Double-gradient drilling device

Abstract

The invention discloses a double-gradient well drilling device which comprises a marine riser, a drill pipe and a pressure adjusting mechanism. The drill pipe comprises an inner pipe, an outer pipe and a marine riser, the outer pipe and the inner pipe are coaxially sleeved in sequence, a first annular area is formed between the inner pipe and the outer pipe, and a second annular area is formed between the outer pipe and the marine riser; the pressure adjusting mechanism comprises at least one of a first pressure adjusting part and a second pressure adjusting part, and at least part of the first pressure adjusting part is arranged in the first annular space area so as to divide the first annular space area into a first upper area and a first lower area; the first pressure adjusting part is used for adjusting the opening degree of a first communication channel between the first upper area and the first lower area; the second pressure adjusting part is used for adjusting the opening degree of the second communication channel between the first annular space area and the second annular space area. According to the scheme, the problem that a double-gradient drilling device involved in the related technology cannot quickly and accurately adjust the pressure when facing the emergency situation of pressure sudden change can be solved.

Description

Technical Field

[0001] This invention relates to the field of drilling technology, and more particularly to a dual-gradient drilling apparatus. Background Technology

[0002] Dual-gradient drilling technology involves installing a riser on the outside of the drill pipe and filling the inside of the riser with seawater or other media. A pump is used in conjunction with a return pipeline to return the drilling fluid, or a low-density medium is injected into the riser to reduce the density of the fluid returning in the riser annulus. This ensures that the entire drilling fluid return loop maintains a dual-density drilling fluid system, effectively controlling the wellbore annulus pressure and bottom hole pressure, and overcoming the problems encountered in deepwater drilling.

[0003] However, existing dual-gradient drilling rigs regulate downhole pressure solely by injecting low-density media via a bypass, and their pressure regulation range and response time are limited. In the event of emergencies such as overflows, kicks, or lost circulation, downhole pressure can rise or fall instantaneously. In other words, existing dual-gradient drilling rigs cannot quickly and accurately regulate pressure in the face of sudden pressure changes, making it difficult to stabilize downhole pressure effectively and promptly. This often results in insufficient time to adjust the pressure back to the normal range, causing downhole equipment to fail due to significant pressure fluctuations. Summary of the Invention

[0004] This invention discloses a side-drilling window opening tool to solve the problem in related technologies where dual-gradient drilling rigs cannot quickly and accurately adjust pressure when faced with sudden pressure changes.

[0005] To address the aforementioned technical problems, the present invention discloses the following technical solutions:

[0006] A dual-gradient drilling rig includes a riser, a drill pipe, and a pressure regulating mechanism;

[0007] The drill pipe includes an inner pipe and an outer pipe. The water-proof pipe, the outer pipe and the inner pipe are coaxially sleeved in sequence. A first annular region is formed between the inner pipe and the outer pipe, and a second annular region is formed between the outer pipe and the water-proof pipe.

[0008] The pressure regulating mechanism includes at least one of a first pressure regulating part and a second pressure regulating part, wherein: at least a portion of the first pressure regulating part is disposed within the first annular region to divide the first annular region into a first upper region and a first lower region, and the first pressure regulating part is used to adjust the opening of a first connecting channel between the first upper region and the first lower region; the second pressure regulating part is used to adjust the opening of a second connecting channel between the first annular region and the second annular region.

[0009] Optionally, the first pressure regulating part includes a fixed plate and a rotating plate, the fixed plate is fixedly connected to the inner tube, the rotating plate is rotatably connected to the inner tube, and the fixed plate and the rotating plate are arranged along the axial direction of the drill pipe;

[0010] The fixed disk is provided with a first through hole, and the rotating disk is provided with a second through hole. The first connecting channel includes the first through hole and the second through hole. During the rotation of the rotating disk relative to the fixed disk, the overlapping area of ​​the orthographic projection of the first through hole and the second through hole in the axial direction of the drill pipe changes, so as to adjust the opening of the first connecting channel.

[0011] Optionally, the first pressure regulating unit further includes an inner connecting pipe and an outer connecting pipe, the outer connecting pipe being sleeved outside the inner connecting pipe, the inner connecting pipe being connected to the inner pipe, the outer connecting pipe being connected to the outer pipe, the fixed plate being fixedly connected to the inner connecting pipe, and the rotating plate being rotatably sleeved outside the inner connecting pipe;

[0012] At least a portion of the rotating disk is located between the inner connecting pipe and the outer connecting pipe, and a first receiving cavity and a second receiving cavity are formed between the outer connecting pipe and the rotating disk and are separated from each other. The first pressure regulating part further includes a medium inlet pipe and a medium outlet pipe. One of the medium inlet pipe and the medium outlet pipe is connected to the first receiving cavity and the other is connected to the second receiving cavity, so that the medium entering through the medium inlet pipe drives the rotating disk to rotate relative to the fixed disk.

[0013] Optionally, the rotating disk includes a rotating part and a dividing part, both of which are located between the inner connecting pipe and the outer connecting pipe. The outer peripheral surface of the rotating part protrudes from the dividing part to divide the space between the outer peripheral surface of the rotating part and the outer connecting pipe into the first receiving cavity and the second receiving cavity.

[0014] Optionally, the number of media inlet pipes is at least two, including a first inlet pipe and a second inlet pipe, and the number of media outlet pipes is at least two, including a first outlet pipe and a second outlet pipe. Of the first inlet pipe and the first outlet pipe, one is connected to the first receiving cavity and the other is connected to the second receiving cavity. Of the second inlet pipe and the second outlet pipe, one is connected to the first receiving cavity and the other is connected to the second receiving cavity.

[0015] When the first inlet pipe is in a conductive state, the first outlet pipe is in a conductive state; when the second inlet pipe is in a conductive state, the second outlet pipe is in a conductive state.

[0016] Optionally, at least a portion of the first pressure regulating part is disposed within the second annular region to divide the second annular region into a second upper region and a second lower region;

[0017] The fixed disk is further provided with a third through hole, and the rotating disk is further provided with a fourth through hole. The third through hole and the fourth through hole are connected to connect the second upper region and the second lower region. At least one of the third through hole and the fourth through hole is an arc-shaped hole extending circumferentially along the rotating disk.

[0018] Optionally, at least a portion of the first pressure regulating part is disposed within the second annular region to divide the second annular region into a second upper region and a second lower region;

[0019] The second pressure regulating part is provided in at least one of the second upper region and the second lower region, wherein the second pressure regulating part located in the second upper region is disposed away from the first pressure regulating part, and the second pressure regulating part located in the second lower region is disposed close to the first pressure regulating part.

[0020] Optionally, the second pressure regulating part includes a pressure regulating cylinder, a piston, a gate, and a driving component. The outer tube is provided with an regulating port. The first upper region and the second upper region, as well as the first lower region and the second lower region, are respectively connected through different regulating ports. The second connecting channel includes the regulating port.

[0021] The pressure regulating cylinder is disposed on the outer tube, and the piston is movably disposed inside the pressure regulating cylinder to divide the inner cavity of the pressure regulating cylinder into a first chamber and a second chamber. The first chamber is connected to the first upper region or the first lower region. One end of the gate extends into the second chamber and is connected to the piston, and the other end of the gate is opposite to the adjustment port. The driving member is used to drive the piston to move relative to the pressure regulating cylinder so as to adjust the opening of the adjustment port through the gate.

[0022] Optionally, at least a portion of the first pressure regulating part is disposed within the second annular region to divide the second annular region into a second upper region and a second lower region;

[0023] The dual-gradient drilling rig also includes a connecting balancer, one end of which is connected to the second upper region and the other end of which is connected to the second lower region.

[0024] The communication balancer includes an upper communication pipe, a lower communication pipe, a balance chamber, and a blocking solenoid valve. The second upper region, the upper communication pipe, the balance chamber, the lower communication pipe, and the second lower region can be connected sequentially. In a direction parallel to the axis of the drill pipe, the cross-sectional area of ​​the inner cavity of the balance chamber first increases and then decreases. The blocking solenoid valve is disposed in the balance chamber.

[0025] Optionally, at least a portion of the first pressure regulating part is disposed within the second annular region to divide the second annular region into a second upper region and a second lower region;

[0026] The dual-gradient drilling rig further includes at least one of a pressurization mechanism, a depressurization mechanism, and a gas injection mechanism, wherein:

[0027] One end of the pressurizing mechanism and one end of the depressurizing mechanism are both connected to the first lower region;

[0028] The gas injection mechanism has an upper gas injection end and a lower gas injection end. The upper gas injection end is connected to the second upper region, and the lower gas injection end is connected to the second lower region.

[0029] The technical solutions disclosed in the embodiments of the present invention have the following technical effects:

[0030] In the dual-gradient drilling apparatus disclosed in this invention, the pressure regulating mechanism includes at least one of a first pressure regulating part and a second pressure regulating part. At least a portion of the first pressure regulating part is disposed within a first annular region to divide the first annular region into a first upper region and a first lower region. The first pressure regulating part is used to adjust the opening of a first connecting channel between the first upper region and the first lower region. When a sudden pressure change occurs downhole, the first pressure regulating part can close the first connecting channel between the first upper region and the first lower region, thereby isolating the first upper region and the first lower region and preventing pressure fluctuations. Sudden pressure changes adversely affect dual-gradient drilling rigs. Furthermore, by adjusting the opening of the first connecting channel between the first upper and lower regions, rapid and accurate pressure control can be achieved in both regions. The second pressure regulating unit can adjust the opening of the second connecting channel between the first and second annulus regions to regulate their pressure, enabling rapid pressure balance and rapid and accurate control of the internal pressures within both regions. This ensures that the downhole pipeline pressure remains at a normal and stable level. Therefore, both the first and second pressure regulating units can quickly and accurately adjust pressure in the face of sudden pressure changes, effectively stabilizing downhole pressure and preventing equipment failure due to large pressure fluctuations caused by insufficient time to adjust the pressure to the normal range. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the dual-gradient drilling device disclosed in the embodiments of the present invention;

[0032] Figure 2 This is a partial cross-sectional view of the dual-gradient drilling apparatus disclosed in an embodiment of the present invention;

[0033] Figure 3 yes Figure 2 Sectional view along axis AA;

[0034] Figure 4 yes Figure 3 The diagram shows the structure after the rotating disk has rotated.

[0035] Figure 5 This is a partial cross-sectional view of the dual-gradient drilling apparatus disclosed in an embodiment of the present invention at another location;

[0036] Figure 6 This is a schematic diagram of the structure of the communication balancer disclosed in an embodiment of the present invention.

[0037] The components in the diagram are labeled as follows:

[0038] 1-Waterproof pipe; 2-Drill pipe; 21-Inner pipe; 22-Outer pipe; 221-Adjusting port; 222-Connecting port; 3-Drill rod; 4-Pressure regulating mechanism; 41-First pressure regulating part; 411-Fixed plate; 412-Rotating plate; 413-Inner connecting pipe; 414-Outer connecting pipe; 415-Medium inlet pipe; 416-Medium outlet pipe; 42-Second pressure regulating part; 421-Gate; 422-Piston; 423-Pressure regulating cylinder; 424-Drive component; 5-Booster compressor Structure; 6-Pressure reduction mechanism; 7-Connecting balancer; 71-Upper connecting pipe; 72-Lower connecting pipe; 73-Balancing chamber; 74-Blocking solenoid valve; 8-Injection mechanism; 001-First annular region; 0011-First upper region; 0012-First lower region; 002-Second annular region; 0021-Second upper region; 0022-Second lower region; 011-Second through hole; 012-Fourth through hole; 013-First through hole; 014-Third through hole. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0040] The technical solutions disclosed in the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0041] Please refer to Figures 1 to 6 This invention discloses a dual-gradient drilling device, which includes a riser 1, a drill pipe 2, a drill rod 3, and a pressure regulating mechanism 4.

[0042] The riser 1 can be connected to the drilling platform. The drill pipe 2 includes an inner pipe 21 and an outer pipe 22. The riser 1, outer pipe 22, and inner pipe 21 are coaxially fitted together in sequence. A first annular region 001 is formed between the inner pipe 21 and the outer pipe 22, and a second annular region 002 is formed between the outer pipe 22 and the riser 1. That is, the centerline of the riser 1, the centerline of the outer pipe 22, and the centerline of the inner pipe 21 are collinear. The gap between the inner pipe 21 and the outer pipe 22 is the first annular region 001, and the gap between the outer pipe 22 and the riser 1 is the second annular region 002. The drill pipe 3 passes through the inner pipe 21, and the lower end of the drill pipe 3 can extend from the lower end of the inner pipe 21 to facilitate drilling operations.

[0043] The pressure regulating mechanism 4, the water-proof pipe 1, and the drill pipe 2 are coaxially arranged. The pressure regulating mechanism 4 includes at least one of a first pressure regulating part 41 and a second pressure regulating part 42. At least a portion of the first pressure regulating part 41 is disposed within the first annular region 001 to divide the first annular region 001 into a first upper region 0011 and a first lower region 0012. The first pressure regulating part 41 is used to adjust the opening of the first connecting channel between the first upper region 0011 and the first lower region 0012. The second pressure regulating part 42 is used to adjust the opening of the second connecting channel between the first annular region 001 and the second annular region 002. It should be noted that, since the first annular region 001 is divided into a first upper region 0011 and a first lower region 0012, the second connecting channel here can be used to connect the first upper region 0011 and the second annular region 002, or to connect the first lower region 0012 and the second annular region 002, or the first upper region 0011 and the second annular region 002, as well as the first lower region 0012 and the second annular region 002, can all be connected through the second connecting channel.

[0044] In this embodiment of the invention, the first upper region 0011 and the first lower region 0012 can be connected through a first connecting channel. The first pressure regulating part 41 is used to adjust the opening of the first connecting channel. When the opening of the first connecting channel is at its minimum, that is, 0, the first connecting channel is in a cut-off state, and the first upper region 0011 and the first lower region 0012 are not connected to each other. When the opening of the first connecting channel is greater than 0, the first connecting channel is in a conducting state, and the first upper region 0011 and the first lower region 0012 are connected. Similarly, the first annular region 001 and the second annular region 002 can be connected through the second connecting channel. The second pressure regulating unit 42 is used to adjust the opening of the second connecting channel. When the opening of the second connecting channel is at its minimum, that is, 0, the second connecting channel is in a cut-off state, and the first annular region 001 and the second annular region 002 are not connected to each other. When the opening of the second connecting channel is greater than 0, the second connecting channel is in a conducting state, and the first annular region 001 and the second annular region 002 are connected.

[0045] When a sudden pressure change occurs downhole, the first pressure regulating unit 41 can close the first connecting channel between the first upper region 0011 and the first lower region 0012, thereby isolating the two regions and preventing the sudden pressure change from adversely affecting the dual-gradient drilling rig. Furthermore, by further adjusting the opening of the first connecting channel between the first upper region 0011 and the first lower region 0012, rapid and accurate pressure control of the two regions can be achieved. The second pressure regulating unit 42 can adjust the opening of the second connecting channel between the first annular region 001 and the second annular region 002 to regulate the pressure of the two annular regions, enabling rapid pressure balance between them. This also allows for rapid and accurate control of the internal pressure of the two annular regions, ensuring that the downhole pipeline pressure remains at a normal and stable level. It is evident that both the first pressure regulating unit 41 and the second regulating unit can quickly and accurately regulate pressure in the face of sudden pressure changes, thereby stabilizing downhole pressure in a timely and effective manner and preventing the downhole equipment from failing due to large pressure fluctuations because there is not enough time to regulate the pressure to the normal range.

[0046] Optionally, the first pressure regulating unit 41 can be a regulating valve with pressure regulating function. In another embodiment, the first pressure regulating unit 41 includes a fixed disk 411 and a rotating disk 412. The fixed disk 411 is fixedly connected to the inner tube 21, and the rotating disk 412 is rotatably connected to the inner tube 21. The fixed disk 411 and the rotating disk 412 are arranged along the axial direction of the drill pipe 2. The fixed disk 411 is provided with a first through hole 013, and the rotating disk 412 is provided with a second through hole 011. The first connecting channel includes the first through hole 013 and the second through hole 011. During the rotation of the rotating disk 412 relative to the fixed disk 411, the overlapping area of ​​the orthographic projection of the first through hole 013 and the second through hole 011 in the axial direction of the drill pipe 2 changes to adjust the opening of the first connecting channel. When the rotating disk 412 rotates relative to the fixed disk 411, the position of the second through hole 011 relative to the first through hole 013 changes, thereby changing the overlapping area of ​​their orthogonal projections in the axial direction of the drill pipe 2. Drilling fluid can flow from the first upper region 0011 to the first lower region 0012 through the overlapping part of the first through hole 013 and the second through hole 011. Therefore, when the area of ​​the overlapping part changes, it means that the flow area of ​​the first connecting channel, i.e., the opening, changes. This change can achieve the purpose of adjusting the pressure.

[0047] Optionally, the first through hole 013 and the second through hole 011 can have the same shape and size. When they are completely aligned in the axial direction of the drill pipe 2, the opening of the first connecting channel is at its maximum. When they are completely offset in the axial direction of the drill pipe 2, the opening of the first connecting channel is at its minimum, and the first connecting channel is in a cut-off state. In addition, one-way valves can be installed in the first through hole 013 and the second through hole 011 to ensure that the liquid flows from the first upper region 0011 to the first lower region 0012 and prevent liquid backflow.

[0048] The above embodiment allows for flexible and precise adjustment of the opening of the first connecting channel by driving the rotating disk 412 to rotate relative to the fixed disk 411, thereby making the pressure adjustment process faster and more accurate.

[0049] Optionally, the fixed disk 411 and rotating disk 412 can be directly installed onto the inner tube 21 or the outer tube 22. Alternatively, the first pressure regulating unit 41 further includes an inner connecting pipe 413 and an outer connecting pipe 414. The outer connecting pipe 414 is sleeved outside the inner connecting pipe 413. The inner connecting pipe 413 is connected to the inner tube 21, and the outer connecting pipe 414 is connected to the outer tube 22. The fixed disk 411 is fixedly connected to the inner connecting pipe 413. Specifically, the fixed disk 411 can be fixedly sleeved outside the inner connecting pipe 413, or the inner connecting pipe 413 can be divided into upper and lower sections, and the fixed disk 412 is rotatably sleeved outside the inner connecting pipe 413. In this case, both the fixed disk 411 and the rotating disk 412 are installed onto the inner tube 21 through the inner connecting pipe 413. This arrangement is more convenient for the installation of the fixed disk 411 and the rotating disk 412.

[0050] In an optional embodiment, there is one fixed disk 411 and one rotating disk 412, which are stacked sequentially. Alternatively, there are at least two rotating disks 412, with rotating disks 412 provided on both sides of the fixed disk 411. This arrangement allows the pressure on both sides of the fixed disk 411 to be adjusted synchronously, which is more conducive to maintaining pressure balance on both sides of the fixed disk 411. Further optionally, the rotating disks 412 on both sides of the fixed disk 411 can be arranged symmetrically.

[0051] At least a portion of the rotating disk 412 is located between the inner connecting pipe 413 and the outer connecting pipe 414. A first receiving cavity and a second receiving cavity, spaced apart from each other, are formed between the outer connecting pipe 414 and the rotating disk 412. The first pressure regulating unit 41 further includes a medium inlet pipe 415 and a medium outlet pipe 416. One of the medium inlet pipe 415 and the medium outlet pipe 416 is connected to the first receiving cavity, and the other is connected to the second receiving cavity, so that the rotating disk 412 is driven to rotate relative to the fixed disk 411 by the medium entering through the medium inlet pipe 415. Optionally, the medium entering through the medium inlet pipe 415 can be a gas or a liquid, such as oil. Oil pressure sensors can be installed in the first and second receiving cavities to monitor the oil pressure within them. When it is necessary to drive the rotating disk 412 to rotate, the medium can be continuously introduced into the first receiving cavity through the medium inlet pipe 415. At this time, a pressure difference appears between the first receiving cavity and the second receiving cavity, causing the rotating disk 412 to rotate. During the rotation of the rotating disk 412, the medium in the second receiving cavity can be discharged through the medium outlet pipe 416, thereby realizing the continuous rotation of the rotating disk 412.

[0052] Of course, in other embodiments, the rotation of the rotating disk 412 relative to the fixed disk 411 can also be achieved by adding a device capable of outputting power, such as a drive motor.

[0053] Optionally, the rotating disk 412 includes a rotating part and a dividing part, both located between the inner connecting pipe 413 and the outer connecting pipe 414. The outer peripheral surface of the rotating part protrudes from the dividing part to divide the space between the outer peripheral surface of the rotating part and the outer connecting pipe 414 into a first receiving cavity and a second receiving cavity. The outer peripheral surface of the rotating part can be a cylindrical surface. In the outer peripheral direction of the rotating part, the radial dimension of the space between the outer peripheral surface and the outer connecting pipe 414 remains essentially constant. Therefore, in this outer peripheral direction, the radial dimensions of the first receiving cavity and the second receiving cavity also remain essentially constant. During the rotation of the rotating disk 412, pressure fluctuations caused by changes in the radial dimension are less likely to occur. Thus, this embodiment can improve the accuracy and stability of pressure regulation.

[0054] In other embodiments, the rotating disk 412 may not include the aforementioned partition. In this case, the outer peripheral surface of the rotating disk 412 can be set as an elliptical surface to form a first receiving cavity and a second receiving cavity.

[0055] The number of media inlet pipe 415 and media outlet pipe 416 can both be one, in which case the rotating disk 412 can be driven in a single rotation direction. In another optional embodiment, the number of media inlet pipes 415 is at least two, including a first inlet pipe and a second inlet pipe, and the number of media outlet pipes 416 is at least two, including a first outlet pipe and a second outlet pipe. One of the first inlet pipe and the first outlet pipe is connected to a first receiving cavity, and the other is connected to a second receiving cavity. Similarly, one of the second inlet pipe and the second outlet pipe is connected to a first receiving cavity, and the other is connected to a second receiving cavity. When the first inlet pipe is in a conductive state, the first outlet pipe is also in a conductive state; when the second inlet pipe is in a conductive state, the second outlet pipe is also in a conductive state. In this embodiment, the first inlet pipe and the first outlet pipe form one set of media inlet and outlet pipes, and the second inlet pipe and the second outlet pipe form another set of media inlet and outlet pipes. When media enters and exits through these two sets of media inlet and outlet pipes respectively, the pressure relationship between the first receiving cavity and the second receiving cavity is different, thereby enabling the rotating disk 412 to rotate in different directions. As can be seen, this embodiment allows the rotating disk 412 to rotate in more directions, thus making it easier to adjust the pressure quickly.

[0056] The first pressure regulating part 41 can be integrally disposed within the first annular region 001. To facilitate installation of the first pressure regulating part 41, in another embodiment, at least a portion of the first pressure regulating part 41 is disposed within the second annular region 002, dividing the second annular region 002 into a second upper region 0021 and a second lower region 0022. That is, a portion of the first pressure regulating part 41 is located within the first annular region 001, and another portion is located within the second annular region 002. This arrangement exposes the first pressure regulating part 41, making it easier to assemble the water-tight pipe 1, the drill pipe 2, and the first pressure regulating part 41 together. The fixed disk 411 also has a third through hole 014, and the rotating disk 412 also has a fourth through hole 012. The third through hole 014 and the fourth through hole 012 are connected to connect the second upper region 0021 and the second lower region 0022. At least one of the third through hole 014 and the fourth through hole 012 is an arc-shaped hole extending circumferentially along the rotating disk 412. During the rotation of the rotating disk 412 relative to the fixed disk 411, the third through hole 014 and the fourth through hole 012 are in different positions relative to each other, so that the two are always connected. In other words, the channel formed by the third through hole 014 and the fourth through hole 012 is in a normally open state, so that the second upper region 0021 and the second lower region 0022 are always connected.

[0057] As previously described, at least a portion of the first pressure regulating unit 41 can be disposed within the second annular region 002 to divide the second annular region 002 into a second upper region 0021 and a second lower region 0022. In this case, a second pressure regulating unit 42 is disposed in at least one of the second upper region 0021 and the second lower region 0022. Specifically, the second pressure regulating unit 42 located in the second upper region 0021 is disposed away from the first pressure regulating unit 41, while the second pressure regulating unit 42 located in the second lower region 0022 is disposed close to the first pressure regulating unit 41. This arrangement allows for flexible selection of the location of the second pressure regulating unit 42, and when second pressure regulating units 42 are disposed in both the second upper region 0021 and the second lower region 0022, pressure regulation can be achieved more quickly. Of course, the distance between the second pressure regulating part 42 and the first pressure regulating part 41 located in the second upper region 0021 can also be equal to the distance between the second pressure regulating part 42 and the first pressure regulating part 41 located in the second lower region 0022.

[0058] Optionally, the second pressure regulating unit 42 may be a regulating valve with pressure regulating function. In another embodiment, the second pressure regulating unit 42 includes a pressure regulating cylinder 423, a piston 422, a gate 421 and a driving member 424. An regulating port 221 is provided on the outer tube 22. The first upper region 0011 and the second upper region 0021, as well as the first lower region 0012 and the second lower region 0022, are connected through different regulating ports 221. The second connecting channel includes the regulating port 221. Specifically, when only one of the second upper region 0021 and the second lower region 0022 is provided with the second pressure regulating part 42, only one regulating port 221 is provided on the outer pipe 22. In one embodiment, the regulating port 221 is located between the first upper region 0011 and the second upper region 0021. By changing the opening of the regulating port 221, the degree of connection between the first upper region 0011 and the second upper region 0021 can be changed. In another embodiment, the regulating port 221 is located between the first lower region 0012 and the second lower region 0022. By changing the opening of the regulating port 221, the degree of connection between the first lower region 0012 and the second lower region 0022 can be changed. When a second pressure regulating part 42 is provided in both the second upper region 0021 and the second lower region 0022, at least two regulating ports 221 are provided on the outer pipe 22. One regulating port 221 is located between the first upper region 0011 and the second upper region 0021. By changing the opening of the regulating port 221, the degree of connection between the first upper region 0011 and the second upper region 0021 can be changed. The other regulating port 221 is located between the first lower region 0012 and the second lower region 0022. By changing the opening of the regulating port 221, the degree of connection between the first lower region 0012 and the second lower region 0022 can be changed.

[0059] A pressure regulating cylinder 423 is mounted on the outer tube 22, and a piston 422 is movably mounted inside the pressure regulating cylinder 423 to divide the inner cavity of the pressure regulating cylinder 423 into a first chamber and a second chamber. The first chamber is connected to a first upper region 0011 or a first lower region 0012. Optionally, a connecting port 222 is also provided on the outer tube 22, through which the first chamber is connected to the first upper region 0011 or the first lower region 0012. One end of a gate 421 extends into the second chamber and is connected to the piston 422, while the other end of the gate 421 is opposite to the regulating port 221. A driving member 424 is used to drive the piston 422 to move relative to the pressure regulating cylinder 423, so as to adjust the opening of the regulating port 221 through the gate 421. That is, by controlling the stroke of the piston 422, the stroke of the gate 421 can be controlled, thereby controlling the opening of the regulating port 221. Optionally, the driving component 424 can be a power-output component such as a motor or cylinder. Alternatively, the driving component 424 can be located outside the water-tight pipe 1, allowing hydraulic oil to be injected into the second chamber. By controlling the pressure difference between the liquids inside the first and second chambers, the piston 422 can be raised and lowered, thereby driving the gate 421 to move. The stroke of the piston 422 controls the degree of coverage of the gate 421 over the regulating port 221, thus controlling the degree of communication between the first annular region 001 and the second annular region 002. Furthermore, hydraulic pressure sensors can be installed in both the first and second chambers to monitor the hydraulic pressure within them.

[0060] In the above embodiment, by injecting hydraulic oil into the second chamber, the gate 421 is precisely driven to move, making the opening adjustment of the second connecting channel more accurate.

[0061] As previously described, at least a portion of the first pressure regulating unit 41 can be disposed within the second annular region 002 to divide the second annular region 002 into a second upper region 0021 and a second lower region 0022. Further, the dual-gradient drilling rig also includes a connecting balancer 7, one end of which is connected to the second upper region 0021, and the other end of which is connected to the second lower region 0022. The opening degree of the connecting balancer 7 can be varied, thereby adjusting the degree of connectivity between the second upper region 0021 and the second lower region 0022, and thus achieving the purpose of regulating the pressure of both. Therefore, this embodiment adds a connecting balancer 7 to further regulate the pressure of the second upper region 0021 and the second lower region 0022, thereby enabling faster and more precise pressure regulation in the face of sudden pressure changes, and thus more timely and effectively stabilizing downhole pressure.

[0062] Optionally, the connecting balancer 7 includes an upper connecting pipe 71, a lower connecting pipe 72, a balancing chamber 73, and a blocking solenoid valve 74. The second upper region 0021, the upper connecting pipe 71, the balancing chamber 73, the lower connecting pipe 72, and the second lower region 0022 can be connected sequentially. In the direction parallel to the axis of the drill pipe 2, the cross-sectional area of ​​the inner cavity of the balancing chamber 73 first increases and then decreases. The blocking solenoid valve 74 is disposed inside the balancing chamber 73. It should be noted that the cross-section here refers to the cross-section perpendicular to the axis of the drill pipe 2. Whether from top to bottom or from bottom to top, the cross-sectional area of ​​the inner cavity of the balancing chamber 73 first increases and then decreases. In this embodiment, the connecting balancer 7 is located entirely outside the water-proof pipe 1, thus making the installation and maintenance of the connecting balancer 7 more convenient. Meanwhile, the cross-sectional area of ​​the inner cavity of the balance chamber 73 first increases and then decreases. The part with a larger cross-sectional area can be conveniently installed with the blocking solenoid valve 74, and the part with a gradually decreasing cross-sectional area can achieve a transitional connection with the upper connecting pipe 71 and the lower connecting pipe 72, which is more conducive to smooth pressure regulation.

[0063] Optionally, pressure sensors and density sensors can be installed in both the upper connecting pipe 71 and the lower connecting pipe 72. The pressure sensor detects the pressure difference between the upper connecting pipe 71 and the lower connecting pipe 72, and then adjusts the opening of the blocking solenoid valve 74 inside the balance chamber 73 in real time based on the pressure difference. By controlling the opening of the blocking solenoid valve 74, the pressure balance between the second upper region 0021 and the second lower region 0022 can be adjusted, so that the pressure between the second upper region 0021 and the second lower region 0022 can accurately and quickly reach a balanced state.

[0064] Of course, the cross-sectional area of ​​the inner cavity of the balance chamber 73 can remain unchanged in the direction parallel to the axis of the drill pipe 2.

[0065] As previously described, at least a portion of the first pressure regulating unit 41 may be disposed within the second annular region 002 to divide the second annular region 002 into a second upper region 0021 and a second lower region 0022. Further, the dual-gradient drilling rig also includes at least one of a pressurizing mechanism 5, a depressurizing mechanism 6, and a gas injection mechanism 8. That is, the dual-gradient drilling rig may also include one, any two, or all three of the pressurizing mechanism 5, depressurizing mechanism 6, and gas injection mechanism 8. One end of the pressurizing mechanism 5 and one end of the depressurizing mechanism 6 are both connected to the first lower region 0012. The other end of the pressurizing mechanism 5 is connected to a liquid source, thereby replenishing the first lower region 0012 with liquid. The other end of the depressurizing mechanism 6 is a discharge end, thereby discharging the liquid from the first lower region 0012.

[0066] The gas injection mechanism 8 has an upper gas injection end and a lower gas injection end. The upper gas injection end is connected to the second upper region 0021, and the lower gas injection end is connected to the second lower region 0022. The gas injection mechanism 8 can inject gas into the second upper region 0021 and the second lower region 0022 respectively.

[0067] The aforementioned pressurizing mechanism 5 and depressurizing mechanism 6 can change the amount of liquid in the first lower region 0012, thereby regulating the pressure within the first lower region 0012. The gas injection mechanism 8 can change the amount of gas in the second upper region 0021 and the second lower region 0022, thereby changing the pressure within the second upper region 0021 and the second lower region 0022. Therefore, the pressurizing mechanism 5, depressurizing mechanism 6, and gas injection mechanism 8 can further regulate the pressure in the first annular region 001 and the second annular region 002, resulting in better pressure regulation.

[0068] In addition, the dual-gradient drilling rig may also include a blowout preventer, which can be installed at the wellhead to prevent blowout accidents, thereby improving the safety of the dual-gradient drilling rig.

[0069] In this embodiment of the invention, the working process of the dual-gradient drilling rig is as follows:

[0070] Under normal operating conditions, the pressure regulating mechanism 4 is in the open state, and the connecting balancer 7 is also in the open state to balance the pressure of the first upper region 0011 and the first lower region 0012. Since the pressure inside the riser 1 and drill pipe 2 is within the normal range under normal operating conditions, the pressurizing mechanism 5 and the depressurizing mechanism 6 are in the off state and will not pressurize or depressurize the pipeline. Simultaneously, the upper injection end of the air injection mechanism 8 regulates the air injection in the second upper region 0021, and the lower injection end of the air injection mechanism 8 regulates the air injection in the second lower region 0022, resulting in a wider and more precise pressure regulation range. An upper pressure control valve can be installed on the connecting pipeline between the upper gas injection end and the second upper region 0021, and a lower pressure control valve can be installed on the connecting pipeline between the lower gas injection end and the second lower region 0022. The inlet end of the gas injection mechanism 8 is connected to the drilling platform, thereby delivering gas-containing low-density drilling fluid to the upper and lower gas injection ends through the drilling platform. The opening of the upper and lower pressure control valves is adjusted in real time according to the pressure feedback from the pressure sensor, thereby achieving precise real-time control of the bottom hole pressure. It should be noted that the pressure sensor mentioned here can be installed in multiple locations, such as within the first annulus region 001, within the second annulus region 002, or at pipeline joints.

[0071] In cases of abnormally high pressure, such as drilling fluid overflow or well kick causing a sudden increase in downhole pressure, it is necessary to promptly depressurize the downhole. At this time, the blowout preventer (BOP) at the wellhead should be immediately closed to prevent well kick. Then, the pressure regulating mechanism 4 should be closed to separate the upper and lower parts of the drill pipe 2 and riser 1, and the connecting balancer 7 should be closed. During an overflow or well kick, the pressure in the lower half of the drill pipe 2 and riser 1 is higher, so this lower half should be depressurized first. At this time, the pressure reducing mechanism 6 should be activated, and the BOP should be gradually opened to prevent sudden pressure changes. The pressure reducing mechanism 6 drains the fluid inside the first lower region 0012 to achieve emergency depressurization. Simultaneously, the upper gas injection end of the gas injection mechanism 8 should be opened to inject low-density drilling fluid containing gas into the second upper region 0021 to regulate and alleviate the internal pressure of the upper half of the drill pipe 2 and riser 1. After the pressure in the lower half of drill pipe 2 and riser pipe 1 decreases and stabilizes, the first pressure regulating part 41 is opened while the second pressure regulating part 42 remains closed, connecting the first upper region 0011 and the first lower region 0012. By adjusting the opening of the first pressure regulating part 41, the pressure in the first upper region 0011 and the first lower region 0012 is regulated to achieve a pressure balance and return to normal pressure levels. Then, the second pressure regulating part 42 is opened, connecting the first annular region 001 and the second annular region 002. By controlling the opening of the second pressure regulating part 42, the pressure in the first annular region 001 and the second annular region 002 is regulated to achieve a pressure balance and return to normal pressure levels. At the same time, the connecting balancer 7 and the air injection mechanism 8 are opened, and the opening degree of the connecting balancer 7 and the air injection volume of the air injection mechanism 8 are adjusted, thereby adjusting the liquid density of the upper and lower parts of the drill pipe 2 and the riser 1. As the pressure changes from high pressure to normal pressure, the discharge volume of the pressure reducing mechanism 6 is gradually reduced until the pressure of the upper and lower parts of the drill pipe 2 and the riser 1 tends to be balanced and reaches the normal pressure level. At this time, the blowout preventer is reopened to realize the normal operation of the entire pipe section.

[0072] In the event of an abnormally low pressure, such as a sudden drop in downhole pressure due to a lost circulation, immediate pressurization is required. At this time, the blowout preventer at the wellhead should be immediately closed, followed by the closure of the pressure regulating mechanism 4 to separate the upper and lower sections of the drill pipe 2 and riser 1. Then, the connecting balancer 7 should be closed. When a lost circulation occurs, the pressure in the lower half of the drill pipe 2 and riser 1 is even lower. Therefore, pressurization should begin in the lower half of the drill pipe 2 and riser 1. The pressurization booster mechanism 5 should be activated and its opening adjusted to inject fluid into the lower half of the drill pipe 2 and riser 1, thus achieving emergency pressurization. Simultaneously, the lower injection end of the gas injection mechanism 8 should be opened to inject high-density drilling fluid into the second lower region 0022 to regulate the internal pressure of the second lower region 0022. After the lower half of the drill pipe 2 and riser pipe 1 has been pressurized and the pressure has stabilized, the first pressure regulating part 41 is opened while the second pressure regulating part 42 remains closed, connecting the first upper region 0011 and the first lower region 0012. By adjusting the opening of the first pressure regulating part 41, the pressure in the first upper region 0011 and the first lower region 0012 is regulated to achieve a pressure balance and return to normal pressure levels. Then, the second pressure regulating part 42 is opened, connecting the first annular region 001 and the second annular region 002. By controlling the opening of the second pressure regulating part 42, the pressure in the first annular region 001 and the second annular region 002 is regulated to achieve a pressure balance and return to normal pressure levels. At the same time, the connecting balancer 7 and the air injection mechanism 8 are activated, and the opening degree of the connecting balancer 7 and the air injection volume of the air injection mechanism 8 are adjusted to regulate the liquid density of the upper and lower parts of the drill pipe 2 and the riser 1. As the pressure changes from low pressure to normal pressure, the replenishment volume of the pressurization mechanism 5 is gradually reduced until the pressure of the upper and lower parts of the drill pipe 2 and the riser 1 tends to be balanced and reaches the normal pressure level. At this time, the blowout preventer is restarted to realize the normal operation of the entire pipe section.

[0073] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A dual-gradient drilling rig, characterized in that, It includes a riser pipe (1), a drill pipe (2), and a pressure regulating mechanism (4); The drill pipe (2) includes an inner pipe (21) and an outer pipe (22). The water-proof pipe (1), the outer pipe (22) and the inner pipe (21) are coaxially sleeved in sequence. A first annular region (001) is formed between the inner pipe (21) and the outer pipe (22), and a second annular region (002) is formed between the outer pipe (22) and the water-proof pipe (1). The pressure regulating mechanism (4) includes at least one of a first pressure regulating part (41) and a second pressure regulating part (42), wherein: at least a portion of the first pressure regulating part (41) is disposed within the first annular region (001) to divide the first annular region (001) into a first upper region (0011) and a first lower region (0012); the first pressure regulating part (41) is used to adjust the opening of a first connecting channel between the first upper region (0011) and the first lower region (0012); and the second pressure regulating part (42) is used to adjust the opening of a second connecting channel between the first annular region (001) and the second annular region (002).

2. The dual-gradient drilling apparatus according to claim 1, characterized in that, The first pressure regulating unit (41) includes a fixed disk (411) and a rotating disk (412). The fixed disk (411) is fixedly connected to the inner tube (21), and the rotating disk (412) is rotatably connected to the inner tube (21). The fixed disk (411) and the rotating disk (412) are arranged along the axial direction of the drill pipe (2). The fixed disk (411) is provided with a first through hole (013), and the rotating disk (412) is provided with a second through hole (011). The first connecting channel includes the first through hole (013) and the second through hole (011). During the rotation of the rotating disk (412) relative to the fixed disk (411), the overlapping area of ​​the first through hole (013) and the second through hole (011) in the axial direction of the drill pipe (2) changes to adjust the opening of the first connecting channel.

3. The dual-gradient drilling apparatus according to claim 2, characterized in that, The first pressure regulating unit (41) further includes an inner connecting pipe (413) and an outer connecting pipe (414). The outer connecting pipe (414) is sleeved on the outside of the inner connecting pipe (413). The inner connecting pipe (413) is connected to the inner pipe (21), and the outer connecting pipe (414) is connected to the outer pipe (22). The fixed plate (411) is fixedly connected to the inner connecting pipe (413), and the rotating plate (412) is rotatably sleeved on the outside of the inner connecting pipe (413). At least a portion of the rotating disk (412) is located between the inner connecting pipe (413) and the outer connecting pipe (414). The outer connecting pipe (414) and the rotating disk (412) form a first receiving cavity and a second receiving cavity that are separated from each other. The first pressure regulating part (41) further includes a medium inlet pipe (415) and a medium outlet pipe (416). One of the medium inlet pipe (415) and the medium outlet pipe (416) is connected to the first receiving cavity, and the other is connected to the second receiving cavity, so that the medium entering through the medium inlet pipe (415) drives the rotating disk (412) to rotate relative to the fixed disk (411).

4. The dual-gradient drilling apparatus according to claim 3, characterized in that, The rotating disk (412) includes a rotating part and a partition part. The rotating part and the partition part are both located between the inner connecting pipe (413) and the outer connecting pipe (414). The partition part is provided on the outer peripheral surface of the rotating part to divide the space between the outer peripheral surface of the rotating part and the outer connecting pipe (414) into the first receiving cavity and the second receiving cavity.

5. The dual-gradient drilling apparatus according to claim 3, characterized in that, The number of media inlet pipes (415) is at least two, including a first inlet pipe and a second inlet pipe, and the number of media outlet pipes (416) is at least two, including a first outlet pipe and a second outlet pipe. One of the first inlet pipe and the first outlet pipe is connected to the first receiving cavity and the other is connected to the second receiving cavity. One of the second inlet pipe and the second outlet pipe is connected to the first receiving cavity and the other is connected to the second receiving cavity. When the first inlet pipe is in a conductive state, the first outlet pipe is in a conductive state; when the second inlet pipe is in a conductive state, the second outlet pipe is in a conductive state.

6. The dual-gradient drilling apparatus according to claim 2, characterized in that, At least a portion of the first pressure regulating unit (41) is disposed within the second annular region (002) to divide the second annular region (002) into a second upper region (0021) and a second lower region (0022); The fixed disk (411) is further provided with a third through hole (014), and the rotating disk (412) is further provided with a fourth through hole (012). The third through hole (014) and the fourth through hole (012) are connected to connect the second upper region (0021) and the second lower region (0022). At least one of the third through hole (014) and the fourth through hole (012) is an arc-shaped hole extending circumferentially along the rotating disk (412).

7. The dual-gradient drilling apparatus according to claim 1, characterized in that, At least a portion of the first pressure regulating unit (41) is disposed within the second annular region (002) to divide the second annular region (002) into a second upper region (0021) and a second lower region (0022); The second pressure regulating part (42) is provided in at least one of the second upper region (0021) and the second lower region (0022), wherein the second pressure regulating part (42) located in the second upper region (0021) is disposed away from the first pressure regulating part (41), and the second pressure regulating part (42) located in the second lower region (0022) is disposed close to the first pressure regulating part (41).

8. The dual-gradient drilling apparatus according to claim 7, characterized in that, The second pressure regulating unit (42) includes a pressure regulating cylinder (423), a piston (422), a gate (421), and a driving member (424). The outer tube (22) is provided with an regulating port (221). The first upper region (0011) and the second upper region (0021), as well as the first lower region (0012) and the second lower region (0022), are connected through different regulating ports (221). The second connecting channel includes the regulating port (221). The pressure regulating cylinder (423) is disposed on the outer tube (22), and the piston (422) is movably disposed inside the pressure regulating cylinder (423) to divide the inner cavity of the pressure regulating cylinder (423) into a first chamber and a second chamber. The first chamber is connected to the first upper region (0011) or the first lower region (0012). One end of the gate (421) extends into the second chamber and is connected to the piston (422). The other end of the gate (421) is opposite to the regulating port (221). The driving member (424) is used to drive the piston (422) to move relative to the pressure regulating cylinder (423) so as to adjust the opening degree of the regulating port (221) through the gate (421).

9. The dual-gradient drilling apparatus according to claim 1, characterized in that, At least a portion of the first pressure regulating unit (41) is disposed within the second annular region (002) to divide the second annular region (002) into a second upper region (0021) and a second lower region (0022); The dual-gradient drilling device also includes a connecting balancer (7), one end of which is connected to the second upper region (0021), and the other end of which is connected to the second lower region (0022). The connecting balancer (7) includes an upper connecting pipe (71), a lower connecting pipe (72), a balance chamber (73), and a blocking solenoid valve (74). The second upper region (0021), the upper connecting pipe (71), the balance chamber (73), the lower connecting pipe (72), and the second lower region (0022) can be connected in sequence. In a direction parallel to the axis of the drill pipe (2), the cross-sectional area of ​​the inner cavity of the balance chamber (73) first increases and then decreases. The blocking solenoid valve (74) is disposed in the balance chamber (73).

10. The dual-gradient drilling apparatus according to claim 1, characterized in that, At least a portion of the first pressure regulating unit (41) is disposed within the second annular region (002) to divide the second annular region (002) into a second upper region (0021) and a second lower region (0022); The dual-gradient drilling rig further includes at least one of a pressurization mechanism (5), a depressurization mechanism (6), and a gas injection mechanism (8), wherein: One end of the boosting mechanism (5) and one end of the depressurizing mechanism (6) are both connected to the first lower region (0012); The gas injection mechanism (8) is provided with an upper gas injection end and a lower gas injection end. The upper gas injection end is connected to the second upper region (0021), and the lower gas injection end is connected to the second lower region (0022).

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