Cairn India Limited, 3rd & 4th Floor, Vipul Plaza, Suncity, Sector 54, Gurgaon 122 002 kondal.reddy@cairnindia.com 10 th Biennial International Conference & Exposition P 277 Reducing the uncertainty in 4D seismic interpretation through an integrated multi-disciplinary workflow: A case study from Ravva field, KG basin, India Kondal Reddy*, Kausik Saikia, Susanta Mishra, Challapalli Rao, Vivek Shankar and Arvind Kumar Summary A 4D seismic survey was carefully planned, executed and interpreted on the Ravva Field. The 4D studies include both qualitative and quantitative interpretation methods. The integration of geoscience, engineering and 4D seismic data have provided key information that defines fault compartments, position of the current OWC and reveals potential undrained areas. The preliminary results from the 4D seismic data has been used to optimize sub-surface targets, and underpinned Cairn India’s infill drilling campaign, which was instrumental in arresting the production decline in the field. The infill drilling results, as well as on-going dynamic reservoir surveillance programs are in line with 4D interpretations. All these results are being used to update the reservoir model for optimal reservoir management and development. 4D seismic interpretations provide vital information about the dynamic changes in the reservoir. However, it also contains inherent uncertainty. In this paper, we will first discuss the qualitative and quantitative 4D seismic interpretation results, and the importance of pressure and saturation decoupling from the 4D signal in order to identify bypassed oil areas. Next, we will discuss the pitfalls and uncertainties in the 4D seismic interpretation and finally we will show how the integrated multidisciplinary workflow helped us in reducing the uncertainty in the 4D seismic interpretation. Keywords: 4D seismic, fault seal analysis, pressure and saturation decoupling, multi-disciplinary, simultaneous AVO inversion. Introduction The Cairn India operated Ravva Field is located off the shore of the Godavari Delta, within the KG Basin, on the east coast of India (Figure.1). The field was discovered in 1987, and consists of two main structural compartments; referred to as the ‘RAD’ and ‘REFB’ blocks, which are separated by a shale-filled erosional unconformity cut of Pliocene age. The field comprises a series of tilted and rollover fault blocks formed as the Pliocene Godavari delta edge collapsed, and these together with the overlying Pliocene shale provide the trapping mechanism in the field. The main reservoirs are multi Darcy sands of Middle Miocene age. The field was put on production in 1993 and the water injection started in 1997. Currently, production in the field is declining with increasing water cut. Figure 1: Location map of Ravva Field.