Wellhead flow guide device suitable for flow-back operation of offshore oil milling casing

Abstract

The invention provides a wellhead flow guide device suitable for flow-back operation of an offshore oil milling casing, and belongs to the field of offshore oil drilling operation, the wellhead flow guide device comprises a circular steel plate, a steel ring, a flow guide cover, a flow guide hole and a flow guide groove, the flow guide cover is welded to the upper end of the circular steel plate, and the steel ring is welded to the lower end of the circular steel plate; meanwhile, a flow guide hole is formed in the connecting position of the flow guide cover and the flow guide groove, and the inner cavity of the flow guide cover communicates with the groove of the flow guide groove through the flow guide hole. The problems that when return objects such as scrap iron and cement generated in the sleeve grinding and milling operation process in the offshore oil field borehole preparation stage pass through a rising pipe, a blowout preventer and a drilling fluid circulating system, pipeline blockage, equipment abrasion and operation efficiency reduction are caused are solved.

Description

Technical Field

[0001] The invention relates to the field of offshore oil drilling operations, and in particular to a wellhead flow guide device suitable for offshore oil milling casing return operations. Background Art

[0002] In the process of offshore oil and gas field development, due to the limited drilling slots on the jacket platform, the traditional wellbore development method is greatly restricted. It is impossible to re-drill a new well without a new well slot. Therefore, it is necessary to re-sidetrack the new well after milling the casing on the old well slot. In offshore oil drilling operations, the milling process of casing will generate a large amount of iron filings and cement debris. If these returned materials are not handled in a timely and effective manner, it will affect the safety and timeliness of subsequent operations, resulting in complex underground phenomena such as pump blockage and twisting, and may cause ground equipment failure.

[0003] The traditional flowback process discharges the iron filings, cement and rock cuttings generated during the milling of the casing through the riser, blowout preventer, and then through the drilling fluid circulation system. The shortcomings of this process are mainly manifested in the following aspects: 1) Blockage risk: Iron filings are prone to bridge during the flowback process, especially long iron filings, which may accumulate and block in the riser or blowout preventer, resulting in blockage of the flowback channel and affecting the progress of the operation; 2) Equipment wear: Iron filings and cement that repeatedly pass through the riser, blowout preventer and drilling fluid circulation system are prone to cause equipment wear. When the drilling ship is working on the conductor frame, due to the long length of the riser, the flowback process places higher requirements on the annular return speed, which may cause damage to equipment such as blowout preventers and drilling fluid pumps, and increase the maintenance and replacement costs of equipment; 3) Low operating efficiency: Due to blockage and poor flowback channels, the smoothness and efficiency of on-site operations are reduced, and the operation cycle is extended.

[0004] Therefore, there is an urgent need for an innovative technical solution or new device to avoid these problems, which can discharge the iron chips generated in the process of casing milling in a timely and safe manner, avoid passing through the riser, blowout preventer and drilling fluid circulation system, improve the timeliness of offshore drilling operations, and reduce equipment maintenance costs. Summary of the invention

[0005] In view of this, the present invention proposes a wellhead diversion device suitable for marine oil milling casing return operations, which aims to promptly divert the generated iron filings, cement and other return materials to the wellhead for discharge outside, avoiding them from passing through risers, blowout preventers and drilling fluid circulation systems, thereby reducing the risk of blockage, improving operating efficiency and reducing costs.

[0006] To achieve the above-mentioned purpose, the technical solution of the present invention is implemented as follows: a wellhead diversion device suitable for marine oil milling casing return operation, including a circular steel plate, a steel ring, a diversion cover, a diversion hole and a diversion groove, the upper end of the circular steel plate is welded with a diversion cover, the lower end is welded with a steel ring, one end of the diversion groove is welded to the diversion cover, and a diversion hole is provided at the connection position between the diversion cover and the diversion groove, and the inner cavity of the diversion cover is connected with the groove of the diversion groove through the diversion hole.

[0007] Furthermore, a plurality of bolt holes are arranged on the circular steel plate, and the circular steel plate is connected to the wellhead casing head through the bolt holes.

[0008] Furthermore, the upper end of the air deflector is an open structure, and two lifting holes are provided on the air deflector.

[0009] Furthermore, the opening of the guide groove is arranged upwards, and a supporting structure is installed on the guide groove, and two ends of the supporting structure are respectively connected to two side walls of the guide groove.

[0010] Furthermore, the guide groove is installed on the guide cover at an angle, and the height of the guide groove away from one end of the guide cover is smaller than the height of the connecting end of the guide groove and the guide cover.

[0011] Compared with the prior art, the wellhead diversion device suitable for offshore oil milling casing flowback operation described in the present invention has the following advantages:

[0012] (1) By installing the wellhead diversion device on the wellhead and connecting it to the wellhead casing head with bolts, the diversion device can directly divert the returned materials such as iron filings and cement to the overboard at the wellhead for discharge into the sea, thus preventing the returned materials from flowing back through the riser, blowout preventer and drilling fluid circulation system, thereby eliminating the risk of blockage and improving operation safety and efficiency;

[0013] (2) Compared with the traditional flowback method, the present invention has significant advantages, including reducing equipment failures, reducing maintenance costs and shortening operation cycles. The wellhead diversion device of the present invention can be widely used in different types of offshore drilling operations such as drilling ships and jacket platforms, and has good adaptability and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0015] Figure 1 It is a structural schematic diagram of the wellhead diversion device of the present invention;

[0016] Figure 2 It is a front view of the wellhead diversion device of the present invention;

[0017] Figure 3 It is a cross-sectional view of the welded parts of the circular steel plate and the steel ring;

[0018] Figure 4 It is a structural diagram of the steel ring.

[0019] Description of reference numerals:

[0020] 1. Round steel plate; 2. Bolt hole; 3. Steel ring; 4. Air deflector; 5. Lifting hole; 6. Air deflector hole; 7. Support structure; 8. Air deflector groove. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0022] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0023] In the field of offshore oil drilling operations, especially in the wellbore preparation stage, there is a risk of iron filings and cement generated during the return flow of milling casing operations clogging risers and blowout preventers. The present invention proposes a diversion and discharge device established at the wellhead, which is a device used to divert the return flow directly to the sea at the wellhead during offshore oil milling casing operations. It can divert the return flow directly to the sea at the wellhead to avoid reflux to the drilling fluid circulation system through the traditional circulation process, and at the same time prevent the blockage of the riser and blowout preventer caused by accumulation, which can improve the safety and efficiency of the operation. Specifically, Figure 1-Figure 4 As shown, the present invention is a wellhead flow guide device suitable for offshore oil milling casing flowback operation, which includes a circular steel plate 1, a steel ring 3, a flow guide cover 4, a flow guide hole 6 and a flow guide groove 8;

[0024] A plurality of bolt holes 2 are provided on the circular steel plate 1, and the circular steel plate 1 is connected to the wellhead casing head through the bolt holes 2; in actual application, the number of connection holes on the wellhead casing head has various specifications according to different usage scenarios, and the number of bolts on the casing head is usually 8, 12, 16, 20, 24 or 32. Since the backflow process does not involve closed high pressure, in actual application, the connection between the flow guide device and the casing head can be ensured by selecting 8 bolt connections. Therefore, the number of bolt holes 2 on the circular steel plate 1 of the present invention is also correspondingly set to eight. It should be noted that in actual use, the number of bolt holes 2 can also be set to 12, 16, 20, 24 or 32, and the specific number can be determined by the staff. The wellhead casing head is a prior art.

[0025] A deflector 4 is welded to the upper end of the circular steel plate 1, and the upper end of the deflector 4 is an open structure. When the offshore oil milling casing is operated, the staff can observe the situation of the return of iron filings, cement and other materials in real time through the open structure at the upper end of the deflector 4. When the return is blocked or the return is not smooth, the staff can observe the situation in time and manually intervene to clear the blockage of the return, ensuring that the return can be discharged in time and safely, thereby avoiding the potential safety hazards caused by the pressure holding, which not only improves the timeliness and safety of the offshore drilling operation, but also reduces the equipment maintenance cost. In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In the description of the present invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0026] Two lifting holes 5 are provided on the deflector 4 so that the deflector and sea discharge device of the present invention can be lifted down from the production platform by the crane on the drilling ship. The drilling ship, the crane, and the production platform are all prior art. Preferably, the horizontal cross-section of the deflector 4 is square, or circular or other shapes, as long as it can ensure that the inner cavity of the deflector 4 can completely cover the through hole on the circular steel plate 1 for the return flow to flow.

[0027] A steel ring 3 is welded to the lower end of the circular steel plate 1, that is, one end of the steel ring 3 and the circular steel plate 1 are welded into one body, and the steel ring 3 is an O-ring structure. In actual application, there is an annular groove on the outer edge of the casing head. The connection seal between the casing heads is achieved by placing an O-shaped steel ring between the two connectors and then providing a seal through compression. Therefore, when the circular steel plate 1 is connected to the wellhead casing head through the bolt hole 2, the steel ring 3 can be sealed and connected to the casing head, thereby effectively preventing fluid leakage in the backflow.

[0028] The opening of the guide trough 8 is set upward. The staff can observe the return of iron filings, cement and other materials in real time through the opening structure at the upper end of the guide trough 8. When the return is blocked or the return is not smooth, the staff can observe the situation in time and clear the blockage to ensure that the return can be discharged in time and safely.

[0029] One end of the guide groove 8 is welded to the guide cover 4, and a guide hole 6 is provided at the connection position between the guide cover 4 and the guide groove 8, and the inner cavity of the guide cover 4 is connected with the groove of the guide groove 8 through the guide hole 6. Iron filings and cement generated during the milling process can flow into the guide cover 4 through the steel ring 3 and the circular steel plate 1 in sequence, and then flow into the guide groove 8 through the guide hole 6 for discharge.

[0030] A support structure 7 is installed on the guide trough 8, and the two ends of the support structure 7 are respectively connected to the two side walls of the guide trough 8. Preferably, the support structure 7 is a small steel bar with a simple structure and low cost. It should be noted that the support structure 7 can also be other structures that can play a supporting and reinforcing role, as long as it can ensure that the two ends of the support structure 7 can be respectively connected to the two side walls of the guide trough 8, and the support structure 7 is arranged at the upper end of the guide trough 8, and will not cause blockage to the discharge of the return flow. When a large flow of seawater or thick slurry carries a mixture of iron filings, cement, etc. and flows back along the guide trough 8 during the milling process, the speed and impact of the water flow will cause turbulence or irregular fluctuations in the fluid. Especially when it contains a large amount of solid matter, the impact will cause strong shaking or unstable flow. At this time, the support structure 7 provides a fixing effect on the guide groove 8 in the structure, which can effectively stabilize the structural frame of the guide groove 8, enhance the stability of the guide groove 8, and enable the guide groove 8 to withstand greater fluid impact and load, ensuring that the guide groove 8 maintains stability under long-term operation, thereby ensuring that the guide groove 8 is not easily deformed or shaken due to the impact of water flow when a large displacement is returned, thereby achieving a smooth return process.

[0031] The guide groove 8 is installed obliquely on the guide cover 4, and the height of the end of the guide groove 8 away from the guide cover 4 is smaller than the height of the connecting end of the guide groove 8 and the guide cover 4, ensuring that the return flow can be discharged efficiently.

[0032] In actual application, since there are oil and gas processing tanks around the production platform, hot work is a dangerous operation. Therefore, after the circular steel plate 1, steel ring 3, deflector 4 and deflector groove 8 are welded into an integrated structure in the processing workshop, the welded overall structure is hoisted down to the production platform by a crane, and then the deflector device is connected to the casing head of the wellhead by bolts for use, avoiding hot work at the wellhead and effectively improving safety.

[0033] When the offshore oil self-elevating drilling platform extends a cantilever beam to cover the well slot of the production platform for milling casing operations, the wellhead guide device of the present invention is installed at the wellhead of the production platform. First, the connecting component of the guide device, the annular steel plate, is firmly connected to the casing head of the wellhead by bolts. Then an extension groove is connected in the discharge direction of the guide groove 8, and the extension groove is used to receive the return materials such as cement and iron filings diverted from the guide groove 8, so as to guide the return materials such as iron filings to be discharged outboard (the well slot position of the wellhead is much farther away from the outboard than the length of the guide groove 8, so it is necessary to build a fixed frame to establish an extension groove connected to the discharge direction of the guide groove 8). The extension groove can adjust its own diversion direction, and fixed frames are also installed on both sides of the extension groove to fix the extension groove, so as to prevent the extension groove from being deformed or shaken due to the impact of water flow when the large displacement is returned. The extension groove and the fixed frame are both prior art.

[0034] When switching operations at different well slots, the discharge angle of the guide device is achieved by adjusting the guide direction of the extension slot. The end of the extension slot away from the guide slot 8 can move left and right in the horizontal direction, thereby adjusting the guide direction of the extension slot. Since the extension slot is connected to the discharge direction of the guide slot 8, that is, the guide connection is established through the extension slot, which serves as the discharge direction of the guide slot 8, the discharge angle of the return material in the guide slot 8 can be adjusted by adjusting the guide direction of the extension slot. After the guide device is fixed, it does not need to be adjusted. After being bolted to the wellhead casing head, it only needs to be connected to the wellhead casing head by building a fixed frame to establish the extension slot to lead outboard.

[0035] During the milling and grinding operation, all the return materials are drained through the diversion device without passing through the riser, blowout preventer and drilling fluid circulation system. When switching operations at different well slots, the discharge angle of the diversion device is adjusted to adapt to different surrounding operating environments, and the return materials such as iron filings are drained to ensure smooth milling operations. Matters not covered by the present invention are known technologies.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A wellhead flow guide device suitable for offshore oil milling casing flowback operation, characterized by: The invention comprises a circular steel plate (1), a steel ring (3), a flow guide cover (4), a flow guide hole (6) and a flow guide groove (8); the flow guide cover (4) is welded to the upper end of the circular steel plate (1), the steel ring (3) is welded to the lower end, one end of the flow guide groove (8) is welded to the flow guide cover (4), and the flow guide hole (6) is arranged at the connection position between the flow guide cover (4) and the flow guide groove (8); the inner cavity of the flow guide cover (4) is connected to the groove of the flow guide groove (8) through the flow guide hole (6).

2. A wellhead flow guide device suitable for offshore oil milling casing flowback operation according to claim 1, characterized in that: A plurality of bolt holes (2) are arranged on the circular steel plate (1), and the circular steel plate (1) is connected to the wellhead casing head through the bolt holes (2).

3. A wellhead flow guide device suitable for offshore oil milling casing flowback operation according to claim 1, characterized in that: The upper end of the air deflector (4) is an open structure, and two lifting holes (5) are provided on the air deflector (4).

4. A wellhead flow guide device suitable for offshore oil milling casing flowback operation according to claim 1, characterized in that: The opening of the guide groove (8) is arranged upwards, and a support structure (7) is installed on the guide groove (8), and two ends of the support structure (7) are respectively connected to two side walls of the guide groove (8).

5. A wellhead flow guide device suitable for offshore oil milling casing flowback operation according to claim 4, characterized in that: The guide groove (8) is installed on the guide cover (4) at an angle, and the height of the guide groove (8) at one end away from the guide cover (4) is smaller than the height of the connecting end of the guide groove (8) and the guide cover (4).

Images