Experimental Study of the Combined Effect of Water Salinity and Flow Rate on Fines Migration in Niger Delta

Abstract This study investigates the combined effects of water salinity and flow rate on fines migration in core plugs sourced from the Niger Delta. The experimental setup involved sand sourced from the Choba River, which was washed, dried, and mechanically sieved to achieve a grain size of 300 microns. Clay minerals obtained from the Ibere clay deposit were incorporated into the sand at a 5% mass percentage for all sand packs. The prepared plugs, containing sand grains of 300 microns and 5% clay content, were saturated with a brine solution of 30 g/L salinity for 72 hours. The pore volume and bulk volume of each sand pack were measured to determine porosity, and the pore volumes of clean effluent were determined. The experimental results were analysed by plotting the pore volume produced before fines breakthrough against flow rates across varying concentrations of water salinity. It was observed that the pore volume produced before fines breakthrough consistently decreased as the flow rate increased from 1 mL/min to 9 mL/min, irrespective of the tested salinity levels. Furthermore, the pore volume produced before fines breakthrough steadily decreased as the injected brine concentration was reduced from 20 g/L to 0 g/L. A mathematical model was developed from the experimental data to describe the relationship between pore volume, flow rate, and water salinity. This model, which aligns closely with the laboratory data, identifies the critical flow rate (CFR) for fines migration as ranging from 6.5 mL/min to 7.5 mL/min, while the critical water salinity (CWS) associated with fines migration is determined to be 15 g/L.