Research on drilling fluid technology for slim hole in deep wells and its application

In order to solve the problems of hole stability,temperature resistance,lubrication,inhibition,and reservoir protection of drilling fluid used for deep windows sidetracking of Qingxi Oilfield in Yumen region,inhibitors,anti-sloughing agents,and film former agents are selected,as well as plugging particles are selected and combined based on the "ideal packing theory".As a result,the high temperature cation-positive gel-organsilicon alcohol drilling fluid system for deep wells is developed.The technology has been applied to the sidetracking and deepened construction of four wells in Qingxi Oilfield.Field application shows that the well bore is stable,the well diameter is regular,the well-hole enlargement is less that 8%,the complex loss rate is zero,the core permeability recovery value exceeds 90%,and the oil output increases by 70%.All this can fulfill the requirement of slim hole drilling for deep wells and reservoir protection.