The Use of Seismic While Drilling in Ultra Deepwater Drilling - A Case history from Andaman Sea

The advancement in logging while drilling (LWD) technologies and computing power has revolutionized the utilization of seismic data in the exploration life cycle. Not only is surface seismic being used for the study of regional geology, petroleum system, prospect identification and volumetrics through integration with well data, it is now being successfully used to ‘guide’ deepwater drilling and manage drilling uncertainties, particularly drilling target depths. This new initiative led to seismic while drilling (SWD) technology being used for first time by Oil and Natural Gas Corporation, ONGC, on their Andaman Seas deepwater drilling campaign. We present a method that makes use of LWD technology with little impact on drilling operations. The SWD checkshot was acquired at every drill string stand depth without disturbing the normal drilling operation and rig time. As drilling continues, the updated velocity model was used to:- • Confirm the drill bit position on the revised surface seismic section as drilling continues • Recalibrated Pore Pressure prediction The case study demonstrated that SWD technique was successfully used during the deepwater exploratory drilling campaign in Andaman Sea by ONGC that help saving of more than 10 drilling days.