Analysis of the stability of open-hole multilateral wells with consideration of intermediate principal stress

Geomechanics is one of the sciences that plays a fundamental role in the production of energy from the earth. Today, this science is widely used in the design and drilling of wells, as well as in reservoir engineering. Safe drilling is an essential parameter in the oil and gas industry. Modern drilling methods, such as multilateral(ML) wells, increase production efficiency. However, drilling such wells is associated with mechanical instability. Those issues depend on the formation strength parameters, in-situ stress, well-direction, pore-pressure, and fluid parameters. The study of stability requires a failure criterion. Hereof, some failure criteria do not consider the role of intermediate principal stress(σ۲), which is proven to have a considerable effect on mechanical failure. Our study uses the three-dimensional(۳D) finite element method(FEM) to investigate the stability and solid deformation of an ML well that follows the Mohr-Coulomb(MC) and Mogi-Coulomb(Mogi-C) failure criterion to studying of mechanical failure. The results were shown in different graphs such as changes in surface pressure, flow lines around the well and fracture for different borehole pressures using Mogi-C and MC fracture criteria. Our results revealed that the weakest range in these wells is at the junction of branches. Due to the principal stress effects, using the Mogi-C criterion is more safe and closer to reality. The results demonstrate an approximate ۳۰% reduction in predicted failure points under pressures exceeding ۳۰ MPa when employing the Mogi-C criterion, with predicted failures decreasing from approximately ۱۵% to ۵% at ۳۵ MPa.

کلیدواژه ها:

Multilateral Well ، Intermediate Principal Stress ، Mogi-Coulomb ، Well stability ، Finite element method (FEM)