Technology of environmental protetive and formation protective drilling fluid for Gaoping 4 horizontal well group

Gaoping 4 horizontal well group are mainly used to develop the reservoir of Chang 10 reservoirs in Ansai oil field. Environmental protective drilling fluid prepared mainly with poly-silicate and xanthan gum is developed in accordance with such distinguishing features as the collapse of Zhiluo and Fuxian faults in upper strata, low drilling rate in the lower strata, and high mud making property of formation. The drilling fluid is beneficial to safe and smart drilling and has less environmental pollution because of its advantages of high inhibition, lubrication and shear thinning behavior. The working project of drilling fluid is determined by the pilot mud lab test. The drilling fluid is diluted after drill-stem testing. And then, the filtrate volume and density are also reduced. Based on the strong solid control and the application of formation protective acid-soluble bridge-plugging agent and filtrate reducer, the reservoir has been protected to the most extent.