What is Topside

Topside refers to the above-water portions of an offshore oil rig, or any parts which are above the water line. The structures which make up the topsides are typically modular, installed onto either a fixed or floating underwater structure.​​​​​​​

BREAKING DOWN Topside

​​​​​​​Components of the topside include the drilling rig, worker accommodations, and sometimes an onboard processing facility. During the exploratory phase of an offshore oil rig’s life, the topside is often a bare structure sitting atop a submerged tower known as a jacket. A drill is fed to the seafloor through the jacket to determine if the drilling site will produce sufficient oil or gas to move forward with further 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 topside will be built up to house drilling, processing, and storage facilities along with worker accommodations and communications facilities. Most offshore rigs house 40 to 60 workers, who work in 12-hours shifts for two weeks at a time. At the end of their assigned work schedule, the company transports them off the rig and replaces them with a new group of workers. 

One of the most common types of offshore rig is known as a jack-up. It is a platform supported by three legs, reaching the seafloor below. When the time comes to move the apparatus, the towers are jacked-up, raising the topside elements. This method allows for the relocation of the rig by a team of tugboats. On the topside of a jack-up rig, the worker accommodations and helipad are at the forward end of the platform. The accommodation block typically consists of four or five decks. Shared spaces, like kitchen and laundry facilities, are on the first deck, while the upper levels accommodate private quarters and office space.

Parts of the Topside

Drilling equipment, dominated by a latticed steel derrick, is on the aft end of the topside on jack-up rigs. At the top of the derrick, a top drive will spin the drill string, which is a series of pipes stretching hundreds or thousands of feet down to the seafloor. At the tip of the drill string, the drill bit bores a vertical shaft into rock and substrate below the seabed.

Other structures found on the topside support both drilling operations and worker facilities. These other structures include a series of cranes for moving large items around the platform, industrial HVAC systems to provide climate control, and generators to produce electricity for the entire rig. Cranes also allow the transfer of equipment and supplies from the topside to surface vessels. 

Worker safety is paramount on an offshore oil or gas rig. Emergency and safety equipment is in place to support all personnel on the rig and allow them to deal with a weather emergency, spills, or fire.

(To learn more about this topic, see: A Primer On Offshore Drilling).