Anyone who wants to be well-versed in oil drilling must understand the crucial role of the blowout preventer (BOP).
Understanding each component of a rig’s safety system means understanding how they work together, as well as their individual contributions, for efficient and safe operation (and injury prevention). Essentially, a blowout preventer (BOP) shuts off the valve leading underneath the machinery to stop any liquid from surfacing in a dangerous explosion, or a kick.
A level of containment must be maintained when working with the mud and substances that could cause breaks in the flow of extraction. There are several features in a BOP that play different roles, and two general types of valves to assist the apparatus in case of a bad kick: Full Opening Safety Valves (TIW valve) and Inside BOP valves (Gray Valve).
A typical subsea deepwater blowout preventer control system (BOP) includes components such as electrical and hydraulic lines, control pods, hydraulic accumulators, test valves, kill and choke lines and valves, riser joint, hydraulic connectors, and a support frame. Let’s take a look at some of these.
The main control unit is called an accumulator. It controls all systems that interconnect to prevent emergency situations. The system activates based on hydraulic pressure, and the typical accumulator houses pumps, a hydraulic reservoir, a control manifold, control valves, compressed gas bottles, and several other facets.
Often, an accumulator holds enough power to allow for BOP units and their backup functions to run when other systems fail, so it is mounted on top of the BOP stack itself.
Annular and RAM
An annular BOP is what closes the space around the diameter of the drill pipe, but since the actual system cannot be closed with a value due to the drill string, this controls the air flow for the mud without cutting off any other systematic elements.
The annular BOP sits at the top of the BOP stack, to provide the most efficient airtight option. A RAM BOP also works to prevent any unwanted materials from exploding in the system, but several are needed in the BOP stack to ensure optimum safety.
RAM Valves and the BOP Stack
All the parts of a RAM BOP (and sometimes an annular BOP component) make up a BOP stack. Types can include:
- Blind RAMs, which close over any portion that lacks a drillstring
- Choke manifolds, a system of adjustable variables and pressure sensors that allow for the control of various fluids in different directions.
- The choke line valve assists in directing mud to the choke manifold when a kick occurs.
- A kill line valve, which acts as a backup to the standard drillpipe
- A casing RAM that can adjust to close around different piping sizes in the event of a kick
RAM valves can be stacked a number of different ways, for multiple types of efficiencies. Some BOP systems can reach massive heights, especially in deep-water drilling where a BOP system has a completely different purpose for successful extraction.
Industry Specification Requirements
BOPs and pressure control equipment are typically checked to verify meeting OEM and API specifications, including specification 16A for drill-through equipment.
Many preventers are also certified under DNV, ABS (American Bureau of Shipping), and Lloyd’s of London.
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