Self-unblocking drillable float collar

Abstract

The invention provides a self-unblocking drillable float collar, which relates to the technical field of well drilling, is used for full-bore floating casing running operation, is mounted at the bottom of a casing string, realizes sealing of the bottom of an air section of floating casing running, prevents fluid in a well from entering the casing, and after the casing runs into a specified position in the well, a rupture disk is crushed through pressure of a well mouth, so that the casing is prevented from being blocked. Fragments obtained after breaking of the breaking disc enter the outer cylinder along with drilling fluid, small breaking disc fragments normally pass through the filter screen, large breaking disc fragments are concentrated on the bearing threaded sleeve, the drilling fluid and the small breaking disc fragments impact the valve element head, the elastic assembly is in a compressed state, and a gap is formed between the valve element head and the valve seat to form a flow channel. Drilling fluid and small fragments of the crushing disc flow along the flow channel, when a pump is stopped, large fragments of the crushing disc slide into the inner wall of the outer cylinder under the action of gravity, and self-blockage removal of the float collar is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of drilling, in particular to a self-blocking drillable floating collar. Background Art

[0002] In recent years, full-bore floating couplings have been widely used in the domestic shale gas market and large-displacement horizontal wells in various oil fields. They use rupture disks as temporary barriers. After the casing is lowered into place, the rupture disks are crushed by the wellhead pressure to achieve full-bore tubing and facilitate subsequent renovation construction.

[0003] However, due to the uneven stress distribution and large volume of the rupture disk, the particle size of its broken fragments is uneven and the large number of broken fragments causes blockage of the floating collar, affecting the subsequent cementing operation. Therefore, in order to meet the requirements of full-bore floating casing construction and keep the wellbore unobstructed, it is necessary to carry out research on safe and reliable anti-blockage drillable floating collars. Summary of the invention

[0004] The purpose of the present invention is to provide a self-unblocking drillable floating collar, so as to alleviate the technical problems existing in the prior art such as uneven stress distribution and large volume in the rupture disk, which lead to uneven particle size of broken fragments and a large number of broken fragments, causing blockage of the floating collar and affecting subsequent cementing operations.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] The self-blocking drillable floating collar provided by the present invention comprises: an outer tube, a supporting screw sleeve, a filter screen, a valve core head, a valve seat and an elastic component;

[0007] The outer cylinder is configured as a hollow structure, with a liquid inlet and a liquid outlet formed at both ends, respectively. The liquid inlet is connected to the casing column, and the inner cavity of the outer cylinder is sequentially installed with the supporting screw sleeve, the filter screen and the valve seat from the liquid inlet toward the liquid outlet, and the elastic component is connected to the valve core head;

[0008] When drilling fluid is pumped into the outer tube, the filter screen is used to retain large pieces of crushing disk fragments carried by the drilling fluid in the support screw sleeve, and small pieces of crushing disk fragments pass through the filter screen along with the drilling fluid to impact the valve core head. When the valve core head is impacted, the elastic component is in a compressed state, and a gap is formed between the valve core head and the valve seat to form a flow channel;

[0009] When the drilling fluid is stopped from being pumped in, the large pieces of crushing disk 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 component makes the valve core head close to the valve seat.

[0010] In an alternative embodiment,

[0011] The elastic component comprises an elastic member 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 member is connected to the valve core head, and the fixing seat is used to support the other end of the elastic member so that the elastic force generated by the elastic member can act on the valve core head.

[0014] In an alternative embodiment,

[0015] The self-blocking drillable floating collar also includes a valve core rod;

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

[0017] In an alternative embodiment,

[0018] A chip receiving groove for receiving large pieces of crushing disk fragments is formed through the middle of the supporting screw sleeve, and the inner wall of the chip receiving groove is inclined so that the large pieces of crushing disk fragments can slide onto the inner wall of the outer cylinder along the inclined surface of the inner wall of the supporting screw sleeve under the action of gravity;

[0019] The inner wall of the outer cylinder is provided with an anti-retraction thread to prevent large pieces of crushing disk fragments that slip out of the chip groove from escaping from the outer cylinder.

[0020] In an alternative embodiment,

[0021] The self-blocking drillable floating collar also includes 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 pieces of crushing disk fragments passing through the filter screen flow along the flow guide pipe.

[0023] In an alternative embodiment,

[0024] One end of the flow guide tube facing the valve seat is provided with a slot, and the upper end surface of the valve seat is inserted into the slot.

[0025] In an alternative embodiment,

[0026] The self-blocking drillable floating collar also includes a poured 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 installing the flow guide pipe, the valve seat and the fixing seat.

[0028] In an alternative embodiment,

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

[0030] In an alternative embodiment,

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

[0032] In an alternative embodiment,

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

[0034] The guide tube, valve core head, valve seat and fixing seat are all made of rubber resin.

[0035] Based on the above technical solutions, the technical effects that can be achieved by the present invention are:

[0036] The self-unblocking drillable floating collar provided by the present invention is used for full-bore floating casing operation and is installed at the bottom of the casing column to realize the bottom sealing of the air section of the floating casing and block the fluid in the well from entering the casing. After the casing is lowered to the specified position in the well, the rupture disk is crushed by pressure at the wellhead, and the crushed fragments of the rupture disk enter the outer cylinder with the drilling fluid, and the small pieces of crushing disk fragments are allowed to pass normally through the filter screen, and the large pieces of crushing disk fragments are concentrated on the supporting screw sleeve. The drilling fluid and the small pieces of crushing disk fragments impact the valve core head, and the elastic component is in a compressed state. A gap is formed between the valve core head and the valve seat to form a flow channel, and the drilling fluid and the small pieces of crushing disk fragments flow along the flow channel. When the pump is stopped, the large pieces of crushing disk fragments slide onto the inner wall of the outer cylinder under the action of gravity, so as to realize the self-unblocking of the floating collar, and alleviate the technical problems existing in the prior art that the particle size of the crushed fragments is uneven and the crushed fragments are large, which affects the subsequent cementing operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 A cross-sectional view of the overall structure of a self-unplugging drillable floating collar provided in an embodiment of the present invention.

[0039] Icon: 1-outer cylinder; 2-supporting screw sleeve; 3-filter screen; 4-guide tube; 5-valve core head; 6-valve seat; 7-elastic part; 8-valve core rod; 9-fixing seat; 10-casting cement layer; 11-liquid inlet; 12-liquid outlet. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 here can be arranged and designed in various different configurations.

[0041] 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 claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0043] Due to the uneven stress distribution and large volume of the rupture disk, the particle size of the broken fragments is uneven and the large number of broken fragments causes the floating collar to be blocked, affecting the subsequent cementing operations.

[0044] In view of this, if Figure 1 As shown, the self-unblocking drillable floating collar provided in this embodiment can achieve the effect of preventing blockage in full-bore floating casing operations, and specifically includes: an outer tube 1, a supporting screw sleeve 2, a filter screen 3, a valve core head 5, a valve seat 6 and an elastic component.

[0045] The outer tube 1 is configured as a hollow structure. Specifically, the outer tube 1 is a cylindrical structure with openings formed at both ends. A liquid inlet 11 and a liquid outlet 12 are formed at the two ends respectively. The liquid inlet 11 is connected to the casing column. It should be noted that when in use, the outer tube 1 is placed horizontally as a whole.

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

[0047] When the drilling fluid is pumped into the outer tube 1, the drilling fluid enters the outer tube 1 through the liquid inlet 11, and the drilling fluid first passes through the supporting screw sleeve 2 in the outer tube 1 and then is filtered through the filter screen 3. The filter screen 3 retains the large pieces of crushing disk fragments carried by the drilling fluid in the supporting screw sleeve 2, and the small pieces of crushing disk fragments pass through the filter screen 3 along with the drilling fluid to impact the valve core head 5. When the drilling fluid is continuously pumped in, when the pressure in the tubing string is greater than the hydrostatic pressure of the annulus, the elastic component is in a compressed state, and a gap is formed between the valve core head 5 and the valve seat 6 to form a flow channel. The small pieces of crushing disk fragments flow along the flow channel along with the drilling fluid and finally flow out through the liquid outlet 12.

[0048] When the drilling fluid is stopped from being pumped in, since the outer tube 1 is in a horizontal state as a whole, the large pieces of crushing disk fragments in the supporting screw sleeve 2 slide onto the inner wall of the outer tube 1 due to gravity, and the elastic force generated by the elastic component makes the valve core head 5 close to the valve seat 6, realizing the self-unblocking of the floating collar.

[0049] The self-unblocking drillable floating collar provided in the present embodiment is used for full-bore floating casing operation, and is installed at the bottom of the casing string to achieve the bottom sealing of the air section of the floating casing, and block the fluid in the well from entering the casing. After the casing is lowered to the designated position in the well, the rupture disk is crushed by pressure at the wellhead, and the broken fragments of the rupture disk enter the outer tube 1 with the drilling fluid, and the small pieces of rupture disk fragments are allowed to pass normally through the filter 3, and the large pieces of rupture disk fragments are concentrated on the supporting screw sleeve 2. The drilling fluid and the small pieces of rupture disk fragments impact the valve core head 5, and the elastic component 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 pieces of rupture disk fragments flow along the flow channel. When the pump is stopped, the large pieces of rupture disk fragments slide onto the inner wall of the outer tube 1 under the action of gravity, so as to achieve the self-unblocking of the floating collar, and alleviate the technical problems existing in the prior art that the particle size of the broken fragments is uneven and the broken fragments are large, which affects the subsequent cementing operation.

[0050] On the basis of the above embodiments, in an optional implementation manner, the elastic component in the self-deblocking drillable floating collar provided in this 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 fixed seat 9 includes a connecting seat, a spring support seat and a connecting rod. The connecting seat is connected to the spring support seat located in the center through multiple connecting rods. The connecting seat is threadedly connected to the valve seat 6 to fix the whole. The spring support seat plays the role of supporting the elastic member 7. In addition, the middle part of the spring support seat has a groove for the valve core rod 8 to extend into.

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

[0053] In an optional embodiment, a chip collecting groove for containing large pieces of crushing disk fragments is formed through the middle of the supporting screw sleeve 2. When the drilling fluid is pumped in, the drilling fluid carries the rupture disk fragments into the outer tube 1. Due to the setting of the filter screen 3, the large pieces of crushing disk fragments are retained in the chip collecting groove. After the pumping of the drilling fluid is stopped, since the outer tube 1 is placed horizontally and the inner wall forming the chip collecting groove is inclined, the large pieces of crushing disk fragments slide along the inclined surface of the inner wall of the supporting screw sleeve 2 to the inner wall of the outer tube 1 under the action of gravity, and the large pieces of crushing disk fragments can fall into the inner wall of the outer tube 1, thereby preventing the large pieces of crushing disk fragments from blocking the chip collecting groove and realizing self-unblocking of the floating hoop.

[0054] In addition, an anti-retraction thread is provided on the inner wall of the outer cylinder 1 to prevent large pieces of crushing disk fragments that slip out of the chip receiving groove from escaping from the outer cylinder 1 .

[0055] In an optional embodiment, the self-declogging drillable floating collar further includes a guide pipe 4; the guide pipe 4 is arranged between the filter screen 3 and the valve seat 6, and the drilling fluid and small pieces of crushing disk fragments passing through the filter screen 3 flow along the guide pipe 4; the guide pipe 4 has a slot at one 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 can be fixed in the slot.

[0056] In an optional embodiment, the self-unblocking drillable floating collar further includes a cast cement layer 10 ; the cast cement layer 10 is located on the inner wall of the outer tube 1 , and the inner side of the cast cement layer 10 is used to install the guide pipe 4 , the valve seat 6 and the fixing seat 9 .

[0057] Specifically, a triangular protrusion structure is provided on the inner wall of the outer tube 1 . After the cement is poured and solidified, the triangular protrusion structure can support the poured cement layer 10 , thereby fixing the poured cement layer 10 in the outer tube 1 .

[0058] In an optional embodiment, the supporting screw sleeve 2 is connected to the inner wall of the outer cylinder 1 by a thread. Specifically, the outer wall of the supporting screw sleeve 2 has an external thread, and the inner wall of the outer cylinder 1 has an internal thread section. The supporting screw sleeve 2 is screwed into the outer cylinder 1 through the cooperation of the internal and external threads.

[0059] In an optional embodiment, a ball head rubber is provided on the outer surface of the valve core head 5, and a ball head rubber seal is provided between the ball head of the valve core head 5 and the valve seat 6 to prevent the wellbore fluid from entering the interior of the casing.

[0060] In an optional embodiment, 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 guide tube 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, rubber and other materials are all easy-to-drill materials, the drillability of the floating hoop is achieved.

[0061] The overall principle of the self-unblocking drillable floating collar provided in this embodiment is as follows:

[0062] The self-unplugging drillable floating collar is connected to the bottom of the casing string and is responsible for the reverse sealing of the bottom of the air section during the floating casing operation. During the lowering process, due to the hydrostatic pressure of the annulus, the ball head of the valve core head 5 and the valve seat 6 are sealed by the ball head rubber to prevent the wellbore fluid from entering the casing.

[0063] After the rupture disk is opened at the designated position in the well, the drilling fluid carries the rupture disk fragments downward, and the drilling fluid is continuously pumped in. When the pressure in the tubing string is greater than the hydrostatic pressure in the annulus, the valve core head 5 compresses the elastic member 7 and the valve core rod 8 and sits in the fixed seat 9 together. At this time, the flow channel is opened, and the annulus in the tubing string is connected with the annulus in the wellbore; a part of the rupture disk fragments descends into the chip receiving groove formed between the supporting screw sleeve 2 and the outer tube 1, and an anti-retraction thread is processed on the inner wall of the outer tube 1 to prevent the rupture disk fragments from detaching; the remaining rupture disk fragments enter the supporting screw sleeve 2, and under the filtration of the filter screen 3, small pieces of fragments are The pieces enter the guide pipe 4 and circulate 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 liquid inlet channel is closed. At this time, the large pieces of rupture disk fragments isolated in the filter screen 3 fall into the inner wall of the outer tube 1 along the inclined surface of the supporting screw sleeve 2 under the action of gravity, so as to realize the self-unblocking of the floating hoop; when the pump is restarted, the large pieces of fragments will enter the chip receiving groove formed between the supporting screw sleeve 2 and the outer tube 1 under the push of the liquid; the liquid inlet channel of the entire casing string is unblocked through filtration and self-unblocking.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-unblocking drillable floating collar, characterized in that: include: 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 component; The outer cylinder (1) is configured as a hollow structure, with a liquid inlet (11) and a liquid outlet (12) formed at both ends respectively, the liquid inlet (11) being connected to the casing column, the inner cavity of the outer cylinder (1) being sequentially installed with the supporting screw sleeve (2), the filter screen (3) and the valve seat (6) in the direction from the liquid inlet (11) toward the liquid outlet (12), and the elastic component being connected to the valve core head (5); When drilling fluid is pumped into the outer cylinder (1), the filter screen (3) is used to retain large pieces of crushing disk fragments carried by the drilling fluid in the support screw sleeve (2), and small pieces of crushing disk fragments pass through the filter screen (3) along with the drilling fluid to impact the valve core head (5). When the valve core head (5) is impacted, the elastic component is in a compressed state, and a gap is formed between the valve core head (5) and the valve seat (6) to form a flow channel; When the drilling fluid is stopped from being pumped in, the large pieces of crushing disk fragments in the supporting screw sleeve (2) slide onto the inner wall of the outer tube (1) due to gravity, and the elastic force generated by the elastic component causes the valve core head (5) to be tightly attached to the valve seat (6).

2. The self-drillable floating collar according to claim 1, characterized in that: The elastic component 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 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).

3. The self-drillable floating collar according to claim 2 is characterized in that: The self-blocking drillable floating collar also includes a valve core rod (8); The valve core rod (8) is connected to a side of the valve core head (5) facing the liquid outlet (12), and the elastic member (7) is sleeved on the valve core rod (8).

4. The self-drillable floating collar according to claim 2 is characterized in that: A chip receiving groove for receiving large pieces of crushing disk fragments is formed through the middle of the supporting screw sleeve (2), and the inner wall of the chip receiving groove is inclined so that the large pieces of crushing disk fragments can 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; The inner wall of the outer cylinder (1) is provided with an anti-retraction thread to prevent large pieces of crushing disk fragments that slip out of the chip receiving groove from escaping from the outer cylinder (1).

5. The self-drillable floating collar according to claim 2 is characterized in that: The self-blocking drillable floating collar also includes 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 pieces of crushing disk fragments that pass through the filter screen (3) flow along the flow guide pipe (4).

6. The self-drillable floating collar according to claim 5 is characterized in that: One end of the flow guide tube (4) facing the valve seat (6) is provided with a slot, and the upper end surface of the valve seat (6) is inserted into the slot.

7. The self-drillable floating collar according to claim 6 is characterized in that: The self-unblocking drillable floating collar also includes 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 to install the flow guide pipe (4), the valve seat (6) and the fixing seat (9).

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

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

10. The self-drillable floating 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 tube (4), the valve core head (5), the valve seat (6) and the fixing seat (9) are all rubber resin.

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