Economical Development of Small Isolated Fields

Abstract

Summary U.K. offshore oil supplies could be in decline in 10 years unless new methods and technology are developed to open fields that are uncommercial by conventional methods. Such technology is being developed, and much of it is aimed at pressure boosting subsea step-out fields to improve production rate and recovery over increasing distances to a host platform. This paper is concerned with the development of small isolated fields for which a new platform facility is not justified or where no suitable existing host platform is available. The isolated-field production system described here comprises a two-stage subsea separator near the subsea well(s) from which production is tied in by flexible flowlines. Oil/water/gas separation is achieved at near atmosphere pressure, allowing safe loading of the "dead" crude into a tanker. The gas is flared at a surface buoy (directly above the separator unit) that also contains power generation and chemical injection facilities. Liquids are pumped to an offshore tanker-loading catenary anchor leg mooring (CALM) buoy, and then to the connected shuttle tanker. Control of the separator system is autonomous based on a programmable logic controller in the subsea control module, with commands and monitoring by an umbilical from a production center on the tanker.