Abstract: Well H2 located at the west slope of Haizhong Sag of Beibuwan Basin, is meaningful to the oil and gas exploration in the Weixi Block of Sinopec. During drilling in this area, hole diameter reduction, collapse and drilling mud leakage by faults easily occur at the shallow, and wellbore collapse is more often at the medium-deep due to the existence of abnormal high pressure. As for Well H2, these drilling risks are more likely occurred because it is a high-inclination directional well. The application of KCl polyol drilling fluid system, a strong inhibition and plugging drilling fluid, improved and retarded the hole diameter reduction, collapse caused by micro fractures in the shale, effectively controlled the solid carrying and suspending of drilling fluid, enhanced the quality of mud cake, ensured the drilling operation successfully. This paper detailed introduces the application and the effects. This drilling fluid system have the advantages of good rheological property, high carrying capacity, good inhibition of lubrication performance and significant collapse-protecting effect. It can also meet the requirements of both geology and engineering.