Drilling Optimization of Deep Geothermal Well Using Geomechanical Modeling- A Case Study of MIP 1S Well Morgantown West Virginia

Abstract The proposed paper endeavors to assess the geological and geomechanical characteristics of the geothermal deep direct-use MIP 1S well, which was drilled and completed in the Appalachian basin. This evaluation is critical for streamlining drilling processes, analyzing wellbore stability, and gauging the potential for heat extraction and storage in both deep and shallow formations, respectively. To achieve this objective, a comprehensive suite of well logs is employed, supplemented by sidewall core analysis and adjacent well injection tests. The assessment encompasses the determination of continuous elastic and rock strength properties, including Young's modulus, Poisson's ratio, friction angle, unconfined compressive strength, and tensile strength. These properties are derived utilizing advanced correlations from open-hole logs, coupled with calibration against available sidewall core lab results. Subsequently, stress and pore pressure profiling are conducted, involving the calculation of overburden stress, pore pressure profiles, and magnitudes of minimum and maximum horizontal stresses, based on poroelastic equations. These calculations are further refined through calibration with direct diagnostic fracture injection tests conducted in adjacent wells. Additionally, stress directions inferred from formation image logs are compared against the fast and slow shear azimuth direction, which is determined from dipole sonic tool data. The conclusion of these efforts results in the development of a validated 1D-geomechanical model. This model undergoes analysis through wellbore stability assessments and comparisons with drilling events, such as stuck pipe occurrences, pack-offs, and cavings, as well as borehole features including image logs and multi-arm caliper data. The 1D-geomechanical model demonstrates a high degree of agreement with wellbore observations, revealing suboptimal execution of drilling practices, particularly utilizing mist air drilling up to a depth of 8868 feet. This suboptimal execution has led to significant wellbore breakout in both shallow and intermediate sections of the well. Consequently, the wellbore diameter has been excessively widened, exceeding 4 inches from the planned 12 ¼-inch diameter to over 16 inches. Such deviations could potentially provoke significant challenges related to cementing, open-hole log data accuracy, and wellbore stability.