Drilling fluid filtration performance evaluation device, testing method and mud cake preparation method

Abstract

The application provides a drilling fluid filtration performance evaluation device, a testing method and a mud cake preparation method. The drilling fluid filtration performance evaluation device comprises an upper cover, a barrel, a piston, a lower cover, a lower cover sealing ring, the upper cover is detachably connected to the upper end of the barrel, the piston is arranged in the barrel and can move along the axial direction of the barrel, the lower cover is detachably connected to the lower end of the barrel, the lower cover comprises a second fixing sleeve and a second forming block, the second fixing sleeve is detachably sleeved outside the second forming block, the second forming block is provided with an inner recess, and a chamfer is formed on the side wall of the inner recess; a through hole is formed in the second forming block, the upper hole of the through hole is formed on the inner recess, and the lower hole is formed on the lower end face of the second forming block; the upper end of the lower cover sealing ring is in abutment with the lower end of the barrel, and the lower end is in abutment with the chamfer; through the cooperation of the chamfer and the sealing ring, the side of the mud cake is not in complete contact with the inner wall of the forming block, space is left for taking the mud cake, complete sampling is realized, and the experimental efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas development experiment devices, in particular to a drilling fluid filtration performance evaluation device, a testing method and a mud cake preparation method. BACKGROUND

[0002] The drilling fluid filtration instrument can simulate the filtration amount of drilling fluid and cement slurry under deep well (high temperature and high pressure) and prepare the filter cake after filtration under high temperature and high pressure. The drilling fluid filtration instrument has the characteristics of high precision, small repeated error, simple operation and accurate test data, and is widely used in oil fields, scientific research institutes and laboratories.

[0003] The high temperature and high pressure drilling fluid filtration instrument is widely used in drilling fluid laboratories. The performance evaluation of the mud cake prepared by the high temperature and high pressure drilling fluid filtration instrument is an important means and index for reflecting the performance of the drilling fluid. In particular, in the experiment of evaluating the plugging performance of the drilling fluid, the drilling fluid needs to be injected to evaluate the filtration amount and filtration speed, and the complete mud cake needs to be taken out for observation after the test is completed. In the process of taking out the mud cake, it is difficult to avoid damaging the mud cake whether the high temperature and high pressure autoclave is disassembled to pour out the mud cake from the lower part of the autoclave body or the high temperature and high pressure autoclave is inverted to take out the mud cake from the upper part of the autoclave body, and the operation needs to be extremely careful.

[0004] The Chinese patent document with the publication number "CN206593932U" "Drilling fluid injection and mud cake taking out device of high temperature and high pressure filtration instrument" discloses a mud cake preparation device structure. When the drilling fluid injection operation is performed, the filter screen in the spacer tube can effectively reduce the damage of the drilling fluid poured into the device to the mud cake formed in the high temperature and high pressure filtration instrument autoclave body. When the mud cake taking out operation is performed, the filter screen and the paper sheet in the spacer tube can buffer the descent of the mud cake in the high temperature and high pressure filtration instrument autoclave body, effectively guaranteeing the integrity of the taken-out mud cake and the preparation of the mud cake. However, the mud cake is in close contact with the inner wall, and the mud cake is also easy to be damaged when the mud cake is taken out, and there is a technical problem that the mud cake cannot be taken out completely. SUMMARY

[0005] The present application aims to solve at least one of the above-mentioned deficiencies in the prior art. For example, one of the purposes of the present application is to provide a drilling fluid filtration performance evaluation device, a testing method and a mud cake preparation method. Through the structural design of the filtration device and the simple disassembly of the mud cake preparation and testing method, the function of obtaining a complete mud cake under high temperature and high pressure conditions is realized.

[0006] In order to achieve the above-mentioned purposes, the technical solutions of the present application are as follows:

[0007] The application discloses a device for evaluating the filtration performance of a drilling fluid, which comprises an upper cover, a barrel, a piston, a lower cover and a lower cover sealing ring.

[0008] Optionally, the upper cover further comprises an upper cover bolt, a first screw hole is formed in the first fixing sleeve, the upper cover bolt is arranged in the first screw hole and can push the first forming block to move downward along the axis.

[0009] Optionally, the upper cover further comprises a first clamping spring, a first ring groove is formed in the outer wall of the first forming block outside the first fixing sleeve, the inner edge of the first clamping spring is embedded in the first ring groove, the inner diameter of the first clamping spring matches the bottom diameter of the first ring groove, the outer diameter of the first clamping spring is larger than the inner diameter of the first through hole, and a center hole is formed in the first forming block and penetrates the upper and lower ends of the first forming block.

[0010] Optionally, the lower cover further comprises a lower cover bolt, a second screw hole is formed in the second fixing sleeve, the lower cover bolt is arranged in the second screw hole and can push the second forming block to move upward along the axis.

[0011] Optionally, the lower cover further comprises a second clamping spring, a second ring groove is formed in the outer wall of the second forming block outside the second fixing sleeve, the inner edge of the second clamping spring is embedded in the second ring groove, the inner diameter of the second clamping spring matches the bottom diameter of the second ring groove, and the outer diameter of the second clamping spring is larger than the inner diameter of the second through hole.

[0012] Optionally, an up-down through air hole can be formed in the piston, the air hole comprises an air hole upper section and an air hole lower section, the inner diameter of the air hole upper section is larger than that of the air hole lower section, a plug is detachably arranged in the air hole upper section, and the outer wall of the plug is attached to the inner wall of the air hole upper section.

[0013] Optionally, a plurality of piston sealing grooves can be formed in the outer wall of the piston, and a piston sealing ring is arranged in each piston sealing groove.

[0014] Optionally, the piston sealing groove can comprise a first piston sealing groove and a second piston sealing groove, the first piston sealing groove being arranged at the upper end of the outer wall of the piston, and the second piston sealing groove being arranged at the lower end of the outer wall of the piston; and the upper end of the piston is provided with a piston threaded hole, which is a blind hole.

[0015] Optionally, the material of the lower cover sealing ring can be polytetrafluoroethylene.

[0016] Optionally, the upper end surface of the barrel can be provided with a barrel sealing groove, and a barrel sealing ring is arranged in the barrel sealing groove.

[0017] A mud cake preparation method based on the drilling fluid filtration performance evaluation device.

[0018] Optionally, the mud cake preparation method can comprise the following steps:

[0019] Put the rock plate into the inner recessed table in the lower cover, and wrap the lower cover sealing ring outside the rock plate, connect the lower cover with the lower end of the barrel, and tighten the lower cover bolt if the lower cover comprises a lower cover bolt;

[0020] Preheat the lower cover sealing ring;

[0021] Close the through hole on the second forming block, pour mud into the barrel, press the piston into the barrel, connect the upper cover with the upper end of the barrel, and heat the barrel;

[0022] Heat the barrel, and when the temperature reaches a preset temperature value, pressurize the inside of the barrel, and when the pressure reaches a preset pressure value and is stable, open the through hole on the second forming block every interval to release liquid while collecting the released liquid;

[0023] Stop heating the barrel, release the pressure in the barrel, and loosen the lower cover bolt if the lower cover comprises a lower cover bolt;

[0024] Pressurize the barrel, stop pressurizing and release the pressure in the barrel when mud spills out of the connection between the lower cover and the barrel, unscrew the lower cover, and observe whether the mud cake is complete after cleaning the mud, if not, repeat the above experimental steps until the mud cake is complete;

[0025] Clean the mud around the mud cake, take out the rock plate, and remove the lower cover sealing ring on the rock plate to obtain the mud cake.

[0026] A drilling fluid filtration performance test method based on the drilling fluid filtration performance evaluation device.

[0027] Optionally, the drilling fluid filtration performance test method can comprise the following steps:

[0028] Step S1: Put the rock plate with mud cake into the inner recess table in the lower cover, install the lower cover at the lower end of the cylinder and add water in the cylinder to submerge the mud cake surface;

[0029] Step S2: Preheat the lower cover gasket;

[0030] Step S3: Fill the cylinder with water, install the upper cover at the upper end of the cylinder, heat the cylinder, and when the temperature reaches the preset temperature value, pressurize the inside of the cylinder, and when the pressure reaches the preset pressure value and is stable, open the through hole on the second forming block every interval time length to release liquid while collecting the released liquid;

[0031] Step S4: Stop heating the cylinder, release the pressure in the cylinder, and in the case that the lower cover comprises a lower cover bolt, loosen the lower cover bolt;

[0032] Step S5: Pressurize the cylinder, and when there is mud overflow at the connection between the lower cover and the cylinder, stop pressurizing and release the pressure in the cylinder, unscrew the lower cover, clean the mud around the mud cake, take out the rock plate, remove the lower cover gasket on the rock plate, and weigh and measure the taken-out rock plate;

[0033] Repeat steps S2-S5 to test the filtration water performance of the mud cake.

[0034] Optionally, the step of preheating the lower cover gasket can comprise:

[0035] Assemble the lower cover, lower cover gasket, rock plate and cylinder and heat to a preset temperature;

[0036] Tighten the lower cover on the cylinder and maintain at the preset temperature for a set time length;

[0037] Tighten the lower cover bolt and end the preheating.

[0038] Optionally, the preset temperature can be 110°C and the set time length can be 10 minutes.

[0039] Optionally, the preset temperature value can be ≤150°C and the preset pressure value can be between 5-20 Mpa.

[0040] Compared with the prior art, the beneficial effects of the present application include at least one of the following:

[0041] The drilling fluid filtration performance evaluation device of the present application is designed by matching the chamfer and the sealing ring, so that the mud cake side surface is not in complete contact with the inner wall of the forming block, and the mud cake taking space is left when the mud cake is taken, the complete sampling of the mud cake is realized, the experimental efficiency is improved, and in addition, the components in the drilling fluid filtration performance evaluation device of the present application are designed in a detachable structure, convenient to use, and wide in application range. BRIEF DESCRIPTION OF DRAWINGS

[0042] The above and other objects and / or characteristics of the present application will become more apparent by describing in detail the best mode for carrying out the present application with reference to the attached drawings, in which:

[0043] Figure 1 The drilling fluid filtration performance evaluation device of the present application is designed by matching the chamfer and the sealing ring, so that the mud cake side surface is not in complete contact with the inner wall of the forming block, and the mud cake taking space is left when the mud cake is taken, the complete sampling of the mud cake is realized, the experimental efficiency is improved, and in addition, the components in the drilling fluid filtration performance evaluation device of the present application are designed in a detachable structure, convenient to use, and wide in application range.

[0044] Figure 2 The drilling fluid filtration performance evaluation device of the present application is designed by matching the chamfer and the sealing ring, so that the mud cake side surface is not in complete contact with the inner wall of the forming block, and the mud cake taking space is left when the mud cake is taken, the complete sampling of the mud cake is realized, the experimental efficiency is improved, and in addition, the components in the drilling fluid filtration performance evaluation device of the present application are designed in a detachable structure, convenient to use, and wide in application range.

[0045] Fig. 3(a) shows a cross-sectional view of the lower cover in the drilling fluid filtration performance evaluation device of the present application.

[0046] Fig. 3(b) shows a top view of the second forming block in the drilling fluid filtration performance evaluation device of the present application.

[0047] Figure 4 The drilling fluid filtration performance evaluation device of the present application is designed by matching the chamfer and the sealing ring, so that the mud cake side surface is not in complete contact with the inner wall of the forming block, and the mud cake taking space is left when the mud cake is taken, the complete sampling of the mud cake is realized, the experimental efficiency is improved, and in addition, the components in the drilling fluid filtration performance evaluation device of the present application are designed in a detachable structure, convenient to use, and wide in application range.

[0048] Figure 5 The drilling fluid filtration performance evaluation device of the present application is designed by matching the chamfer and the sealing ring, so that the mud cake side surface is not in complete contact with the inner wall of the forming block, and the mud cake taking space is left when the mud cake is taken, the complete sampling of the mud cake is realized, the experimental efficiency is improved, and in addition, the components in the drilling fluid filtration performance evaluation device of the present application are designed in a detachable structure, convenient to use, and wide in application range.

[0049] BRIEF DESCRIPTION OF DRAWINGS

[0050] 100 - upper cover, 110 - first fixed sleeve, 111 - first through hole, 112 - first screw hole, 120 - first forming block, 121 - center hole, 122 - first ring groove, 130 - first snap spring, 140 - upper cover bolt;

[0051] 200 - cylinder, 210 - cylinder sealing groove;

[0052] 300 - piston, 310 - air hole, 311 - upper section of air hole, 312 - lower section of air hole, 320 - piston sealing groove, 321 - first piston sealing groove, 322 - second piston sealing groove, 330 - piston screw hole, 340 - plug;

[0053] 400 - lower cover, 410 - second fixing sleeve, 411 - second through hole, 412 - second screw hole, 420 - second forming block, 421 - inner recessed platform, 422 - chamfer, 423 - through hole, 424 - liquid guide groove, 425 - second ring groove, 430 - second clamping spring, 440 - lower cover bolt;

[0054] 500 - lower cover sealing ring. DETAILED DESCRIPTION

[0055] Hereinafter, the drilling fluid filtration performance evaluation device, the testing method and the mud cake preparation method of the present application will be described in detail in conjunction with exemplary embodiments.

[0056] It should be noted that "first", "second", "third", "fourth" and the like are merely for the convenience of description and differentiation, and cannot be understood as indicating or implying relative importance. "Upper", "lower", "inner", "outer", "front", "rear", "left", "right" are merely for the convenience of description and constitute relative positional relationship, and are not intended to indicate or imply that the components must have the specific orientation or position. For ordinary skilled persons in the art, the term "pressure" in this paper is equivalent to pressure.

[0057] In one aspect, the present application provides a drilling fluid filtration performance evaluation device, comprising: an upper cover, the upper cover comprising a first fixing sleeve and a first forming block, the first fixing sleeve being provided with a first through hole, and the first forming block being arranged in the first through hole; a cylinder, the upper end of the cylinder being connectable with the upper cover in a detachable manner; a piston, the piston being arranged in the cylinder, the outer wall of the piston being attached to the inner wall of the cylinder and being movable along the axial direction of the cylinder; a lower cover, the lower cover being connectable with the lower end of the cylinder in a detachable manner, the lower cover comprising a second fixing sleeve and a second forming block, the second fixing sleeve being provided with a second through hole, and the second forming block being arranged in the second through hole, the upper end surface of the second forming block being provided with an inner recessed platform, and the side wall of the inner recessed platform being formed with a chamfer; a through hole being formed in the second forming block, the upper aperture of the through hole being formed in the concave surface of the inner recessed platform, and the lower aperture being formed in the lower end surface of the second forming block; and a lower cover sealing ring, the upper end of the lower cover sealing ring being abuttable with the lower end of the cylinder, and the lower end being abuttable with the chamfer.

[0058] Figure 1 A cross-sectional view of the drilling fluid filtration performance evaluation device of the exemplary embodiment of the present application is shown.

[0059] As shown in the Figure 1 The drilling fluid filtration performance evaluation device comprises an upper cover 100, a cylinder 200, a piston 300, a lower cover 400, and a lower cover sealing ring 500.

[0060] In the embodiment, the inner wall of the upper cover 100 is provided with an internal thread, the outer wall of the upper end of the barrel 200 is provided with an external thread, and the upper cover 100 is sleeved on the outer wall of the upper end of the barrel 200 through the internal and external thread cooperation, but the present application is not limited to this, and the upper cover 100 can also be connected with the barrel 200 through other detachable connection modes such as interference fit.

[0061] The barrel 200 is a straight cylinder structure, the piston 300 is arranged in the barrel 200, the outer wall of the piston 300 is tightly attached to the inner wall of the barrel 200, and the piston 300 can freely move in the barrel 200 along the axis direction of the barrel 200.

[0062] In the embodiment, the outer wall of the lower end of the barrel 200 is also provided with an external thread, the inner wall of the lower cover 400 is provided with an internal thread, and the lower cover 400 can be sleeved on the lower end of the barrel 200 through the internal and external thread cooperation, but the present application is not limited to this, and the lower cover 400 can also be connected with the barrel 200 through other detachable connection modes such as interference fit.

[0063] Figure 2 A sectional view of the upper cover of the drilling fluid filtration performance evaluation device is shown.

[0064] As shown in FIGS. 1, 2 and 3, Figure 1 and Figure 2 The upper cover 100 includes a first fixed sleeve 110, a first forming block 120, a first clamping spring 130 and an upper cover bolt 140, the middle of the first fixed sleeve 110 is provided with a first through hole 111, the first forming block 120 is arranged in the first through hole 111, the first forming block 120 can freely move in the first through hole 111 along the axis, the outer wall of the upper end of the first fixed sleeve 110 is provided with a first ring groove 122, the first clamping spring 130 is annular structure, the inner edge of the first clamping spring 130 is embedded in the first ring groove 122, the inner diameter of the first clamping spring 130 is the same as the bottom diameter of the first ring groove 122, and the outer diameter of the first clamping spring 130 is greater than the outer diameter of the first ring groove 122 of the first forming block 120, that is, the outer diameter of the first clamping spring 130 is greater than the inner diameter of the first through hole 111, and when the first forming block 120 moves downward along the axis, the lower end surface of the first clamping spring 130 can abut against the upper end surface of the first fixed sleeve 110.

[0065] In the embodiment, the first fixed sleeve 110 is provided with two first screw holes 112, and the upper cover bolt 140 is arranged in each first screw hole 112, but the present application is not limited to this, and the number of the first screw holes 112 can also be one, three or more. By rotating the upper cover bolt 140 downward, the lower end of the upper cover bolt 140 can abut against the upper end surface of the first forming block 120 and push the first forming block 120 to move downward along the axis until the lower end surface of the first clamping spring 130 abuts against the upper end surface of the first fixed sleeve 110.

[0066] The first forming block 120 has a central hole 121 that runs vertically through the middle. During the experiment of the drilling fluid filtration performance evaluation device of the present invention, the upper end of the central hole 121 can be connected to a pressurizing device (such as a hand pump), so that pressure can be applied through the pressurizing device and transmitted to the mud in the cylinder 200 along the central hole 121.

[0067] Figure 3(a) shows a cross-sectional view of the lower cover in the drilling fluid filtration performance evaluation device of an exemplary embodiment of the present invention, and Figure 3(b) shows a top view of the second molding block in the drilling fluid filtration performance evaluation device of an exemplary embodiment of the present invention.

[0068] like Figure 1 As shown in Figures 3(a) and 3(b), in this embodiment, the lower cover 400 includes a second fixing sleeve 410, a second molding block 420, a second retaining spring 430, and a lower cover bolt 440. A second through hole 411 is provided in the middle of the second fixing sleeve 410, and the second molding block 420 passes through the second through hole 411. The second molding block 420 can move freely along the axis within the second through hole 411. A second annular groove 42 is provided on the outer wall of the second molding block 420 below the lower end face of the second fixing sleeve 410. 5. The second snap ring 430 is a ring structure. The inner edge of the second snap ring 430 is embedded in the second ring groove 425. The inner diameter of the second snap ring 430 is the same as the bottom diameter of the second ring groove 425. The outer diameter of the second snap ring 430 is larger than the outer diameter of the second forming block 420 at the second ring groove 425. That is to say, the outer diameter of the second snap ring 430 is larger than the inner diameter of the second through hole 411. When the second forming block 420 moves upward along the axis, the upper end face of the second snap ring 430 can abut against the lower end face of the second fixing sleeve 410.

[0069] In this embodiment, the second fixing sleeve 410 has two second screw holes 412, and a lower cover bolt 440 passes through each second screw hole 412. However, the present invention is not limited to this, and the number of second screw holes 412 may also be one, three or more. By tightening the lower cover bolt 440 upwards, the upper end of the lower cover bolt 440 can be brought into contact with the lower end face of the second molding block 420, and the second molding block 420 is pushed to move upwards along the axis until the upper end face of the second retaining spring 430 is brought into contact with the lower end face of the second fixing sleeve 410.

[0070] The upper end of the second forming block 420 is inwardly recessed to form an inner recessed platform 421, the edge of the inner recessed platform 421 (i.e. the side wall of the inner recessed platform) is provided with a chamfer 422 at the edge of the upper end of the second forming block 420, and the lower cover sealing ring 500 is installed on the chamfer 422, that is, the lower end of the lower cover sealing ring 500 is in abutment with the chamfer 422. The upper end of the lower cover sealing ring 500 is in abutment with the lower end of the barrel 200, and the lower cover sealing ring 500 is squeezed between the upper barrel 200 and the lower chamfer 422, thereby realizing the sealing effect between the barrel 200 and the lower cover 400. In the experimental process of the drilling fluid filtration property evaluation device, a circular rock plate is placed in the inner recessed platform 421, and the upper end surface of the circular rock plate is higher than the upper end of the lower cover sealing ring 500, so that the lower cover sealing ring 500 can surround the outside of the rock plate. After the experiment is completed, the upper end surface of the rock plate is covered with a mud cake, and the mud cake is also higher than the upper end of the lower cover sealing ring 500. The chamfer 422 provided on the inner recessed platform 421 makes the outside of the lower cover sealing ring 500 higher than the upper end surface of the second forming block 420, thereby leaving a space for the rock plate and the mud cake. When the rock plate is taken out, the taking tool can be easily clamped on the outside of the lower cover sealing ring 500, so that the rock plate can be conveniently taken out of the inner recessed platform 421. The taking tool does not directly contact the rock plate and the mud cake, so that the mud cake is not damaged, thereby ensuring the integrity of the mud cake. The surface of the inner recessed platform 421 is provided with a liquid guide groove 424, and the inner recessed platform 421 is provided with a through hole 423 penetrating upward and downward, the upper end of the through hole 423 is in communication with the liquid guide groove 424, and the lower end of the through hole 423 is provided with a valve (not shown in the figure). By controlling the opening and closing of the valve, the through hole 423 can be opened and closed. In the experimental process of the drilling fluid filtration property evaluation device, the lower end of the second forming block 420 is connected with a connecting pipeline, the valve at the lower end of the second forming block 420 is opened, the through hole 423 is in communication with the connecting pipeline, and as the mud in the barrel 200 is compressed downward, the liquid phase component in the filtered mud passing through the rock plate flows into the connecting pipeline through the small holes in the rock plate, the liquid guide groove 424 and the through hole 423, and is then discharged out of the drilling fluid filtration property evaluation device. The solid phase component in the mud does not pass through the rock plate and is attached to the rock plate to form a mud cake.

[0071] In this embodiment, the material of the lower cover sealing ring 500 is polytetrafluoroethylene, which has the characteristics of high temperature resistance, corrosion resistance, non-stickiness and non-toxicity, and meets the experimental requirements. However, the material of the lower cover sealing ring 500 can also be other materials with similar properties to polytetrafluoroethylene.

[0072] Figure 4 A cross-sectional view of a piston in the drilling fluid filtration property evaluation device of the exemplary embodiment of the present application is shown.

[0073] As Figure 1 and Figure 4As shown in the figure, the piston 300 is a cylindrical structure, and a gas hole 310 is formed through the upper and lower ends of the piston 300. In this embodiment, the gas hole 310 includes an upper gas hole section 311 and a lower gas hole section 312, the inner diameter of the upper gas hole section 311 is larger than that of the lower gas hole section 312, and a plug 340 is arranged in the upper gas hole section 311. The plug 340 can be screwed into the upper gas hole section 311, but the present application is not limited thereto. The gas hole 310 can also be designed as a through hole with the same inner diameter from top to bottom or a tapered hole with a larger upper diameter and a smaller lower diameter, and the plug 340 can also be designed as a tapered body that can be matched with the tapered hole, so that the threads on the plug 340 and the gas hole 310 can be cancelled. In the experimental process of the drilling fluid filtration performance evaluation device described in the present application, the lower cover 400 provided with a rock plate and a lower cover sealing ring 500 is first connected to the lower end of the cylinder body 200 through threads, the valve below the lower cover 400 is closed, the mud is poured into the cylinder body 200, and then the piston 300 is assembled into the cylinder body 200. At this time, the plug 340 is not assembled in the upper gas hole section 311. When the piston 300 is lowered to the mud liquid level and installed in the cylinder body 200, the plug 340 is screwed into the upper gas hole section 311 to block the gas hole 310. At this time, the mud below the piston cannot flow to the upper part of the piston 300 through the gas hole 310, and the sealing function of the piston 300 is realized.

[0074] A piston sealing groove 320 is further arranged on the outer wall of the piston 300. In this embodiment, the number of the piston sealing groove 320 is two, including a first piston sealing groove 321 and a second piston sealing groove 322. The first piston sealing groove 321 is arranged on the outer wall of the piston 300 close to the upper end surface of the piston 300, and the second piston sealing groove 322 is arranged on the outer wall of the piston 300 close to the lower end surface of the piston 300. The sealing ring can be arranged in the first piston sealing groove 321 and the second piston sealing groove 322, but the present application is not limited thereto. The number of the piston sealing groove 320 can also be one, three or more, and the sealing ring can be arranged in each piston sealing groove 320 to improve the sealing performance of the piston 300. When the piston 300 is assembled in the cylinder body 200, the outer wall of the piston 300 is attached to the inner wall of the cylinder body 200, and the sealing ring in the first piston sealing groove 321 and the second piston sealing groove 322 is compressed between the inner wall of the cylinder body 200 and the groove bottom of the first piston sealing groove 321 and the second piston sealing groove 322, thereby realizing the sealing between the outer wall of the piston 300 and the inner wall of the cylinder body 200.

[0075] In this embodiment, a piston screw hole 330 is formed in the upper end surface of the piston 300. The piston screw hole 330 is a blind hole, and an internal thread is arranged on the inner wall of the piston screw hole 330. When the piston 300 needs to be removed from the cylinder body 200, a screw rod matched with the piston screw hole 330 is screwed into the piston screw hole 330, so that the piston 300 can be conveniently disassembled from the cylinder body 200, but the present application is not limited thereto. Other structures that can facilitate the disassembly of the piston 300 are also available.

[0076] Figure 5 A cross-sectional view of the cylinder in an exemplary embodiment of the drilling fluid filtration performance evaluation device of the present invention is shown.

[0077] like Figure 1 , Figure 2 Figure 3(a) and Figure 5 As shown, a cylinder sealing groove 210 is provided on the upper end face of the cylinder 200. A sealing ring can be installed in the cylinder sealing groove 210. After the cylinder 200 and the upper cover 100 are installed by threaded connection, by tightening the upper cover bolt 140 downward, the lower end of the upper cover bolt 140 can be abutted against the upper end face of the first forming block 120, and the first forming block 120 is pushed to move downward along the axis until the lower end face of the first snap ring 130 abuts against the upper end face of the first fixing sleeve 110. At this time, the lower end face of the first forming block 120 abuts against the upper end face of the cylinder 200, and the sealing ring installed in the cylinder sealing groove 210 can be compressed between the lower end face of the first forming block 120 and the bottom of the cylinder sealing groove 210, thereby achieving a seal between the upper cover 100 and the cylinder 200.

[0078] After the cylinder 200 and the lower cover 400 are installed with threaded connection, the upper end of the lower cover bolt 440 can be brought into contact with the lower end face of the second forming block 420 by tightening the lower cover bolt 440 upward, and the second forming block 420 is pushed to move upward along the axis until the upper end face of the second retaining spring 430 is brought into contact with the lower end face of the second fixing sleeve 410. At this time, the lower cover sealing ring 500 installed between the lower cover 400 and the cylinder 200 is compressed in the middle by the chamfer 422 and the lower end of the cylinder 200, thereby achieving a seal between the lower cover 400 and the cylinder 200.

[0079] Another aspect of the present invention provides a method for preparing mud cake and a method for testing the drilling fluid filtration performance using the drilling fluid filtration performance evaluation device described in the present invention.

[0080] The method for preparing mud cake and the method for testing the filtration performance of drilling fluid include the following steps:

[0081] Step 1: Before the experiment, the operator takes safety precautions and prepares tools and materials.

[0082] Step 2: Weigh and record the weight of the rock slab. Place the rock slab into the recessed platform 421 in the lower cover 400. Put the lower cover sealing ring 500 on the outside of the rock slab. Grasp the bottom of the lower cover 400 and tighten it after the internal thread of the lower cover 400 matches the external thread at the lower end of the cylinder 200. Then tighten the lower cover bolt 440 until the upper end face of the second retaining spring 430 is pressed against the lower end face of the second fixing sleeve 410.

[0083] Step 3: Preheat the lower cover sealing ring 500. The preheating steps include:

[0084] 1, The lower cover 400, the lower cover sealing ring 500, the rock plate, the cylinder body 200 are assembled and fixed on the special support, and the heating tile is sleeved on the outer side of the cylinder body 200.

[0085] 2, Check the installation of the heating tile and the temperature probe.

[0086] 3, Turn on the heating switch on the control box, set the temperature to 110℃, and wait for the temperature to rise.

[0087] 4, After the temperature reaches 110℃, use a wrench to repeatedly tighten the lower cover 400 on the cylinder body 200 for 10 minutes.

[0088] 5, Tighten the lower cover bolt 440 for secondary tightening, turn off the heating switch, and the preheating is completed.

[0089] Step four: Close the valve at the lower end of the lower cover 400, pour the mud into the cylinder body 200, press the piston 300 into the cylinder body 200, screw the plug 340 into the air hole 310 and tighten it, block the air hole 310, install the O-shaped sealing ring in the cylinder body sealing groove 210 on the upper end surface of the cylinder body 200, tighten the inner thread of the upper cover 100 and the outer thread of the upper end of the cylinder body 200, and then tighten the upper cover bolt 140 until the lower end surface of the first snap spring 130 is tightly pressed against the upper end surface of the first fixed sleeve 110. The drain port of the hand pump is connected to the center hole 121 of the upper cover 100, and the pressure sensor is installed on the upper cover 100.

[0090] Step five: Check the device, set the experimental temperature, and wait for heating.

[0091] The experimental temperature set in this step needs to be determined according to different experimental requirements, generally not more than 150℃.

[0092] Step six: When the temperature reaches the experimental temperature, use the hand pump to pressurize the inside of the cylinder body 200 to the experimental required pressure, and after the pressure is stable, open the valve at the lower end of the lower cover 400 every 2 minutes and 30 seconds to release the liquid, collect the discharged liquid with a glass measuring cylinder, and record the amount of liquid discharged at the same time.

[0093] The experimental required pressure in this step is between 5-20Mpa, and the reading on the pressure sensor needs to be observed at any time to control the pressure.

[0094] Step seven: After the experiment is completed, turn off the heating switch, release the pressure in the cylinder body 200, turn off the power, and after the drilling fluid filtration performance evaluation device is completely cooled, remove the connecting pipeline below the lower cover 400, and loosen the lower cover bolt 440.

[0095] Step eight: slowly pressurize the barrel 200 with a hand pump, stop pressurizing and release the pressure when the mud spills out from the threads between the lower cover 400 and the barrel 200, unscrew the lower cover 400, tilt and pour out the flowing mud, observe whether the mud cake is complete, if not, repeat the experiment until the mud cake is complete.

[0096] The standard for judging whether the mud cake is complete in this step is whether the shape of the mud cake is a complete circle and whether the surface of the mud cake is flat.

[0097] Step nine: clean the mud around the mud cake, take out the rock plate with the mud cake and the lower cover sealing ring 500 together, then remove the lower cover sealing ring 500 from the rock plate, weigh, measure the thickness, take a photo of the rock plate taken out, and make a good record, and clean the device.

[0098] In this step, the upper end surface of the rock plate and the mud cake covering the upper end surface of the rock plate are higher than the upper end of the lower cover sealing ring 500, and the inner recessed table 421 is provided with a chamfer 422, so that the outer side of the lower cover sealing ring 500 is higher than the upper end surface of the second forming block 420, leaving a space for the rock plate and the mud cake, and the taking tool can be easily clamped on the outer side of the lower cover sealing ring 500 to conveniently take out the rock plate from the inner recessed table 421 without damaging the mud cake.

[0099] Step ten: place the rock plate with the mud cake into the inner recessed table 421 in the lower cover 400, install the lower cover 400 and add a small amount of water into the barrel 200 to submerge the surface of the mud cake.

[0100] Since the next step needs to preheat the lower cover sealing ring 500 to a temperature of 110 DEG C, the water added in this step is to protect the surface of the mud cake from being baked dry to avoid affecting the filtration water performance of the mud cake.

[0101] Step eleven: preheat the lower cover sealing ring 500, and the preheating step is the same as step three.

[0102] Step twelve: fill the barrel 200 with clean water, install the upper cover 100, and repeat steps five to nine.

[0103] In this step, the clean water is filled and steps five to nine are repeated to test the amount of clean water that penetrates through the mud cake under a certain pressure within a certain time, so as to test the filtration water performance of the mud cake.

[0104] In summary, the drilling fluid filtration performance evaluation device has simple structure design and is easy to use, the cooperation of the chamfer and the sealing ring makes the side surface of the mud cake not in complete contact with the inner wall of the forming block, leaving a space for taking the mud cake, realizing complete sampling of the mud cake, improving the experimental efficiency, and the detachable design structure of each component in the drilling fluid filtration performance evaluation device is convenient to use and has wide application range.

[0105] While the application has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the application is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements.

Claims

1. A drilling fluid filtration performance evaluation device, characterized in that, The drilling fluid filtration performance evaluation device includes: The top cover includes a first fixing sleeve and a first molding block. The first fixing sleeve has a first through hole, and the first molding block passes through the first through hole. The upper end of the cylinder can be connected to the top cover, and the connection method is a detachable connection. A piston that can be inserted into a cylinder, with its outer wall in contact with the inner wall of the cylinder and able to move along the axial direction of the cylinder; The lower cover can be connected to the lower end of the cylinder in a detachable manner. The lower cover includes a second fixing sleeve and a second forming block. The second fixing sleeve has a second through hole, and the second forming block passes through the second through hole. The upper end face of the second forming block has an inner concave platform, and the upper edge of the side wall of the inner concave platform has a chamfer. The second forming block has a through hole, with the upper opening of the through hole formed on the concave surface of the inner concave platform and the lower opening formed on the lower end surface of the second forming block. as well as, The lower cover sealing ring has an upper end that can abut against the lower end of the cylinder and a lower end that can abut against the chamfer.

2. The drilling fluid filtration performance evaluation device according to claim 1, characterized in that, The upper cover also includes an upper cover bolt. The first fixing sleeve has a first screw hole, and the upper cover bolt passes through the first screw hole and can push the first molding block to move downward along the axis.

3. The drilling fluid filtration performance evaluation device according to claim 2, characterized in that, The upper cover also includes a first retaining spring. The first molded block has a first annular groove on its outer wall outside the first fixing sleeve. The inner edge of the first retaining spring is embedded in the first annular groove. The inner diameter of the first retaining spring matches the bottom diameter of the first annular groove. The outer diameter of the first retaining spring is larger than the inner diameter of the first through hole. The first molded block has a central hole that passes through both the upper and lower ends of the first molded block.

4. The drilling fluid filtration performance evaluation device according to claim 1, characterized in that, The lower cover also includes a lower cover bolt. The second fixing sleeve has a second screw hole, and the lower cover bolt passes through the second screw hole and can push the second molding block to move upward along the axis.

5. The drilling fluid filtration performance evaluation device according to claim 4, characterized in that, The lower cover also includes a second retaining spring. The second molding block has a second annular groove on its outer wall outside the second fixing sleeve. The inner edge of the second retaining spring is embedded in the second annular groove. The inner diameter of the second retaining spring matches the bottom diameter of the second annular groove. The outer diameter of the second retaining spring is larger than the inner diameter of the second through hole.

6. The drilling fluid filtration performance evaluation device according to claim 1, characterized in that, The piston has a through-hole, which includes an upper section and a lower section. The inner diameter of the upper section is larger than that of the lower section. A plug is detachably inserted into the upper section, and the outer wall of the plug fits against the inner wall of the upper section.

7. The drilling fluid filtration performance evaluation device according to claim 1, characterized in that, The outer wall of the piston is provided with several piston sealing grooves, and piston sealing rings are installed in the piston sealing grooves.

8. The drilling fluid filtration performance evaluation device according to claim 7, characterized in that, The piston sealing groove includes a first piston sealing groove and a second piston sealing groove. The first piston sealing groove is formed at the upper end of the outer wall of the piston, and the second piston sealing groove is formed at the lower end of the outer wall of the piston. A piston threaded hole is formed at the upper end of the piston, and the piston threaded hole is a blind hole.

9. The drilling fluid filtration performance evaluation device according to claim 1, characterized in that, The material of the lower cover sealing ring is polytetrafluoroethylene.

10. The drilling fluid filtration performance evaluation device according to claim 1, characterized in that, The upper end face of the cylinder is provided with a cylinder sealing groove, and a cylinder sealing ring is installed in the cylinder sealing groove.

11. A method for preparing mud cakes, characterized in that, The method is implemented based on the drilling fluid filtration performance evaluation device according to any one of claims 1 to 10.

12. The method for preparing mud cake according to claim 11, characterized in that, The mud cake preparation method includes the following steps: Place the rock slab into the recessed platform in the lower cover, put the sealing ring of the lower cover on the outside of the rock slab, so that the lower cover is connected to the lower end of the cylinder, and tighten the lower cover bolts if the lower cover includes lower cover bolts. Preheat the lower cover sealing ring; Seal the through hole on the second molding block, pour the mud into the cylinder, and then press the piston into the cylinder to connect the top cover to the upper end of the cylinder. The cylinder is heated, and when the temperature reaches a preset temperature value, pressure is applied to the inside of the cylinder. When the pressure reaches a preset pressure value and stabilizes, the through hole on the second molding block is opened at regular intervals to release liquid and collect the released liquid. Stop heating the cylinder, release the pressure inside the cylinder, and loosen the lower cover bolts if the lower cover includes lower cover bolts; Pressurize the cylinder. When mud overflows from the connection between the lower cover and the cylinder, stop pressurizing and release the pressure inside the cylinder. Unscrew the lower cover, clean the mud, and observe whether the mud cake is intact. If it is not intact, repeat the above experimental steps until the mud cake is intact. With the mud cake intact, clean the mud around the mud cake, remove the rock slab, and remove the lower cover sealing ring on the rock slab to obtain the mud cake.

13. The method for preparing mud cake according to claim 12, characterized in that, The step of preheating the lower cover sealing ring includes: After assembling the lower cover, lower cover sealing ring, rock plate, and cylinder, heat them to a preset temperature. Tighten the lower cover onto the cylinder and maintain it at a preset temperature for a set period of time. Tighten the lower cover bolts to complete the preheating process.

14. The method for preparing mud cake according to claim 13, characterized in that, The preset temperature is 110℃ and the preset duration is 10 minutes.

15. The method for preparing mud cake according to claim 12, characterized in that, The preset temperature value is ≤150℃, and the preset pressure value is between 5 and 20 MPa.

16. A method for testing the filtration performance of drilling fluid, characterized in that, The method is implemented based on the drilling fluid filtration performance evaluation device according to any one of claims 1 to 10.

17. The drilling fluid filtration performance testing method according to claim 16, characterized in that, The drilling fluid filtration performance testing method includes the following steps: Step S1: Place the rock slab with mud cake into the recessed platform in the lower cover, install the lower cover at the lower end of the cylinder, and add water into the cylinder to submerge the surface of the mud cake; Step S2: Preheat the lower cover sealing ring; Step S3: Fill the cylinder with water, install the top cover on the upper end of the cylinder, heat the cylinder, and pressurize the inside of the cylinder when the temperature reaches the preset temperature value. When the pressure reaches the preset pressure value and stabilizes, open the through hole on the second molding block at intervals to release the liquid and collect the released liquid. Step S4: Stop heating the cylinder, release the pressure inside the cylinder, and loosen the lower cover bolts if the lower cover includes lower cover bolts; Step S5: Pressurize the cylinder. When mud overflows from the connection between the lower cover and the cylinder, stop pressurizing and release the pressure inside the cylinder. Unscrew the lower cover, clean the mud around the mud cake, take out the rock slab, remove the lower cover sealing ring on the rock slab, and weigh and measure the taken-out rock slab. Repeat steps S2 to S5 to test the water loss performance of the mud cake.

18. The drilling fluid filtration performance testing method according to claim 17, characterized in that, The step of preheating the lower cover sealing ring includes: After assembling the lower cover, lower cover sealing ring, rock plate, and cylinder, heat them to a preset temperature. Tighten the lower cover onto the cylinder and maintain it at a preset temperature for a set period of time. Tighten the lower cover bolts to complete the preheating process.

19. The drilling fluid filtration performance testing method according to claim 18, characterized in that, The preset temperature is 110℃ and the preset duration is 10 minutes.

20. The drilling fluid filtration performance testing method according to claim 17, characterized in that, The preset temperature value is ≤150℃, and the preset pressure value is between 5 and 20 MPa.

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