Abstract

Encouraged by the proven presence of hydrocarbons during production testing of two objective levels within Jalangi Formation in the well G # 1 in Gobindpur area of Bengal Basin, a 3-D seismic survey was designed to delineate the extension of pay sands encountered in the well. One crew from the southern sector of ONGC was entrusted the task of acquiring 3-D seismic data in an area of approximately 70 square km (full fold migrated area) over the structure, making it as the first attempt in ONGC for inter-regional crew mobilization so far as acquisition of 3-D seismic data is concerned. Stateof-the-art technology was deployed at all stages of acquisition starting from planning and designing suitable survey geometry to data collection in the field, real time data quality monitoring in the field and in-field data processing for quality check. The 3-D survey geometry was designed by MESA software package while the data was acquired by SN408UL recording instrument. Data was recorded with 1176 channels utilizing orthogonal geometry consisting of 12-receiver lines. The SQC Pro was utilized for real time QC check and data analysis. Quality norms in accordance with ISO 9001 standard procedures were strictly adhered to for achieving good quality data. Preliminary processed stack sections show high-resolution seismic reflection data that can now be interpreted to image the structural and stratigraphic features of the subsurface with greater certainty. The thrust of the work was on quality aspects of data acquisition. The systematic planning, execution and successful completion of the project are documented as a