The Effect of Residual Oil on Deep-Bed Filtration of Particles in Injection Water

Abstract

Summary Production of hydrocarbons is usually accompanied by the production of water. This produced water consists of formation water and/or water that has previously been injected into the formation. As more oil is produced, the amount of produced water increases. Unfortunately, the produced water is not a saleable product; hence an operator must find ways to handle relatively large amounts of water in an environmentally-acceptable manner at the lowest cost. One way of managing this water is to re-inject it for disposal, pressure maintenance, or enhanced oil recovery. An important and difficult task in the re-injection process is the prediction of the impact of water quality on well injectivity. This is mainly because of the poor understanding of the deposition mechanisms by which suspended solids and oil droplets present in the produced water are retained by the formation. As part of a study on formation damage, different concentrations of hematite particles suspended in water were injected into sandstone core samples at residual oil saturation. The theories of deep-bed filtration are evaluated. The effects of residual oil on the filtration coefficient λ and the formation damage factor β are examined. The presence of oil caused greater apparent damage (reduction of permeability). It was also observed that there is rather deeper invasion at residual oil saturation than at full brine saturation.