CN204113261U - A layered fracturing string - Google Patents

Abstract

The utility model discloses a layered fracturing pipe string, which belongs to the field of downhole construction equipment for oil exploitation, and comprises at least two stages of pipe strings connected in sequence, each stage of pipe string is provided with a packer, and the gap between adjacent packers is There is an unblocking and throwing short joint, which includes an upper joint, a cylindrical jacket, a nut, a connecting claw, a piston, a connecting head and a central tube; the upper joint, the jacket and the nut are connected in sequence, and one end of the connecting claw Set in the upper joint, the other end of the connecting claw is a contracted locking claw, the piston is set outside the locking claw, the piston is sandwiched between the locking claw and the outer casing and at a certain distance from the upper joint, the connecting claw and the piston One end of the connector is clamped in the lock claw, one end of the central tube is connected with the other end of the connector by a loose pin, the nut is sleeved on the outer wall of the central tube, the connector and the screw There is a certain distance between the caps, which reduces the unpacking load of the packer, and can be unstuck step by step.

Description

A layered fracturing string

technical field

The utility model relates to the technical field of underground construction equipment for oil and natural gas exploitation, in particular to a layered fracturing pipe string.

Background technique

The layered fracturing technology at home and abroad has made great progress since the last century. The selection of fracturing wells has developed from vertical wells to highly deviated wells, extended reach wells, and horizontal wells. Layered fracturing strings have gradually formed The fracturing string is protected by card sealing, sand filling (cement plug or lower bridge plug) fracturing string, ball-pitching partial pressure string, double-seal dragging fracturing string and sliding sleeve multi-stage layered fracturing pipe type of column.

At present, the sliding sleeve type multi-stage layered fracturing string is widely used in the field, and the multi-stage packer of the multi-stage layered fracturing string is unsealed or unstuck as a whole when it is unsealed or stuck.

In the process of realizing the utility model, the inventor finds that the prior art has at least the following problems:

Since the wellbore axis of highly deviated wells seriously deviates from the vertical line, the working conditions of the downhole tools used for layered fracturing are worse than those of vertical wells. The single-stage packer is unblocked and unjammed as a whole, and the unpacking load and lifting load of the multi-stage packers are superimposed, which makes it difficult to unseal the pipe string and has a large lifting load, making it difficult for the pipe string to be pulled out of the well.

Utility model content

In order to solve the problems of the prior art, the embodiment of the utility model provides a layered fracturing string, and the technical solution is as follows:

The embodiment of the utility model provides a layered fracturing string, the layered fracturing string includes at least two stages of pipe strings connected in sequence, each stage of pipe string is equipped with a packer, and the adjacent two An unpacking and discarding short joint is arranged between the packers, and the unsealing and discarding sub joint includes an upper joint, a cylindrical jacket, a nut, a connecting claw, a piston, a connecting head and a central pipe;

The upper joint, the jacket and the nut are connected coaxially in sequence, and the connecting claws, the piston, the connecting head and the central pipe are all arranged in the jacket,

One end of the connecting claw is set in the upper joint, the other end of the connecting claw is a locking claw in a retracted state, the piston is set outside the locking claw, and the connecting claw and the outer sleeve There is a gap, the piston is sandwiched between the locking pawl and the outer casing and is spaced a certain distance from the upper joint, and the connecting claw and the piston are connected by a starting pin;

One end of the connecting head is clamped in the locking pawl, the other end of the connecting head is connected with one end of the central tube through a loose pin, and the nut is sleeved on the outer wall of the central tube , there is a gap between the central tube and the jacket, and a certain distance is set between the connecting head and the nut.

Further, the end of the layered fracturing string near the bottom of the well is provided with a setting sandblasting sliding sleeve.

Further, the inner diameters of the sliding sleeve ball seats of the plurality of packers increase one by one from the bottom of the well to the head of the well.

Further, the packer closest to the wellhead of the layered fracturing string is a Y341 type washable hydraulic packer.

Further, the packer in the middle of the layered fracturing string is a Y241 sliding sleeve hydraulic packer.

Further, one of the packers closest to the bottom of the layered fracturing string is a Y241 hydraulic packer.

Further, in the multi-stage tubing string, except for the tubing string closest to the bottom of the well and the tubing string closest to the wellhead, each stage of the tubing string includes a packer, a sliding sleeve connected in sequence Sand blasters, hydraulic anchors and unblocking drop-off subs.

Further, among the multi-stage pipe strings, the pipe string closest to the wellhead is provided with a hydraulic safety joint.

Further, a hydraulic anchor is connected between the hydraulic safety joint and the packer.

The beneficial effect of the technical scheme that the utility model embodiment provides is:

By setting up a multi-layered fracturing string with multi-stage packers, the unpacking and throwing subs are set between the packers, and the packers can be set and sealed sequentially from the bottom of the well to the wellhead by pressurization, and at the same time, they are equipped with a ball dropper The compression realizes the layered fracturing of the pipe string; when the activation pin is cut off, the upper joint drives the jacket and the nut to move relative to the central pipe, and the distance between the nut and the connector provides enough space for the unsealing of the packer. stroke, which reduces the unpacking load of the packer. When the string is stuck, the pin can be cut off by continuing to lift the string, and the connection head is separated from the central pipe to realize the drop-off, which reduces the pull-out load of the string and realizes The pipe string is salvaged in sections.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some implementations of the present invention. For example, those of ordinary skill in the art can also obtain other drawings based on these drawings on the premise of not paying creative efforts.

Fig. 1 is a schematic structural view of a layered fracturing string provided by an embodiment of the present invention;

Fig. 2 is a schematic diagram of the structure of the first unblocking and discarding short joint provided by the embodiment of the utility model.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present utility model clearer, the implementation of the present utility model will be further described in detail below in conjunction with the accompanying drawings.

Example

Referring to Fig. 1-2, the embodiment of the utility model provides a layered fracturing string. The layered fracturing string includes at least two stages of strings connected in sequence, and each stage of the string is equipped with a packer 1, An unpacking and throwing short joint 2 is arranged between two adjacent packers 1,

The unpacking and throwing short joint 2 includes an upper joint 21, a cylindrical jacket 22, a nut 23, a connecting claw 24, a piston 25, a connecting head 26 and a central tube 27; the upper joint 21, the outer jacket 22 and the nut 23 are connected coaxially in sequence , the connecting claw 24, the piston 25, the connecting head 26 and the central tube 27 are all arranged in the outer jacket 22,

One end of the connecting claw 24 is set in the upper joint 21, the other end of the connecting claw 24 is a locking claw 24a in a contracted state, and the piston 25 is set outside the locking claw 24a. Interposed between the locking pawl 24a and the outer casing 22 and at a certain distance from the upper joint 21, the connecting pawl 24 and the piston 25 are connected by a starting pin 28;

One end of the connecting head 24 is clamped in the locking pawl 24a, the other end of the connecting head 26 is connected with one end of the central pipe 27 by a pin 29, the nut 23 is sleeved on the outer wall of the central pipe 27, and the central pipe 27 is connected with the central pipe 27. There is a gap between the jackets 22 , and there is a certain distance between the connecting head 26 and the nut 23 .

After the fracturing construction is completed, each packer needs to be unsealed and the fracturing string should be lifted out. In the prior art, there is no retractable part between the adjacent packers on the layered fracturing string, so that a single The first-stage packer does not have enough travel space when it is unsealed, and it will drive the adjacent packers to move at the same time, which will eventually lead to the unseal of the multi-stage packer as a whole when unsealed, and the unsealed load is very large. The sealing operation is relatively difficult, but in this embodiment, the unsealing sub-joint 2 is hydraulically controlled, and the unsealing packer 1 is segmented one by one along the direction from the wellhead to the bottom of the well. The fluid enters the inside of the first-stage pipe string from the center pipe 27 through the pipe string, and fills between the piston 25 and the connection head 26, and then pushes the piston 25 to move toward the upper joint 21. When the fluid pressure rises When the height reaches the set value, the starting pin 28 is cut off. At this time, the locking claw 24a at one end of the connecting claw 24 loses the support of the piston 25 and the connecting head 26 is disengaged and unlocked. The connecting head 26 moves relatively, and the distance between the nut 23 and the connecting head 21 provides enough travel for the unsealing of the first-stage packer 1 of the tubing string, and the unsealing of the first-stage packer 1 does not drive the second The second-stage packer 1 reduces the unpacking load of the first-stage packer 1. After the first-stage packer 1 is unpacked, the high-pressure fluid enters the interior of the second-stage string's unpacked hand sub-joint 2 , to assist in completing the unsealing of the second-stage packer 1. When there are multi-stage packers, the unsealing can be performed stage by stage.

When the pipe string is stuck, the lifting load when lifting the pipe string is very large, and when the continuous lifting of the pipe string reaches a certain strength, the throwing pin 29 of the unsealed throwing joint 2 in the first-stage pipe string will be cut off. When the connecting head 26 is separated from the center pipe 27, the first-stage pipe string can be discarded, and then part of the pipe string can be salvaged. Next, other downhole tools can be used to cooperate with the salvage of the second-stage pipe string. After the lost hand pin 29 of the hand pup joint 2 is cut off, part of the pipe string is salvaged, and finally the pipe string is salvaged step by step, and the whole layered fracturing pipe string is salvaged step by step, which reduces the risk of accidental accidents. Lifting load when stuck.

Further, the end of the layered fracturing string near the bottom is provided with a setting sandblasting sliding sleeve 3 .

Specifically, the setting and sandblasting sliding sleeve 3 is lowered to a position close to the bottom of the artificial well. When performing layered fracturing, the hydraulic setting is first applied to the pipe string to seal an isolation near the setting sandblasting sliding sleeve 3. Device 1, after continuing to pressurize, control setting and sandblasting sliding sleeve 3 to set first and then fracture the bottom layer.

Further, the inner diameters of the sliding sleeve ball seats of the plurality of packers 1 increase one by one along the direction from the bottom of the well to the head of the well.

Specifically, after the construction of the lowest fracturing layer is completed, it is necessary to successively open the setting fluid flow channel of the packer 1 to the upper fracturing layer and the inlet of the sliding sleeve sand blaster 4 by throwing balls. At the same time, the balls put in will fall on the ball seat of the lowest layer packer 1 for sealing. After the lowermost layer fracturing channel is blocked, the fracturing of the corresponding fracturing layer by the sliding sleeve sandblasting device 4 can be carried out During construction, the inner diameter of the sliding sleeve ball seat of the packer 1 should be reduced one by one from the upper layer to the bottom layer, so that balls of different sizes can be put in order to realize the plugging of the corresponding fracturing layer and the construction of the next fracturing layer.

Further, the packer 1 closest to the wellhead of the multi-layer fracturing string adopts a Y341 type washable hydraulic packer. The packer 1 in the middle of the layered fracturing string is a Y241 sliding sleeve hydraulic packer. The packer 1 closest to the bottom of the layered fracturing string is a Y241 hydraulic packer.

Specifically, in this embodiment, the packer 1 and its supporting tools are all hydraulically controlled. Compared with the mechanical setting method of the Y221 packer commonly used in the prior art, the stratification of deep wells and highly deviated wells The setting force can be efficiently transmitted during fracturing, reducing the risk of setting failure. The Y241 packer is a relatively mature packer with high setting stability efficiency. The Y341 well-washable hydraulic packer is being completed After setting, it also has the function of auxiliary well washing.

Furthermore, in the multi-stage string, except for the string closest to the bottom of the well and the string closest to the wellhead, each string includes a packer 1, a sliding sleeve sand blaster 4, and a hydraulic anchor connected in sequence. 5 and unsealed throw short section 2.

Specifically, in this embodiment, a setting sandblasting sliding sleeve 3 is installed on the pipe string closest to the bottom of the well, a hydraulic safety joint and other devices are installed on the pipe string closest to the wellhead, and multi-stage packers can be installed in the middle. 1. Unsealing the drop-off short joint 2. Sliding sleeve sandblasting device 4. The pipe string of hydraulic anchor 5. During construction, after injecting high-pressure fluid from the tubing of the pipe string, the fluke of hydraulic anchor 5 is under the action of high pressure It will compress its own inner compression spring and outer compression spring, and the anchor claw will be pushed to the casing wall, and finally clamped on the inner wall of the casing, so as to overcome the axial thrust generated by the pipe string during operation and construction, and achieve a fixed hydraulic force. The effect of a section of pipe string near the anchor 5, after the pressure of the oil jacket is balanced, the anchor fluke of the hydraulic anchor 5 can be retracted under the force of its own spring to release the anchor.

Further, among the multi-stage pipe strings, the pipe string closest to the wellhead is provided with a hydraulic safety joint 6 . A hydraulic anchor 5 is connected between the hydraulic safety joint 6 and the packer 1 .

Specifically, the hydraulic safety joint 6 is a safety tool that is easy to release and buckle. It is generally installed at the position where the pipe string needs to be released. It can transmit torque and withstand various composite stresses together with the pipe string. , the tripping and stabbing of the operating string can be completed through wellhead operations.

In the layered fracturing string provided by the embodiment of the utility model, by setting the layered fracturing string with multi-stage packers, and setting the unpacking and throwing short joints between the packers, it can be pressurized along the well The packers are set in sequence from the bottom to the wellhead, and at the same time, they are equipped with balls to suppress the pressure to realize the layered fracturing of the pipe string; when the starting pin is cut off, the upper joint drives the jacket and the nut to move relative to the central pipe, and the nut and the The distance between the connectors provides enough travel for the unsealing of the packer, which reduces the unpacking load of the packer. When the pipe string is stuck, continue to lift the pipe string to cut off the lost pin. The connector and the center The pipe is separated to realize hands-off, reduce the lifting load of the pipe string, and realize segmental salvage and lifting of the pipe string.

The above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present utility model shall be included in this utility model. within the scope of protection of utility models.

Claims (9)

1. A layered fracturing string, the layered fracturing string includes at least two stages of strings connected in sequence, each stage of the string is provided with a packer, it is characterized in that the two adjacent There is an unpacking and throwing short joint between the above packers, The unpacking and throwing short joint includes an upper joint, a cylindrical jacket, a nut, a connecting claw, a piston, a connecting head and a central pipe; The upper joint, the jacket and the nut are connected coaxially in sequence, and the connecting claws, the piston, the connecting head and the central pipe are all arranged in the jacket, One end of the connecting claw is set in the upper joint, the other end of the connecting claw is a locking claw in a retracted state, the piston is set outside the locking claw, and the connecting claw and the outer sleeve There is a gap, the piston is sandwiched between the locking pawl and the outer casing and is spaced a certain distance from the upper joint, and the connecting claw and the piston are connected by a starting pin; One end of the connecting head is clamped in the locking pawl, the other end of the connecting head is connected with one end of the central tube through a loose pin, and the nut is sleeved on the outer wall of the central tube , there is a gap between the central tube and the jacket, and a certain distance is set between the connecting head and the nut. 2 . The layered fracturing string according to claim 1 , characterized in that, one end of the layered fracturing string near the bottom of the well is provided with a setting sandblasting sliding sleeve. 3 . 3 . The layered fracturing string according to claim 1 , wherein the inner diameters of the sliding sleeve ball seats of the plurality of packers increase one by one along the direction from the bottom of the well to the wellhead. 4 . 4. The layered fracturing string according to claim 3, characterized in that, the packer closest to the wellhead of the layered fracturing string is a Y341 type washable hydraulic packer. 5. The layered fracturing string according to claim 3, characterized in that, the packer in the middle of the layered fracturing string is a Y241 sliding sleeve hydraulic packer. 6. The layered fracturing string according to claim 3, characterized in that, the packer closest to the bottom of the layered fracturing string is a Y241 hydraulic packer. 7. The layered fracturing string according to claim 1, characterized in that, in the multi-stage string, except for the string closest to the bottom of the well and the string closest to the wellhead, The tubing string at each stage includes a packer, a sliding sleeve sand blaster, a hydraulic anchor and an unsealed drop-out sub that are sequentially connected. 8 . The layered fracturing string according to claim 7 , wherein, among the multi-stage strings, the string closest to the wellhead is provided with a hydraulic safety joint. 9. The layered fracturing string according to claim 8, wherein a hydraulic anchor is connected between the hydraulic safety joint and the packer.