Rotary BOP is a dynamic sealing device for drilling under negative pressure, foam and air. It is often using to close the wellhead during oil testing, workover, completion and other operations to prevent blowout accidents. It has the characteristics of simple structure, easy operation and high pressure resistance.
The rotating BOP structure and working principle
The rotating BOP is mainly composing of a shell, a sealant core, and a rotary bearing assembly with high pressure dynamic seal. Its structure is roughly shown in Figure 1 below:
Mainly composed of: 1- lower shell. 2- sealant core. 3- Bolt 1. 4- sliding seal ring. 5- bearing gasket 1. 6-bolt 2; 7- Thrust bearing 1; 8- Upper shell; 9- Central tube; 10- righting bearings. 11- Bearing gasket 2. 12- Thrust bearing 2; 13-O sealing ring, a total of 13 parts.
- 2- Sealant core and 9-center tube through 3-bolt 1 to form part 1. The drill pipe is inserting into the middle hole of the 2-sealant core at work. And the drill pipe is interfering with the 2-sealant core.
- At the same time, the 2-sealant core works under the action of mud pressure to ensure. That the drill pipe is closely matching with the 2-sealant core. And the mud will not leak from the matching position.
- 1- Lower shell and 8-upper shell through 6-bolt 2 to form part 2. Component 2 with 2-sealant core and 9-center tube to form part 1 through 7-thrust bearing 1. 10- righting bearings; 12- Push bearing 2 fit together. The 7-thrust bearing 1 is to prevent part 1 from sliding upward relative to part 2. 12- Thrust bearing 2 is to prevent part 1 from sliding downward relative to part 2. The 10-righting bearing is designing to ensure that part 1 rotates concentrically with part 2.
- 4- The function of the sliding seal ring is to prevent mud intrusion into the interior of 7-thrust bearing 1, affecting its normal operation.
- The function of the 13-O sealing ring is to prevent. The internal lubrication of 12-push bearing 2 from leaking and affecting the service life of 12-push bearing 2.
- When the drill pipe passes through the BOP. The rubber core generates a pre-tightening force under its own elastic action and holds the drill pipe tightly. In other words At the same time. A sealing force is obtaining under the action of well pressure, which increases the sealing effect of rotating BOP. The inner diameter of the rubber core can be adjusting within a certain range. So a rubber core can adapt to a variety of sizes of drilling tools. At the same time, the rubber core can also be changing to adapt to the size of the drill tool to ensure the reliability of the seal.
Rotating BOP in use due to precautions
Rotating BOP In actual use, rotating BOP due to pay attention to several aspects of the problem.
- The rotating BOP should be installing on the relatively low side of the terrain. to ensure that the mud flows from the low side to the high side in the reaming;
- Always pay attention to whether the rotating BOP is used normally.
- Therefore Pay attention to the damage of the rubber core and replace it in time;
- Pay attention to the damage of the rotary bearing assembly of the high pressure dynamic seal, and timely repair;
- Ensure that the drill tool is concentric with the BOP.
- Otherwise it will affect the sealing effect and service life of the rubber core;
- Calculate the required BOP parameters in advance according to the site.
- monitor mud pressure and other parameters during construction to prevent BOP failure.