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Sequence Stratigraphic Framework of Eastern Offshore Petroleum Province of India - Implications to Hydrocarbon Exploration

Adhikari, Subhrashis; Mathur, Sudhir; Jana, Bikashkali; Naidu, Bodapati N.; Mohapatra, Pinakadhar
Cairn India Ltd, Gurgaon, India.

A regional sequence stratigraphic analysis of the eastern offshore petroleum province of India has been undertaken to define new plays and yet-to-find potential. The project includes analysis of available free air gravity and magnetic data, paleobathymetry data, 40,000 LKM of 2D and 3000 sq km of 3D seismic data, in addition to data from over 100 wells. Detailed choronostratigraphic charts and relative sea-level (RSL) curves for each of the basins along the eastern sea board of India have been reconstructed using regional sequence boundaries, calibrated with the biostratigraphic information.

Seven major sequences are identified by correlating well-logs, cores and cuttings descriptions and RSL curves. Detailed study of the seismic data revealed four distinct facies in the rift-fill: bright parallel continuous reflectors (BPCR), dipping seismic reflectors (DSR), discontinuous reflectors (DR) and mounded reflectors (MR). The BPCR were interpreted as lacustrine deposits with good source-rock potential. DSR and MR are interpreted as alluvial fans and deltas. Similarly, the depositional facies distribution in the overlying passive margin sequences - fluvial, delta, slope and deep-water fans have been identified based on the seismic data and well information. Gross Depositional Environment (GDE) maps and Composite Common Risk Segment (CCRS) maps have been prepared for each sequence to identify and rank the sweet-spots.

The project reveals significant potential of the hitherto less explored Late Jurassic to Early Cretaceous rift-fill sequence along this margin. A recent discovery by Cairn India Limited in the rift-fill sequence has further proven the importance of undertaking such projects to identify untested exploration targets.

 

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012