The Application Of Oil-in-water Drilling Fluid System In ChangLing 2 Well

With the high geothermal gradient of southern SongLiao basin, deep-well drilling has high requirement to the anti-temperature performance of drilling fluid and under-balanced drilling has particular requirement to the drilling fluid. Based on the analysis of the performance of oil-in-water drilling fluid, we studied the oil-in-water drilling fluid system which applied to JiLin oilfield. After analyzing the emulsifier and adjusting the proportion of elements, we developed the formulation of new oil-in-water emulsion drilling fluid, which includes 35%-65% water, 3% mud, 65%-35% diesel oil, 5% emulsifier, 2%-4% stabilizer, 0.1%-0.2% filtrate reducer, 0.02%-0.04% caustic soda. The compare between oil-in-water drilling fluid system and some commonly used drilling fluid systems indicates that oil-in-water drilling fluid has evident advantages in adapting to formation pressure, improving sidewall stability, high temperature resistance, low temperature resistance, solids-carrying capacity, antipollution and safety. In addition, it has higher specitic resistance and lower cost. We made trail of the fluid in ChangLing 2 well. The laboratory experiments and field trial show that the fluid can be used in temperature up to 180℃and keep sidewall stable with stable emulsifying performance, reasonable rhelgogy, strong inhibition and low filtration during drilling. The above proves that the fluid can meet the needs of under-balanced or near-balanced drilling of deep formation in JiLin oilfield.