Quantitative Theory for Fines Migration and Formation Damage

摘要

Particle detachment from the matrix during suspension transport in porous media was widely observed for laboratory corefloods and flows in natural reservoirs. A new mathematical model for detachment of particles is based on mechanical equilibrium of a particle positioned on the internal cake in the pore space. The torque balance of drag, electrostatic, lifting and gravity forces, acting on the particle from the matrix and the moving fluid, is considered. The torque balance determines maximum retention concentration during particle capture. The particle torque equilibrium is determined by dimensionless ratio between the drag and normal forces acting on the particle on cake surface. The maximum retention function of the dislodging number closes system of governing equations for colloid transport with particle release. One-dimensional problem of coreflooding by suspension accounting for particle release allows for exact solution under the assumptions of constant filtration coefficient and porosity. The explicit formulae permit the calculation of the model parameters (maximum retention concentration, filtration and formation damage coefficients) from the history of the pressure drop across the core during suspension injection. The values for maximum retention concentration, as obtained from two coreflood tests, have been matched by torque balance on the micro scale.