The term blowout preventers refer to large specialized valves which are used to seal, monitor and control oil wells in order to prevent blowouts or explosions, the release of crude oil and also the escape of natural gas from oil wells. Blowout preventers are designed to cope with extreme underwater pressures and uncontrolled flow (known as kicks) from well reservoirs. They are also instrumental in controlling pressure and preventing tubing. As a result of their functions, blowout preventers (BOP) are very critical in the drilling process; as it ensures the safety of the drilling crew, the rig, the environment and is also instrumental in subsea pipeline monitoring.
A standard BOP is usually made of an assembly of several blowout preventers stacked together in varying sizes and functions. These blowout preventers together form a whole, which is quite effective in ensuring control of oil wells. Annular and RAM blowout preventers are the most prevalent categories of BOP. Most BOPs is assembled having both categories; with an annular BOP atop several ram BOPs the most common structure.
Role Of BOP In Drilling Operations
BOPs play a crucial role in oil drilling. While most individuals understand what the basic functions of this device, that is not enough. There is a need to understand each component of BOPs, their individual functions and how they work together in order for increased safety and efficiency. Taking a look at the basic components of every BOP.
- Accumulator: The accumulator is the main control unit of a blowout preventer. It is responsible for the control of all systems that interconnect in preventing emergency situations. It is activated based on hydraulic pressure. The accumulator houses hydraulic reservoirs, control valves, pumps, control manifold, and compressed gas bottles among other features.
An accumulator is usually mounted on the top of the BOP stack. This helps to avoid breakdown, as the accumulator provides power for other BOP units to run during system failures.
- Annular BOP: The annular BOP is responsible for closing the space around the drill pipe. It does this by controlling the air flow to prevent mud, without affecting the operation of the system. It is effective in maintaining a seal around the drill pipe during the process of drilling. Annular BOP is on top of the stack other BOPs to ensure efficient airflow control.
- RAM BOP: The basic function of the Ram BOP is to prevent unwanted materials from exploding in the system during drilling. Several Ram BOPs perform other functions to ensure safety. Some of them are:
– Blind RAMs: This RAM closes over any portion, without a drill string.
– Choke Manifolds: This is a system of pressure sensors which control the flow of fluids in various directions.
– Kill Line Valve: This acts as a backup to the standard drill pipe.
– Choke Line Valve: It directs mud to the choke manifold in the case of a kick.
All of these components work together to ensure ease and safety of drilling. BOPs are built in different capacities for different drilling requirements. Some are used for land wells, others for offshore rigs, and a third-class for subsea wells. In conclusion, BOP control is very important in avoiding breakdown of the system. There are about five control measures with ROVs intervention being the most deployed. However, the drilling purposes will inform the BOP control methods that are best for each preventer