Study on the Stability of Whole Well Section in the Western Margin of Ordos Basin

In the western margin region of Ordos Basin, the lithology of the whole well section is complicated, and the complicated situations such as collapse, leakage and stuck drill are prominent, which seriously affect the economic and efficient development of deep marine shale gas resources. Based on laboratory physical experiments, field engineering parameters and field caving and leaking engineering information, the formation mechanical parameter model of the whole well section in the western margin area was established, and the distribution law of mechanical parameters of different lithologic strata was evaluated. Coupled with in-situ stress and indoor rock mechanics test, the four pressure profiles of the whole well section were established considering the influence of mechanical weak surface. The results show the stress concentration caused by the large horizontal principal stress difference and the development of fracture zone and coal seam are easy to lead to wellbore instability. The established rock mechanical properties and four pressure profiles in the western margin of Ordos Basin can provide scientific basis for optimization design of well structure and key engineering parameters in this area, guarantee safe and efficient drilling and reduce exploration and development costs.