Modelling of formation damage due to mud filtrate invasion in a radial flow system

摘要

This paper is a sequel of our previous paper that has addressed on mud filtrate invasion into oil formation in a linear flow system. As a natural extension, here we present a mathematical model to estimate skin factor due to mud filtrate invasion into oil formation in a radial flow system. In the model, solid particle invasion and irreducible water saturation are taken into account. The present model consists of mud cake thickness model, flow rate of mud filtrate into oil formation, mud filtrate concentration, and penetration depth of mud filtrate. The estimation for reduction of oil effective permeability and skin factor near wellbore are also presented. The model is simulated and verified using three vertical well data cited from the literature. The estimation results of oil effective permeability reduction and skin factor from the model are in agreement with the data. Beside that, for the case of static filtration in radial flow, we find a critical mud cake thickness above which the rate change of thickness is increasing.