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Seismic Facies and Geomorphology at Korolev Oil Field, Pricaspian Basin, Kazakhstan: Integration of Seismic, Image Log, and Core Leads to Improved Static Models


Korolev Field is an isolated carbonate platform (4x2 km) located 12 km NE of the giant Tengiz oil field. Microbial deposits at Korolev Field share some significant similarities and critical differences with those at Tengiz Field. Integrated reservoir characterization of Korolev was completed with seismic interpretation coupled with FMI and core, which yielded new insights into the architecture of the field and provided a basis for improved management of this complex, naturally fractured field. Recent core studies at Korolev suggest dominantly deeper water deposition in the platform interior of Korolev Field compared to the platform interior of Tengiz. At Korolev, abundant microbial boundstone occurs from late Visean through Serpukhovian, and Visean boundstone deposits are interpreted to occur across the entire platform. Microbial boundstone distribution in Korolev Field has contributed to the widely varying connectivity and observed well performance. At Tengiz, high rate wells are confined to the margin and upper slope locations where fractures are common in microbial boundstone. At Korolev, all well penetrations, ranging from the platform to the slope, exhibit high fracture connectivity. Newly acquired seismic data was used to update the Korolev stratigraphic framework and provide seismic facies to help constrain mapping of key reservoir facies. Seismic facies include parallel continuous reflectors (platform interior), chaotic seismic reflectors (upper slope to deep platform microbial boundstone), and inclined parallel continuous reflectors (slope and basin). Integration of the seismic with core, wireline and FMI data suggests a highly asymmetric, southward-facing, distribution of microbial boundstone facies (Serpukovian and Visean A strata) and the earlier development of boundstone facies across the entire platform (Visean B strata). The margins of the platform are aggradational throughout most of Visean time, then prograde strongly to the south during the Serpukovian. Partial drowning of the platform during Visean B time may have allowed the deposition of deeper water boundstone facies across the platform. This updated facies model explains the observed high productivity in the central portion of Korolev (different from Tengiz) based on the distribution of fractured boundstone across the platform. Using seismically mapped facies to constrain fracture models results in a more robust distribution of fractures density in the new static geologic model.