Darcy-Scale Experimental Investigation of Intermittent Particle Transport in Porous Media and its Impact on Injectivity

Water constitutes an increasing proportion of the production stream from mature oil field. To reduce discharges to the sea, produced water is often reinjected into the reservoir. Produced water typically contains traces of oil and particles, which may reduce injectivity upon reinjection. A common assumption for understanding particle filtration and deposition in these systems is that the flow remains constant. However, due to operational constraints, maintenance, and unforeseen events, the flow frequently varies. As new power sources, including offshore wind, are utilized to power injection facilities, more dynamic flow conditions are expected. This paper investigates the combined impact of reinjection of produced water and cyclic injection on particle filtration and formation damage. The study utilized dynamic core displacement on Bentheimer sandstone core samples, with brine containing suspended quartz particles used as a simplified analogue for produced water. The core sample was placed in a core holder designed with multiple pressure ports, allowing for the monitoring of differential pressures along the core during injection. Three different injection cycles were applied during the core flooding process and compared to a continuous injection baseline. The results demonstrated that both internal and external filter cakes were formed during core flooding for all injection cycles. The results further indicated that when the sample is subjected to injection cycles of increasing frequency, a more compressed and stable external filter cake is formed. The internal filter cake penetrated the core to an estimated depth of 5 mm to 12 mm, whereas the external filter cakes exhibited permeabilities below 10 mD. Our findings indicated that samples with lower permeability are more susceptible to formation damage caused by invaded particles while seeing shallower invasion zone.