Ravva oil and gas field is located offshore, eastern India, in the shallow waters of the Bay of Bengal. The field is operated by a Joint Venture of which Cairn India Ltd. is the Operator. The field has completed 15 years of production from Middle Miocene reservoir, with over 9 years on plateau production of 50,000 BOPD. The field has two oil blocks, designated as RA/D block and RE/F/B block. The latter is the smaller of the two: it accounts for nearly a quarter of Ravva STOIIP. Until an integrated reservoir modeling study was undertaken in 2004/05, the RE/F/B block was generally recognized as an area with poor understanding of structure and hydrodynamics. This lack of understanding was attributable to three main factors: a) attenuated seismic response in the central RF area due to the presence of gas at the shallower Late Miocene level b) complex compartmentalization with low net-to-gross and c) the Class II AVO response presented by hydrocarbon-charged Middle Miocene reservoir sands. To overcome these challenges, shear reflectivity (Rs) data, in conjunction with derivative rock property attributes and validated by dynamic pressure data, was used to develop a new geological model: the basis of an infill drilling campaign comprising of one producer and two injectors. The infill drilling campaign has now been carried out and the proposed wells have achieved their objectives.
This paper presents the novelty of the multi-disciplinary approach, in which shear information, inherent in the p-wave seismic gathers, was leveraged and integrated with reservoir pressures and other geotechnical data to make a representative model and realize a successful drilling campaign.