A reservoir numerical simulation study was done to model a polymer gel treatment pilot test without mechanical isolation, that was performed to improve the injection profiles and the sweep efficiency in a water injector well of an hexagonal pattern in the Lagomar field located in the Maracaibo Lake in western Venezuela.
The gel treatment pilot test was performed in the C-4 reservoir, a layered highly heterogeneous Eocene sandstone. In this reservoir water injection for secondary have been performed for over tree decades. High water cuts have forced management to shut in several producing wells.
A reservoir characterization analysis that included PLT logs, core analyses, and geomechanics, identified the presence of induced fractures as a cause of low sweep efficiency. Based on this reservoir study, a polymer gel treatment was designed for an injection well located in the center of a hexagonal well pattern.
A commercial gel polymer technology (MARCITsm) was selected to modify the injection profile in this pilot test. The results from the test injecting 3700 barrels of gel in the water injector well were very promising, showing an average reduction of 30% in water cut and 26,850 barrels of incremental oil five months after the treatment.
A reservoir simulation study was developed using STARS, a K-value compositional reservoir simulator with gel modelling capabilities. The model reproduces reasonably the performance observed in the field pilot test.
The simulation study is a first approach to developing a predictive tool to assist in the planning and design of future non selective gel treatments in water injector wells, applicable in the Lagomar field and analogous water injection projects.