ELASTIC-PLASTIC SOLUTIONS FOR ANALYZING WELLBORE STABILITY

Abstract

Selecting a good practical prediction method of wellbore instability has extensively become an important issue in order to overcome the resulting instability problems during drilling. Therefore, the aim of this paper isto simulate the actual stresses around wellbore using elastoplastic rock behavior in order to describe the actual cases of wellbore instability problems. The description of the stress state around wellbore, as well as common failure criteria are presented further in this paper. We also made a selection of the most applicable equations for description of stress state using elastoplastic rock behavior. Experimental data are used to calculate the cylindrical stresses surrounding the drilling hole wall at various diameters. Furthermore, a sensitivity analysis is done to test changing the radial stress with overbalance support and wellbore radius.

Keywords

• elastic-plastic rock
• instability problems
• stress state
• radial stress
• tangential stress