The Otter field, formely known as wendy is a small oil and gas accumulation discovered by Phillips Petroleum in 1977. In 1997 Fina appraised the reserves with a second exploration well and TotalFina proved the geological model in 2000 with a third exploration well.
The Otter filed is located in 210/15a block in the Norther UK North Sea sector and he s2030 m below sea level in 185 m depth of water. Many development scenarios had been considered but the oil price, reserves in place and the low reservoir pressure requiring artificial lift to extract the crude initially proved a standalone development uneconomic
However, spare processing capacities of neighbouring offshore facilities re-activeted interest in the development. In January 2001 Fina Exploration Ltd, a wholly owned subsidiary of the TotalFinaElf group, was commissioned on behalf of other block licencees (Agip, Exxon Mobil and shell) to operate the development. At the time of writing the sub sea facilities are in the process of being deployed and crude production is expected 3rd quarter 2002.
Figure 1 illustrates the general Otter Field architecture Figure 2 is a schematic illustrating the crude patgh through the downhole assembly, subsea facilities and the platform
The Otter development will produce from three subsea production wells and will have reservoir pressure support via 2 subsea water injection wells. The filed will initially flow naturally for 6 months to 1 year, but thereafter production will require to be maintained by the use of down hole installed Electrical Submersible Pumps(ESPs)
Reservoir product will flow through a 5–1/2 tubing string, Via the Xmas tree and subsea manifold. And finallythrough the sea line to Elder platform processing facilities. Elder is operated by shell and located 21 km South East of the Otter sub sea facilities. The reservoir effluent will initially be a mixture of oil and gas but increasing percentage of water will be produced being either pure formation and injected waters.
The subsea facilities are based on an integrated template / manifold system incorporating 3 production and I water injection wells. The second injection well is a satellite lied back to the manifold and is some 25 m distant. Each well will have horizontal trees installed.
For reservoir management purposes, the subsea manifold incorporates facilities for routing the production from individual well via a subsea multiphase meter mounted within the manifold piping. The manifold also incorporates facilities for round trip pigging.(The Figures is available in full paper) The subsea chemicals distribution provides the manifold, X/mas trees and the wellswith chemical injection, as appropriate, for hydrate mitigation, scale, corrosion, H2S and emulsion control
The effluent will be evacuated via a 10 10″ insulated carbon steel sealine to the Eider platform Injection water will be provided by Eider platform via a 10″ non-insulated pipline.