Komar University of Science and Technology, Iraq
Conventional method of injection that uses only a high concentration and molecular weight of single polymer, often leads to fingering effects due to mobility ratio, and the entrapment of pore throats in the injected area due to the difference in size between the pore throat and the hydrodynamic polymer chain radius. To avoid this unfavorable phenomenon, a sequential method of polymer injection is used by injecting varying molecular weight of polymers starting from low to high concentration in three stages of sequential injections. Polymer injection/flooding is considered one of the most effective and successful method for the enhancements of oil recovery.
In this work we have investigated the feasibility of sequential polymer injection in different reservoir rocks characterized by different heterogeneities. It is apparent that heterogeneity is one of the main factor associates with poor EOR performance. Therefore, investigating heterogeneity and the factors affect EOR efficiency is of great importance to oil/gas industry.
The static model was developed from an example field data in the region. Reservoir rock properties were correlated and modeled using Kiring and Gaussian geostatistics simulation. Thereafter the model was brought to reservoir simulation software to investigate EOR performance. The REVEAL and in house simulator software have been used for assessing the efficiency EOR model using sequential chemicals injection.
Results indicated that sequentially injected polymers varying in concentrations can be a viable alternative to conventional polymer flooding methods, particularly in very heterogeneous reservoir if compared to results obtained with conventional method of polymer injection.