Laboratory Modeling of Residual Oil Mobilization in Flooded Reservoirs

Abstract

Abstract Currently more and more oil fields reach their final development stage, characterized by increased water cut and decline of the oil production flow. Having said that, the residual oil saturation is still high, which means a presence of significant residual recoverable reserves within the flooded fields. Efficient recovery of these reserves is impossible without a prior analysis of their structure and location within the reservoirs. Modern approaches to evaluation of residual oil saturation and displacement efficiency are based on determination of only one parameter and its relationship with porosity and permeability. With these methods residual oil saturation values are simulated on the bases of unlimited flow and unified predetermined filtering parameters, which correspond to the reservoir mean values. The methods are also based on maximum injection rates, ten times higher than the average injection rate values. As a result of reservoir development simulation, flooded zones will have the lowest residual oil saturation, while the residual oil saturation will be concentrated within the unflooded areas. An experimental research was carried out to assess the impact of displacement parameters on oil displacement efficiency. A special test procedure was developed, which involves special core preparation so that the samples retain their surface properties. The obtained data allow for a conclusion, that there is a relationship between capillary and hydrodynamic forces (capillary number) and rate of oil recovery from the core pore space. Conditionally mobile residual oil saturation values and their relationship with the rock surface properties were determined.