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Secondary oil recovery projects in naturally fractured carbonate reservoirs (NFR) often introduce uncertainties and challenges that are not common to conventional waterflood. The recovery mechanism in NFRs relies on ability of fracture network to deliver enough injected fluid to the matrix, as well as rate and magnitude of capillary interactions within the matrix rock, during which hydrocarbon displacement occurs. The imbibition measurements can be performed in the lab using core samples, but due to reservoir heterogeneity, certain limitation of the lab equipment and quality of the core material, scalability of the core results to a reservoir model can be challenging.
This paper describes the design, execution and evaluation of the Log-Soak-Log (LSL) pilot test conducted in a giant naturally fractured carbonate reservoir with tight matrix in Western Kazakhstan, where repeatable and reliable measurements of water saturation change were achieved across large intervals (tens of meters) using a time-lapsed pulse neutron logging technique. Periodic measurements provided valuable observations of dynamic change of saturation and fluid level over time and allowed estimation of the rate and magnitude of imbibition in the slope margins, depositional settings and rock types of interest. Incorporation of the LSL results into reservoir models validated the ranges of water-oil relative permeability curves, residual oil saturation to water, irreducible water saturation, and capillary pressure assumptions. This validation constrained key subsurface uncertainty and updated oil recovery forecast in Improved Oil Recovery (IOR) waterflood project.
Yegor Se is a Cased Hole Petrophysicist in Chevron Energy Technology Company, Houston. He currently specializes in well integrity, production optimization and through casing reservoir characterization for various Chevron operations worldwide, consulting on all stages of cased hole logging operations from planning and execution to interpretation and results diagnostic.
In his previous assignments, Yegor supported active drilling campaign and major capital IOR projects and has rich cross-discipline operational experience with well planning, drilling and completion, workover, production optimization and stimulation, reservoir surveillance, modeling and simulation in naturally fractured carbonate reservoirs.
He obtained his BS in Petroleum Engineering from Colorado School of Mines in 2009. Yegor later graduated from the first Chevron Petrophysics Organizational Program in 2011.
Yegor has played active role in regional SPE activities, serving as Technical Chairman and Chairman of SPE Atyrau Section and Technical program committee and session chair during SPE Caspian Technology Conference and Exhibition. His technical contributions were recognized by SPE in 2016, when he received SPE Regional Technical Award in Formation Evaluation in Russian and Caspian Region.