Abstract

Nowadays as majority of giant hydrocarbon fields are in their late development phases consequently project teams are looking for a way to extend the field life economics using a proper approach. In such a case having a much robust reservoir model would be a great favor to reduce the risk and uncertainty of EOR/IOR plans. Successful development plan for the marginal project is highly controlled by the validity of conceptual model particularly where the complex structure or lithology components exist such as effective clay minerals and low saline water (in or ex-situ). In this study, it is focused on one of the EOR target reservoirs in Baram Delta which has significantly produced over 40 years. The main objective of this study is to characterize the variation of swept leg's reservoir properties when the low saline formation water exposes to the clay reach oil bearing intervals. The combination of different data sources such as nuclear magnetic resonance measurement, existing core data and invasion profiles together with conventional logs have been utilized to quantify the behavior of flow paths before and after water exposure. The results demonstrate the interaction between formation water and lithology components has no major impact on total porosity but there are drastic changes on pore geometry particularly on pore size distribution and tortuosity of the flow path. The most negative impact has been introduced to the reservoir permeability since it is highly controlled by the pore geometry. At the field scale both injectivity performance and sweep efficiency have been significantly affected by changing the ideal flow path and connectivity at the target sands. Eventually, an empirical equation was developed to characterize the magnitude of the damaged as the function of pore geometry. The result is expected to be used as an optimization algorithm to minimize the risk of upcoming development plan while it provides a better understanding of the real mechanism of fluid flow, uncertainty of the reservoir model, and performance of EOR plan.

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