Structural Permeability Assessment Using Geological Structural Model Integrated with 3D Geomechanical Study and Discrete Facture Network Model in Wayang Windu Geothermal Field, West Java, Indonesia

Abstract

This paper presents the application of a structural permeability assessment using a Geological Structural Model integrated with a 3D Geomechanical Study and Discrete Fracture Network (DFN) Model in order to obtain a better understanding of the structure permeability distribution in the Wayang Windu geothermal reservoir. In this study, we assess critically stressed, hydraulically conductive fractures that control permeability and fluids flow through the interaction between the in situ stress state and the character and orientation of fractures or discontinuities. A multidisciplinary data set has been used comprising geology (rock types, fault structures, alteration, thermal manifestation, etc.), geophysics (MT, gravity, MEQ, image logging data, etc.), geochemistry (chemistry trends, tracer test results, etc.), production (temperature, pressure and spinner data), geomechanical properties and drilling information to construct a geological structure model, to analyze in-situ state of stress (geomechanical study) and to develop a DFN model as well as deterministic hydro-structures planes interpreted from MEQ events constrained by stress and permeable fractures from the wells. The model results have been integrated to assess the potential structures/fractures permeability area that may associate with fluid pathways. Over the reservoir structure, the predominant stress sensitive fracture intensities appear to align to form permeable fracture corridors or hydro-structures. The results will be utilized to guide development and to improve the output from the field through a combination of new well drilling and treatment initiatives of selected wells. The study workflow is proposed to become the standard process to assess subsurface structure permeability distribution.