Fines Migration in Aquifers and Oilfields: Laboratory and Mathematical Modelling

Abstract

Migration of natural reservoir fines is one of the main causes of formation damage in oil and gas fields. Yet, fines migration can be employed for enhancing reservoir sweep and water production control. Permeability decline due to fine particles’ detachment from reservoir rocks, mobilisation, migration and straining has been widely reported in the petroleum industry since the 1960s and is being researched worldwide. The topic of colloidal-suspension flows with particle detachment is also of wide interest in environmental, chemical and civil engineering. The current work begins with a detailed introduction on laboratory and mathematical modelling of fines migration, along with new mathematical models and experimental results. Each of the next three sections explores a particular cause of fines mobilisation, migration and straining. Section 2 covers high flow velocity that causes particle detachment accompanied by consequent permeability decline. Section 3 covers low-salinity water injection, where the decreased electrostatic attraction leads to particle mobilisation. Section 4 covers the effect of high temperature on production rate and low-salinity water injection in geothermal reservoirs. We attribute the long permeability stabilisation period during coreflooding with fines migration, to slow fines rolling and sliding and to diffusive delay in particle mobilisation. We derive the analytical models for both phenomena. Laboratory fines-migration coreflood tests are carried out, with the measurement of breakthrough fines concentration and pressure drop across the whole core and the core’s section. Treatment of the experimental data and analysis of the tuned coefficients show that the slow-particle model contains fewer coefficients and exhibits more typical strained concentration dependencies of the tuned parameters than does the delay-release model.