Prevention of Shallow Gas Migration Through Cement

Abstract

Abstract The problem of surface gas migration is a common and dangerous one. Its presence can prove to be not only a nuisance but more importantly a serious source of well control problems. Various solutions have been tried worldwide with differing rates of success. The problem of surface gas migration was encountered during the development of a field in Saudi Arabia. Detailed analyses of samples showed the gas to be mostly nitrogen coming from depths between 400 ft and 1000 ft. Several techniques were utilized to combat the problem including the use of conventional fluid loss, conventional gas migration slurry as well as changes in the casing design programs. The only successful solution involved the use of a novel low-temperature gas migration product coupled with several modifications in the drilling practices. This paper discusses the nature of the problem and the different techniques applied with a focus on the particulars of the only successful method, P. 67