BOP Control System
Operational Recommendations
A blowout preventer (BOP) is a large, high-pressure safety valve used to prevent the uncontrolled flow of liquids and gases during well drilling operations. Pressure control is a critical part of the drilling process, and, as a fail-safe component, a blowout preventer is essential to the safety of your rig.
Well control procedures are previously discussed. These procedures are intended to inform of possible well control practices that have proven practical. They should not be interpreted to be a solution to all problems. BOP Control system manufacturers generally make the following operational recommendations.
During normal drilling, the blowout preventer control valves are typically in the “open” position, kill and choke valves are typically in the “closed” position. This will hydraulically lock the BOP in position, give visual indication of the annular BOP, ram or valve position and most importantly, indicate leaks in the valves, lines or BOP which can be detected by the pumps coming on too frequently.
Ensure all pump system (air and electric) power is “online” at all times.
Ensure all accumulator banks are “on tine” at all times.
Ensure pump system automatic “on”/”off” limits are properly set. Setting the pump system cut off too low results in significantly reducing usable fluid capacity o f the accumulator system. Setting the pump system “on” point too low results in accumulator pressure being too low, and the usable fluid capacity reduced significantly so that the BOP performance is adversely affected.
Ensure the BOP control system nitrogen precharge in all of the accumulators is properly maintained within the specified limits. Reduced precharge decreases the recoverable (usable) fluid from the accumulator. Zero precharge (probable ruptured bladder) equals nil recoverable fluid. The nitrogen precharge must be measured when there is zero hydraulic pressure on the accumulators. This means they must be bled back to the reservoir to measure precharge.
Operate with the fluid reservoir approximately half full. Reservoirs are typically sized to hold at least twice the recoverable (usable) fluid of the accumulator system. This means bleeding down all of the accumulators is possible without overflowing the reservoir. Newer systems built in accordance with API RP 16E have twenty-five percent (25%) accumulator bank isolation. They also have isolation and bleed valves on each bank permitting checking precharge on one bank at a time without shutting down operations.
Ensure all components of the BOP control system are in proper working order, clean, and, where required, lubricated.
