GEOMECHANICAL MODELING USING DYNAMIC BOUNDARY CONDITIONS FROM TIME-LAPSE DATA

摘要

A method for modelling geomechanical effects in the subsurface by conditioning geomechanical model parameters to time-lapse observations. The model is driven by displacement boundary conditions derived from observed time-lapse travel time shift and time strain. The displacements at the boundaries of the model are extracted from time-lapse data, converted from travel time shift to depth shift and lateral shifts if necessary, and applied as displacement increments on the initial geomechanical model. Subsequently, increments of stresses and strains are calculated by the geomechanical simulator, and time-lapse related parameters in the interior of the model are compared with the time-lapse observations. This enables a comprehensive study of mismatch between simulations and observations that can be used to update material properties, faults, fractures and the rock strain-velocity change relationship (R factor). The updated material properties may be used to make understand subsurface conditions including identifying drilling hazards, well integrity or reservoir integrity.