New Technology for Developing Hydrocarbon Reserves of Complex Reservoirs with Underlying Water

Abstract

This study presents a novel technique for developing complex oil reservoirs with bottom water. The method involves injecting freshwater below the oil-water contact (OWC) and subsequently stabilizing it with a polymer to create a barrier. This approach is designed to reduce water cut, enhance oil recovery (EOR), and sustain production rates in mature fields. Based on an analysis of experimental and field data, criteria for the technology’s application have been established. A key mechanism is the reduction of permeability in terrigenous reservoirs following freshwater injection, a phenomenon confirmed by laboratory core studies. Using a radial hydrodynamic model, this study assessed the technology’s effects and performed a sensitivity analysis to optimize perforation placement and injected agent volume. The results can be used to evaluate not only freshwater but also other water-control agents, although field-specific core flow studies are necessary to justify any application. The model also identified two primary mechanisms of bottom water inflow to production perforations. The first is water coning, which is driven by production induced pressure gradients. The second mechanism is channeling along the casing string, which is caused by factors like poor cement quality or the presence of natural and induced fractures. Finally, a calculation of production losses resulting from this water flow was performed.