A shale swelling performance evaluation device and method

Abstract

The present application relates to a kind of shale expansion performance evaluation device and method.The device includes cup body with cup mouth upward and cup cover with cup body sealing cooperation, the cup body includes side wall and bottom wall, the side wall and bottom wall of cup body form inner cavity for containing core and to be measured liquid;Side wall of cup body is equipped with liquid level measuring tube that extends to the outer wall surface of cup body side wall and extends upward, scale line is engraved on liquid level measuring tube, the diameter of liquid level measuring tube is less than the diameter of cup body, the upper end surface of liquid level measuring tube is higher than the cup mouth of cup body;The shale expansion performance evaluation device is also provided with liquid injection port for injecting to be measured liquid into the inner cavity.The device realizes the contact and penetration of core and to be measured liquid in the inner cavity of cup body, the expansion of core causes the change of liquid level of test solution in cup body, the change is accurately read out by the liquid level measuring tube with small diameter, and then it is favorable to improve the test efficiency of shale expansion test, improve the accuracy of test result.

Description

Technical Field

[0001] This invention belongs to the field of shale expansion performance testing, specifically relating to a device and method for evaluating shale expansion performance. Background Technology

[0002] One of the important functions of drilling fluids is to inhibit the expansion of shale in the formation upon contact with water, maintain wellbore stability, and prevent accidents such as wellbore narrowing, collapse, and stuck pipe. Accurately evaluating the shale expansion performance or the expansion inhibition effect of drilling fluids and chemicals is crucial for the optimal selection of inhibitors and other chemical agents.

[0003] Existing methods for evaluating shale swelling mainly include the linear swelling method and the rock cuttings recovery rate method.

[0004] The linear expansion method utilizes Figure 1 The experimental apparatus shown involves adding a test solution to a core cylinder 3 containing an artificial core 4 made of bentonite. The hydration and expansion of the artificial core 4 causes an increase in the axial displacement of the upper surface. The displacement changes before and after the addition of the test solution are measured by the displacement transmission rod 1 and the displacement tester 2. The expansion performance of shale or the expansion inhibition effect of drilling fluid and chemical agents are calculated and evaluated based on the core expansion displacement data.

[0005] The test steps of the linear expansion method are as follows: Add 10.0g of bentonite to the steel core cylinder 3, place it under a press and press it for 5 minutes at 8MPa using a steel piston; install the core cylinder 3 together with the pressed artificial core 4 on the linear shale expansion tester; place the displacement rod 1 with the base plate 5 into the core cylinder 3 and make it contact the upper surface of the artificial core 4. After connecting the displacement rod 1 to the lower end of the displacement tester 2, add the test liquid into the core cylinder and start timing; after the predetermined time is reached, read the expansion displacement data of the artificial core (simultaneously test the expansion data of the blank test liquid and the test liquid); calculate and evaluate the shale expansion performance or the expansion inhibition effect of drilling fluid and chemical agent.

[0006] The linear expansion method for evaluating the expansion performance of shale has the following shortcomings: First, the contact area between the test solution and the core is small (only contacting the upper surface of the artificial core), resulting in insufficient penetration of the test solution and even core drying. This leads to a smaller absolute displacement value, directly affecting the repeatability of the test results. Second, because the test solution only contacts the upper surface of the artificial core, the penetration rate of the test solution and the expansion rate of the core are slow, resulting in low test efficiency (test time is generally 8-24 hours). Third, the hydrated core is relatively soft with low expansion force; the weight of the metal displacement rod itself offsets some of the core expansion force, affecting the displacement data transmitted by the sensor. Fourth, the flexibility of the displacement rod and the sensitivity of the displacement sensor are not high, significantly affecting the repeatability of the test results. All these factors contribute to the low accuracy and efficiency of the linear expansion method in testing the expansion performance of shale. Summary of the Invention

[0007] The purpose of this invention is to provide a shale expansion performance evaluation device, thereby solving the problem of poor accuracy of evaluation results in existing shale expansion performance evaluation devices.

[0008] The second objective of this invention is to provide a method for evaluating the expansion performance of shale, thereby solving the problems of poor test accuracy and low test efficiency of existing testing methods.

[0009] To achieve the above objectives, the technical solution adopted by the shale expansion performance evaluation device of the present invention is as follows:

[0010] A shale expansion performance evaluation device includes a cup body with its opening facing upwards and a cup lid that seals with the cup body. The cup body includes a side wall and a bottom wall, which together form an inner cavity for holding a rock core and a liquid to be tested. A liquid level measuring tube is provided on the side wall of the cup body, extending upwards from the outer surface of the side wall. The liquid level measuring tube is engraved with scale lines, and its diameter is smaller than that of the cup body. The upper end of the liquid level measuring tube is higher than the opening of the cup body. The shale expansion performance evaluation device is also provided with an injection port for injecting the liquid to be tested into the inner cavity.

[0011] The shale expansion performance evaluation device provided by this invention achieves contact and penetration between the core and the test liquid within the inner cavity of the cup. The contact surface between the core and the test liquid is larger than that of the linear expansion method, which can promote the penetration of the test liquid and reduce interference factors on the core expansion. The expansion of the core causes a change in the liquid level of the test liquid within the cup, which can be accurately read through a small-diameter liquid level measuring tube, thereby improving the test efficiency and accuracy of the shale expansion test.

[0012] To facilitate liquid injection and establish a connection with the liquid level measuring tube on the side wall of the cup, preferably, the cup lid is also equipped with an injection tube extending vertically, communicating with the inner cavity when the lid and cup body are closed. The upper end of the injection tube is higher than the upper end of the cup lid, and the inlet of the injection tube forms the injection port. This injection tube, by establishing a connection with the liquid level measuring tube, facilitates the removal of gas from the cup during injection, not only simplifying the injection process but also ensuring that changes in the liquid level accurately reflect the expansion and contraction of the artificial rock core.

[0013] To facilitate liquid injection, the injection tube includes a straight section and a funnel-shaped inlet section connected to the upper end of the straight section, with the inlet of the funnel-shaped inlet section forming the injection port.

[0014] To further improve the accuracy of liquid level reading, facilitate the verification and comparison of the read data, and facilitate the leveling of the device, preferably, the injection tube is also engraved with liquid level marking lines corresponding to the scale lines of the liquid level measuring tube.

[0015] Preferably, the initial graduation of the scale line is higher than the upper surface of the cup. This way, when adding liquid, the liquid to be tested can be added to the initial graduation, ensuring that the cup is full of liquid and allowing for more accurate and intuitive reading of the liquid level change after the core expands.

[0016] To further improve the contact between the artificial core and the liquid to be tested and to promote the full penetration of the test liquid, preferably, the inner cavity is also provided with a core tray that is parallel to and spaced apart from the bottom wall of the cup. The core tray is engraved with multiple through holes, and the upper end surface of the core tray forms a bearing surface for supporting the core.

[0017] To simplify the arrangement of the tray and facilitate the handling of the core samples, preferably, the core tray is fixed to a hook by multiple pull rods connected around the perimeter of the core tray, and a lifting ring is provided on the lower end face of the cup lid. The hook and the lifting ring are engaged to achieve the parallel spacing between the tray and the bottom wall of the cup.

[0018] The technical solution adopted in the shale expansion performance evaluation method of the present invention is as follows:

[0019] A method for evaluating the expansion performance of shale includes the following steps: placing a core in a measuring cup, adding a test liquid to the measuring cup to immerse the core, measuring the liquid level change of the test liquid after a specified time, and calculating the volume expansion of the core based on the liquid level change data.

[0020] The shale expansion performance evaluation method provided by this invention measures the expansion change of the core after contact with the test liquid using the volume expansion method. The contact area between the test liquid and the core is large and the penetration is fast, which can shorten the test time (less than 2 hours) and improve the test efficiency. In addition, compared with the linear expansion method, this method has fewer interference factors and can more accurately test the expansion change of the core, thus improving the test accuracy. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a conventional linear expansion method testing instrument;

[0022] Figure 2 This is a schematic diagram of an embodiment of the shale expansion performance evaluation device of the present invention;

[0023] Figure 3 This is a schematic diagram of the test principle of an embodiment of the shale expansion performance evaluation method of the present invention - the core sample before expansion;

[0024] Figure 4 This is a schematic diagram of the test principle of an embodiment of the shale expansion performance evaluation method of the present invention - the rock core after expansion;

[0025] In the diagram, 1-displacement transmission rod, 2-displacement tester, 3-core cylinder, 4-artificial core, 5-base plate, 6-cup body, 7-cup lid, 8-liquid level measuring tube, 80-scale line, 9-liquid injection measuring tube, 90-liquid level marking line, 10-tray, 11-core to be tested, 110-core to be tested before expansion, 111-core to be tested after expansion. Detailed Implementation

[0026] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0027] Specific embodiments of the shale expansion performance evaluation device of the present invention are as follows: Figure 2 As shown, the device includes a cup body 6 with its opening facing upwards and a cup lid 7 that seals with the cup body 6. The cup body 6 includes a cylindrical side wall and a bottom wall, which together form an inner cavity for holding the core sample and the liquid to be tested. A liquid level measuring tube 8 is provided on the cylindrical side wall of the cup body 6, extending upwards from the outer surface of the cylindrical side wall. The liquid level measuring tube 8 includes a bent section connected to the cylindrical side wall and communicating with the inner cavity, a vertically upward-extending liquid level measuring section connected to the upper end of the bent section, and a funnel-shaped opening section connected to the upper end of the liquid level measuring section. The liquid level measuring tube 8 is engraved with graduation lines 80. The diameter of the liquid level measuring tube 8 is smaller than the diameter of the cup body 6, and the upper end face of the liquid level measuring tube 8 is higher than the opening of the cup body 6.

[0028] A liquid metering tube 9 is vertically inserted into the cup lid 7, penetrating the cup lid 7. The liquid metering tube 9 includes a liquid level metering section extending in the vertical direction and a funnel-shaped opening section connected to the upper end of the liquid level metering section. The inlet of the funnel-shaped opening section forms a liquid injection port for injecting the liquid to be measured into the cup body 6.

[0029] The liquid level marking line 90 is engraved on the liquid level metering tube 9, corresponding to the scale line 80 on the liquid level metering tube 8. The scale line 80 and the liquid level marking line 90 have the same scale data in the horizontal direction. The initial scale of the scale line 80 and the liquid level marking line 90 is higher than the lower end face of the cup cover 7 when the cup body 6 is sealed. The final scale of the scale line 80 and the liquid level marking line 90 is higher than the upper end face of the cup cover 7.

[0030] The shale expansion performance evaluation device also includes a tray 10 for supporting the core sample 11 to be tested. The tray 10 is fixed to a hook by multiple tie rods evenly spaced around its perimeter. A lifting ring is provided on the lower end face of the cup lid 7, and the hook is hooked onto the lifting ring to suspend the tray 10 in the inner cavity of the cup body 6, achieving a parallel and spaced arrangement between the tray 10 and the bottom wall of the cup body 6. The tray 10 has through holes for the liquid to be tested to flow freely through, and the upper end face of the tray 10 forms a bearing surface for supporting the core sample 11 to be tested.

[0031] The usage process of the shale expansion performance evaluation device in this embodiment is as follows: Place the pressed artificial rock core in the middle of the tray 10, then suspend the tray 10 at the lower end of the cup lid 7, seal the cup lid 7 and the cup body 6 together, at this time the tray 10 is suspended in the inner cavity of the cup body 6; inject the liquid to be tested into the cup body 6 through the injection metering tube 9, stop the injection when the liquid reaches the initial scale (or a certain scale), and start timing. After the specified time, record the volume change data of the liquid to be tested.

[0032] Both the injection metering tube 9 and the level metering tube 8 are fine-diameter level metering tools, which can accurately reflect the level changes caused by the volume expansion of the core. In addition, the influence of different test liquids on the core expansion performance can be evaluated based on the level changes.

[0033] The combined use of the injection metering tube 9 and the level metering tube 8 can serve a leveling function. When the device is used on the construction site or in other situations, the levelness of the device can be verified by checking whether the liquid levels in the two metering tubes are aligned, thus more accurately reflecting minute changes in liquid level and volume. It can also serve a venting function. Since the inner diameters of the two metering tubes are both small, the interconnection between the injection metering tube 9 and the level metering tube 8 allows for venting through the other metering tube when liquid is injected through one of them, making liquid injection more convenient.

[0034] In other embodiments of the shale expansion performance evaluation device of the present invention, the liquid injection metering tube 9 on the cup cover 7 can be omitted, and two or more liquid level metering tubes can be symmetrically arranged on the side wall of the cup body 6 to achieve the functions of leveling, connecting and venting. Multiple support legs can be provided at the lower end of the tray 10 to directly support the tray 10 horizontally in the inner cavity of the cup body 6.

[0035] A specific embodiment of the shale expansion performance evaluation method of the present invention includes the following steps: placing the core in a measuring cup, adding the liquid to be tested to the measuring cup to immerse the core, measuring the liquid level change of the liquid to be tested after a specified time, and calculating the volume expansion of the core through the liquid level change data.

[0036] An evaluation diagram of the evaluation method in the embodiment is shown below. Figure 3 and Figure 4 As shown, Figure 3 The core sample 110 was in its state before expansion, with a volume of V1. After the liquid to be tested was added, the core underwent the following changes: Figure 4 The expansion shown in the figure results in the volume of the tested core 111 becoming V2 after expansion. The influence of this test liquid on the core expansion performance can be evaluated by the change in liquid level before and after expansion.

[0037] The volume change data of blank test solution and sample test solution can be calculated according to formula (1) and formula (2).

[0038] ΔV1=V1-V2(1);

[0039] ΔV2=V 1′ -V 2′ (2);

[0040] ΔV1 and ΔV2 represent the volume changes of the blank solution (water) and the sample solution (e.g., water + inhibitor), respectively. V1 and V2 represent the volumes of the blank solution before and after core expansion, respectively, in milliliters. 1′ V 2′ These represent the volume of sample solution before and after core expansion, respectively, in milliliters.

[0041] The relative inhibition rate of the inhibitor is calculated according to formula (3).

[0042]

[0043] In the formula, X is the relative inhibition rate, %.

[0044] The repeatability, reproducibility, and accuracy of the shale expansion performance evaluation device and method of the present invention will be explained below with reference to experimental examples.

[0045] Experimental Example 1

[0046] Four sulfonated asphalt samples were selected, and repeatability tests of shale expansion reduction rate were conducted using the shale expansion performance evaluation device and evaluation method described in the embodiment. The results are shown in Table 1.

[0047] Table 1. Repeatability test data (%) of the evaluation device and evaluation method of the embodiments on sulfonated asphalt.

[0048]

[0049] As can be seen from the test results in Table 1, for the four sulfonated asphalt samples, the range and maximum relative deviation of the evaluation results of the example are small, indicating that the repeatability of the evaluation results is good.

[0050] Experimental Example 2

[0051] Four potassium polyacrylamide salt samples were selected, and repeatability tests of shale swelling reduction rate were conducted using the shale swelling performance evaluation device and evaluation method described in the example. The results are shown in Table 2.

[0052] Table 2. Repeatability test data (%) of the evaluation apparatus and evaluation method for potassium polyacrylamide in the examples.

[0053]

[0054] As can be seen from the test results in Table 2, for the four potassium polyacrylamide salt samples, the maximum relative deviation of the repeatability data of the evaluation results of the embodiment is 0.45%, which is no greater than 0.6% (general standard requirements are no greater than 1.0%), indicating that the evaluation device and evaluation method of the embodiment have good repeatability.

[0055] Experimental Example 3

[0056] In six different laboratories, the shale swelling reduction rate reproducibility test was conducted on four sulfonated asphalt samples from Example 1 using the evaluation device and evaluation method of the embodiment. The test data are shown in Table 3.

[0057] Table 3. Reproducibility test data (%) of the evaluation apparatus and method used in the embodiments for sulfonated asphalt.

[0058]

[0059] As can be seen from the test data in Table 3, the maximum relative deviation of the reproducibility data of the evaluation device and evaluation method in the application embodiment is 1.17%, which is no greater than 1.2% (general standard requirements are no greater than 2.0%), indicating that the reproducibility of the evaluation device and evaluation method is good.

[0060] Test Example 4

[0061] In six different laboratories, the shale swelling reduction rate reproducibility test was conducted on four polyacrylamide potassium salt samples from Example 2 using the evaluation device and evaluation method of the example. The test data are shown in Table 4.

[0062] Table 4. Reproducibility test data (%) of the evaluation device and evaluation method in the embodiments.

[0063]

[0064] As can be seen from the test data in Table 4, the maximum relative deviation of the reproducibility data of the evaluation device and evaluation method in the application embodiment is 1.04%, which is no greater than 1.2% (general standard requirements are no greater than 2.0%), indicating that the reproducibility of the evaluation device and evaluation method is good.

[0065] Experimental Example 5

[0066] This experimental example compares the test results of different test methods with the rock cuttings recovery rate method.

[0067] The principle of the cuttings recovery method is as follows: Rock cuttings of a specific particle size are obtained from natural formation cores obtained at the drilling site through crushing. A certain amount of these cuttings is added to a test solution and placed in a sealed aging tank. A rolling test is then conducted in a rolling oven simulating the temperature and flow conditions under drilling conditions. During the rolling process, some components of the cuttings detach from the core under the influence of hydration expansion, dispersion, and fluid washing, becoming fine particles that enter the test solution. After a certain period, the test solution is removed, and the cuttings are washed and filtered using a standard test sieve to recover them. By calculating the change in the mass loss of the cuttings before and after the test, the swelling performance of the core or the swelling inhibition effect of the inhibitor is evaluated.

[0068] The rock cuttings recovery rate method uses rock cuttings made from real natural strata cores as the base material for testing. Although this method cannot be promoted as a standard method due to the difficulty in obtaining natural rock cores, its test results are closest to the actual field situation and best represent the true expansion performance or expansion inhibition effect of the sample under test.

[0069] This experiment selected seven drilling fluid chemicals as test samples. The volume expansion method, linear expansion method, viscosity method and cuttings recovery rate method used in this invention were compared with the test data. The results are shown in Table 5.

[0070] Table 5. Comparative experimental data (%) of different evaluation methods

[0071] Sulfonated asphalt 68.5 37.6 82.7 68.1 Shale Inhibitor XX-023 19.4 37.1 86.0 20.6 Potassium polyacrylamide 80.7 52.8 -19.2 78.4 Polyols 11.5 8.7 -9.6 11.0 Cationic asphalt powder 12.0 39.8 86.8 10.9 Potassium chloride 39.7 -15.7 65.6 38.5 polyamine 28.6 -4.9 12.4 27.2 Maximum deviation from the cuttings recovery rate method - 55.4 99.9 2.3

[0072] As can be seen from the results in Table 5, the evaluation device and method of the present invention are most consistent with the rock cuttings recovery rate method compared with the test data of the linear expansion method and the viscosity method (the maximum deviation is only 2.3%), indicating that the evaluation results of the evaluation method and evaluation device of the present invention are accurate.

Claims

1. A method for evaluating the expansion performance of shale, characterized in that, Includes the following steps: The core is placed in a measuring cup, and the liquid to be tested is added to the measuring cup to immerse the core. After a specified time, the change in the liquid level is measured, and the volume expansion of the core is calculated from the liquid level change data. During the evaluation, the volume of the core sample before expansion was V1. After the test liquid was added, the core expanded, and the volume of the core sample after expansion became V2. The effect of the test liquid on the expansion performance of the core was evaluated by the liquid level change before and after expansion. The volume change data of the blank test liquid and the sample test liquid were calculated according to formulas (1) and (2): ΔV1=V1-V2(1; ΔV2=V 1′ -V 2′ (2); ΔV1 and ΔV2 represent the volume changes of the blank solution and the sample solution, respectively. V1 and V2 represent the volumes of the blank solution before and after core expansion, respectively, in milliliters. 1′ V 2′ These are the sample solution volumes before and after core expansion, respectively, in milliliters; the sample solution includes water and inhibitor. The relative inhibition rate of the inhibitor is calculated according to equation (3): （3）； In the formula, X is the relative inhibition rate, %.

2. An evaluation device for implementing the shale expansion performance evaluation method as described in claim 1, characterized in that, The device includes a cup body with its opening facing upwards and a lid that seals with the cup body. The cup body includes a side wall and a bottom wall, which together form an inner cavity for holding the core sample and the liquid to be tested. A liquid level measuring tube extends upwards from the outer surface of the side wall of the cup body, and is engraved with graduation lines. The diameter of the liquid level measuring tube is smaller than the diameter of the cup body, and its upper end is higher than the opening of the cup body. The lower end of the liquid level measuring tube connects to the side wall at the top of the cup body and is lower than the lower edge of the lid when in use. An injection tube extending vertically is inserted into the lid, communicating with the inner cavity when the lid is closed. The upper end of the injection tube is higher than the upper end of the lid, and its inlet forms an injection port. The injection tube is also engraved with liquid level markings corresponding to the graduation lines of the liquid level measuring tube. The shale expansion performance evaluation device also includes an injection port for injecting the liquid to be tested into the inner cavity.

3. The evaluation device as described in claim 2, characterized in that, The injection tube includes a straight section and a funnel-shaped inlet section connected to the upper end of the straight section, with the inlet of the funnel-shaped inlet section forming the injection port.

4. The evaluation device as described in claim 2, characterized in that, The initial graduation of the scale line is higher than the upper surface of the cup.

5. The evaluation device as described in claim 2, characterized in that, The inner cavity is also provided with a core tray that is parallel to and spaced apart from the bottom wall of the cup. The core tray is engraved with multiple through holes, and the upper end surface of the core tray forms a bearing surface for bearing the core.

6. The evaluation device as described in claim 5, characterized in that, The core tray is fixed to a hook by multiple pull rods connected around the core tray. A lifting ring is provided on the lower end face of the cup lid. The hook and the lifting ring are engaged to achieve the parallel spacing between the tray and the bottom wall of the cup.

Images