A prototype single well subsea completion system, compatible with established floating rig drilling, has been built and tested successfully. The equipment is suitable for water depths to 1500' and is designed to be installed and operated without the aid of divers or submersibles.
Although initially planned for Santa Barbara Channel subsea environment, the system is appropriate for a majority of offshore areas worldwide. It is suitable for either flowing or artificial lift well conditions. Provision is made for well maintenance either through the flow line (TFL) or by vertical access through riser pipe.
Descriptions of the wellhead equipment, tree, flow line connectors, control systems, and related running tools are included. TFL tools tested with the subsea system are described. Some of the tools are new development outgrowths of the test program.
In late 1971, after more than two years of on-land testing and debugging, a no producing subsea test was conducted in 214' of water, 9 miles offshore from Ventura, California. Results of all tests are presented.
In 1962, Standard Oil Company of California, Western Operations, Inc., began actively to develop techniques and equipment that would permit drilling and completing oil wells in deep waters in an efficient and economic manner. Deep water was defined roughly as any depth in excess of that normally practicable for hard hat diver work. The initial effort was directed toward drilling operations. It resulted in a system of ocean floor bases from which casing could be hung and on which a B.O.P. stack could be landed. Remotely controlled latches and connectors made it possible to install and remove ocean floor equipment without putting divers on bottom. Also included were riser pipe, choke and kill lines, hydraulic control hoses, and wire guide lines.
In 1964, this drilling system was used successfully in 550 feet of water. Since then, it and other similar systems have been used by various companies in conjunction with floating and semi-submersible rigs to drill hundreds of exploratory and development wells. In 1967, prior to the Federal lease sale in the Santa Barbara Channel where Stand board Oil Company of California was interested in acquiring considerable acreage in deep waters, a part of the engineering effort was redirected from drilling to completion equipment.
Prevailing conditions that influenced planning in 1967 were as follows:
The anticipated Santa Barbara Channel Federal lease sale involved parcels with water depths of more than 1000'.
Diver operations below 250-300' were costly. Below approximately 400', working dives were impractical and hazardous.
Platform designs were available for immediate construction in water depths of 300-400' with near term extension to the 600' range. Beyond 600-700' platform design was nebulous and beyond state-of the- art.
Higher cost estimates for deep water drilling and production platforms made optimum placement increasingly more critical. If, prior to platform construction, ocean floor exploratory wells could be completed and produced for several weeks or even for several months, more accurate reservoir data would result in improved placement of platforms.