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Depositional Processes and Reservoir Characterization of Kamalapuram Formation, Nagapattinam Sub Basin, Cauvery Basin, India

Syamalendu Mahanti1, Prabhakaran Selvaraj2, and Harinder Upadhyay1
1ONGC, Dehradun, India
2ONGC, Karaikal, India

Hydrocarbons bearing multi-layer sandstones of Kamalapuram Formation (Paleocene - Early Eocene) in Cauvery basin are distributed in East - West trending submarine canyon. A number of conventional cores from the canyon of Nagapattinam-Tranquebar area were studied to understand the depositional processes, sand distribution patterns and reservoir characterization.

Systematic sedimentological investigations of cores have enabled identification of five major sedimentary facies namely, clast free sandstone, clast dominated sandstone, bioturbated sandstone, slump associated sandstone and pelagic shale. Based on the study, a conceptual depositional model is made which demonstrates three dominant processes - debris flows, slumps and bottom current reworking, defining the sedimentation pattern. Sandy and locally muddy debris flows are the main mechanisms transporting sediments from the shelfal part to the deep canyon. Bottom current reworking of sediments, due to deep marine tidal processes is common in the wells located in the axial part of the canyon. These reworked sand units are thin and elongated parallel to canyon axis. Sand geometry is expected to be of ribbon type distributed in an east- west direction. The deep marine tidal sands are better reservoirs which are fine grained, moderately to well-sorted quartz arenite, quartz wacke and occasional calcareous arenite. Chemical diagenetic imprints in the form of pore filling authigenic kaolinite, mixed layer and chlorite clays and patchy occurrence of calcite cements are noticed which has little effect on the modification of porosity and fluid transmission.

Presentation GEO India Expo XXI, Noida, New Delhi, India 2008©AAPG Search and Discovery