Drilling Fluid Technology for Well Moshen-1.

Well Moshen-1 is an exploration well with a completion depth of 7,500 m. MMH drilling fluid was used in the first interval to drill the flowing sand zones and good hole cleaning was achieved. The second interval was drilled with polymer/calcium polymer sulfonates mud which inhibited the hydration of long shale section. The third interval was drilled with a high temperature high density polymer chloride drilling fluid which was used to address the contamination and low penetration problems. In the last interval, a high temperature polymer sulfonates mud was applied to deal with the high temperature in the lower part of the hole. Formation bearing resistance was enhanced with a special technology and downhole troubles were minimized.