Optimization Design of Drilling Fluids Used in Block Chang 68 of Weibei Oil and Gas Field

Reservoirs in Block Chang 68 of Weibei Oil and Gas Field belonged to reservoirs with low porosity and low permeability and high salinity in formation water,the reservoirs were easy to be damaged.On the basis of analyzing the fundamental reservoir characteristics and potential damage factors,a new drilling fluid system of broad-spectrum of oil-film temporary plugging with co-acting stimulation of ideal packing was optimized.The laboratory test results show that the drilling fluid system has excellent rheological properties,strong inhibition and anti-pollution ability,high plugging rate of permeability is 100%,permeability restoring rate is 98.1% and initial flow pressure is obviously reduced.It can be used to prevent solid and fluid from invading into formation during drilling,and is favorable for flow back of oil and gas during production.The reservoir protection can be greatly improved.