Anchorage device for multi-rib carbon fiber composite sucker rod and preparation method

Abstract

The invention discloses an anchorage device for a multi-rib carbon fiber composite sucker rod and a preparation method, relates to the technical field of oil extraction, and solves the problem that the carbon fiber composite sucker rod is often subjected to transverse damage in anchoring. The device comprises an anchorage device, a wire separating plate, a conical clamping piece, a rear cover plate and a multi-rib-bundle carbon fiber composite sucker rod, the anchorage device is of a cylindrical structure, and the inner wall of the anchorage device is of a continuous conical structure; a wire separating plate is arranged in the anchorage device, and the tail end of the multi-rib carbon fiber composite sucker rod penetrates through the wire separating plate. The multi-rib carbon fiber composite sucker rod is sleeved with a conical clamping piece, and the conical clamping piece is inserted into the through hole of the wire separating plate; a rear cover plate is arranged at the tail end of the anchorage device. According to the invention, miniaturization of the multi-rib carbon fiber composite sucker rod anchorage device is realized, so that the multi-rib carbon fiber composite sucker rod exerts higher tensile strength and fatigue performance, and the anchoring efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil production, and particularly to an anchor for a multi-strand carbon fiber composite sucker rod and a preparation method thereof. Background Art

[0002] In the development of oil and gas fields, the sucker rod, as the core component of the rod pumping system, plays a key role in transmitting the ground power to the downhole pump barrel. With the gradual extension of oil and gas resource development to deep wells, ultra-deep wells and complex geological environments, traditional metal sucker rods have shown significant limitations during service: the self-weight of metal sucker rods accounts for 60%-80% of the hook load. Especially in deep wells (>3000m), the excessive inertial load leads to a sharp increase in motor energy consumption (the system efficiency is generally lower than 30%), and it also aggravates the wear of surface equipment. In a corrosive environment containing high salinity formation water, metal sucker rods are prone to electrochemical corrosion and stress corrosion cracking. The rod breakage accidents caused by corrosion perforation account for more than 40% of the pump inspection operations, greatly increasing the maintenance cost of oil wells; under the large fatigue load of metal sucker rods in deep wells, fatigue fractures occur due to stress concentration effects such as surface defects and corrosion pits in actual working conditions, and the fatigue fracture period is often less than 70% of the designed life, and frequent replacement increases the production cost. In horizontal wells and highly deviated wells, the eccentric wear problem caused by the friction between metal sucker rods and tubing is difficult to cure, which aggravates the double loss of the rod and tubing, and seriously restricts the economic development of unconventional oil and gas resources.

[0003] The carbon fiber reinforced resin composite (CFRP) rod is produced by mixing carbon fiber and resin matrix through a pultrusion process. Compared with metals, CFRP pultruded rods have excellent properties such as light weight, high strength, corrosion resistance and fatigue resistance, and have been widely used in bridge cables, marine mooring cables and prestressed concrete structures, which can greatly improve the structural bearing capacity and service life. Using CFRP instead of metal to prepare sucker rods can effectively solve the problems of heavy self-weight, poor durability and fatigue resistance faced by traditional metal sucker rods in deep wells and corrosive wells. It can significantly improve the pumping efficiency of oil wells and the service life of sucker rods, with remarkable economic benefits. Thus, carbon fiber sucker rods have broad application prospects in oil fields. In view of the complex service environment faced by sucker rods in deep wells and corrosive wells, through the innovative design of carbon fiber sucker rods, realizing the high load-bearing, corrosion-resistant and fatigue-resistant properties of sucker rods is the key to promoting the large-scale application of carbon fiber sucker rods in oil wells.

[0004] However, the carbon fiber composite sucker rod belongs to an anisotropic material, and its transverse mechanical properties are poor. The problem of transverse failure often occurs during anchoring, resulting in a low strength utilization rate of the multi-strand carbon fiber composite sucker rod, which greatly reduces its service performance. Therefore, an efficient anchoring system is the key to exerting the mechanical properties of the multi-strand carbon fiber composite sucker rod. Summary of the Invention

[0005] In order to solve the problem that the carbon fiber composite sucker rod mentioned above often undergoes transverse failure during anchoring, the present invention hereby provides an anchor for a multi-strand carbon fiber composite sucker rod and a preparation method thereof. The present invention realizes the miniaturization of the anchor for the multi-strand carbon fiber composite sucker rod, enables the multi-strand carbon fiber composite sucker rod to exhibit high tensile strength and fatigue performance, and improves the anchoring efficiency.

[0006] The present invention provides an anchor for a multi-strand carbon fiber composite sucker rod, which specifically includes an anchor, a wire splitting plate, conical clamping pieces, a rear cover plate, and a multi-strand carbon fiber composite sucker rod. The anchor is of a cylindrical structure, and its inner wall is a continuous conical structure; a wire splitting plate is arranged inside the anchor, and the tail end of the multi-strand carbon fiber composite sucker rod passes through the wire splitting plate; conical clamping pieces are sleeved on the multi-strand carbon fiber composite sucker rod, and the conical clamping pieces are inserted into the through holes of the wire splitting plate; a rear cover plate is arranged at the tail end of the anchor.

[0007] Furthermore, the tail end of the multi-strand carbon fiber composite sucker rod is split, and a wedge piece is arranged in the split gap.

[0008] Furthermore, epoxy resin is applied to the wedge piece.

[0009] Furthermore, the inside of the anchor is filled with an anchoring filler.

[0010] Furthermore, the rear cover plate and the wire splitting plate are connected by bolts.

[0011] Furthermore, a straight section is arranged at the front end of the inner wall of the anchor.

[0012] Furthermore, the conical clamping pieces are slit along the diameter direction.

[0013] A method for preparing the above-mentioned anchor for a multi-strand carbon fiber composite sucker rod includes the following steps:

[0014] Step 1: Pass the multi-strand carbon fiber composite sucker rod through the anchor.

[0015] Step 2: Sequentially insert the multi-strand carbon fiber composite sucker rod into the corresponding holes of the wire splitting plate, and sleeved conical clamping pieces on the multi-strand carbon fiber composite sucker rod.

[0016] Step 3: Split the tail end of the multi-strand carbon fiber composite sucker rod; after applying epoxy resin to the wedge piece, insert it into the gap at the tail end of the multi-strand carbon fiber composite sucker rod.

[0017] Step 4: Connect the rear cover plate, the anchor, and the wire splitting plate.

[0018] Step 5: Pour the anchoring filler into the inside of the anchor and cure it at high temperature.

[0019] The beneficial effects of the anchor and its preparation method for multi-strand carbon fiber composite sucker rods of the present invention are as follows:

[0020] (1) The anchor and its preparation method for multi-strand carbon fiber composite sucker rods of the present invention solve the problem of frequent transverse damage of carbon fiber composite sucker rods during anchoring. The multi-strand carbon fiber composite sucker rod is clamped by the conical clamping piece and the wire splitting plate, and a wedge piece is arranged at the split seam at the tail of the multi-strand carbon fiber composite sucker rod to prevent the multi-strand carbon fiber composite sucker rod from slipping out of the conical clamping piece, strengthening the anchoring effect; the present invention realizes the miniaturization of the anchor for multi-strand carbon fiber composite sucker rods, enables the multi-strand carbon fiber composite sucker rod to exert higher tensile strength and fatigue performance, and improves the anchoring efficiency.

[0021] (2) The anchor and its preparation method for multi-strand carbon fiber composite sucker rods of the present invention are provided with a straight section at the front end of the inner wall of the anchor to reduce the compressive stress concentration at the load end; a continuous conical anchor cup is adopted, which can distribute the tensile force borne by the sucker rod to the middle and rear parts of the anchor, enhancing the stress transfer ability of the anchor, thereby improving the anchor efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0023] In the drawings:

[0024] Figure 1 is a three-dimensional structural schematic diagram of an anchor for multi-strand carbon fiber composite sucker rods of the present invention;

[0025] Figure 2 is an axonometric view of the fume absorption unit of the anchor for multi-strand carbon fiber composite sucker rods of the present invention;

[0026] Figure 3 is a three-dimensional structural diagram of the fume absorption unit of the anchor for multi-strand carbon fiber composite sucker rods of the present invention;

[0027] Among them: 1 - anchor, 2 - wire splitting plate, 3 - conical clamping piece, 4 - wedge piece, 5 - rear cover plate, 6 - tail end of the anchor, 7 - multi-strand carbon fiber composite sucker rod, 8 - front end of the anchor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0029] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Specific Embodiment 1: Refer to Figures 1 - 3 Specifically illustrate this embodiment. The anchor for a multi-strand carbon fiber composite sucker rod described in this embodiment specifically includes an anchor 1, a wire splitting plate 2, a conical clamping piece 3, a rear cover plate 5, and a multi-strand carbon fiber composite sucker rod 7. The anchor 1 is a cylindrical structure, and the inner wall is a continuous conical structure. By using a continuous conical anchor cup, the tensile force borne by the sucker rod can be distributed to the middle and rear parts of the anchor 1, enhancing the stress transfer ability of the anchor 1, thereby improving the efficiency of the anchor 1. For example, Figure 3As shown in the figure; a wire dividing plate 2 is arranged inside the anchor 1. The wire dividing plate 2 is in the shape of a frustum of a cone and is matched with the conical inner wall of the anchor 1 and clamped inside the anchor 1. A number of through holes are arranged on the wire dividing plate 2, and the tail end of the multi-strand carbon fiber composite sucker rod 7 passes through the through holes of the wire dividing plate 2. A conical clamping piece 3 is sleeved on the multi-strand carbon fiber composite sucker rod 7, and the conical clamping piece 3 is inserted into the through holes of the wire dividing plate 2. The conical clamping piece 3 is slit along the diameter direction and is not of full length to ensure the deformation of the clamping piece and reduce the damage to the sucker rod. A rear cover plate 5 is arranged at the tail end of the anchor, and the inside of the anchor 1 is filled with an anchoring filler. The rear cover plate 5 and the anchor 1 are connected by bolts to prevent leakage during the grouting of the anchoring filler. A number of small-diameter through holes are arranged on the wire dividing plate 2, and the anchoring filler flows to the space between the wire dividing plate 2 and the rear cover plate 5 through the small-diameter through holes.

[0033] The tail end of the multi-strand carbon fiber composite sucker rod 7 is slit and a wedge piece 4 is arranged in the split gap.

[0034] Epoxy resin is smeared on the two surfaces of the wedge piece 4 in contact with the multi-strand carbon fiber composite sucker rod 7, so that the wedge piece 4 and the multi-strand carbon fiber composite sucker rod 7 form a stable structure.

[0035] The rear cover plate 5 and the wire dividing plate 2 are connected by bolts.

[0036] A straight section is arranged at the front end of the inner wall of the anchor 1 to reduce the compressive stress concentration at the load end.

[0037] A method for manufacturing the anchor for the multi-strand carbon fiber composite sucker rod according to claim 4, characterized by comprising the following steps:

[0038] Step 1: Pass the multi-strand carbon fiber composite sucker rod 7 through the anchor 1;

[0039] Step 2: Sequentially pass the multi-strand carbon fiber composite sucker rod 7 through the corresponding through holes of the wire dividing plate 2, sleeved with the conical clamping piece 3 on the multi-strand carbon fiber composite sucker rod 7 and insert the conical clamping piece 3 into the corresponding through holes of the wire dividing plate 2;

[0040] Step 3: Slit the tail end of the multi-strand carbon fiber composite sucker rod 7; smear epoxy resin on both sides of the wedge piece 4 and then insert it into the gap at the tail end of the multi-strand carbon fiber composite sucker rod 7;

[0041] Step 4: Connect the rear cover plate 5, the anchor 1 and the wire dividing plate 2;

[0042] Step 5: Pour the anchoring filler into the inside of the anchor 1 and cure it at high temperature to complete the preparation of the anchor for the multi-strand carbon fiber composite sucker rod.

[0043] Summarizing the above embodiments, an anchor for a multi-strand carbon fiber composite sucker rod according to the present invention solves the problem that the carbon fiber composite sucker rod often undergoes transverse failure during anchoring. The multi-strand carbon fiber composite sucker rod is clamped by the cooperation of the conical clamping piece 3 and the wire splitting plate 2, and a wedge piece 4 is arranged at the split seam at the tail of the multi-strand carbon fiber composite sucker rod 7 to prevent the multi-strand carbon fiber composite sucker rod 7 from slipping out of the conical clamping piece 3, strengthening the anchoring effect; the present invention realizes the miniaturization of the anchor for the multi-strand carbon fiber composite sucker rod, enables the multi-strand carbon fiber composite sucker rod to exhibit high tensile strength and fatigue performance, and improves the anchoring efficiency. An anchor for a multi-strand carbon fiber composite sucker rod and a preparation method thereof according to the present invention are provided with a straight section at the front end of the inner wall of the anchor 1 to reduce the compressive stress concentration at the load end; by adopting a continuous conical anchor cup, the tensile force borne by the multi-strand carbon fiber composite sucker rod 7 can be distributed to the middle and rear parts of the anchor 1, enhancing the stress transfer ability of the anchor 1, thereby improving the efficiency of the anchor 1.

[0044] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the invention. It can also be a reasonable combination of the features described in the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An anchor for a multi-ribbon carbon fiber composite sucker rod, characterized in that: The invention comprises an anchor (1), a wire dividing plate (2), a conical clamp (3), a rear cover plate (5) and a multi-ribbed carbon fiber composite material sucker rod (7); the anchor (1) is a cylindrical structure, and the inner wall is a continuous conical structure; a wire dividing plate (2) is arranged inside the anchor (1), and the tail end of the multi-ribbed carbon fiber composite material sucker rod (7) passes through the wire dividing plate (2); a conical clamp (3) is mounted on the multi-ribbed carbon fiber composite material sucker rod (7), and the conical clamp (3) is inserted into the through hole of the wire dividing plate (2); and a rear cover plate (5) is arranged at the tail end (6) of the anchor.

2. The anchor for a multi-ribbon carbon fiber composite sucker rod according to claim 1, characterized in that: The tail end of the multi-ribbon carbon fiber composite material sucker rod (7) is split, and a wedge (4) is arranged in the split gap.

3. The anchor for a multi-ribbon carbon fiber composite sucker rod according to claim 2, characterized in that: Epoxy resin is applied on the wedge (4).

4. The anchor for a multi-ribbon carbon fiber composite sucker rod according to claim 3, characterized in that: The interior of the anchor (1) is filled with anchoring filler.

5. The anchor for a multi-ribbon carbon fiber composite sucker rod according to claim 1, characterized in that: The rear cover plate (5) and the wire dividing plate (2) are connected by bolts.

6. The anchor for a multi-ribbon carbon fiber composite sucker rod according to claim 1, characterized in that: The front end of the inner wall of the anchor (1) is provided with a straight section.

7. The anchor for a multi-ribbon carbon fiber composite sucker rod according to claim 1, characterized in that: The conical clamping piece (3) is slotted along the diameter direction.

8. A method for preparing the anchor for the multi-ribbon carbon fiber composite sucker rod according to claim 4, characterized in that: The following steps are involved: Step 1: Pass the multi-ribbon carbon fiber composite sucker rod (7) through the anchor (1); Step 2: insert the multi-ribbed carbon fiber composite material sucker rod (7) into the corresponding holes of the wire dividing plate (2) in sequence, and insert the conical clamping piece (3) onto the multi-ribbed carbon fiber composite material sucker rod (7); Step 3: Splitting the tail end of the multi-ribbed carbon fiber composite sucker rod (7); applying epoxy resin on the wedge (4) and inserting it into the gap at the tail end of the multi-ribbed carbon fiber composite sucker rod (7); Step 4: Connect the rear cover plate (5), the anchor (1) and the wire dividing plate (2); Step 5: Pour anchoring filler into the anchor (1) and cure it at high temperature.

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