Identification and Study of the Lower Permian Reef–Bank Bodies in the Pre-Caspian Basin
Reef–bank reservoir is one of the targets for exploration of marine carbonate rocks in the Pre-Caspian Basin (Fig. 1). Within this basin, the reef–bank bodies were primarily developed in the subsalt Devonian–Lower Permian formations and are dominated by carbonate platform interior and margin reef–banks. The Lower Permian reef–bank present in the eastern part of the basin is considered prospective. This article provides a sequence and sedimentary facies study utilizing drilling and other data, as well as an analysis and identification of the Lower Permian reef–bank features along the eastern margin of the Pre-Caspian Basin using sub-volume coherence and seismic inversion techniques. The results indicate that the sub-volume coherence technique gives a better reflection of lateral distribution of reefs, and the seismic inversion impedance enables the identification of reef bodies’ development phases in the vertical direction, since AI (impedance) is petrophysically considered a tool for distinguishing the reef limestone and the clastic rocks within the formation (limestone exhibits a relatively high impedance than clastic rock). With this method, the existence of multiple phases of the Lower Permian reef–bank bodies along the eastern margin of the Pre-Caspian Basin has been confirmed. These reef–bank bodies are considered good subsalt exploration targets due to their lateral connectivity from south to north, large distribution range, and large scale.
KeywordsReef–bank body Carbonate rock Pre-Caspian Sub-volume coherence Petrophysics
This work is supported by Special and Significant Project of National Science and Technology “Global oil and gas resources assessment and constituencies with research” (No: 2016ZX05029)., and is published with the approval of Research Institute of Petroleum Exploration and Development, PetroChina.
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