Simulation of progressive increase and decrease in permeability around underground well, comprises determining initial data by laboratory measurements of initial, damaged and restored permeability as function of distance from well wall

摘要

Initial data are obtained by laboratory measurements of the initial (ki), damaged (kd) and restored (kf) permeability around the well as a function of distance (r) from the well wall. The damaged zone is discretized by a 3D cylindrical mesh forming blocks of small radial thickness relative to the well diameter. Fluid flows through the cakes are calculated to model evolution of the permeability Simulating the optimal conditions to impose on a well drilled through an underground formation at a particular angle, for the progressive removal using the formation's fluids of deposits or cakes which are formed in at least one zone at the periphery of the well after the drilling and completion operations, comprises resolving the diffusivity equation in the mesh modelling the fluid flows through the cakes, taking into consideration the initial measured data and modelling the evolution of the permeability as a function of the fluid flows (Q) through the cakes to deduce the optimal conditions to apply during operation of the well. The restoration of permeability is modelled at all points at distance (r) from the well wall considering that the permeability varies proportionally with the difference between the damaged permeability and the restored permeability. The coefficient of proportionality depends on an empirical law of variation of the permeability as a function of the quantity (Q) of fluid passing through the cakes.