Performance assessment of miscible and immiscible water-alternating gas floods with simple tools

Water-alternating-gas (WAG) floods are designed to lessen the mobility of CO2 and thereby increase sweep efficiency. Common factors that often lead to less-than-ideal flood performance include reservoir heterogeneity triggering nonintuitive injector/producer connectivity, lack of conformance control, and injection at pressure greater than the fracture pressure, among others. Therefore, intensive reservoir monitoring and data interpretation should be the cornerstone of any prudent reservoir-management practice. tudy uses a slate of analytical tools to monitor flood performance in miscible and immiscible WAG floods. These tools include the capacitance-resistance model (CRM) and several diagnostic plots, such as the reciprocal-productivity index (RPI), the water–oil ratio (WOR), EOR-efficiency-measure plot, and modified Hall plot (MH). This paper offers several alternative CRM solutions to account for unbalanced patterns.