Anti-channeling for cementing shallow gas zone in Mazatage structure

Abstract

Mazatage Gas Field has shallow reservoir formations which are very structurally complex. Gas channeling in annulus and pressureat wellhead in the annulus after cementing are the problems that bring risks and difficulties to the development of the gas field, with high H2S concentration in the natural gas produced. A cementing fluid that has staging densities and multi setting-point, is used with low-viscosity turbulent flow ahead fluid technology to solve the cementing problems. The cementing slurry is early strengthened, impermeable, and swelling. During cementing, the flow rate of cement slurry is intentionally changing and measures against H2S are taken, and gas-tight thread casing string is used. This cement slurry technology is used in nearly 10 wells in Mazatage shallow gas structure and top cementing job quality is realized.