Abstract

Over the past few decades, India’s oil and gas explorers have aimed to unlock the hidden potential of the country's hydrocarbon resources along the west coast of India, specifically in Shallow Water and Transition Zone areas, to strengthen the nation's energy security. The area, especially the Gulf of Cambay, was sparsely covered by 2D seismic surveys due to logistical challenges. Acquiring 3D seismic data in the shallow water and transition zones of this region has always been a highly challenging task. Multiple attempts to initiate 3D seismic surveys were unsuccessful. However, Sun Petrochemicals Pvt Ltd. accepted the challenge and decided to commence 3D seismic acquisition in this transition zone area. The area under focus lies at the confluence of two rivers - the Sabarmati River on the western side and the Mahi River on the eastern side - with numerous creeks and channels, along with a rugged seabed topography. Operational challenges such as high tides (up to 10 meters), strong underwater currents (up to 5 knots), a limited operational time window (2–5 hours), and sticky, marshy, mud-filled channels make seismic acquisition logistically demanding and extremely difficult. Another challenge was faced during acquisition is that time duration between two consecutive low/high tide was very short to get the deployment, shooting and retrieval done before the next tide. To overcome the logistic challenges faced, entire seismic operation was synchronised with tidal variations. This paper presents the geophysical and logistical challenges encountered during 3D seismic acquisition in this region (up to 5 meters water depth during high tide), as well as the methodology and innovative approaches adopted to overcome these challenges through proper resource planning and management, and optimization of field geometry and acquisition parameters.