Cost-Effectiveness and Flexibility Through the Brent Gas-Lift Insert String Completions

Abstract

Abstract The Brent field, developed as an oil producing field in the mid 70's, is now approaching the end of its economic life. However, the large quantity of remaining oil, although only 40% of initial reserves, and the high Gas-Oil ratio of the oil allow extended production from the field by reducing the reservoir pressure. The de-pressurisation will add some 10-15 year of economic life to the field. The de-pressurisation project, unique in the world due to the size and complexity of the Brent field, brings many uncertainties. The well completion design is key in the management of these uncertainties. Cost-effective reservoir management (zonal solation) is a pre-requisite and the choosen completion design should accommodate sand, scale and even H2S management. Furthermore certain wells will require artificial (gas) lift, although the number and location of these wells will be largely unknown up front. The adopted monobore completion design combines maximum flexibility and cost-effectiveness with simplicity and is readily adaptable to gas lift installation. The Brent monobore completion design has reduced cost by 30% and installation time by 65% as opposed to the Multi-Straddle Assembly completion run previously in Brent. Key features of the completion and retrofit gas lift installation are described in this paper. P. 169