Drillships are marine vessels that contain a drilling derrick and other equipment and look like modified tankers or cargo ships. Able to drill oil and gas wells, these ships typically have mooring/positioning equipment and helipads. They’re designed to work in deep waters up to 10,000 feet. A moon pool enables workers to pass drilling equipment through the hull and connect it too well equipment located below the waterline.
When close to the shore, multiple anchors can keep a drillship in place. In deep waters, dynamic positioning systems keep it stable via thrusters controlled by a computer, which adapts to motion caused by waves and the wind.
Accidents Involving Drillships
- June 2017: An explosion occurred on the Brazilian offshore drill ship, the NS 32, according to Reuters. Four people were wounded, three of whom were burned, while one died. The vessel was not seriously damaged.
- October 2017: A worker was struck in the head by an object, and died, while a pipe assembly was being lowered onto the sea floor. The crew was conducting exploratory operations 250 miles from Lake Charles, Louisiana, in the Gulf of Mexico. Out of sight of the pipe movers, the floor hand had to communicate by radio. When the pipe hit a closed latch, it bowed and recoiled, hitting the worker.
An Evercore ISI report in 2017 noted that 40 percent of accidents occur on the drill floor. Injuries often involve people struck by objects, who fall or work in mechanized areas. Deficiencies found by a Coast Guard investigation of the Noble Discoverer, an artic drillship that exploded, represent some of the common safety factors. Some of these included:
- Lack of preventative maintenance on the engine, leading to propulsion and exhaust failures.
- Self-closing fire screen doors in stairways passing through more than one deck did not operate.
- Sludge and oil contaminated the engine piston cooling water.
- Non-conducting mats were not placed on the electrical switchboard in the engine room, or on floor gratings.
- Regular back-fires in the exhaust system, which had resulted in a previous stack fire.
- A fractured pipe passing through a bilge holding tank, causing water to flow in.
- An oily water separator system and its alarms were not operating.
- Abnormal propeller shaft vibrations were reported the previous November, requiring the main engine to be shut down.
- Fire protection insulation was found to be oil soaked.
- Dead wires and improper wire splices in the main engine room.
- Monthly Emergency Evacuation Plan drills were not conducted for a period of time, based on deck logs.
These cover many of the causes of accidents, such as equipment problems and failure to follow procedures. The repercussions of such incidents are a greater consideration as drillships become larger with higher capacities. For example, the GWR-D1 drillship design, covered by Offshore magazine in February 2017, can produce up to 30,000 barrels per day and contain up to 100,000 barrels per day. It’s capable of storing 730,000 barrels and accommodates 220 people. The main rig lifting capacity is 1,500 short tons. In addition, it contains automated robotic systems, an ability to separate liquid from gas, and an oil spill containment system.