Petroleum Engineering Services Limited

James Crabb

Stuart C Brown

This invention relates to well-head structures, and particularly to so-called christmas trees, i.e. the complex of valves and pipes installed at a well-head to control the flow of high pressure oil or gas. The invention more particularly, but not exclusively relates to such structures for use in sub-sea structures. In order to accommodate all the required valves and pipes, known trees are normally undesirably high--i.e. of the order of 18 feet or so. In order that trawler nets do not snag on such trees, expensive protection structures or well reinforcing may be required to be installed around each tree. However, the present invention provides a christmas tree including a valve assembly comprising one or more valves installed at a well-head to control the flow of produce thereat, at least one of the one or more valves being retained within an outlet of the well-head.

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Aberdeen, United Kingdom

James Crabb