The two deepest oil and gas production hubs are operated by the Shell corporation in the Gulf of Mexico. Shell engineered these hubs to safely work in ultra-deep waters with innovative technologies that allow for extreme weather and deep ocean water pressure.
#1 Stones Floating Rig
The Stones floating production, storage and offloading (FPSO) facility is tethered to a mooring system that operates in 9,500 feet of water. This floating vessel, 200 miles off the coast of New Orleans, connects to a subsea rig infrastructure. The reservoirs in the Stones field are about 30,000 feet below sea level. Production from the Stones field oil and gas reservoirs started in 2016 with the capacity to generate up to 50,000 barrels of oil (or the gas equivalent) per day.
#2 Perdido Spar Platform
The Perdido oil rig platform operates in 8,000 feet of water about 120 miles off the coast of southeast Texas in the Alaminos Canyon. Anchored by massive cables to the ocean floor, it uses a ‘spar’ design to float in the water. The Perdido spar is almost as tall as the Eiffel tower and weighs about 60,000 tons. It was built in Finland and towed to Texas. Production from the three oil fields connected to the Perdido rig began in 2010 with the capacity to generate up to 100,000 barrels of oil (or the gas equivalent) per day.
What Are the Types of Ocean Drilling Rigs?
The Gulf of Mexico hosts about 175 drilling rigs that range from the extremely large scale to smaller short-term operations. Most oil rigs fit into these categories:
- Movable drilling structures
- Fixed platforms
- Floating platforms or vessels
- Fixed towers
How Does the Drilling Equipment Get to the Ocean Floor?
Oil wells can be served from a stationary rig or a rigless tower. Oilfield service providers offer customized PRT rental tools (production, resources, tools) for deepwater applications. These companies offer surface and ocean well drilling hardware solutions based on the need of the project.
One specialized requirement for these applications is a subsea landing string system that connects to the subsea blowout preventer (BOP) on the well. PRT offshore companies specialize in the manufacture of subsea landing string services. They sell offshore rental equipment and consulting.
What is a Subsea Landing String?
The subsea landing string system is a component of the complete assembly that connects from the surface rig to the well. The assembly includes the following parts:
- Inline Compensator – Supplies passive compensation
- Coiled Tubing Frame Lift – Installs surface equipment with a hydraulic hoist
- Surface Test Tree – Connects to landing string with surface isolation
- Quick Union – Connects to surface test tree
- Lubricator Valve – Contains pressure around the landing string
- Subsea Landing String – Cutting and landing with hydraulically controlled valves
How Does a Subsea Landing String Improve Safety and Reliability?
The subsea landing string system interfaces with a blowout preventer (BOP) system on the well. The BOP stops gas or oil from gushing into the pipes. The subsea landing system and blowout preventor work together to initiate an automatic cutoff in an emergency.
It is critical that all systems from the rig to the well are integrated with the blowout preventer. The systems must incorporate a failsafe feature that seals the well.
What happens when the Rig Stops Producing Oil?
Large scale oil fields require a decommissioning process when the well no longer produces oil. A decommission project requires engineering oversight and planning. This expensive process, costing in the millions of dollars, must satisfy all Federal environment and regulatory requirements. When possible, the construction materials should be recycled. Finally, the well must be permanently sealed to prevent any leakage of oil or gas in the future.