WELLBORE STABILITY ANALYSIS OF EXTENDED REACH WELLS

Stability of extended reach wells is an important subject. Instability problems like lost circulation and borehole collapse during drilling operation lead to poor hole conditions causing a lot of problems like poor cement displacement and others. As a result, excessive nonproductive time and expensive wells are experienced.
This paper is based on a linear elastic and isotropic mechanics models for stress distribution around extended wells, with the aim of improve understanding the general behavior of extended wells. According to the established stability mechanics models, a wellbore stability simulator is developed, which runs under Microsoft Windows with friendly interface, high efficiency of field problem analysis. By using the software, the influence of certain factors on wellbore stability is analyzed. These factors include in-situ stress state, deviation, azimuth, strength rock, mechanical property and mud performance. Finally, the guide to determination of the azimuth and the safe mud density range for extended reach wells is presented.