Speed tubular column system and construction method thereof

Abstract

The invention relates to a speed pipe column system and a construction method thereof, the speed pipe column system comprises a butt joint device, a first suspension packer, a first rotary connector, at least two sections of first-stage speed pipes and a first blanking plug, and the two sections of first-stage speed pipes are both arranged below a safety valve; the butt joint device is arranged between two adjacent sections of first-stage speed tubes and used for connecting the two sections of first-stage speed tubes, the first section of first-stage speed tube is located below the butt joint device, and the second section of first-stage speed tube is located above the butt joint device; the first suspension packer is connected with the upper end of the second-section first-stage velocity tube; the two ends of the first rotary connector are connected with the first suspension packer and the first-stage speed tube respectively; and the first blanking plug is connected with the lower end of the first-section first-stage speed tube. And the first-stage speed pipe is tripped in sections, so that the problem that the length of the speed pipe below the safety valve is limited is solved, and the liquid carrying capacity of a gas well is improved.

Description

Technical Field

[0001] This application relates to the technical field of oil extraction equipment, and particularly relates to a velocity string system and a construction method thereof. Background Art

[0002] During the process of natural gas extraction in the oil industry, as the production time extends and the formation energy decreases, the flow rate of the natural gas production well is insufficient to carry the liquid in the well out of the wellbore. Over time, the liquid level in the well will become higher and higher until the liquid level height is greater than the pressure of the formation natural gas. At this time, water flooding will occur, resulting in the inability of the natural gas well to produce.

[0003] In related technologies, in order to solve the problem of discharging the liquid in the natural gas well, a certain length of coiled tubing is usually suspended at the wellhead, which can reduce the critical liquid-carrying flow rate to a certain extent, thereby improving the liquid-carrying capacity of the gas well, bringing the liquid in the wellbore out, and ensuring the normal production of the gas well. The tubing string of the gas well is generally provided with a safety valve. Due to the influence of the maximum lifting weight of the crane on the offshore platform and the rope capacity of the drum, the length of the velocity string below the safety valve is limited, affecting the liquid drainage capacity of the gas well. Summary of the Invention

[0004] This application provides a velocity string system and a construction method thereof to solve the technical problem that the existing velocity string length is limited, affecting the liquid drainage capacity of the gas well.

[0005] This application provides a velocity string system for a production tubing string structure with a safety valve. The velocity string system includes a docking device, a first hanging packer, a first rotary connector, a first-stage velocity string, and a first plug. The first-stage velocity string has at least two sections, and both sections of the first-stage velocity string are arranged below the safety valve;

[0006] The docking device is arranged between two adjacent sections of the first-stage velocity string for connecting the two sections of the first-stage velocity string. Among them, the section of the first-stage velocity string below the docking device is the first section of the first-stage velocity string, and the section of the first-stage velocity string above the docking device is the second section of the first-stage velocity string;

[0007] The first hanging packer is connected to the upper end of the second section of the first-stage velocity string for hanging and setting the first-stage velocity string;

[0008] Both ends of the first rotary connector are respectively connected to the first hanging packer and the first-stage velocity string;

[0009] The first plug is connected to the lower end of the first section of the first-stage velocity string for plugging the first-stage velocity string.

[0010] In a possible implementation, the velocity string system further includes a second hanging packer, a second rotary connector, a secondary velocity string, and a second plug, which are arranged from top to bottom. The secondary velocity string is disposed above the safety valve, and the second hanging packer is connected to the upper end of the secondary velocity string;

[0011] The two ends of the second rotary connector are respectively connected to the second hanging packer and the secondary velocity string, and are used for transmitting the torque between the second hanging packer and the secondary velocity string;

[0012] The second plug is connected to the lower end of the secondary velocity string and is used for plugging the secondary velocity string.

[0013] In a possible implementation, the docking device includes a docking connecting rod, a first quick-connect nut, an upper connecting body, and a lower connecting body. The upper connecting body is sleeved on the upper end of the docking connecting rod and is used for connecting the second section of the primary velocity string;

[0014] The upper end of the first quick-connect nut is sleeved on the outer peripheral side of the upper connecting body and is connected to the lower end of the upper connecting body by threads. The lower end of the first quick-connect nut is slidably sleeved on the outer peripheral side of the docking connecting rod;

[0015] The lower connecting body is sleeved on the lower end of the docking connecting rod and is used for connecting the first section of the primary velocity string.

[0016] In a possible implementation, a guiding conical surface is provided at the upper end of the docking connecting rod.

[0017] In a possible implementation, a limiting step is provided on the outer peripheral side of the docking connecting rod, and a limiting groove is provided on the inner side wall of the first quick-connect nut. The limiting step abuts against the limiting groove.

[0018] In a possible implementation, a first set screw is provided at the upper end of the first quick-connect nut, and the first quick-connect nut is connected to the upper connecting body by the first set screw.

[0019] In a possible implementation, a first sealing ring is provided on the inner side wall of the upper connecting body, and the upper connecting body is hermetically connected to the docking connecting rod through the first sealing ring;

[0020] A second sealing ring is provided on the inner side wall of the lower connecting body, and the lower connecting body is hermetically connected to the docking connecting rod through the second sealing ring.

[0021] In a possible implementation, the docking device includes a pressing mechanism. The pressing mechanism includes a pressing nut, a slip joint, and a pressing ring. The pressing nut, the slip joint, and the pressing ring are sequentially sleeved on the outer peripheral side of the primary velocity string. The inner side wall of the pressing nut is slidably connected to the slip joint. Locking teeth are provided on the inner side wall of the slip joint. The pressing nut is threadedly connected to the upper connecting body or the lower connecting body.

[0022] In a possible implementation, a second set screw is provided on the circumferential side of the upper connector, and the upper connector is connected to the second-stage first-stage velocity pipe through the second set screw; a third set screw is provided on the circumferential side of the lower connector, and the lower connector is connected to the first-stage first-stage velocity pipe through the third set screw.

[0023] In a second aspect, the present application provides a construction method for a velocity pipe string system, which is applied to the velocity pipe string system as described above. The construction method includes:

[0024] Install a first plug at one end of the first-stage first-stage velocity pipe, and send the first-stage first-stage velocity pipe into the first preset position in the wellbore through a surface feeding tool, and perform pipe cutting operation on the first-stage first-stage velocity pipe so that the upper end of the first-stage first-stage velocity pipe remains at the wellhead;

[0025] Connect one end of the docking device to the upper end of the first-stage first-stage velocity pipe, and connect the other end of the docking device to one end of the second-stage first-stage velocity pipe located on the well surface to form a first-stage velocity pipe string;

[0026] Send the first-stage velocity pipe string into the second preset position in the wellbore through a surface feeding tool, and perform pipe cutting operation on the second-stage first-stage velocity pipe. At this time, the upper end of the second-stage first-stage velocity pipe remains at the wellhead;

[0027] Install a rotary connector, a first hanging packer and a setting auxiliary tool on the upper end of the second-stage first-stage velocity pipe in sequence to obtain a first-stage velocity pipe tool string;

[0028] Lower the first-stage velocity pipe tool string, set the first hanging packer, perform sealing inspection on the first-stage velocity pipe, and release the tool after the sealing inspection is qualified. At this time, the upper end of the second-stage first-stage velocity pipe is below the safety valve.

[0029] In a possible implementation, the construction method further includes:

[0030] Install a second plug at one end of the second-stage velocity pipe, and send the second-stage velocity pipe into the third preset position in the wellbore through a surface feeding tool, and perform pipe cutting operation on the second-stage velocity pipe so that the upper end of the second-stage velocity pipe remains at the wellhead.

[0031] Install a second hanging packer and a setting auxiliary tool on the upper end of the second-stage velocity pipe in sequence to obtain a second-stage velocity pipe tool string.

[0032] Lower the second-stage velocity pipe tool string, set the second hanging packer, perform sealing inspection on the second-stage velocity pipe, and release the tool after the sealing inspection is qualified. At this time, the lower end of the second-stage velocity pipe is above the safety valve.

[0033] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0034] The velocity string system and its construction method provided by the embodiments of the present application suspend two sections of first-stage velocity pipes into the production tubing. Since there is no coiled tubing passing through the safety valve, it will not affect the opening and closing of the safety valve, solving the well control risk. The production channel of gas is changed from the original production tubing to the velocity pipe, which increases the gas flow velocity, improves the liquid-carrying capacity of the gas well, extends the production cycle of the gas well, and increases the recovery rate. Moreover, since the first-stage velocity pipes below the safety valve are lowered in sections, the maximum length of the velocity pipes below the safety valve will not be affected by the maximum lifting weight of the crane on the offshore platform and the rope capacity of the drum, solving the problem of limited length of the velocity pipes below the safety valve and further improving the liquid-carrying capacity of the gas well. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present application and, together with the specification, are used to explain the principles of the present application.

[0036] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0037] One or more embodiments are exemplarily illustrated by the pictures in the corresponding accompanying drawings. These exemplary illustrations do not limit the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the drawings in the figures do not constitute a proportional limitation.

[0038] Figure 1 It is a schematic structural diagram of a velocity string system provided by the embodiments of the present application;

[0039] Figure 2 For Figure 1 It is a schematic structural diagram of the connector of the velocity string system shown;

[0040] Figures 3 - 5 For Figure 2 It is a schematic diagram of the connection process between the connector and the first-stage velocity pipe shown, where Figure 3 It is the state where the lower connecting body of the connector is connected to the first section of the first-stage velocity pipe, and the upper connecting body is connected to the second section of the first-stage velocity pipe, Figure 4 It is the state where the two sections of the first-stage velocity pipes are inserted and docked to form a seal, Figure 5 It is the state where the two sections of the first-stage velocity pipes are completely docked after the first quick-connect nut is tightened;

[0041] Figure 6 For Figure 1 It is a schematic structural diagram of the first rotary connector of the velocity string system shown;

[0042] Figures 7 - 8 is Figure 6 a schematic diagram showing the connection process of the first rotary connector and the first-stage velocity pipe, where Figure 7 the lower joint of the docking device is connected to the first section of the first-stage velocity pipe, and the upper joint is connected to the second section of the first-stage velocity pipe, Figure 8 is the state where the two sections of the first-stage velocity pipe are completely docked after the second quick-connect nut is tightened;

[0043] Figure 9 is the flow chart of the construction method of the velocity pipe string system provided by the embodiment of the present application Figure 1 ;

[0044] Figure 10 is the flow chart of the construction method of the velocity pipe string system provided by the embodiment of the present application Figure 2 .

[0045] Explanation of reference numerals:

[0046] X - radial direction; Y - axial direction;

[0047] 1, casing; 2, hydraulic control pipeline; 3, safety valve; 4, production tubing;

[0048] 5, first hanging packer;

[0049] 6, first rotary connector; 61, connection body; 62, upper joint; 63, lower joint; 64, second quick-connect nut;

[0050] 7, first-stage velocity pipe; 71, first section of the first-stage velocity pipe; 72, second section of the first-stage velocity pipe;

[0051] 8, first plug;

[0052] 9, docking device; 91, docking link; 911, guiding conical surface; 912, limiting step; 92, first quick-connect nut; 921, first set screw; 93, upper connection body; 931, first sealing ring; 932, second set screw; 933, fourth sealing ring; 94, lower connection body; 941, second sealing ring; 942, third set screw; 943, third sealing ring; 95, pressing mechanism; 951, pressing nut; 952, slip; 953, pressing ring;

[0053] 10, second hanging packer; 11, second rotary connector; 12, second-stage velocity pipe; 13, second plug;

[0054] 14, setting auxiliary tool; 141, coiled tubing; 142, composite joint; 143, releasing device; 144, setting and hanging device. Detailed implementation manners

[0055] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some but not all of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0056] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure of this application, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit this application. In addition, this application may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0057] For ease of description, spatially relative relationship terms may be used in the text to describe the relative positional relationship or movement of one element or feature shown in the figure relative to another element or feature. These relative relationship terms such as "inside", "outside", "inner side", "outer side", "below", "beneath", "above", "over", "front", "rear", etc. This spatially relative relationship term is intended to include different orientations of the device in use or operation other than the orientation depicted in the figure. For example, if the device in the figure undergoes a position flip, posture change, or motion state change, then these directional indications will change accordingly. For example, an element described as "below" or "beneath" other elements or features will then be oriented as "above" or "over" other elements or features. Therefore, the exemplary term "below" can include both upward and downward orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions) and the spatially relative relationship descriptors used in the text are interpreted accordingly.

[0058] In the related art, in order to ensure well control safety, safety valves are generally provided in the gas well string. The hanging speed string at the wellhead affects the opening and closing of the downhole safety valve, seriously affecting well control safety. When using a speed string suspended in the well, in order to ensure the normal opening and closing of the safety valve, the speed string can only be hung below the safety valve through a hanging packer. The safety valve is generally set at a downhole position several hundred meters away from the wellhead, while the depth of the gas well may reach several thousand meters, or even more than ten thousand meters. Since the crane on the offshore platform is usually limited by the maximum lifting weight and the rope capacity of the drum, the working drum diameter of the coiled tubing is limited and cannot accommodate the winding of an ultra-long string. If the length of the speed string suspended below the safety valve is too long and the weight of the string is too heavy, the platform crane cannot lift the coiled tubing drum, resulting in a limited length of the speed string below the safety valve and also affecting the liquid drainage capacity.

[0059] In order to solve the technical problem that in the existing speed string system, due to the influence of the maximum lifting weight and the rope capacity of the drum of the crane on the offshore platform, the length of the speed string below the safety valve is limited, affecting the liquid drainage capacity, the present application provides a speed string system and its construction method. The first-stage speed string below the safety valve is segmented and lowered. The maximum length of the speed string below the safety valve will not be affected by the maximum lifting weight and the rope capacity of the drum of the crane on the offshore platform, solving the problem of the limited length of the speed string below the safety valve and further improving the liquid carrying capacity of the gas well.

[0060] As Figure 1 shown, an embodiment of the present application provides a speed string system for a production string structure with a safety valve 3. The production string structure includes a production tubing 4, and the safety valve 3 is provided on the production tubing 4. A casing 1 with a hydraulic control line 2 is provided downhole. The production tubing 4 is lowered into the casing 1, and the hydraulic control line 2 is connected to the safety valve 3 so that the safety valve 3 can be controlled to open and close through a ground hydraulic control valve. One of the valve plates must be able to open and close normally when there is no object in the pipe affecting the opening and closing of the valve plate.

[0061] The speed string system includes a docking connector 9, a first hanging packer 5, a first rotary connector 6, a first-stage speed string 7, and a first plug 8. The first-stage speed string 7 has at least two sections, and both sections of the first-stage speed string 7 are provided below the safety valve 3. Lowering a small-diameter first-stage speed string 7 into the original production tubing 4 as the production string can increase the gas flow velocity and improve the liquid drainage capacity. Since the first-stage speed string 7 is provided below the safety valve 3, it does not affect the normal opening and closing operation of the downhole safety valve 3, thus ensuring well control safety.

[0062] The docking connector 9 is provided between two adjacent sections of the first-stage speed string 7 for quickly connecting the two sections of the first-stage speed string 7. Among them, the first section of the first-stage speed string 71 is located below the docking connector 9, and the second section of the first-stage speed string 72 is located above the docking connector 9.

[0063] The first suspension packer 5 is connected to the upper end of the second-stage first-stage velocity string 72 for suspending and setting the two-stage first-stage velocity string; both ends of the first rotary connector 6 are respectively connected to the first suspension packer 5 and the first-stage velocity string 7. The first rotary connector 6 can transmit the torque between the first suspension packer 5 and the first-stage velocity string 7, or not transmit the torque and only be used as a bearing.

[0064] The first plug 8 is connected to the lower end of the first-stage first-stage velocity string 71 for plugging the first-stage velocity string 7. The first plug 8 can adopt an integral plug to prevent the pressure in the well from entering the first-stage velocity string 7 and ensure the well control safety when the first-stage velocity string 7 is run in the hole.

[0065] For the convenience of description and understanding, the axial direction described in this application may be the Y direction shown in the figure, and the radial direction may be the X direction shown in the figure. It can be understood that the first-stage velocity string 7 is divided into two sections. First, the first plug 8 is installed at the lower end of the first-stage first-stage velocity string 71, and the first-stage first-stage velocity string 71 is run into the well to the first preset position through a surface conveyance tool. At the wellhead, it is quickly connected to the second-stage first-stage velocity string 72 through the docking device 9, and the two-stage first-stage velocity string 7 is continued to be run in until the second-stage first-stage velocity string 72 is run into the well to the second preset position. Then, after connecting through the first rotary connector 6 and the first suspension packer 5 at the wellhead, a first-stage velocity string is formed, and the first-stage velocity string is sent to the designed position below the safety valve 3 by the coiled tubing 141. After the first suspension packer 5 is set and released, the first-stage suspension is completed. After the construction of the first-stage velocity string 7 is completed, pressure is applied inside the first-stage velocity string 7, and the first plug 8 is opened under the action of the hydraulic pressure, and a new production channel is formed inside the first-stage velocity string 7. The two-stage first-stage velocity string 7 is suspended in the production tubing 4. Since there is no coiled tubing 141 passing through the safety valve 3, it will not affect the opening and closing of the safety valve 3, solving the well control risk. The production channel of the gas changes from the original production tubing 4 to the velocity string, increasing the gas flow velocity, enhancing the liquid carrying capacity of the gas well, extending the production cycle of the gas well, and improving the recovery rate; moreover, since the first-stage velocity string 7 below the safety valve 3 is divided into at least two sections and the first-stage velocity string 7 is run in sections, the maximum length of the velocity string below the safety valve 3 will not be affected by the maximum lifting weight of the crane on the offshore platform and the rope capacity of the drum, solving the problem of the limited length of the velocity string below the safety valve 3 and further enhancing the liquid carrying capacity of the gas well.

[0066] It should be noted that the first-stage velocity pipe 7 can be divided into multiple sections for lowering. That is to say, the first-stage velocity pipe 7 below the safety valve 3 can include the first-section first-stage velocity pipe 71, the second-section first-stage velocity pipe 72... the nth-section first-stage velocity section. After the first-section first-stage velocity pipe 71 is lowered, the quick connection between the first-section first-stage velocity pipe 71 and the second-section first-stage velocity pipe 72 is completed at the wellhead through the docking device 9. Then, the first-section first-stage velocity pipe 71 and the second-section first-stage velocity pipe 72 are continuously lowered, and the quick connection between the second-section first-stage velocity pipe 72 and the third-section first-stage velocity pipe is completed at the wellhead through the docking device 9, and so on. A first-stage velocity pipe string can be formed below the safety valve 3.

[0067] The surface feeding tool includes a lifting device (such as a crane). A drum, a gooseneck, tools such as a head, a blowout preventer box, a blowout preventer, a blowout prevention pipe, a blowout preventer, a gas production tree, etc. can be arranged on the crane. The structures and working principles of the above tools can refer to the prior art, and the present application will not elaborate on this.

[0068] In the prior art, if there is no velocity pipe above the safety valve 3, after the natural gas comes out through the velocity pipe below the safety valve 3, it will enter the production channel above the safety valve 3. Due to the sudden increase in the channel size, the flow rate decreases, and the liquid-carrying capacity of the natural gas will decline, and there may be an incomplete liquid drainage situation. Therefore, in the present application, a second-stage velocity pipe 12 is also provided above the safety valve 3 to improve the liquid-carrying capacity.

[0069] In some embodiments, such as Figure 1As shown in the figure, the velocity string system further includes a second suspension packer 10, a second rotary connector 11, a secondary velocity string 12, and a second plug 13, which are arranged in sequence from top to bottom. The secondary velocity string 12 is arranged above the safety valve 3. The second suspension packer 10 is connected to the upper end of the secondary velocity string 12 and is used for suspending and setting the secondary velocity string 12. The two ends of the second rotary connector 11 are respectively connected to the second suspension packer 10 and the secondary velocity string 12. The specific structure and working principle of the second rotary connector 11 can refer to the first rotary connector 6. The second plug 13 is connected to the lower end of the secondary velocity string 12 and is used for plugging the secondary velocity string 12. After the first-stage suspension is completed, a first plug 8 is installed at the lower end of the secondary velocity string 12, and the secondary velocity string 12 is lowered into the well through a surface feeding tool until the lower end of the secondary velocity string 12 reaches the designed position above the safety valve 3. Then, after connecting the second rotary connector 11 and the second suspension packer 10 at the wellhead, a first-stage velocity string is formed, and the first-stage velocity string is sent into the designed position below the safety valve 3 by a coiled tubing 141. After the second suspension packer 10 is set and released, the second-stage suspension is completed. After the construction of the secondary velocity string 12 is completed, pressure is applied to the inside of the secondary velocity string 12, and the second plug 13 and the first plug 8 are successively opened under the action of hydraulic pressure, and a new production channel is formed inside the first-stage velocity string 7 and the secondary velocity string 12. The secondary velocity string 12 is arranged above the safety valve 3, and multiple sections of the first-stage velocity string 7 are arranged below the safety valve 3, and the full-wellbore flow velocity is increased through the staged velocity strings.

[0070] The first-stage velocity string 7 is divided into multiple sections and lowered into the well. In order to prevent the torsional stress accumulated by the lower velocity string during the well entry process from being transmitted to the upper string or tool, the structure design of the docking device 9 of the present application is described as follows.

[0071] In some embodiments, as Figure 2 shown, the docking device 9 includes a docking link 91, a first quick-connect nut 92, an upper connecting body 93, and a lower connecting body 94. The upper connecting body 93 is sleeved on the upper end of the docking link 91 and is used for connecting the second section of the first-stage velocity string 72. The upper end of the first quick-connect nut 92 is sleeved on the outer peripheral side of the upper connecting body 93 and is connected to the lower end of the upper connecting body 93 through a thread. The lower end of the first quick-connect nut 92 is slidably sleeved on the outer peripheral side of the docking link 91. The lower connecting body 94 is sleeved on the lower end of the docking link 91 and is used for connecting the first section of the first-stage velocity string 71. When it is necessary to dock two sections of the first-stage velocity string 7, as Figure 3 shown, at the wellhead, the first quick-connect nut 92 of the docking device 9 is disassembled, the lower connecting body 94 is quickly connected to the first section of the first-stage velocity string 71, and the upper connecting body 93 is quickly connected to the second section of the first-stage velocity string 72. As Figure 4As shown, then push the docking link 91 into the upper connector 93. At this time, the two sections of the first-stage velocity pipes do not need to rotate. Only need to rotate the first quick-connect nut 92 and tighten the first quick-connect nut 92 on the upper connector 93 to achieve the quick docking of the two sections of the first-stage velocity pipes 7, as Figure 5 shown. After connection, the docking link 91 can rotate within the upper connector 93, enabling the two sections of the first-stage velocity pipes 7 to only transmit axial loads and not transmit circumferential torques. Using this docking device 9 in the velocity pipe string can prevent the torsional stress accumulated by the lower velocity pipe during the process of entering the well from being transmitted to the upper pipe string or tools, especially at the hanging packer. In this way, the sealing and hanging performance of the hanging packer can be ensured.

[0072] This docking device 9 can achieve the quick docking of two sections of velocity pipes at the wellhead, and can connect velocity pipes with the same diameter as well as velocity pipes with different diameters.

[0073] In some embodiments, as Figure 2 shown, the upper end of the docking link 91 is provided with a guiding conical surface 911. During the process of pushing the docking link 91 into the upper connector 93, the guiding conical surface 911 can play a guiding and centering role, enabling the two sections of the first-stage velocity pipes 7 to be centered and docked, with a smooth production channel, thus facilitating the improvement of the flow velocity throughout the wellbore.

[0074] In some embodiments, as Figure 2 shown, a limiting step 912 is provided on the outer peripheral side of the docking link 91, and a limiting groove is provided on the inner side wall of the first quick-connect nut 92. The limiting step 912 abuts against the limiting groove. Specifically, the limiting step 912 is arranged in a circumferential direction around the docking link 91 to form an annular limiting step 912. After the two sections of the first-stage velocity pipes 7 are docked, the first quick-connect nut 92 is screwed tightly onto the docking link 91, and the limiting groove of the first quick-connect nut 92 abuts against the limiting step 912. The limiting step 912 bears a part of the weight of the first-stage velocity pipe 7, thus ensuring the connection reliability.

[0075] In some embodiments, as Figure 2 shown, a first set screw 921 is provided at the upper end of the first quick-connect nut 92, and the first quick-connect nut 92 is connected to the upper connector 93 through the first set screw 921. Optionally, multiple first set screws 921 are provided, and the multiple first set screws 921 are evenly distributed along the circumferential direction of the first quick-connect nut 92 to provide a pressing force on the upper connector 93, thereby improving the connection reliability.

[0076] In some embodiments, as Figure 2As shown, a first sealing ring 931 is provided on the inner side wall of the upper connecting body 93. The upper connecting body 93 is hermetically connected to the docking connecting rod 91 through the first sealing ring 931. The first sealing ring 931 can prevent the liquid in the pipe from leaking through the connection gap between the upper connecting body 93 and the docking connecting rod 91, thereby improving the sealing reliability of the docking device 9.

[0077] A second sealing ring 941 is provided on the inner side wall of the lower connecting body 94. The lower connecting body 94 is hermetically connected to the docking connecting rod 91 through the second sealing ring 941. The second sealing ring 941 can prevent the liquid in the pipe from leaking through the connection gap between the lower connecting body 94 and the docking connecting rod 91, thereby improving the sealing reliability of the docking device 9.

[0078] Of course, a third sealing ring 943 can also be provided on the inner side wall of the lower connecting body 94. The third sealing ring 943 can prevent the liquid in the pipe from leaking through the connection gap between the first-stage primary velocity pipe 71 and the lower connecting body 94, thereby improving the sealing reliability. A fourth sealing ring 933 can also be provided on the inner side wall of the upper connecting body 93. The fourth sealing ring 933 can prevent the liquid in the pipe from leaking through the connection gap between the second-stage primary velocity pipe 72 and the upper connecting body 93, thereby improving the sealing reliability.

[0079] In some embodiments, as Figure 2 shown, the docking device 9 includes a pressing mechanism 95. The pressing mechanism 95 includes a pressing nut 951, a collet 952, and a pressing ring 953. The pressing nut 951, the collet 952, and the pressing ring 953 are sequentially sleeved on the outer peripheral side of the primary velocity pipe 7. The inner side wall of the pressing nut 951 is slidably connected to the collet 952. Locking teeth are provided on the inner side wall of the collet 952. The pressing nut 951 is threadedly connected to the upper connecting body 93 or the lower connecting body 94. Multiple collets 952 can be provided, and the multiple collets 952 are evenly arranged along the circumferential direction of the primary velocity pipe 7. A first tapered surface is provided on the outer side wall of the collet 952, and a second tapered surface slidably adapted to the first tapered surface is provided on the inner side wall of the pressing nut 951. Two sets of pressing mechanisms 95 are provided. One set of pressing mechanisms 95 is used to clamp the first-stage primary velocity pipe 71, and the other set of pressing mechanisms 95 is used to clamp the second-stage primary velocity pipe 72. The pressing nut 951 of one set of pressing mechanisms 95 is threadedly connected to the lower connecting body 94. After the first-stage primary velocity pipe 71 is inserted into the hollow channel of the lower connecting body 94, the pressing nut 951 is rotated. Under the radial pressure of the first tapered surface and the second tapered surface, the collet 952 gradually moves inward relative to the pressing nut 951, and a reliable connection is achieved by using the pressing force between the locking teeth of the collet 952 and the first-stage primary velocity pipe 71. The pressing nut 951 of the other set of pressing mechanisms 95 is threadedly connected to the upper connecting body 93. Similarly, a reliable connection can be achieved by using the pressing force between the locking teeth of the collet 952 and the second-stage primary velocity pipe 72.

[0080] It should be noted that the inner diameter of the compression nut and the number of locking teeth of the slip 952 can be designed according to the outer diameter of the first-stage velocity tube 7.

[0081] In some embodiments, a second set screw 932 is provided on the circumferential side of the upper connector 93, and the upper connector 93 is connected to the second-stage first-stage velocity tube 72 through the second set screw 932. Optionally, a plurality of second set screws 932 are provided, and the plurality of second set screws 932 are arranged along the circumferential direction of the first quick-connect nut 92 to provide a pressing force on the second-stage first-stage velocity tube 72, thereby improving the connection reliability. A third set screw 942 is provided on the circumferential side of the lower connector 94, and the lower connector 94 is connected to the first-stage first-stage velocity tube 71 through the third set screw 942. Optionally, a plurality of third set screws 942 are provided, and the plurality of third set screws 942 are arranged along the circumferential direction of the first quick-connect nut 92 to provide a pressing force on the first-stage first-stage velocity tube 71, thereby improving the connection reliability.

[0082] In an exemplary embodiment, as Figure 6 shown, the first rotary connector 6 includes a connection body 61, an upper joint 62 and a lower joint 63 are respectively provided at both ends of the connection body 61. The upper joint 62 is used to connect the second-stage first-stage velocity tube 72, and the lower joint 63 is used to connect the first-stage first-stage velocity tube 71. A second quick-connect nut 64 is sleeved on the connection body 61, and the second quick-connect nut 64 is detachably connected to the upper joint 62 through a thread. As Figure 7 shown, loosen the second quick-connect nut 64, connect the upper joint 62 to the second-stage first-stage velocity tube 72, and connect the lower joint 63 to the first-stage first-stage velocity tube 71; then, as Figure 8 shown, after the upper joint 62 is docked with the connection body 61, tighten the second quick-connect nut 64. Then, the first-stage velocity tube 7 and the first suspension hanger 5 in the well do not need to be rotated, and the two-stage first-stage velocity tubes 7 can be quickly connected by rotating the second quick-connect nut 64, and the connection is convenient, fast and safe. Of course, the first rotary connector 6 can also adopt other existing coiled tubing connectors.

[0083] As Figure 9 shown, the embodiment of the present application also provides a construction method for a velocity string system, which is applied to the velocity string system as described above. The construction method includes the following steps:

[0084] S1. Install a first plug 8 at one end of the first-stage first-stage velocity tube 71, and send the first-stage first-stage velocity tube 71 into the first preset position in the well through a ground feeding tool, and perform a pipe cutting operation on the first-stage first-stage velocity tube 71. At this time, the upper end of the first-stage first-stage velocity tube 71 remains at the wellhead.

[0085] During the lowering process of the first-stage primary velocity pipe 71 in the first section, the initial lowering speed does not exceed 5 m / min. After passing 50 m below the wellhead, the lowering speed is not greater than 10 m / min. When reaching complex well sections (such as the inner diameter of the downhole safety valve 3, the build point, the reducer joint, the sliding sleeve, and the packer becomes smaller), the lowering speed is reduced to within 5 m / min 50 m in advance; for every 300 m of lowering, a weight test of lifting is carried out.

[0086] S2. Install the docking device 9: Connect one end of the docking device 9 to the upper end of the first-stage primary velocity pipe 71 in the first section, and connect the other end of the docking device 9 to one end of the second-stage primary velocity pipe 72 located on the well surface to obtain a primary velocity pipe string.

[0087] Specifically, loosen the first quick-connect nut 92 of the docking device 9, separate the upper connecting body 93 from the docking link 91, then connect the upper end of the first-stage primary velocity pipe 71 to the lower connecting body 94 of the docking device 9, connect the lower end of the second-stage primary velocity pipe 72 to the upper connecting body 93 of the docking device 9, and then tighten the first quick-connect nut 92.

[0088] S3. Send the primary velocity pipe string into the second preset position in the well through a surface feeding tool, and perform a pipe cutting operation on the second-stage primary velocity pipe 72. At this time, the upper end of the second-stage primary velocity pipe 72 remains at the wellhead. At this time, the lowering depth of the first-stage primary velocity pipe 71 can reach more than 4000 m.

[0089] S4. Install a rotary connector, a first hanging packer 5 and a setting auxiliary tool 14 in sequence at the upper end of the second-stage primary velocity pipe 72 to obtain a primary velocity pipe tool string.

[0090] The setting auxiliary tool 14 includes a coiled tubing 141, a composite joint 142, a releasing device 143 and a setting and hanging device 144. Among them, the function of the releasing device 143 is that in case of an accident, it can be disconnected to create conditions for subsequent operations, avoiding the situation that the entire coiled tubing 141 cannot be processed in the well, thus ensuring well control safety. The setting and hanging device 144 and the hanging packer are connected together in advance, not connected at the wellhead. The function of the setting auxiliary tool 14 is to set the hanging packer.

[0091] S5. Lower the primary velocity pipe tool string, the first hanging packer 5 is set, the primary velocity pipe is tested for sealing, and after the sealing test is qualified, release it. At this time, the upper end of the second-stage primary velocity pipe 72 is below the safety valve 3.

[0092] Pressurize the coiled tubing 141. The first hanging packer 5 is successfully set, and after the sealing test is qualified, release it. Lift the setting auxiliary tool 14, and the coiled tubing 141, the composite joint 142, the releasing device 143 and the setting and hanging device 144 do not remain in the well.

[0093] By the above construction method, the first-stage velocity pipes are lowered in sections, and the maximum length of the velocity pipes below the safety valve 3 will not be affected by the maximum lifting weight of the crane on the offshore platform and the rope capacity of the drum, solving the problem of limited length of the velocity pipes below the safety valve 3 and further improving the liquid-carrying capacity of the gas well.

[0094] In some embodiments, as Figure 10 shown, the construction method further includes the following steps:

[0095] S6. Install a second plug 13 at one end of the second-stage velocity pipe 12, and send the second-stage velocity pipe 12 to the third preset position in the wellbore through a surface feeding tool, and perform pipe cutting operation on the second-stage velocity pipe 12. At this time, the upper end of the second-stage velocity pipe 12 remains at the wellhead.

[0096] S7. Install a second hanging packer 10 and a setting auxiliary tool 14 in sequence at the upper end of the second-stage velocity pipe 12 to obtain a second-stage velocity pipe tool string.

[0097] S8. Lower the second-stage velocity pipe tool string, set the second hanging packer 10, and perform seal inspection on the second-stage velocity pipe 12. After the seal inspection is qualified, release the tool string. At this time, the lower end of the second-stage velocity pipe 12 is above the safety valve 3.

[0098] After the construction of the second-stage velocity pipe 12 is completed, pressure is applied inside the second-stage velocity pipe 12, and the second plug 13 and the first plug 8 are successively opened under the action of liquid pressure, and a new production channel is formed inside the first-stage velocity pipe and the second-stage velocity pipe 12. The second-stage velocity pipe 12 is arranged above the safety valve 3, and multiple sections of the first-stage velocity pipes are arranged below the safety valve 3, and the full wellbore flow velocity is increased through the stepped velocity pipes.

[0099] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" as used herein may also include the plural forms. The terms "comprising", "including", "containing", and "having" are inclusive and thus specify the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the particular order described or illustrated, unless the order of performance is explicitly stated. It should also be understood that alternative or additional steps may be used.

[0100] Although terms such as first, second, third, etc. may be used herein to describe multiple elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or section from another region, layer, or section. Unless the context clearly indicates otherwise, terms such as "first", "second", and other numerical terms do not imply an order or sequence when used in this document. Thus, the first element, component, region, layer, or section discussed below may be referred to as the second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0101] The above description is only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather will conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A velocity string system, used for a production string structure with a safety valve, characterized in that: The velocity string system comprises a docking device, a first suspension packer, a first rotary connector, a primary velocity pipe and a first plugging device, wherein the primary velocity pipe is provided with at least two sections, and the two sections of the primary velocity pipe are both provided below the safety valve; The butt joint is disposed between two adjacent sections of the first-stage velocity tubes and is used to connect the two sections of the first-stage velocity tubes, wherein the first section of the first-stage velocity tube is located below the butt joint, and the second section of the first-stage velocity tube is located above the butt joint; The first suspension packer is connected to the upper end of the second section of the primary velocity tube and is used to suspend and set the primary velocity tube; The two ends of the first rotary connector are respectively connected to the first suspension packer and the primary velocity tube; The first plugging device is connected to the lower end of the first section of the primary velocity tube and is used to plug the primary velocity tube.

2. The velocity string system according to claim 1, characterized in that: The velocity string system further comprises a second suspension packer, a second rotary connector, a secondary velocity tube and a second plugger arranged from top to bottom, wherein the secondary velocity tube is arranged above the safety valve, and the second suspension packer is connected to the upper end of the secondary velocity tube; The two ends of the second rotary connector are respectively connected to the second suspension packer and the secondary velocity tube, and are used to transmit the torque between the second suspension packer and the secondary velocity tube; The second plugging device is connected to the lower end of the secondary velocity tube and is used for plugging the secondary velocity tube.

3. The velocity string system according to claim 1 or 2, characterized in that: The docking device comprises a docking connecting rod, a first quick-connect nut, an upper connecting body and a lower connecting body, wherein the upper connecting body is sleeved on the upper end of the docking connecting rod and is used to connect the second-section primary velocity tube; The upper end of the first quick-connect nut is sleeved on the outer peripheral side of the upper connecting body and connected to the lower end of the upper connecting body through a thread, and the lower end of the first quick-connect nut is slidably sleeved on the outer peripheral side of the docking connecting rod; The lower connecting body is sleeved on the lower end of the butt-jointed connecting rod and is used for connecting the first-section primary velocity tube.

4. The velocity string system according to claim 3, characterized in that: The upper end of the butt-jointed connecting rod is provided with a guiding cone surface.

5. The velocity string system according to claim 3, characterized in that: A limiting step is provided on the outer peripheral side of the butt-jointed connecting rod, and a limiting groove is provided on the inner side wall of the first quick-connect nut, and the limiting step abuts against the limiting groove.

6. The velocity string system according to claim 4, characterized in that: A first set screw is disposed at the upper end of the first quick-connect nut, and the first quick-connect nut is connected to the upper connector through the first set screw.

7. The velocity string system according to claim 3, characterized in that: The inner side wall of the upper connector is provided with a first sealing ring, and the upper connector is sealed and connected to the butt-jointed connecting rod via the first sealing ring; The inner side wall of the lower connecting body is provided with a second sealing ring, and the lower connecting body is sealedly connected to the butt connecting rod via the second sealing ring.

8. The velocity string system according to claim 3, characterized in that: The docking device includes a clamping mechanism, which includes a clamping nut, a slip and a clamping ring. The clamping nut, the slip and the clamping ring are sequentially sleeved on the outer peripheral side of the first-level velocity tube. The inner side wall of the clamping nut is slidably connected to the slip. The inner side wall of the slip is provided with locking teeth. The clamping nut is connected to the upper connector thread or the lower connector thread.

9. The velocity string system according to claim 3, characterized in that: A second set screw is provided on the circumferential side of the upper connector, and the upper connector is connected to the second-stage primary speed tube via the second set screw; a third set screw is provided on the circumferential side of the lower connector, and the lower connector is connected to the first-stage primary speed tube via the third set screw.

10. A construction method of a velocity string system, applied to the velocity string system according to any one of claims 1 to 9, characterized in that: The construction method comprises: A first plug is installed at one end of the first section of the primary velocity pipe, the first section of the primary velocity pipe is sent to a first preset position underground by a ground delivery tool, and the first section of the primary velocity pipe is cut so that the upper end of the first section of the primary velocity pipe remains at the wellhead; Connecting one end of the butt joint to the upper end of the first segment of the primary velocity tube, and connecting the other end of the butt joint to one end of the second segment of the primary velocity tube located on the well surface to form a primary velocity tube string; The first-stage velocity pipe string is sent to a second preset position in the well by a surface delivery tool, and the second-stage first-stage velocity pipe is cut, and the upper end of the second-stage first-stage velocity pipe is left at the wellhead; A rotary connector, a first hanging packer and a setting auxiliary tool are sequentially installed on the upper end of the second section of the first-stage velocity tube to obtain a first-stage velocity tube tool string; The first-stage velocity tube tool string is lowered, the first suspension packer is set, and the first-stage velocity tube is tested for sealing. After the test is qualified, the packer is released. At this time, the upper end of the second section of the first-stage velocity tube is below the safety valve.

11. The construction method according to claim 10, characterized in that: Also includes: A second plug is installed at one end of the secondary velocity tube, and the secondary velocity tube is sent to a third preset position underground by a ground delivery tool, and the secondary velocity tube is cut so that the upper end of the secondary velocity tube remains at the wellhead. A second hanging packer and a setting auxiliary tool are sequentially installed on the upper end of the secondary velocity tube to obtain a secondary velocity tube tool string. The secondary velocity tube tool string is lowered, the second suspension packer is set, and the secondary velocity tube is tested for sealing. After the test is qualified, the packer is released. At this time, the lower end of the secondary velocity tube is above the safety valve.

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