DUAL GRADIENT DRILLING SYSTEM

摘要

A dual gradient drilling system comprises a primary riser that is coupled to a drilling rig and a subsea wellhead and an auxiliary riser that is coupled to the drilling rig and to the primary riser by a fluid conduit that is disposed at a point between the drilling rig and the wellhead. The fluid conduit provides fluid communication between the primary riser and the auxiliary riser. A pump system is disposed within the auxiliary riser and is in fluid communication with the fluid conduit. A drive string is disposed within the auxiliary riser and is coupled to the pump system so as to operably couple the pump system to the drilling rig.