CN111779464A - Downhole blowout preventer for double-layer tubular dual-gradient managed pressure drilling - Google Patents

Abstract

The invention relates to a downhole blowout prevention device for double-layer pipe double-gradient pressure-controlled drilling. The downhole blowout prevention device mainly consists of upper and lower joints of an inner pipe, and upper and lower valve seats of the blowout prevention device, which are installed between the upper and lower valve seats. The coaxial throttle sliding sleeve is composed of a double-layer tube inner tube sealing structure installed on the lower valve seat, and a double-layer tube centralizing structure installed on the upper and lower valve seats. The double-layer tube inner tube sealing structure is mainly composed of a poppet valve disc, a poppet valve mounting block and a pin. The double-layer pipe righting structure is mainly composed of righting blocks with flow passages. The beneficial effects of the invention are that the blowout prevention device can be automatically closed when a well kick or blowout occurs at the bottom of the well; the annulus passages of the inner and outer pipes of the double-layer pipe and the inner pipe passages can be blocked at the same time, and the double-gradient pressure control of the double-layer pipe can be ensured. Safety of drilling; after the well kill is completed and the kick and blowout are controlled, the blowout preventer can be automatically reopened to ensure the normal operation of drilling.

Description

Downhole blowout preventer for double-layer tubular dual-gradient managed pressure drilling

technical field

The invention relates to the technical field of double-layer pipe double-gradient pressure-controlled drilling, in particular to a double-layer pipe double-gradient pressure-controlled drilling downhole blowout prevention device.

Background technique

After several years of exploration and development, the exploitation of oil resources on land has been close to saturation, and seeking new oil and gas resources from the ocean is a new hot direction for oil and gas development in the world. However, most of the rich oil and gas and natural gas hydrate resources in the South my country Sea are stored in the deep-sea waters. In the face of deep-water drilling operations, the pressure window is narrow, leak-prone production layers, safe drilling of loose seabed surface layers, and shallow seabed hydrates. Due to problems such as low layer leakage pressure, double-layer tubular dual-gradient managed pressure drilling technology is a feasible technology.

In double-layer tubular dual-gradient managed pressure drilling operations, dangerous conditions such as well invasion, overflow and even blowout are prone to occur when drilling shallow gas and reservoirs. If these dangerous conditions are not controlled in time, serious Casualties, economic losses and environmental pollution. In order to effectively avoid the above situation, it is necessary to design a downhole blowout preventer according to the structure of the double-layer pipe, so as to realize rapid response and control to dangerous conditions such as blowout, so as to ensure the safe operation of double-layer pipe dual-gradient managed pressure drilling.

The existing problems of the blowout preventer for the double-pipe structure are as follows:

(1) The blowout preventer is composed of a set of separate blowout preventers, which block the annular channel of the double-layer pipe and the inner pipe channel of the double-layer pipe respectively, and need to be opened manually. The annular space of the layer tube and the inner tube channel of the double-layer tube are blocked.

(2) The existing blowout preventer for double-layer pipes uses the pressure difference between blowout and normal drilling as the driving force. The tube channel becomes smaller, which seriously affects the migration of cuttings in the inner tube.

(3) Traditional plugging structures such as arrow valves and cone valves are eroded by the circulating medium for a long time during the normal drilling process, and their service life and reliability are seriously reduced.

(4) The traditional bottom-hole blowout preventer cannot be opened automatically after it is closed, and parts need to be recovered and replaced, which is not convenient enough to use.

SUMMARY OF THE INVENTION

In order to solve the above problems, the patent of the present invention provides a downhole blowout prevention device for double-layer pipe dual-gradient pressure-controlled drilling. The double-layer tube inner and outer tube annular channel blocking structure is set on the upper part, and the flow rate of the circulating medium passing through the coaxial throttling sliding sleeve is different between normal drilling and blowout accidents, which is generated at the throttling place of the coaxial throttling sliding sleeve. The pressure difference is the driving force to push the coaxial choke sleeve to close the downhole blowout preventer. In the event of a blowout and other dangerous accidents, the downhole blowout preventer can be automatically closed, which can realize the double pipe annular channel and the double pipe inner pipe channel. At the same time, it is blocked, which solves the problem that the traditional blowout preventer needs to be manually opened; in the process of normal drilling, the lower end of the coaxial throttle sliding sleeve is covered on the inner pipe cone valve disc, which solves the problem that the conventional blowout preventer needs to be opened during normal drilling. In the process of feeding, the inner tube plugging structure is eroded for a long time and the service life and reliability are reduced; at the same time, the coaxial throttling sliding sleeve designed according to the principle of "neck and throttling" can retain a large enough diameter in the inner tube for Cuttings migration can solve the difficult problem of cuttings migration in traditional double-pipe blowout preventers; when the bottom hole pressure is reduced by means of killing wells, under the action of the return spring set in the blowout preventer, the coaxial The choke sleeve pushes open the poppet valve disc, and the downhole blowout preventer is turned on again, so that drilling can continue. It solves the problem of manually opening or replacing parts after the traditional downhole blowout preventer is closed, and achieves the purpose of reusability.

The following technical solutions adopted by the patent of the present invention to solve the technical problems are: a double-layer pipe double-gradient pressure-controlled drilling downhole blowout preventer is connected by an inner pipe upper joint; the upper valve seat is connected with the inner pipe upper joint through threads, and is provided with an upper joint on the inner pipe. The centering block I of the flow hole is installed between the upper joint and the upper valve seat, and is positioned by the shaft shoulder; the coaxial throttle sliding sleeve realizes the circumferential positioning through the upper valve seat and the lower valve seat, and the coaxial throttle sliding sleeve is arranged on the upper valve seat. There are an outer sliding sleeve and an inner sliding sleeve, wherein the inner sliding sleeve and the inner wall of the inner tube of the double-layer tube are in clearance fit, and the outer sleeve and the outer wall of the inner tube of the double-layer tube are in clearance fit. Stepped cone sealing structure; a return spring is installed between the upper valve seat and the coaxial throttle sliding sleeve; the cone valve installation block and the convex cone valve disc are connected by pins, and the cone valve installation block and the concave cone valve disc are connected together Connected together by pins, both the convex cone valve disc and the concave cone valve disc can rotate within a certain angle on the pins; the cone valve mounting block is installed on the lower valve seat by screws; the lower joint of the inner pipe is connected to the lower valve through threads The centering block II, which is provided with a flow hole on it, is installed between the lower valve seat and the lower joint, and is positioned through the shaft shoulder; finally, the lower joint of the outer pipe and the upper joint of the outer pipe are threaded to form the downhole blowout preventer. the outer casing.

The inner pipe upper joint is provided with a taper male buckle and an inner thread connected with the upper valve seat.

The inner tube lower joint is provided with a conical female buckle and an inner thread connected with the lower valve seat.

The righting block I is provided with a flow-through hole.

The righting block II is provided with a flow-through hole.

The step-shaped conical surface sealing structure is composed of two bosses with a small upper and a large lower.

The coaxial throttle sliding sleeve is provided with an inner sliding sleeve, an outer sliding sleeve, an O-ring groove I located at the upper part of the outer sliding sleeve, and an O-ring sealing groove II located at the lower part of the outer sliding sleeve. The O-ring groove III on the upper part of the shaft throttling sliding sleeve, the O-ring sealing groove IV located on the upper part of the inner sliding sleeve, and the groove with four arc-shaped drainage holes located between the inner sliding sleeve and the outer sliding sleeve. Partition plate.

There are four said cone valve discs in total, of which two concave cone valve discs are installed symmetrically, and two convex cone valve discs are symmetrically installed.

The lower valve seat is provided with an inner tube wall boss II, a positioning shaft shoulder II, and an outer thread connected with the lower joint of the inner tube. There are four through holes evenly distributed, and the poppet valve mounting block is installed on the inner wall of the lower valve seat by screws.

The cone valve mounting block is provided with pin holes and threaded holes.

The upper joint of the outer pipe is provided with a positioning shoulder IV, an external thread connected with the lower joint of the outer pipe, and a boss whose upper part is large and the lower part is small and which is matched with the stepped cone surface sealing structure.

The lower joint of the outer tube is provided with a positioning shoulder III and an inner thread connected with the upper joint of the outer tube.

The beneficial effects of the invention are as follows: (1) The inner pipe channel of the double-layer pipe and the annular channel of the double-layer pipe can be simultaneously blocked to ensure the safety of the drilling platform when dangerous conditions such as blowout occur at the bottom of the well. (2) The coaxial throttling sliding sleeve is designed based on the principle of "necking and throttling" to leave a large diameter in the inner pipe for the movement of cuttings. (3) The double-pipe downhole blowout preventer designed by the present invention, in the normal drilling process, the coaxial throttling sliding sleeve is covered on the double-pipe inner pipe sealing structure, which greatly reduces the cone in the inner pipe plugging structure. The degree of erosion of the valve disc can increase the service life of the poppet valve disc. (4) The double-pipe downhole blowout preventer designed by the present invention is provided with a return spring. After the blowout preventer is closed due to blowout and other reasons, when the well kill is completed, the bottom hole pressure is reduced and the blowout preventer is opened under the action of the return spring to continue. use. (5) The present invention is provided with a standard joint of the double-layer pipe and the outer pipe, and the inner pipe has a snap-in connection structure, which is convenient to use and can be directly connected to the drill pipe.

Description of drawings

1 is a schematic diagram of the open state of the blowout preventer and the closed state of the blowout preventer according to the present invention;

FIG. 2 is a three-dimensional schematic diagram of a quarter cross-sectional view of an upper joint of an inner pipe of the present invention;

FIG. 3 is a three-dimensional schematic diagram of a quarter cross-section of the lower joint of the inner pipe of the present invention;

FIG. 4 is a three-dimensional schematic diagram of a quarter cross-sectional view of the upper valve seat of the present invention;

FIG. 5 is a three-dimensional schematic diagram of a quarter cross-sectional view of the lower valve seat of the present invention;

6 is a schematic diagram of the installation block of the poppet valve of the present invention;

Fig. 7 is the assembly schematic diagram of the poppet valve disc and the poppet valve mounting block of the present invention:

8 is a three-dimensional comparison diagram of the open state and the closed state of the poppet valve flap of the present invention;

Fig. 9 is a quarter cross-sectional schematic diagram of the coaxial throttle sliding sleeve of the present invention;

Fig. 10 is the schematic diagram of the righting block of the present invention;

Fig. 11 is a quarter cross-sectional schematic diagram of the upper joint of the outer pipe of the present invention;

Fig. 12 is a quarter cross-sectional schematic diagram of the lower joint of the outer pipe of the present invention;

Figure 13 is a three-dimensional schematic diagram of two kinds of poppet valve flaps of the present invention.

In the picture 1- upper joint of inner pipe, 101- inner thread, 2- upper valve seat, 201- outer thread, 202- locating shoulder I, 203- limiting shoulder, 204- inner pipe wall boss I, 3- Righting block I, 301-flow hole, 4-coaxial throttle sliding sleeve, 401-inner layer sliding sleeve, 402-outer layer sliding sleeve, 403-stepped cone surface sealing structure, 404-O-type sealing ring groove Ⅰ , 405-O-ring groove Ⅱ, 406-O-ring groove Ⅲ, 407-O-ring groove Ⅳ, 408-dividing plate, 409-arc drain hole, 5-return spring, 6-cone Valve mounting block, 601-pin hole Ⅰ, 602-threaded hole, 7-pin, 8-concave cone valve disc, 801-pin hole Ⅱ, 9-convex cone valve disc, 901-pin hole Ⅲ, 10-down Valve seat, 1001-through hole, 1002-inner pipe wall boss II, 1003-positioning shoulder II, 1004-external thread, 11-inner pipe lower joint, 1101-internal thread, 12-centering block II, 1201-over Orifice, 13-outer pipe lower joint, 1301-positioning shoulder III, 1302-internal thread, 14-outer pipe upper joint, 1401-positioning shoulder IV, 1402- boss, 1403-external thread.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings, and the protection scope of the present invention is not limited to the following description:

As shown in 1, a downhole blowout prevention device for double-layer pipe dual-gradient managed pressure drilling, which includes an inner pipe upper joint 1, an upper valve seat 2, a centering block I3, a coaxial choke sliding sleeve 4, a return spring 5, a cone Valve installation block 6, pin 7, concave cone valve disc 8, convex cone valve disc 9, lower valve seat 10, inner tube lower joint 11, righting block II 12, outer tube lower joint 13, outer tube upper joint 14; The upper pipe joint 1 and the upper valve seat 2 are connected by threads; the centralizing block I3 with the flow hole is positioned through the shaft shoulder and installed between the upper joint and the upper valve seat; the coaxial throttle sliding sleeve 4 is installed on the upper Between the valve seat and the lower valve seat, the inner layer sliding sleeve 401 on the coaxial throttling sliding sleeve 4 is in clearance fit with the inner wall of the inner pipe of the double-layer pipe, and the outer layer sleeve 402 on the coaxial throttling sliding sleeve 4 and the double-layer pipe are in clearance fit. The inner and outer walls of the tube are clearance fit; the return spring 5 is installed between the upper valve seat 2 and the coaxial throttle sliding sleeve 4 and a certain pre-tightening force is set; the cone valve mounting block 6 and the concave cone valve disc 8 are connected by pins 7 The cone valve mounting block 6 is connected with the convex cone valve disc 9 through the pin 7; the cone valve mounting block 6 is connected with the lower valve seat 10 by screws, and the lower valve seat 10 is connected with the lower joint 11 of the inner pipe through the screw connection. The centering block II12 of the overflow hole is positioned through the shaft shoulder, and is installed between the lower valve seat 10 and the lower joint 11 of the inner pipe. Finally, the lower joint 13 of the outer pipe and the upper joint 14 of the outer pipe are connected by threads to form the shell of the downhole blowout preventer. body.

The working process of the present invention is as follows:

During the normal drilling process, the downhole blowout preventer is in the open state, the drilling fluid is pumped from the double-layer pipe annulus, and the drilling fluid flows into the double-layer drill pipe annulus connected to the upper part of the downhole blowout preventer through the outer sliding sleeve 401 and the outer layer. The annular channel formed by the inner wall of the joint 14 on the outer pipe flows into the double-layer drill pipe annulus connected to the lower part of the downhole blowout preventer to the bottom of the well. When the drilling fluid passes through the inner layer sliding sleeve 401 of the downhole blowout preventer, in the variable diameter section, due to the gradual reduction of the flow passage, the pressure at the large diameter end is greater than the pressure at the small diameter end at the variable diameter section, thereby forming a pressure drop. An upward thrust is generated. Due to the presence of the spring preload, the coaxial choke sleeve 4 will not be pushed, the downhole blowout preventer remains open, and the drilling fluid returns the cuttings from the inner pipe channel to the surface mud system.

When encountering dangerous conditions such as blowout during the drilling process, a large amount of bottom-hole fluid quickly passes through the double-layer pipe annulus, and the inner pipe channel of the double-layer pipe flows upward, and a large amount of bottom-hole fluid returns from the inner pipe to the downhole blowout prevention. When the inner sliding sleeve 401 of the device is used, the pressure at the large diameter end of the reducing section of the inner sliding sleeve 401 is greater than the pressure at the small diameter end, thereby forming a pressure drop, generating upward thrust in the reducing section, and the generated thrust overcomes the return spring 5. Tighten force, push the coaxial throttle sliding sleeve 4 to move up along its axis, until the inner layer sliding sleeve 401 moves to the limit shaft shoulder 203, at this time, the stepped end face sealing structure 403 on the coaxial throttle sliding sleeve and the outer tube The bosses 1402 on the upper joint 14 cooperate to form two conical surface seals, and the bottom hole fluid can no longer flow upward through the annulus channels of the inner and outer pipes of the double-layer pipe. At the same time, the lower small diameter end of the inner layer sliding sleeve 401 covering the concave cone valve disc 8 and the convex cone valve disc 9 moves upward at the same time, and the convex cone valve disc 9 installed on the cone valve mounting block 6 acts on the bottom hole fluid. The bottom begins to close, the concave cone valve disc 8 starts to close under the action of the bottom hole fluid and the convex cone valve disc 9 at the same time, when the four cone valve discs are completely closed, the inner tube channel of the double-layer pipe is blocked, and the well The bottom fluid can no longer flow upward through the inner pipe channel of the double-layer pipe, and the downhole blowout preventer of the double-layer pipe is now turned from the open state to the closed state. When the well kill work is completed, the bottom hole pressure decreases, under the action of the reset spring 5, the coaxial choke sleeve tops open the concave cone valve disc 8 and the convex cone valve disc 9, and the double-pipe downhole blowout preventer automatically opens again. , to ensure the continuation of drilling.

From the above, the present invention is a downhole blowout prevention device for double-layer pipe dual-gradient pressure-controlled drilling. When a blowout occurs at the bottom of the well, a large amount of fluid returning from the bottom of the well flows through the inner sliding sleeve of the blowout prevention device. Under the action of the flow, an upward thrust is generated, and the thrust overcomes the pre-tightening force of the return spring and pushes the coaxial throttling sliding sleeve to move in the axial direction until the stepped cone sealing structure on the same outer sliding sleeve and the joint on the outer pipe The set bosses cooperate to complete the sealing of the annular channel of the inner and outer tubes of the double-layer tube. At the same time, because the lower small diameter end of the inner layer sliding sleeve covering the poppet valve disc moves up along the axis, the poppet valve disc is closed under the action of fluid. The inner tube channel of the double-layer tube is blocked. So far, the bottom hole fluid can no longer flow upward through the two channels of the double-layer pipe. The downhole blowout preventer of the double-layer pipe is switched from the open to the closed state. The inner and outer pipes of the double-layer pipe are annular, and the inner pipe channel of the double-layer pipe is completely blocked. , When the well kill is completed, under the action of the return spring, the double-layer pipe downhole blowout preventer will automatically open and continue to use. The invention can annulate the inner and outer pipes of the double-layer pipe when a dangerous condition such as a blowout occurs at the bottom of the well, and the channels of the inner pipe of the double-layer pipe can be completely blocked at the same time, which can effectively prevent the occurrence of drilling accidents caused by the blowout.

Finally, it should be noted that the above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: this patent can still be modified. Or equivalent replacements, without departing from the spirit and scope of the present invention, any modifications or partial replacements shall be included in the scope of the claims of the present invention.

Claims (9)

1. A double-layer pipe double-gradient pressure-controlled downhole blowout prevention device related to the present invention, the inner layer structure of the downhole blowout prevention device is connected with the upper joint (1) of the inner pipe and the upper joint (1) of the inner pipe through the thread. The upper valve seat (2) is installed between the upper joint (1) of the inner pipe and the upper valve seat (2), positioned through the shaft shoulder, and the centering block I (3) is provided with a flow hole (301), installed The coaxial throttling sleeve (4) between the upper valve seat (2) and the lower valve seat (10), the inner layer sliding sleeve (401) on the coaxial throttling sleeve (4) and the inner tube of the double-layer pipe The wall is a clearance fit, the outer sleeve (402) on the coaxial throttle sliding sleeve (4) is a clearance fit with the outer wall of the inner tube of the double-layer pipe, and the coaxial throttle sliding sleeve (4) has a stepped cone surface sealing structure (403), the return spring (5) installed between the upper valve seat (2) and the coaxial throttle sliding sleeve (4), the poppet valve mounting block (6) connected with the lower valve seat (10) through screws, Connect the poppet valve mounting block (6) with the concave poppet valve disc (8) through the pin (7), connect the poppet valve mounting block (6) with the male poppet valve disc (9) through the pin (7), The inner tube lower joint (11) connected with the lower valve seat (10) is installed between the lower valve seat (10) and the inner tube lower joint (11), positioned through the shaft shoulder, and is provided with a flow hole (1201) ) of the righting block II (12), the outer structure of the downhole blowout preventer is composed of the lower outer pipe joint (13), the outer pipe upper joint (14), the outer pipe lower joint (13) The outer pipe upper joint (14) The outer casing of the downhole blowout preventer is formed by screw connection. 2. The downhole blowout prevention device for double-layer pipe dual-gradient pressure-controlled drilling according to claim 1 is characterized in that: the upper valve seat (2) is provided with an external thread (201) connected to the upper joint (1) of the inner pipe ), the positioning shoulder I (202) for positioning the centralizing block I (3), the limiting shoulder (203) for the inner sliding sleeve (401), and the inner tube wall boss I (204). 3. The downhole blowout prevention device for double-layer pipe dual-gradient pressure-controlled drilling according to claim 1, characterized in that: the coaxial choke sliding sleeve (4) is provided with an inner layer sliding sleeve (401) and an outer layer sliding sleeve (401). Sleeve (402), O-ring groove I (404) at the upper part of the outer sliding sleeve (402), O-ring sealing groove II (405) at the lower part of the outer sliding sleeve (402), located at the coaxial throttle The O-ring groove III (406) on the upper part of the sliding sleeve (4), the O-ring groove IV (407) on the upper part of the inner sliding sleeve (401), the inner sliding sleeve (401) and the outer sliding sleeve Divider plate (408) with four arcuate drain holes (409) between (402). The downhole blowout prevention device for double-layer pipe dual-gradient pressure-controlled drilling according to claim 1, characterized in that: the stepped conical surface sealing structure (403) is composed of two bosses with a small upper part and a large lower part, The thickness of the small boss is greater than the thickness of the outer sliding sleeve (402), and the sealing end face is the conical surface on the two bosses. 5. The downhole blowout prevention device for double-layer pipe dual-gradient pressure-controlled drilling according to claim 1, characterized in that: there are two concave cone valve discs (8) in total, and pin holes are provided on the concave cone valve discs II (801), two concave cone valve discs are installed symmetrically. The downhole blowout prevention device for double-layer pipe dual-gradient pressure-controlled drilling according to claim 1, characterized in that: there are two convex cone valve discs (9) in total, and pin holes are provided on the convex cone valve discs. III (901), two convex cone valve discs (9) are installed symmetrically. The downhole blowout prevention device for double-layer pipe dual-gradient pressure-controlled drilling according to claim 1, characterized in that: the lower valve seat (10) is evenly distributed with four through holes (1001), inner pipe wall bosses II (1002), positioning shoulder II (1003), and external thread (1004) connected with the lower joint (11) of the inner pipe. 8 . The downhole blowout prevention device for double-layer pipe dual-gradient pressure-controlled drilling according to claim 1, characterized in that: the cone valve mounting block (6) is provided with a pin hole I (601) and a threaded hole (602). 9. The double-layer pipe downhole blowout preventer according to claim 1, characterized in that: the upper joint (14) of the outer pipe is provided with a positioning shoulder IV (1401) and a stepped cone surface sealing structure (403) Matching upper and lower bosses (1402), and external threads (1403) connected to the lower joint (13) of the outer pipe.

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