ACIDIZING KINETICS AND ITS APPLICATION TO PLANNING AND OPTIMISATION OF RESERVOIR STIMULATION AND FORMATION DAMAGE REMOVAL

Abstract

Kinetic aspects of sandstone acidizing with mixtures of hydrofluoric (HF) and hydrochloric (HC1) acids have been studied experimentally using cores taken from a natural sandstone reservoir rock. The matrix reactivity and the resulting changes in porosity and permeability due to acid reactions were measured as a function of experimental conditions: (1) acid concentration, (2) injection rate and (3) temperature. The model parameters were correlated by a power law model. A numerical simulator was developed for linear flow to predict changes in core properties due to acidizing. Values from the simulator were verified by experimental results. This simulator was subsequently extended to radial flow, and therefore can be used to simulate field acid jobs of sandstone formations.