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Overview of Advancement in Core Analysis and Its Importance in Reservoir Characterization for Maximizing the Recovery

Abstract

Recoveries in offshore fields are lower compared to onshore fields predominantly due to larger well spacing, inadequate reservoir characterization and shorter life cycles of the projects. Efforts are in vogue to maximize the recovery by applying EOR techniques. Reservoir rocks saturated with hydrocarbons are complex on both at macroscopic and microscopic scale and this complexity controls the initial quantity and distribution of hydrocarbons and flow behavior of fluids within the reservoir. Flow behavior becomes more complex with injected fluid used for improving the recovery. Therefore, reservoir characterization is of utmost importance for EOR processes evaluation. Core and log analysis along-with pressure-production data greatly help to adequately define the reservoir and reduce the uncertainty associated with it. This paper discusses about the importance and criticality of core analysis starting from core acquisition, preservation, laboratory studies, analysis and application of data for EOR. Discussion is made for the selection of most appropriate coring technique and lab studies on cores for reservoir description, estimation of EOR incremental oil and formation damage during injection and production processes. Critical analysis is made to highlight the quality and quantity of core analysis data needed for petrophysical interpretation, understanding the storage and flow behavior during primary, secondary and tertiary recovery stages. Also important guidelines are provided for selection of number of plug samples for studies, laboratory methodologies, their strengths and weaknesses, and QC/QA techniques. The paper further elaborates the recent advances related to core analysis for understanding the EOR processes, in-situ saturation monitoring, interaction between injectants and rock-fluid along-with mitigation experiments. Digital core/Pore network modeling is one such emerging technique for the visualization, characterization and SCAL measurements of reservoir rocks. It can provide routine and special core analysis measurements and petrographic analysis which can be used in the quick evaluation of static and dynamic petrophysical properties and flow behavior.