Multiphysics Model Of Borehole Environment And Joint Inversion Of Well Logs

Multiphysics model of borehole environment was proposed. It describes main factors of generation and evolution of near well zone: mechanical impact on reservoir by well, flow of multiphasic fluids, salt transfer, lithologic characteristics of reservoir, mud cake growth and destruction. Software system for joint computer simulation of electromagnetic, hydrodynamic and geomechanical processes in the borehole environment has been constructed. Theoretical logs of VIKIZ (high frequency induction isoparametric wireline logging tool) and BKZ (Russian lateral log) are simulated for calculated electrical resistivity distribution. In consequence of deformation processes during and after drilling porosity and permeability near borehole are decreased, therefore mud filtrate invasion and salt transfer acquire another character. VIKIZ and BKZ logs are strongly depended on geomechanical parameters, such as break point stress or internal friction point and properties of pore fluid. Authors have suggested interpretation technique taking into account deformation processes and there consequences, this make it possible to improve formation evaluation. Proposed integrated interpretation methodology was verified for West Siberia well logs. Input parameters of joint model were determined from data of geophysical study of borehole and core analysis. For this purpose technique of evaluation of parameters, which are responsible for filtration-volumetric and strain characteristics of rocks were devised. Joint multidisciplinary mathematical and computer model of borehole environment make the opportunity to perfect interpretation of well data and reservoir evaluation.