Self-unblocking drillable float collar

Abstract

The application provides a self-unblocking drillable floating collar, relates to the technical field of drilling, and is used for full-bore floating casing operation. The floating collar is installed at the bottom of a casing string, realizes the sealing of the bottom of an air section of the floating casing, and prevents the fluid in a well from entering the casing. After the casing is lowered into a designated position in the well, the well mouth is pressed to break the rupture disc, the broken pieces of the rupture disc enter the outer cylinder along with the drilling fluid, the small broken disc pieces normally pass through the filter screen, the large broken disc pieces are concentrated on the bearing screw, the drilling fluid and the small broken disc pieces impact the valve core head, the elastic assembly is in a compressed state, a gap is formed between the valve core head and the valve seat to form a flow channel, the drilling fluid and the small broken disc pieces flow along the flow channel, and when the pump is stopped, the large broken disc pieces slide onto the inner wall of the outer cylinder under the action of gravity, and the floating collar is self-unblocked.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of drilling technology, in particular to a self-unblocking drillable float collar. BACKGROUND

[0002] In recent years, full gauge float collar is widely used in shale gas market and large displacement horizontal wells in various oilfields. It uses the rupture disc as a temporary barrier. After the casing is positioned, the rupture disc is crushed by pressure at the wellhead to achieve full gauge of the pipe string, facilitating subsequent modification and construction.

[0003] However, due to uneven stress distribution and large volume of the rupture disc, the broken fragments are not uniform in size, and the float collar is blocked, which affects subsequent cementing operations. Therefore, in order to meet the requirements of full gauge float collar construction and keep the wellbore unobstructed, safe and reliable anti-blocking drillable float collar needs to be developed. SUMMARY

[0004] The present application aims to provide a self-unblocking drillable float collar to alleviate the technical problems in the prior art, such as uneven stress distribution and large volume of the rupture disc, which leads to uneven size of broken fragments, more broken fragments, and blocking of the float collar, affecting subsequent cementing operations.

[0005] To solve the above technical problems, the technical solution provided by the present application is as follows:

[0006] The self-unblocking drillable float collar provided by the present application comprises an outer cylinder, a supporting screw sleeve, a filter screen, a valve core head, a valve seat and an elastic assembly.

[0007] The outer cylinder is provided with a hollow structure, and the two ends are respectively formed with a liquid inlet and a liquid outlet. The liquid inlet is connected to the casing string. The inner cavity of the outer cylinder is sequentially provided with the supporting screw sleeve, the filter screen and the valve seat from the direction of the liquid inlet to the liquid outlet. The elastic assembly is connected with the valve core head.

[0008] When drilling fluid is pumped into the outer cylinder, the filter screen is used to intercept large broken disc fragments carried by the drilling fluid in the supporting screw sleeve, and small broken disc fragments pass through the filter screen and impact the valve core head along with the drilling fluid. When the valve core head is impacted, the elastic assembly is in a compressed state, and the valve core head and the valve seat have a gap to form a flow channel.

[0009] When the pumping of drilling fluid is stopped, the large broken disc fragments in the supporting screw sleeve slide onto the inner wall of the outer cylinder due to gravity, and the elastic force generated by the elastic assembly makes the valve core head tightly adhere to the valve seat.

[0010] In an optional embodiment,

[0011] The elastic assembly comprises an elastic piece and a fixing seat;

[0012] The fixing seat is threadedly connected to one end of the valve seat close to the liquid outlet;

[0013] One end of the elastic piece is connected to the valve core head, and the fixing seat is used for supporting the other end of the elastic piece, so that the elastic force generated by the elastic piece can act on the valve core head.

[0014] In an optional embodiment,

[0015] The self-unblocking drillable floating collar further comprises a valve core rod;

[0016] The valve core rod is connected to the side of the valve core head facing the liquid outlet, and the elastic piece is sleeved on the valve core rod.

[0017] In an optional embodiment,

[0018] The inner wall of the chip containing groove formed in the middle of the supporting screw sleeve is inclined, so that the large broken disc fragments slide along the inclined surface of the inner wall of the supporting screw sleeve to the inner wall of the outer cylinder under the action of gravity;

[0019] The inner wall of the outer cylinder is provided with an anti-backout thread to prevent the large broken disc fragments sliding out of the chip containing groove from being separated from the outer cylinder.

[0020] In an optional embodiment,

[0021] The self-unblocking drillable floating collar further comprises a flow guide pipe;

[0022] The flow guide pipe is arranged between the filter screen and the valve seat, and the drilling fluid and small broken disc fragments passing through the filter screen flow along the flow guide pipe.

[0023] In an optional embodiment,

[0024] The end of the flow guide pipe facing the valve seat has a slot, and the upper end surface of the valve seat is inserted into the slot.

[0025] In an optional embodiment,

[0026] The self-unblocking drillable floating collar further comprises a cast cement layer;

[0027] The cast cement layer is located on the inner wall of the outer cylinder, and the inner side of the cast cement layer is used for mounting the flow guide pipe, the valve seat and the fixing seat.

[0028] In an optional embodiment,

[0029] The supporting screw sleeve is connected with the inner wall of the outer cylinder through threads.

[0030] In an optional embodiment,

[0031] The outer surface of the valve core head is provided with a ball head rubber for sealing with the valve seat.

[0032] In an optional embodiment,

[0033] The materials of the supporting screw sleeve, filter screen, valve core rod and elastic member are all aluminum alloy.

[0034] The materials of the flow guide pipe, valve core head, valve seat and fixing seat are all rubber resin.

[0035] The technical effects that can be achieved by the application are as follows:

[0036] The self-unblocking drillable float collar provided by the application is used for full-bore floating casing operation, is installed at the bottom of a casing string, realizes sealing at the bottom of an air section of the floating casing, blocks well fluid from entering the casing, and after the casing is lowered into a designated position in the well, the rupture disc is broken by pressure at the wellhead, the broken pieces of the broken disc enter the outer cylinder along with drilling fluid, small broken disc pieces normally pass through the filter screen, large broken disc pieces are concentrated in the supporting screw sleeve, drilling fluid and small broken disc pieces impact the valve core head, the elastic assembly is in a compressed state, a gap is formed between the valve core head and the valve seat to form a flow channel, drilling fluid and small broken disc pieces flow along the flow channel, and when the pump is stopped, the large broken disc pieces slide onto the inner wall of the outer cylinder under the action of gravity, the self-unblocking of the float collar is realized, and the technical problems in the prior art, such as uneven particle size of broken disc pieces and too many broken disc pieces caused by uneven stress distribution and large volume of the broken disc in the broken disc, causing the float collar to be blocked, and affecting subsequent cementing operation, are solved. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0038] Figure 1 The overall structure of the self-unblocking drillable float collar is shown in the sectional view.

[0039] Figure legend: 1-outer cylinder; 2-supporting screw sleeve; 3-filter screen; 4-flow guide pipe; 5-valve core head; 6-valve seat; 7-elastic member; 8-valve core rod; 9-fixing seat; 10-cement layer; 11-liquid inlet; 12-liquid outlet. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0042] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0043] Uneven stress distribution and large volume within the fractured disk lead to uneven particle size of the broken fragments and a large number of broken fragments, causing blockage of the float ring and affecting subsequent cementing operations.

[0044] In view of this, such as Figure 1 As shown, the self-unblocking drillable floating hoop provided in this embodiment can achieve the effect of preventing blockage during full-bore floating casing operation. Specifically, it includes: outer cylinder 1, supporting threaded sleeve 2, filter screen 3, valve core head 5, valve seat 6, and elastic component.

[0045] The outer cylinder 1 is a hollow structure, specifically a cylindrical structure with openings at both ends. The two ends are respectively formed with a liquid inlet 11 and a liquid outlet 12. The liquid inlet 11 is connected to the sleeve column. It should be noted that the outer cylinder 1 is placed horizontally during use.

[0046] The inner cavity of the outer cylinder 1 is sequentially equipped with a support screw sleeve 2, a filter screen 3 and a valve seat 6 from the liquid inlet 11 toward the liquid outlet 12, and the elastic component is connected to the valve core head 5.

[0047] When pumping drilling fluid into the outer cylinder 1, the drilling fluid enters the outer cylinder 1 through the liquid inlet 11, and is filtered by the filter screen 3 after passing through the bearing sleeve 2 in the outer cylinder 1. The filter screen 3 retains large broken disc fragments in the bearing sleeve 2, and small broken disc fragments pass through the filter screen 3 and impact the valve core head 5. When the pressure in the pipe string is greater than the annular static fluid pressure, the elastic assembly is in a compressed state, there is a gap between the valve core head 5 and the valve seat 6 to form a flow channel, and the small broken disc fragments flow along the flow channel with the drilling fluid and finally flow out through the liquid outlet 12.

[0048] When stopping pumping the drilling fluid, the large broken disc fragments in the bearing sleeve 2 slide onto the inner wall of the outer cylinder 1 due to gravity, and the elastic force generated by the elastic assembly causes the valve core head 5 to tightly adhere to the valve seat 6, thereby achieving self-unblocking of the float collar.

[0049] The self-unblocking drillable float collar provided in the embodiment is used for full-bore floating casing operation, is installed at the bottom of the casing string, and realizes bottom sealing of the floating casing air section, thereby preventing well fluid from entering the casing. After the casing is lowered to a designated position in the well, the broken disc is crushed by pressure at the wellhead, the broken fragments of the broken disc enter the outer cylinder 1 with the drilling fluid, the small broken disc fragments pass through the filter screen 3 normally, the large broken disc fragments are concentrated in the bearing sleeve 2, the drilling fluid and the small broken disc fragments impact the valve core head 5, the elastic assembly is in a compressed state, there is a gap between the valve core head 5 and the valve seat 6 to form a flow channel, and the drilling fluid and the small broken disc fragments flow along the flow channel. When pumping is stopped, the large broken disc fragments slide onto the inner wall of the outer cylinder 1 under the action of gravity, thereby achieving self-unblocking of the float collar and solving the technical problem that the broken disc fragments are not uniform in size and there are many broken disc fragments due to uneven internal stress distribution and large volume of the broken disc in the prior art, which causes the float collar to be blocked and affects subsequent cementing operation.

[0050] On the basis of the above embodiment, in an optional implementation, the elastic assembly in the self-unblocking drillable float collar provided in the embodiment includes an elastic member 7 and a fixing seat 9. The fixing seat 9 is threadedly connected to one end of the valve seat 6 close to the liquid outlet 12. One end of the elastic member 7 is connected to the valve core head 5, and the fixing seat 9 is used to support the other end of the elastic member 7, so that the elastic force generated by the elastic member 7 can act on the valve core head 5.

[0051] Specifically, the fixing seat 9 specifically includes a connecting seat, a spring support seat and a connecting rod. The connecting seat is connected to the centrally located spring support seat through a plurality of connecting rods, and the connecting seat is threadedly connected to the valve seat 6, so that the whole can be fixed. The spring support seat serves to support the elastic member 7, and in addition, the middle part of the spring support seat has a groove for the valve core rod 8 to extend into.

[0052] In the optional embodiment, the self-unblocking drillable float collar further comprises a valve core rod 8; the valve core rod 8 is connected to the side of the valve core head 5 facing the outlet 12, and the elastic member 7 is sleeved on the valve core rod 8; the valve core rod 8 moves together with the valve core head 5.

[0053] In the optional embodiment, a chip containing groove is formed in the middle of the supporting screw sleeve 2 for containing large broken disc fragments; when the drilling fluid is pumped in, the drilling fluid carries the broken disc fragments into the outer cylinder 1; due to the setting of the filter screen 3, the large broken disc fragments are intercepted in the chip containing groove; after the pumping of the drilling fluid is stopped, since the outer cylinder 1 is horizontally placed and the inner wall forming the chip containing groove is obliquely arranged, the large broken disc fragments slide along the inclined surface of the inner wall of the supporting screw sleeve 2 to the inner wall of the outer cylinder 1 under the action of gravity, i.e. the large broken disc fragments fall into the inner wall of the outer cylinder 1, thereby avoiding the large broken disc fragments from blocking the chip containing groove, and realizing the self-unblocking of the float collar.

[0054] Moreover, the anti-back-off thread is arranged on the inner wall of the outer cylinder 1 to prevent the large broken disc fragments sliding out of the chip containing groove from being separated from the outer cylinder 1.

[0055] In the optional embodiment, the self-unblocking drillable float collar further comprises a flow guide pipe 4; the flow guide pipe 4 is arranged between the filter screen 3 and the valve seat 6, and the drilling fluid and small broken disc fragments passing through the filter screen 3 flow along the flow guide pipe 4; the flow guide pipe 4 has a slot at the end facing the valve seat 6, and the upper end surface of the valve seat 6 is inserted into the slot, so that the valve seat 6 is fixed in the slot.

[0056] In the optional embodiment, the self-unblocking drillable float collar further comprises a cast cement layer 10; the cast cement layer 10 is arranged on the inner wall of the outer cylinder 1, and the inner side of the cast cement layer 10 is used for mounting the flow guide pipe 4, the valve seat 6 and the fixing seat 9.

[0057] Specifically, the triangular protruding structure is arranged on the inner wall of the outer cylinder 1, and after the cement is cast and solidified, the triangular protruding structure can support the cast cement layer 10, thereby fixing the cast cement layer 10 in the outer cylinder 1.

[0058] In the optional embodiment, the supporting screw sleeve 2 and the inner wall of the outer cylinder 1 are connected through threads, specifically, the outer wall of the supporting screw sleeve 2 has external threads, the inner wall of the outer cylinder 1 has an internal thread segment, and the supporting screw sleeve 2 is screwed in the outer cylinder 1 through the cooperation of the internal and external threads.

[0059] In the optional embodiment, the outer surface of the valve core head 5 is provided with a ball head rubber, and the ball head of the valve core head 5 and the valve seat 6 are sealed through the ball head rubber, thereby preventing the wellbore fluid from entering the casing interior.

[0060] In the optional embodiment, the materials of the supporting screw 2, the filter screen 3, the valve core rod 8 and the elastic member 7 are all aluminum alloy; the materials of the flow guide pipe 4, the valve core head 5, the valve seat 6 and the fixing seat 9 are all rubber resin. Since the above-mentioned aluminum alloy, cement, resin and rubber are all easy-to-drill materials, the float collar is realized to be drillable.

[0061] The overall principle of the self-deblocking drillable float collar provided by the embodiment is as follows:

[0062] The self-deblocking drillable float collar is connected to the bottom of the casing string and is responsible for the reverse sealing of the bottom of the air section in the floating casing operation. During the running-in process, the ball head of the valve core head 5 and the valve seat 6 are sealed by the ball head rubber under the action of the annular hydrostatic pressure, so as to block the wellbore fluid from entering the inside of the casing.

[0063] After being opened at the designated position in the well, the drilling fluid carries the broken disc fragments downward, and the drilling fluid continues to be pumped. When the pressure in the pipe string is greater than the annular hydrostatic pressure, the valve core head 5 compresses the elastic member 7 and the valve core rod 8 to jointly seat in the fixing seat 9. At this time, the flow passage is opened, the annulus in the pipe string is connected with the wellbore annulus, a part of the broken disc fragments enter the chip holding groove between the supporting screw 2 and the outer cylinder 1, the inner wall of the outer cylinder 1 is processed with anti-back thread to prevent the broken disc fragments from separating, the remaining broken disc fragments enter the supporting screw 2, and the small fragments enter the flow guide pipe 4 through the filter screen 3 and are circulated out of the annulus in the pipe string along with the drilling fluid through the gap between the valve core head 5 and the valve seat 6. When the pump is stopped, the valve seat 6 and the valve core rod 8 are reset under the action of the elastic member 7, and the inlet passage is closed. At this time, the large broken disc fragments isolated in the filter screen 3 fall into the inner wall of the outer cylinder 1 along the inclined surface of the supporting screw 2 under the action of gravity, so as to realize the self-deblocking of the float collar. When the pump is restarted, the large fragments will enter the chip holding groove between the supporting screw 2 and the outer cylinder 1 under the pushing of the liquid. Through the filtering and self-deblocking, the inlet passage of the entire casing string is unblocked.

[0064] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A self-debris-removing drillable float collar, characterized in that, The self-unblocking drillable float collar comprises an outer cylinder (1), a supporting screw sleeve (2), a filter screen (3), a valve core head (5), a valve seat (6) and an elastic assembly. The outer cylinder (1) is provided as a hollow structure, and a liquid inlet (11) and a liquid outlet (12) are respectively formed at two ends of the outer cylinder (1), the liquid inlet (11) is connected to a casing column, and the inner cavity of the outer cylinder (1) is sequentially provided with the supporting screw sleeve (2), the filter screen (3) and the valve seat (6) from the liquid inlet (11) to the liquid outlet (12), and the elastic assembly is connected to the valve core head (5). When the drilling fluid is pumped into the outer cylinder (1), the filter screen (3) is used to intercept large broken disc fragments carried by the drilling fluid in the supporting screw sleeve (2), and small broken disc fragments are impacted on the valve core head (5) along with the drilling fluid passing through the filter screen (3), the elastic assembly is in a compressed state when the valve core head (5) is impacted, and a gap between the valve core head (5) and the valve seat (6) forms a flow channel. In use, the outer cylinder (1) is placed horizontally as a whole. When the pumping of the drilling fluid is stopped, the large broken disc fragments in the supporting screw sleeve (2) slide onto the inner wall of the outer cylinder (1) due to gravity, and the elastic force generated by the elastic assembly makes the valve core head (5) tightly adhere to the valve seat (6). A chip containing groove is formed in the middle of the supporting screw sleeve (2) for containing large broken disc fragments, and the inner wall of the chip containing groove is provided in an inclined manner, so that the large broken disc fragments slide onto the inner wall of the outer cylinder (1) along the inclined surface of the inner wall of the supporting screw sleeve (2) under the action of gravity.

2. The self-unblocking drillable float collar according to claim 1, wherein the elastic assembly comprises an elastic member (7) and a fixing seat (9). The fixing seat (9) is threadedly connected to one end of the valve seat (6) close to the liquid outlet (12). One end of the elastic member (7) is connected to the valve core head (5), and the other end of the elastic member (7) is supported by the fixing seat (9), so that the elastic force generated by the elastic member (7) can act on the valve core head (5).

3. The self-unblocking drillable float collar according to claim 2, wherein the self-unblocking drillable float collar further comprises a valve core rod (8). The valve core rod (8) is connected to one side of the valve core head (5) close to the liquid outlet (12), and the elastic member (7) is sleeved on the valve core rod (8).

4. The self-unblocking drillable float collar according to claim 2, wherein the inner wall of the outer cylinder (1) is provided with an anti-back-off thread to prevent the large broken disc fragments sliding out of the chip containing groove from being separated from the outer cylinder (1).

5. The self-unblocking drillable float collar according to claim 2, wherein the self-unblocking drillable float collar further comprises a flow guide pipe (4). The flow guide pipe (4) is arranged between the filter screen (3) and the valve seat (6), and the drilling fluid and small broken disc fragments passing through the filter screen (3) flow along the flow guide pipe (4).

6. The self-unblocking drillable float collar according to claim 5, wherein ​ ​ ​ ​ ​ The flow guide pipe (4) has a slot at one end thereof, and the upper end surface of the valve seat (6) is inserted into the slot.

7. The self-deblocking drillable float collar according to claim 6, characterized in that, The self-deblocking drillable float collar further comprises a cast cement layer (10). The cast cement layer (10) is located on the inner wall of the outer cylinder (1), and the inner side of the cast cement layer (10) is used for mounting the flow guide pipe (4), the valve seat (6) and the fixing seat (9).

8. The self-deblocking drillable float collar according to claim 1, characterized in that, The supporting screw sleeve (2) is connected with the inner wall of the outer cylinder (1) through threads.

9. The self-deblocking drillable float collar according to claim 1, characterized in that, The outer surface of the valve core head (5) is provided with a ball head rubber, which is used for sealing with the valve seat (6).

10. The self-deblocking drillable float collar according to claim 7, characterized in that, The materials of the supporting screw sleeve (2), the filter screen (3), the valve core rod (8) and the elastic member (7) are all aluminum alloy; The materials of the flow guide pipe (4), the valve core head (5), the valve seat (6) and the fixing seat (9) are all rubber resin.

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