore 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. Corresponding through-holes are provided on the rotating disk 14, through which one end of the simulated wellbore 2 can pass and be located within the simulated wellbore wall 13. In this case, when the rotating disk 14 rotates, even if the position of the fluid flow channel 3 is not changed, the circumference of the spherical core 12 corresponding to the fluid flow channel 3 can be changed, allowing the permeability and conductivity of the spherical core 12 to 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.

[0043] 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. This is a conventional setting.

[0044] The injection-production system is a conventional system in this field, and its specific structure will not be described in detail here.

[0045] Example 2: A method for measuring anisotropic permeability tensor without polarity, using the apparatus of Example 1, comprising the following steps:

[0046] S1. Cut a hole in the rubber sleeve 11 so that the guide tube 17 extends into the rubber sleeve 11. Use a sealant to seal the guide tube 17 and the rubber sleeve 11. After sealing, install the equipment.

[0047] S2. The confining pressure pump 6 applies confining pressure to the pressure chamber 10, the injection pump 5 injects fluid into the spherical core 12 at a constant rate, the meter 7 measures the produced fluid from the flow guide tube 17, and the first pressure gauge 4 and the second pressure gauge 18 record the pressure changes at the inlet and outlet of the spherical core during the experiment. After the experiment, the pressure chamber 10 is depressurized.

[0048] S3. Remove the core holder 1 and the sealant, seal the holes 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 holes on the rubber sleeve 11 can be sealed with a commonly used rubber sealant, such as acrylic sealing paste. Those skilled in the art may also use other sealing agents.

[0049] S4, replace the new liquid flow channel 3, repeat S1-S3, and complete the core non-step permeability measurement;

[0050] S5. Calculate the permeability tensor: , where K xx , K yy , K zz The three main permeability coefficients on the diagonal line represent 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;

[0051] 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 :

[0052] ,

[0053] Where, , , 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.

[0054] The above description is merely 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 this profession can make some changes or modifications to equivalent embodiments of the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications 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 are still 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 on the inside of the spherical core; A core holder, the core holder being composed of a shell having at least two parts, and a pressure chamber being provided inside the core holder, the spherical core being disposed inside the pressure chamber, and a gap being provided between the spherical core and the inner wall of the core holder; the core holder also being provided with a simulated wellbore, one end of which is disposed inside the simulated wellbore wall and the other end of which is disposed outside the core holder, and when the simulated wellbore rotates, the spherical core is driven to rotate; the core holder also being provided with a plurality of liquid flow channels and a confining pressure channel, a flow guide tube being provided in the liquid flow channel, one end of which is disposed inside the rubber sleeve; The injection-production system includes an injection pump, a confining pressure pump and a meter. 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. 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 provided between the two shells, and one end of the simulated wellbore passes through the rotating disk and is provided 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 the positioning blocks.

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

6. The device according to claim 1, characterized in 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.

7. A method for measuring anisotropic permeability tensor using the apparatus 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 sealing, install the equipment. S2. Apply confining pressure to the pressure chamber using a confining pressure pump, inject fluid into the spherical core at a constant rate using an injection pump, measure the produced fluid from the flow tube using a meter, and simultaneously record 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, depressurize the pressure chamber; 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 the new liquid flow channel and repeat S1-S3 to complete the stepless 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 : ， Where, , , 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 They represent the seepage velocity components along the X, Y, and Z axes respectively.

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