Abstract: Borehole unstability is one of the major problems that hamper the drilling in Huo'erguosi anticline. Comprehensive analysis of geological and engineering data indicates that, due to the extrusion of tectonic movement, the anticline features high in-situ stresses and broken formations, causing frequent borehole collapse and lost circulation problems. In this paper, in-situ stress models for Huo'erguosi anticline are put forward with the data from the core analysis and hydraulic fracturing test. Then, the in-situ stress profile and distribution of Wellblock Huo-10are established. They could be as guides for the borehole stability research in this area.

Key words: borehole unstability, tectonic movement, model, in-situ stress profile