Definition of surface

What is the top?

The surface (or upper surfaces) refers to the parts above the water of an offshore oil rig, or any part that is above the waterline. The structures that make up the surfaces are typically modular, installed on a fixed or floating submarine structure.

Key takeaways

  • Top refers to the parts of an offshore drilling rig that are above the waterline.
  • Top surfaces often include the drilling rig, homes, and processing facilities.
  • One of the most common types of offshore rig is known as a jack-up.

Understanding the top

Overhead components include the drilling rig, worker housing, and sometimes an onboard processing facility. During the exploratory phase of the life of an offshore oil rig, the top is often a bare structure that sits atop a submerged tower known as a jacket. A drill is fed to the seafloor through the jacket to determine if the drill site will produce enough oil or gas to continue additional drilling operations.

If the oil company decides to go ahead with drilling, the rig enters the production stage. A drilling contractor is hired and the top will be built to house the drilling, processing and storage facilities along with worker accommodation and communications facilities. Most offshore platforms house 40 to 60 workers, working 12-hour shifts for two weeks in a row. At the end of their assigned work schedule, the company transports them off the platform and replaces them with a new group of workers.

The Jack-Up

One of the most common types of offshore rig is known as a jack-up. It is a platform supported by three legs, which reaches the seabed below. When it is time to move the apparatus, the towers are raised by raising the upper elements. This method allows the relocation of the platform by a team of tugs.

At the top of a forklift platform, worker accommodation and the helipad are located at the front end of the platform. The accommodation block generally consists of four or five decks. Shared spaces, such as the kitchen and laundry room, are on the first deck, while the upper levels house private bedrooms and office space.

Parts of the top

The rig, dominated by a latticed steel derrick, sits at the aft end of the top of the tail lifts. At the top of the tower, a top drive will rotate the drillstring, which is a series of pipes that extend hundreds or thousands of feet to the seafloor. At the tip of the drillstring, the bit drills a vertical axis into the rock and substrate below the seabed.

Other overhead structures support both drilling operations and worker installations. These other structures include a series of cranes to move large items around the platform, industrial HVAC systems to provide climate control, and generators to produce electricity for the entire platform. The cranes also allow the transfer of equipment and supplies from overhead to surface vessels.

Worker safety is paramount on an offshore oil or gas platform. Emergency and security teams are in place to support all personnel on the platform and enable them to deal with a weather emergency, spill or fire.

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Mark Holland

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