Review of BP's Global Gas Injection Projects

Abstract Miscible gas flooding is an established method for enhancing oil recovery that can be successfully deployed in secondary or tertiary mode. BP has developed a range of innovative techniques to maximize economic oil recovery from its miscible gas floods. While some of these gas floods have been applied early in field life, in other cases gas flooding has significantly extended the life of mature, water-flooded fields. The results have been reported in a series of publications over the past three decades. The purpose of this paper is to provide an overview of BP's experience of establishing, managing and optimizing miscible gas floods. Prudhoe Bay (Alaska) is the world's largest rich hydrocarbon miscible gas project. Conventional and unconventional methods have been applied in a variety of different settings in secondary and tertiary mode. An extensive surveillance program has facilitated a good understanding of the processes operating at field scale and routine surveillance data are used to optimize the flood. In 2002, a large-scale gas cap water injection project was implemented to slow the decline in field pressure. This project has enhanced the efficiency of the various recovery processes operating across the field, resulting in additional recovery. As a result of the success in Prudhoe, miscible gas flooding has been extended to numerous other fields on the North Slope of Alaska. BP has two active miscible gas projects in the North Sea, Magnus and Ula. In both cases, gas injection began after extensive water flooding. Tertiary miscible water-alternating-gas (WAG) flooding in Magnus field started in 2002 after construction of a gas pipeline from fields located west of the Shetlands and its impact on reservoir performance is significant and well understood. Tertiary miscible WAG injection in Ula field started in 1998 and has played a key role in arresting production decline. In both fields, the miscible gas flood is currently being expanded. In addition to these miscible gas projects, BP jointly operates a CO2 injection project in Algeria and, with its heritage companies, has a long history of operating CO2 floods in the US. BP is actively pursuing new opportunities for gas flooding around the world. Miscible gas injection has generated considerable benefits for BP over the past three decades and will continue to do so. The potential availability of large sources of CO2 in the future, supplied by carbon capture, could help maintain a leading role for miscible gas injection for years to come.