Horizontal subsea trees allow frequent deepwater workovers
- FMC Wellhead Equipment Division, Houston, TX (United States)
- Amoco Corp., Shekou (China)
- China Offshore Nanhai East Corp., Shekou (China)
Horizontal subsea wellheads have found application in the Liuhua oil field in the South China Sea. These trees allow installation and retrieval of downhole equipment through the tree without having to disturb the tree or its external connections to flow lines, service lines, or control umbilicals. This access to the well is important because the Liuhua wells will be produced with electrical submersible pumps (ESPs), which may have relatively short intervals between maintenance, leading to frequent well work. The wells will be completed subsea in about 300 m of water. The large bore, horizontal trees allow all downhole equipment to be pulled without removal of the subsea tree. This wellhead configuration also provides well control and vertical access to downhole equipment through a conventional marine drilling riser and subsea blowout preventer (BOP), eliminating the need for costly specialized completion risers. Another benefit of the horizontal tree is its extremely compact profile with a low number of valves for well control. Valve size and spacing are decoupled from the size and bore spacing of the tubing hanger. The tree`s low profile geometry reduces costs of manufacturing the tree and framework and optimize load transfer to the wellhead.
- OSTI ID:
- 40352
- Journal Information:
- Oil and Gas Journal, Journal Name: Oil and Gas Journal Journal Issue: 18 Vol. 93; ISSN OIGJAV; ISSN 0030-1388
- Country of Publication:
- United States
- Language:
- English
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