Several studies explored the possibility of improving both areal and vertical sweep efficiency in mature water-alternating-gas (WAG) patterns in the Magnus oil field. Key surveillance data, such as 4D seismic, production-logging-tool (PLT) data, and well performance and openhole saturation logs, have been coupled with simulations to study options for sweep improvement. Optimizing the WAG patterns enables a more efficient use of the available gas, which makes this a more-commercially-viable and -cost-effective tertiary-recovery option.
Introduction
The Magnus oil field was discovered in 1974 and is on the UK continental shelf of the North Sea. The field started production in 1983 through seven predrilled subsea wells by use of a fixed, steel-jacket platform.
