Estimation of the effect of temperature difference between formation and drilling fluid on optimum wellbore trajectory using thermo-poro-elastic model

Estimation of the effect of temperature difference between formation and drilling fluid on optimum wellbore trajectory using thermo-poro-elastic model

Wellbore stability has a very important role in drilling operation. Wellbore instability may cause stop in operation and some extra time and cost. Determination of optimum trajectory reduces many of the problems caused due to collapse or fracturing during drilling. To aim this, mud window should be calculated for different directions. The best trajectory is one with the widest mud window. Mud window may be reduced in trajectories with the least collapse pressure and increase the ROP. Determine the stress around wellbore is critical to optimize the trajectory. Different models are proposed for this determination. In this article, results of Kirschʹs equations and thermos-poro-elastic models are compared. The only reason of stresses around wellbore stability is known due to in-situ stresses by Kirschʹs equations, whereas, thermo-poro-elastic model considers induced stresses due to differences between temperature and pressure and drilling fluid and formation as well as in-situ stresses. In the first step of this study, mechanical earth model of a reservoir is built to gain in-situ stresses and Geomechanical parameters. Then, calculated stresses using two models are applied into Mogi-Coulomb failure criteria. According to the faulting region, two model predict a horizontal well as optimized wellbore to continue drilling in the reservoir but they are different in prediction of lower limit of mud window and optimized azimuth