Drilling Equipment

Marine Riser Systems

A major technical problem facing the early designers of floating drilling equipment was to devise a method for providing a closed circuit mud circulating system between the well at the sea floor and the drilling vessel at the surface.

In 1946, Union Oil Co. of California (Unocal) and Continental Oil Co. (Conoco) formed a joint venture to obtain cores offshore from floating vessels. In 1948, Unocal filed a patent on a technique using a marine riser to provide both a conduit for the drill pipe and a necessary return path for mud and cuttings.

By 1953, Unocal and Conoco had been joined by The Superior Oil Co. and Shell Oil Co. in an organization called the CUSS Group. CUSS installed a coring rig on a small wooden hulled ex-Navy patrol craft, the Submarex, and successfully drilled holes as deep as 2,700 feet in shallow waters off the coast of California. At that time however, return circulation was provided by rubber hoses connected to a circulating head which sealed around the drill pipe at the seabed.

In 1957, the CUSS Group, using the vessel CUSS I offshore California, and the Offshore Co., using the vessel D-1 offshore Trinidad, successfully implemented a true marine riser. Both designs incorporated a slip joint at the top to accommodate vessel heave.

Enhancements were provided in 1963 when the Offshore Co. added control lines and choke and kill lines to the basic riser configuration. Later improvements involved the means for latching individual riser sections together. The leader in developing these coupling improvements is generally acknowledged to be Regan Forge and Engineering Co.

Recognizing the pioneering efforts of the following individuals and companies who contributed to the development of this technology:

Robert F. Bauer, George Savage, Bruce Watkins
CUSS Group [Conoco, Unocal, The Superior Oil Co. (ExxonMobil) and Shell Oil Co.], The Offshore Co. (Transocean Inc.), and Regan Forge (ABB Vetco Gray).