10 Years of WAG Injection in Lower Brent at the Gullfaks Field

Abstract

Abstract The Gullfaks field is a large oil field in the Norwegian sector of the North Sea. Production started in 1986 with water flooding as the primary recovery method. A WAG injection pilot in lower Brent well A-11 was initiated in March 1991. The well is located south in the GFA-area. A simulation model was built and history-matched until January 1993 for the whole pilot area, including upper Brent. Predictions to the end of year 2005 indicated an increased oil recovery of 0.3 mill. Sm3 in addition to some accelerated production. Most of the predicted increased oil recovery was however reached during 1993. The WAG injection has continued in A-11 but with fewer gas periods the last years. The updated estimate of increased oil recovery from WAG injection in A-11 up to year 2001 is 2 mill. Sm3. The paper will also give a short evaluation of WAG injection in two other lower Brent injectors at Gullfaks with a joint estimated increased oil recovery of 0.7 mill Sm3.