Horizontal well segmented multi-cluster fracturing artificial rock sample preparation device and method

Abstract

The invention provides a horizontal well segmented multi-cluster fracturing artificial rock sample preparation device and method.The horizontal well segmented multi-cluster fracturing artificial rock sample preparation device comprises a pouring cavity, a through hole used for being inserted into an artificial shaft is formed in one side of the pouring cavity, a clamping device used for fastening the artificial shaft is arranged at the position of the through hole, and a positioning piece used for positioning the artificial shaft is arranged in the clamping device; the clamping device is designed in an up-down split mode, the front end of the artificial shaft is clamped through the clamping device, and the artificial shaft is kept in a horizontal and fixed state in the pouring cavity. Through cooperation of the upper part and the lower part of the clamping device, the position of the multi-cluster fracturing artificial wellbore can be effectively restrained, the problems of wellbore inclination, sinking, dislocation and the like in the artificial rock sample pouring process are prevented, the qualified rate of the poured artificial rock sample is remarkably increased, and preparation of the artificial rock sample is more standard, efficient and convenient.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas field development, in particular to a horizontal well segmented multi-cluster fracturing artificial rock sample preparation device and method. BACKGROUND

[0002] The horizontal well segmented multi-cluster fracturing technology is one of the main technical methods for efficient development of unconventional low-permeability oil and gas reservoirs at the present stage. However, due to insufficient understanding of the balanced expansion law of multi-cluster hydraulic fractures in the reservoir, the application effect of this technology is still unstable. At present, large-size true triaxial fracturing physical simulation experiment is one of the most effective technical means for studying the expansion law of multi-cluster hydraulic fractures. Compared with the natural outcrop which is rare in quantity and difficult to process, the artificial rock sample is widely used in fracturing experiments.

[0003] However, when using artificial rock samples to carry out fracturing experiments, the phenomenon of experimental failure or even damage to experimental equipment often occurs due to unqualified rock sample production. The main reason for the unqualified production of artificial rock samples is the non-standard embedding method of artificial wellbore. Unlike the single injection port of the conventional hydraulic fracturing experiment, the multi-cluster fracturing experiment requires multiple separate injection interfaces in the wellbore, which can realize simultaneous or sequential liquid injection of multiple pipelines, and there will be no communication between each pipeline. The commonly used artificial wellbore embedding method at the present stage is the pre-embedding method, that is, the horizontal wellbore is placed on the already poured concrete rock layer during sample pouring, and then the cement is continuously poured. However, using the pre-embedding method for rock sample preparation will cause the whole or part of the wellbore to sink in the rock sample that has not completely solidified due to gravity, which cannot guarantee that the wellbore is in the center of the rock sample and maintain the horizontal state of the wellbore axis. In addition, the natural placement without constraints may also have the risk of wellbore misplacement, which will cause the wellhead end surface to separate from the rock sample wall and produce concave or convex problems. The above situations will make the rock sample unable to closely fit the loading device, resulting in uneven or improper stress loading, which will cause damage to the rock sample or equipment and lead to experimental failure.

[0004] In summary, the current large-size true triaxial fracturing physical simulation experiment artificial rock sample production device and method should have the following two characteristics: 1. Prevent the whole or part of the artificial wellbore from sinking, and ensure that the wellbore is in the center of the artificial rock sample and maintain the horizontal state of the wellbore axis; 2. Effectively constrain the position of the wellbore to avoid the wellhead end surface from separating from the rock sample wall and producing concave or convex problems.

[0005] Therefore, it is necessary to propose a horizontal well segmented multi-cluster fracturing artificial rock sample preparation device and method to effectively improve the qualification rate of horizontal well segmented multi-cluster experimental artificial rock sample preparation. SUMMARY

[0006] The present application aims to solve the problems existing in the prior art, and provides a horizontal well segmented multi-cluster fracturing artificial rock sample preparation device and method, which can effectively constrain the position of the multi-cluster fracturing artificial wellbore, prevent problems such as wellbore tilting, sinking and wellhead misplacement in the rock sample pouring process, and effectively improve the qualified rate of artificial rock sample preparation.

[0007] The present application is implemented as follows: The present application provides a horizontal well segmented multi-cluster fracturing artificial rock sample preparation device, characterized in that: a pouring cavity is arranged, a through hole for inserting an artificial wellbore is arranged on one side of the pouring cavity, a clamping device for fastening the artificial wellbore is arranged at the through hole, a positioning member for positioning the artificial wellbore is arranged in the clamping device, and the clamping device is designed in an upper and lower split type, the front end of the artificial wellbore is clamped by the clamping device, and the artificial wellbore is kept horizontal and fixed in the pouring cavity.

[0008] According to the above technical scheme, the pouring cavity includes a bottom plate, a front cover plate, a rear cover plate, a left cover plate and a right cover plate, and the plurality of cover plates and the bottom plate are connected and fixed by clamping members to form the pouring cavity.

[0009] According to the above technical scheme, a through hole is arranged at the center position of the front cover plate, and the artificial wellbore is embedded through the hole into the pouring cavity.

[0010] According to the above technical scheme, the clamping device includes an upper clamping member and a lower clamping member, which are arranged in an upper and lower symmetrical manner, and a central annular space is formed when the two are buckled, the lower clamping member is fixed on the front cover plate, the upper clamping member is a freely movable component, and the upper and lower clamping members are clamped by fastening members.

[0011] According to the above technical scheme, the clamping device is in a vertical state with the front cover plate, and the central annular space and the through hole at the front cover plate are in a concentric relationship.

[0012] According to the above technical scheme, a plurality of strip-shaped pores are arranged near the front cover plate of the clamping device, which are used for the entry and exit of the artificial wellbore injection pipeline.

[0013] According to the above technical scheme, a through hole for threading the fastening member is arranged at the position away from the cover plate of the clamping device, the through hole of the lower clamping member is threaded, the through hole of the upper clamping member is smooth, and the upper and lower clamping members of the device are connected by the fastening member.

[0014] According to the above technical scheme, the positioning member is a positioning shaft shoulder arranged at the annular space of the fastening device, which is used to determine the length of the artificial wellbore entering the pouring cavity.

[0015] A horizontal well segmented multi-cluster fracturing artificial rock sample preparation method, characterized by comprising the following steps: Step 1: Assemble the sample preparation device; Step 2: configure the concrete slurry of water, cement and quartz sand in a specified proportion according to requirements; Step 3: gradually pour the configured concrete slurry into the pouring cavity, and temporarily stop pouring when the upper surface of the concrete slurry reaches below the through hole; Step 4: insert the artificial wellbore into the pouring cavity through the through hole of the front cover plate, tightly fit the front end of the artificial wellbore with the shaft shoulder on the inner side of the lower clamping part of the clamping device, cover the upper clamping part of the clamping device on the artificial wellbore, so that the clamping device completely covers the front end of the artificial wellbore, and the two parts of the clamping device are connected by fasteners to clamp the artificial wellbore, so as to ensure that the artificial wellbore is fixed in a horizontal state.

[0016] Step 5: continue to pour the rock sample until the height of the rock sample is level with the height of the sample preparation device; Step 6: let the rock sample stand for a few days, and after the rock sample is completely solidified, remove the sample preparation mold, and the sample preparation is completed.

[0017] According to the above technical scheme, machine oil is uniformly brushed on the inner wall of the pouring cavity.

[0018] The beneficial effects of the present application are: through the cooperation of the upper and lower two parts of the clamping device, the position of the multi-cluster fracturing artificial wellbore can be effectively constrained, the problems such as inclination, sinking and misplacement of the artificial rock sample during pouring are prevented, the qualified rate of the poured artificial rock sample is significantly improved, and the preparation of the artificial rock sample is more standardized, efficient and convenient. The horizontal well staged multi-cluster fracturing artificial rock sample preparation device and method provided by the present application can effectively improve the qualified rate of the multi-cluster fracturing artificial rock sample preparation, and further improve the accuracy of the fracturing experiment. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present application, but not limit the present application.

[0020] Figure 1 It is a device structure diagram of the present application.

[0021] Figure 2 It is a schematic diagram of the front cover plate and the lower clamping part of the clamping device of the present application.

[0022] Figure 3 It is a schematic diagram of the upper clamping part of the clamping device and the fastening bolt of the present application.

[0023] Figure 4 It is a schematic diagram of the cooperation of the wellbore, the front cover plate and the clamping device of the present application.

[0024] Figure 5 It is an explosion schematic diagram of the cooperation of the wellbore, the front cover plate and the clamping device of the present application.

[0025] Figure 6 It is a cross-sectional schematic diagram of the fitting part of the wellbore, front cover plate and clamping device of the present invention.

[0026] In the picture: 1-front cover, 2-left cover, 3-rear cover, 4-bottom plate, 5-right cover, 6-sample preparation device, 7-fastening bolt, 8-lower clamping piece, 9-upper clamping piece, 10-artificial wellbore, 11, 12, 13-injection pipeline, 14-through hole, 15-positioning shaft shoulder, 16-wellbore connector. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0029] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0030] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0032] In the description of the present application, it is further necessary to explain that, unless explicitly defined and limited otherwise, the terms "set", "install", "connect", "connect" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0033] In the present application, unless explicitly defined and limited otherwise, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0034] The features and properties of the present application are further described in detail below in conjunction with the embodiments.

[0035] The present embodiment provides a horizontal well segmented multi-cluster fracturing artificial rock sample preparation device 6, which comprises a pouring cavity, a through hole 14 for inserting an artificial wellbore is arranged on one side of the pouring cavity, a clamping device for fastening the artificial wellbore 10 is arranged at the through hole 14, a positioning member for positioning the artificial wellbore is arranged in the clamping device, the clamping device is designed in an upper and lower split type, the front end of the artificial wellbore is clamped by the clamping device, and the artificial wellbore is kept in a horizontal and fixed state in the pouring cavity.

[0036] In the present embodiment, the pouring cavity comprises a bottom plate 4, a front cover plate 1, a rear cover plate 3, a left cover plate 2 and a right cover plate 5, a plurality of cover plates and the bottom plate 4 are connected and fixed by clamping members to form the pouring cavity. Specifically, the plurality of cover plates are provided with through holes, and are connected and fixed by small bolts.

[0037] Further, the front cover plate 1 is provided with a through hole 14 at the center position, and the artificial wellbore 10 is pre-buried and positioned and fixed through the pouring cavity and the hole. Specifically, the artificial wellbore 10 is positioned by the positioning member in the fastening device, the upper and lower two parts of the fastening device are connected by the fastening bolt 7, the connector 16 at the front end of the wellbore is clamped by the fastening device, and the wellbore 10 is kept in a horizontal and fixed state in the pouring cavity.

[0038] In this embodiment, the clamping device includes an upper clamping member 9 and a lower clamping member 8, which are symmetrically arranged in an upper and lower manner. When the two are buckled together, a central annulus is formed in the middle. The lower clamping member 8 is fixed to the front cover 1, and the upper clamping member 9 is a free moving part. The upper clamping member 9 and the lower clamping member 8 are clamped by the fastening bolt 7. Figure 3 As shown, the clamping device is provided with a through hole for inserting a fastening bolt 7 away from the cover plate. The through hole of the lower clamping piece is threaded, and the through hole of the upper clamping piece is smooth. The upper and lower clamping pieces of the device are connected by the fastening bolt 7.

[0039] In this embodiment, the clamping device is perpendicular to the front cover plate 1 , and the central annulus and the through hole at the front cover plate are in a concentric circle relationship. Specifically, the lower clamping member 8 is perpendicular to the front cover plate 1 .

[0040] like Figure 1 and Figure 4 As shown, the clamping device is provided with a plurality of strip-shaped holes near the front cover plate 1 for the entry and exit of artificial wellbore injection pipelines, specifically three injection pipelines 11, 12, and 13.

[0041] In this embodiment, Figure 6 As shown, the positioning member is a positioning shoulder 15 provided at the annulus of the fastening device, which is used to determine the length of the artificial wellbore entering the casting cavity.

[0042] Through the cooperation of the upper and lower parts of the fastening device, the present invention can effectively constrain the position of multiple clusters of fracturing artificial wellbores, prevent problems such as wellbores tilting, sinking and dislocation during the casting of artificial rock samples, and significantly improve the qualified rate of cast artificial rock samples, making the preparation of artificial rock samples more standardized, efficient and convenient.

[0043] This embodiment also proposes a method for preparing artificial rock samples for staged multi-cluster fracturing of horizontal wells. The goal of this embodiment is to produce artificial rock samples with a size of 300 mm × 300 mm × 600 mm for fracturing experiments. The specific implementation steps include the following steps: Step 1: Assemble the four cover plates and the bottom plate 4 according to their positions, connect and fix them with bolts, and place the assembled sample preparation device 6 on a level ground; evenly apply engine oil on the inner wall of the device to ensure that after the rock sample is poured, the rock sample can be smoothly separated from the sample preparation device 6 when the device is disassembled; Step 2: Prepare a concrete slurry of water, cement, and quartz sand in the specified proportions according to the experimental design requirements, and stir the concrete slurry thoroughly to completely eliminate the internal bubbles; Step 3: gradually inject the prepared concrete slurry into the sample preparation device 6. When the height of the cast rock sample reaches the position near the through hole 14, temporarily stop pouring; Step 4, the artificial wellbore is put into the pouring cavity, the artificial wellbore 10 is inserted into the through hole 14 in the horizontal direction, the end surface of the connecting head 16 at the front end of the artificial wellbore is attached to the positioning shaft shoulder 15 in the fastening device, the upper clamping piece 9 of the fastening device is combined on the lower clamping piece 8 of the fastening device, then the upper and lower clamping pieces 8 and 9 of the fastening device are completely attached and fixed by using the fastening bolt 7; the artificial wellbore is tightened to ensure that the wellbore is fixed in a horizontal state.

[0044] Step 5, after the poured rock sample is initially solidified, the rock sample is continuously poured until the height of the rock sample is flush with the height of the sample preparation device, and the pouring is stopped; Step 6, the rock sample is left for several days, and after the rock sample is completely solidified, the sample preparation mold is removed, and the sample preparation is completed.

[0045] After the artificial rock sample is demolded, daily watering and maintenance are carried out to prevent the rock sample from cracking, and the rock sample is completely wrapped with a preservative film and is ready for use.

[0046] The artificial rock sample prepared by using the conventional preparation device and method has obvious problems of wellbore sinking and concave, and Figure 6 The multi-cluster fracturing artificial rock sample prepared by using the preparation device and method provided by the present application shown in the figure does not have the above problems.

[0047] The present application effectively avoids many problems that may occur when the wellbore is pre-buried during the preparation of the artificial rock sample by adding the fastening device and the fastening bolt 7, so that the preparation of the artificial rock sample is more standardized, efficient and convenient.

[0048] The above-described embodiments are part of the embodiments of the present application, rather than all the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

Claims

1. A device for preparing artificial rock samples for staged multi-cluster fracturing of horizontal wells, characterized by: It includes a casting cavity, and a through hole for inserting an artificial well shaft is provided on one side of the casting cavity. A clamping device for fastening the artificial well shaft is arranged at the through hole. A positioning piece for positioning the artificial well shaft is provided in the clamping device. The clamping device is designed as an upper and lower split type. The front end of the artificial well shaft is clamped by the clamping device to keep the artificial well shaft in a horizontal and fixed state in the casting cavity.

2. The device for preparing artificial rock samples for staged multi-cluster fracturing of horizontal wells according to claim 1, characterized in that: The casting cavity comprises a bottom plate, a front cover plate, a rear cover plate, a left cover plate and a right cover plate. The multiple cover plates and the bottom plate are connected and fixed by clamping pieces to form the casting cavity.

3. The device for preparing artificial rock samples for staged multi-cluster fracturing of horizontal wells according to claim 2, characterized in that: A through hole is provided at the center of the front cover plate, and the artificial well shaft is pre-buried through the hole and enters the casting cavity.

4. The device for preparing artificial rock samples for staged multi-cluster fracturing of horizontal wells according to claim 1 or 2, characterized in that: The clamping device includes an upper clamping part and a lower clamping part, which are symmetrically arranged in an upper and lower manner. When the two are buckled together, a central annulus is formed in the middle. The lower clamping part is fixed on the front cover plate, and the upper clamping part is a freely movable part. The upper clamping part and the lower clamping part are clamped by fasteners.

5. The device for preparing artificial rock samples for staged multi-cluster fracturing of horizontal wells according to claim 4, characterized in that: The clamping device is in a vertical state with the front cover plate, and the central annulus and the through hole at the front cover plate are in a concentric circle relationship.

6. The device for preparing artificial rock samples for staged multi-cluster fracturing of horizontal wells according to claim 5, characterized in that: The clamping device is provided with a plurality of strip-shaped holes near the front cover plate for the entry and exit of the artificial wellbore injection pipeline.

7. The device for preparing artificial rock samples for staged multi-cluster fracturing of horizontal wells according to claim 4, characterized in that: The clamping device is provided with a through hole for inserting a fastener away from the cover plate. The through hole of the lower clamping piece is threaded, and the through hole of the upper clamping piece is smooth. The upper and lower clamping pieces of the device are connected by fasteners.

8. The device for preparing artificial rock samples for staged multi-cluster fracturing of horizontal wells according to claim 1 or 2, characterized in that: The positioning piece is a positioning shoulder provided at the annulus of the fastening device, and is used to determine the length of the artificial wellbore entering the casting cavity.

9. A method for preparing artificial rock samples for staged multi-cluster fracturing of horizontal wells, characterized by: The following steps are involved: Step 1: Assemble the sample preparation device according to any one of claims 1 to 8; Step 2: Prepare concrete slurry as required; Step 3: Gradually inject the prepared concrete slurry into the pouring cavity. When the upper surface of the concrete slurry reaches the bottom of the through hole, temporarily stop pouring; Step 4: Insert the artificial well shaft into the through hole of the front cover through the casting cavity, fit the front end of the artificial well shaft tightly with the inner shoulder of the lower clamping piece of the clamping device, cover the upper clamping piece of the clamping device on the artificial well shaft, make the clamping device completely cover the front end of the artificial well shaft, and connect the upper and lower parts of the clamping device with fasteners to clamp the artificial well shaft and ensure that the artificial well shaft is fixed in a horizontal state; Step 5: Continue pouring the rock sample until the rock sample height is level with the sample preparation device height; Step 6: Let the rock sample stand for a few days. After the rock sample is completely solidified, remove the sample mold and the sample preparation is completed.

10. The method for preparing artificial rock samples for staged multi-cluster fracturing of horizontal wells according to claim 9, characterized in that: Brush the inner wall of the casting cavity in step 1 with machine oil evenly.

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