CN104747121B - Protective sleeve for Christmas tree - Google Patents

Abstract

A christmas tree protective sleeve, used to isolate the inner cavity of the christmas tree from the liquid in the oil pipe to protect the christmas tree. An upper flange and a lower flange are formed on the christmas tree to communicate with the inner cavity and face up and down. It is characterized in that the protective cover of the Christmas tree includes: a tubular shell, the lower end of which is fixedly connected with the upper flange formed on the Christmas tree; it is coaxially sleeved in the shell, and can be connected with the shell along the common axis. For the relatively moving insertion tube, when the insertion tube moves to a predetermined first position relative to the housing, the lower end of the insertion tube is accommodated in the housing, and when the insertion tube moves to a second position relative to the housing, the lower end of the insertion tube moves from the housing Insert into the oil pipe; the lower end of the insertion pipe is covered with a tubular seal, which is used to form a sealed connection with the oil pipe when the lower end of the insertion pipe is inserted into the oil pipe, so that the inner cavity of the Christmas tree is isolated from the liquid in the oil pipe. The christmas tree protection cover of the invention can protect the christmas tree and is extremely convenient to use.

Description

X-mas tree protection cover

technical field

The invention relates to the field of crude oil extraction equipment, and more specifically relates to a Christmas tree protective cover.

Background technique

In the field of oil exploitation, it is often necessary to perform fracturing operations, that is, use surface high-pressure pumps to squeeze fracturing fluid with relatively high viscosity into the oil layer through the Christmas tree. When the rate of injection of fracturing fluid exceeds the absorption capacity of the oil layer, a very high pressure will be formed on the oil layer at the bottom of the well. When this pressure exceeds the fracture pressure of the oil layer near the bottom of the well, the oil layer will be pushed open and fractures will be generated. At this time, if the fracturing fluid is continuously squeezed into the oil layer, the fracture will continue to expand into the oil layer. In order to keep the fractures opened, the sand-carrying fluid with proppant (usually quartz sand) is squeezed into the oil layer. After the sand-carrying fluid enters the fracture, on the one hand, the fracture can continue to extend forward; On the one hand, it can support the cracks that have been opened so that they will not close. Then inject displacement fluid to replace all the sand-carrying fluid in the wellbore into the fracture, and support the fracture with quartz sand. Finally, the injected high-viscosity fracturing fluid will be automatically degraded and discharged out of the wellbore, leaving one or more fractures of varying length, width, and height in the oil layer, creating a new fluid channel between the oil layer and the wellbore. After fracturing, the production of oil and gas wells generally increases significantly.

In the petroleum industry, the rated working pressure of the Christmas tree must be greater than the maximum formation pressure of the well to ensure that the Christmas tree can work normally. But because the required pressure is higher than the formation pressure when the formation breaks, and it is often greater than the rated working pressure of the Christmas tree. When the pressure required for formation fracture is greater than the rated working pressure of the Christmas tree, the fracturing operation can only be abandoned.

Contents of the invention

In order to solve the above problems, the purpose of the present invention is to provide a Christmas tree protective cover, which is used to isolate the inner cavity of the Christmas tree from the liquid in the oil pipe to protect the Christmas tree. The upper and lower flanges facing up and down that communicate with each other in the cavity, the Christmas tree protective cover includes:

a tubular casing, the lower end of the casing is fixedly butted against the upper flange formed on the Christmas tree;

an insertion tube coaxially sleeved in the housing and capable of relative movement with the housing along a common axial direction; when the insertion tube moves to a predetermined first position relative to the housing, the The lower end of the insertion tube is received into the housing, and when the insertion tube moves to a second position relative to the housing, the lower end of the insertion tube is inserted into the oil pipe from the housing;

The lower end of the insertion pipe is covered with a tubular seal, which is used to form a sealed connection with the oil pipe when the lower end of the insertion pipe is inserted into the oil pipe, so that the inner cavity of the Christmas tree Isolated from the fluid in the tubing.

The Christmas tree protective sleeve according to the present invention further includes a piston assembly, which is used for transmission connection with an external hydraulic drive system, and relies on the power of the hydraulic drive system to drive the insertion tube relative to the shell Physical activity.

According to the christmas tree protective sleeve of the present invention, a sealed oil storage space is formed between the casing and the insertion tube, and the piston assembly includes a piston, an upper liquid inlet opened on the casing and the lower liquid inlet, the piston is fixedly sleeved in the middle of the insertion tube, the piston divides the oil storage space into an upper oil storage area and a lower oil storage area, the upper liquid inlet and the upper The oil storage area is connected, and the lower liquid inlet is connected with the lower oil storage area.

In the Christmas tree protective sleeve according to the present invention, the piston is fixedly connected with the insertion pipe through screw fit.

According to the christmas tree protective sleeve of the present invention, it further includes a guide nut, the lower end of the insertion pipe is provided with an external thread matched with the guide nut, and the lower end of the seal is clamped between the guide nut and the guide nut. Insert between the lower ends of the tube.

The Christmas tree protective sleeve according to the present invention further includes a conduit, the lower end of the conduit is screwed and fixed to the upper end of the insertion pipe, or the conduit and the insertion pipe are integrally formed.

In the Christmas tree protective sleeve according to the present invention, the diameter of the upper end of the conduit is expanded to form a first flange joint, which is used for flange connection to externally connected fracturing equipment.

According to the christmas tree protection sleeve of the present invention, the lower end of the conduit expands to form an upper locking flange, and the upper end of the casing expands to form a lower locking flange, and the upper locking flange and The lower locking flange is fixed through flange connection.

In the christmas tree protective sleeve according to the present invention, the lower end of the housing is enlarged to form a second flange joint, and the second flange joint is flange-connected to the upper flange, so that the housing The lower end is docked and fixed with the upper flange of the Christmas tree.

In the Christmas tree protective sleeve according to the present invention, the housing includes: a first pipe section including the upper end of the housing, a second pipe section in the middle, and a third pipe section including the lower end of the housing, the first pipe section including the lower end of the housing. Both ends of the second pipe section are respectively fixedly sleeved on the lower end of the first pipe section and the upper end of the third pipe section.

The christmas tree protection sleeve implementing the invention can isolate the fracturing fluid from the christmas tree during the fracturing operation, can protect the christmas tree, and is extremely convenient to use.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment, in the accompanying drawing:

Fig. 1 is a schematic structural view of the Christmas tree protective sleeve according to the first embodiment of the present invention when the insertion pipe is in the first position relative to the casing.

Fig. 2 is a schematic diagram of the connection between the Christmas tree protection sleeve and the Christmas tree in the first working condition according to the second embodiment of the present invention.

Fig. 3 is a schematic diagram of the connection between the Christmas tree protection sleeve and the Christmas tree in the second working condition according to the second embodiment of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific examples described here are only used to explain the present invention, not to limit the present invention.

Please refer to FIG. 1 , in the field of crude oil extraction, a Christmas tree 5 is usually used to control the terminal stage of crude oil extraction. In FIG. 1 , the Christmas tree 5 includes an inner cavity (not labeled). An upper flange 51 and a lower flange 52 communicating with the inner cavity are provided on the Christmas tree 5 . The upper flange 51 and the lower flange 52 face each other up and down. The upper flange 51 is generally closed during oil production, and externally connected to fracturing equipment during fracturing operations. The existing oil pipe 6 is docked with the lower flange 52, and is used to draw crude oil out of the well, or inject fracturing fluid from the oil pipe 6 into the well.

Please refer to FIG. 1 . FIG. 1 is a schematic structural view of the Christmas tree protection sleeve according to the first embodiment of the present invention when the insertion pipe is in the first position. As shown in FIG. 1 , the Christmas tree protective cover includes a tubular shell 1 and an insertion tube 2 integrally formed. The insertion tube 2 is coaxially sleeved in the housing 1 and can move relative to the housing 1 along a common axial direction. The diameter of the lower end of the housing 1 is expanded to form a second flange joint 11, and the diameter of the upper end of the housing 1 is expanded to form a lower locking flange 12. The second flange joint 11 and the lower locking flange 12 are respectively provided with A plurality of threaded holes 110 and a plurality of threaded holes 120 for bolt connection.

A sealed tubular oil storage space (not labeled) is formed between the casing 1 and the insertion tube 2 , and the oil storage space is divided into an upper oil storage area 31 and a lower oil storage area 32 by a piston 33 . The upper end of the housing 1 is provided with an upper liquid inlet 34 communicating with the upper oil storage area 31, and the lower end of the housing 1 is provided with a lower liquid inlet 35 communicating with the oil storage space 32. The upper liquid inlet 34 and the lower liquid inlet The port 35 can be used to allow the externally connected hydraulic drive system to inject hydraulic oil into the upper oil storage area 31 and the lower oil storage area 32 or discharge hydraulic oil from the upper oil storage area 31 and the lower oil storage area 32 .

The lower end fixed sleeve of the insertion tube 2 is provided with a seal 21, and the outer fixed sleeve of the seal 21 is provided with a guide nut 22. The guide nut 22 and the lower end of the insertion tube 2 are tightly connected by threads, and the seal 21 is clamped between the guide nut 22 and the insertion tube. between 2.

In this embodiment, the piston 33 is fixedly sleeved on the housing 1 through a screw connection. Piston 33 , upper liquid inlet 34 and lower liquid inlet 35 form a piston assembly (not labeled), and an external hydraulic drive system (not shown) drives the piston assembly to drive the insertion tube 2 to move up and down relative to the housing 1 . When the hydraulic pump of the hydraulic drive system pumps oil forward, the upper oil storage area 31 injects hydraulic oil through the upper liquid inlet 34, and the lower oil storage area 32 releases hydraulic oil through the lower liquid inlet 35. At this time, the pressure difference between the upper and lower sides The piston 33 drives the insertion tube 2 to move downward.

The Christmas tree protection cover also includes a conduit 4, the lower end of the conduit 4 is expanded to form an upper locking flange 41, the upper end of the conduit 4 is expanded to form a first flange joint 42, and the upper locking flange 41 and the first flange A plurality of threaded holes 410 , 420 for bolt connection are respectively opened on the joint 42 . The lower end of the conduit 4 is tightly connected with the upper end of the insertion tube 2 through thread fit, and at the same time, the upper locking flange 41 and the lower locking flange 12 are fixed and locked through threaded holes 410, 120 with bolts and nuts. After the upper end of the conduit 4 is docked with the fracturing equipment, it passes through the threaded hole 420 provided on the first flange joint 42 and is equipped with bolts and nuts so as to be firmly connected with the fracturing equipment.

Please refer to FIG. 2 . FIG. 2 is a schematic diagram of the connection between the Christmas tree protection sleeve and the Christmas tree in the first working condition according to the second embodiment of the present invention.

Different from the integrally formed casing 1 in the first embodiment, the casing 1 in this embodiment is divided into a first pipe section 1A, a second pipe section 1B and a third pipe section 1C. Wherein, the first pipe section 1A includes a lower locking flange 12 formed by expanding the diameter of the upper end of the shell 1 , and the third pipe section 1C includes a second flange joint 11 formed by expanding the diameter of the lower end of the shell 1 . One end 13 and the other end 14 of the second pipe section 1B are respectively fixedly sleeved on the lower end of the first pipe section 1A and the upper end of the third pipe section 1C, and the fixed connection method is preferably threaded connection, and the fixed connection method can also be welding or threaded connection , interference fit connection or other known fixing methods. Through the above-mentioned screw connection of each part of the housing 1, the housing 1, the insertion tube 2 and the piston assembly can be manufactured and assembled conveniently.

The X-mas tree protection sleeve is fastened and bolted to the upper flange 51 of the X-mas tree through the threaded hole 110 provided on the second flange joint 11 , so as to be installed on the X-mas tree 5 . At this time, the insertion tube 2 is in the first position relative to the casing 1, which is the highest position in the figure.

In the first working condition, the lower end of the insertion tube 2 is brought into the housing 1 . The lumen of the Christmas tree communicates with the lumen of the tubing. At this time, the Christmas tree protection sleeve does not affect other normal operations except fracturing, such as oil production operations, and the operation is very convenient.

Please refer to FIG. 3 . FIG. 3 is a schematic diagram of the connection between the Christmas tree protection sleeve and the Christmas tree in the second working condition according to the second embodiment of the present invention. Referring to Fig. 2, after installing and connecting the christmas tree protection cover and christmas tree 5 as shown in Fig. The oil storage area 32 discharges the hydraulic oil through the lower liquid inlet 35, and at this moment, the pressure difference between the upper and lower sides makes the piston 33 drive the insertion tube 2 to move downward from the highest position. When the casing 1 moves down to the lowest position as shown in FIG. 3 , the hydraulic pump is turned off and enters the second working condition shown in FIG. 3 .

At this time, the lower end of the insertion pipe 2 is inserted into the oil pipe 6, and the seal 21 assembled on the lower end of the insertion pipe 2 makes the lower end of the insertion pipe 2 form a sealed connection with the oil pipe 6, so that the inner cavity of the oil pipe 6 and the inner cavity of the Christmas tree 5 isolated.

At this time, the upper locking flange 41 formed after expanding the diameter of the lower end of the conduit 4 is bolted to the lower locking flange 12 formed on the upper end of the housing 1 by bolts and then locked. The upward movement of the insertion tube 2 relative to the housing 1 is prevented by the screw fastening connection.

In the second working condition, since the inner cavity of the tubing 6 is isolated from the inner cavity of the Christmas tree 5, the fracturing fluid can enter the tubing 6 through the inner cavity of the externally connected fracturing equipment through the inner cavity of the 4 and the inner cavity of the insertion tube 2 , but will not enter into the inner cavity of the Christmas tree 6, and the fracturing operation at this time will not generate destructive pressure on the Christmas tree 5.

When turning from the second working condition to the first working condition, it is only necessary to make the hydraulic pump reversely pump oil, the upper oil storage area 31 releases hydraulic oil through the upper liquid inlet 34, and the lower oil storage area 32 injects hydraulic pressure through the lower liquid inlet 35. At this time, the pressure difference between the upper and lower sides makes the piston 33 drive the insertion tube 2 to move upward. When the insertion tube 2 rises to the first position, that is, the highest position, the lower end of the insertion tube 2 retracts into the housing 1, which is transformed into the first working position. condition. If the Christmas tree protective cover is not used for a long time, it can also be easily removed.

Those skilled in the art can understand that, when the flanges of the present invention are connected, the positions and sizes of the threaded holes on the connected flanges correspond one-to-one, and match with the bolts and nuts fastening the flanges. In addition, the joints of the flanges of the Christmas tree protection sleeve in the present invention can be additionally sealed and strengthened, such as using known sealing means such as sealing gaskets for sealing and strengthening.

The first working condition referred to in the present invention can be oil extraction operation, certainly can also be the normal operation such as gas extraction operation; The second working condition indicated in the present invention can be fracturing operation, certainly can also be workover Maintenance operations such as operations or well killing operations.

The method of using the Christmas tree protective cover of the present invention will be described in more detail below only by using the Christmas tree protective cover of the second embodiment. The using method of the Christmas tree protection cover of the present invention comprises steps:

a) Install the seal 21 on the insertion tube 2, then tighten the guide nut 22, and apply grease on the guide nut 22 and the seal 21;

b) Place the gasket ring on the upper flange 51, lift the whole device vertically, align the second flange joint 11 of the Christmas tree protective sleeve with the upper flange 51, and tighten it with bolts;

c) Connect the upper liquid inlet 34 and the lower liquid inlet 35 with the outlet pipeline interface of the reversing valve on the hydraulic control station of the external hydraulic drive system with hydraulic pipelines;

d) Operate the reversing valve handle of the hydraulic control station so that the upper liquid inlet 34 of the tree protection cover enters the high-pressure oil, and pushes the piston assembly and the insertion pipe 2 downward, so that the insertion pipe 2 and the seal 21 enter the inner cavity of the oil pipe 6, and at the same time, The locking flange 41 goes down together with the insertion tube 2 and falls on the lower locking flange 12;

e) Tighten the upper locking flange 41 and the lower locking flange 12 with bolts;

f) Use other connectors such as non-connectors, plug valves, high-pressure elbows and pipelines to connect the first flange joint 42 to the fracturing manifold and then carry out construction operations, such as fracturing operations.

In addition, after the construction work is completed, the above steps are reversed, so that the insertion pipe 2 can be pulled out from the oil pipe 6, and the fracturing protective cover of the Christmas tree can be easily removed from the Christmas tree 5 .

If the diameter of the fracturing ball that needs to be put into the oil pipe in the next stage of fracturing is larger than the inner diameter of the insertion pipe 2, it can be disassembled when the pressure in the oil pipe drops below the rated working pressure of the Christmas tree 5 after the fracturing operation stops the pump. The upper locking flange 41 and the lower locking flange 12 are turned, and the handle of the reversing valve of the hydraulic control station is pulled to make the piston 33 and the insertion pipe 2 go upward, and the lower end of the insertion pipe 2 is stored in the casing 1, and then the The 5 wing valves pitched way to continue the frac operation.

The christmas tree protective cover of the present invention can be conveniently switched between the first working condition and the second working condition through the hydraulic drive system, and after the construction work is completed, only the insertion pipe 2 can be raised without dismantling the christmas tree protective cover After reaching the first position, other normal operations such as oil production can be carried out. Even when not in use for a long time, it is very convenient to disassemble.

Claims (10)

1. A christmas tree protective cover, used to isolate the inner cavity of the christmas tree (5) from the liquid in the oil pipe (6), to protect the christmas tree (5), the christmas tree (5) is formed The upper and lower flanges (51) and lower flanges (52) facing up and down that communicate with the inner cavity are characterized in that the Christmas tree protective cover includes: a tubular casing (1), the lower end of the casing (1) is fixedly connected to the upper flange (51) formed on the Christmas tree (5); The insertion tube (2) is coaxially sleeved in the housing (1) and can move relative to the housing (1) along the common axial direction. The insertion tube (2) is opposite to the When the housing (1) moves to a predetermined first position, the lower end of the insertion tube (2) is received into the housing (1), and the insertion tube (2) is opposite to the housing (1) When moving to the second position, the lower end of the insertion pipe (2) is inserted into the oil pipe (6) from the casing (1); The lower end of the insertion tube (2) is sleeved with a tubular seal (21), and the seal (21) is used to communicate with the oil tube (6) when the lower end of the insertion tube (2) is inserted into the oil tube (6). The tubing (6) forms a sealed connection to isolate the inner cavity of the tree (5) from the fluid in the tubing (6). 2. The christmas tree protective cover according to claim 1, further comprising a piston assembly, the piston assembly is used for transmission connection with an external hydraulic drive system, and relies on the power of the hydraulic drive system to drive the The insertion tube (2) moves up and down relative to the casing (1). 3. The Christmas tree protective sleeve according to claim 2, characterized in that a sealed oil storage space is formed between the casing (1) and the insertion tube (2), and the piston assembly includes a piston (33), the upper liquid inlet (34) and the lower liquid inlet (35) provided on the housing (1), the piston (33) is fixedly sleeved in the middle of the insertion tube (2), The piston (33) separates the oil storage space into an upper oil storage area (31) and a lower oil storage area (32), and the upper liquid inlet (34) communicates with the upper oil storage area (31) , the lower liquid inlet (35) communicates with the lower oil storage area (32). 4. The Christmas tree protective sleeve according to claim 3, characterized in that, the piston (33) is fixedly connected to the insertion tube (2) through screw fit. 5. The christmas tree protective sleeve according to claim 1, characterized in that, it also comprises a guide nut (22), and the lower end of the insertion pipe (2) is provided with an external thread matched with the guide nut (22), The lower end of the seal (21) is clamped between the guide nut (22) and the lower end of the insertion tube (2). 6. The christmas tree protective cover according to claim 1, characterized in that, it also comprises a conduit (4), the lower end of the conduit (4) is threaded and fixed to the upper end of the insertion pipe (2) or the conduit (4) integrally formed with the insertion tube (2). 7. The Christmas tree protective sleeve according to claim 6, characterized in that, the upper end of the conduit is enlarged to form a first flange joint (42), which is used for flange connection to externally connected fracturing equipment. 8. The Christmas tree protective sleeve according to claim 7, characterized in that, the lower end of the conduit (4) is expanded to form an upper locking flange (41), and the upper end of the housing (1) is expanded to A lower locking flange (12) is formed, and the upper locking flange (41) and the lower locking flange (12) are fixed through flange connection. 9. The christmas tree protective sleeve according to claim 1, characterized in that, the second flange joint (11) is formed after the lower end of the housing (1) is expanded in diameter, and the second flange joint (11) is The flange is connected to the upper flange (51), so that the lower end of the housing (1) is docked and fixed with the upper flange (51) of the Christmas tree (5). 10. The Christmas tree protective sleeve according to any one of claims 1 to 9, characterized in that, the casing (1) comprises: a first pipe section (1A) including the upper end of the casing (1), The second pipe section (1B) in the middle, and the third pipe section (1C) including the lower end of the housing (1), the two ends (13, 14) of the second pipe section (1B) are respectively fixedly sleeved on the The lower end of the first pipe section (1A) and the upper end of the third pipe section (1C).