Well inflow performance under fines migration during water-cut increase

Abstract

Fines migration is a widespread cause of productivity problems for oil production wells. Modelling efforts often focus on the effect of high fluid velocities in the near wellbore region on fines detachment and straining. Recent studies have highlighted the importance of capillary detachment of clays by the oil–water meniscus during imbibition, which occurs during commingled oil and water production during water-cut increase. In this study, we develop a new model to quantify the total detachment during increase in water saturation with two-phase flow and the consequent formation damage to production well. The fines-detachment model proposed is presented in the form of the maximum retention concentration as a function of saturation. The model shows good agreement with laboratory measurements. Finally, the maximum retention function (MRF) is incorporated into an inflow-performance homogeneous reservoir model. The resulting model allows calculating the productivity decline occurring during the increase of water-cut due to fines migration. The results are presented as the well impedance versus the water-cut (fractional flow). These curves, summarising well productivity history, allow predicting the growth of formation damage during the well life, determining the time for well stimulation, and calculating the final impedance at abandonment. The model is compared with production histories for three wells, and good agreement is found.