The Oil India Limited (OIL) has conducted the first-ever Airborne Gravity Gradiometry and Gravity-Magnetic (AGG & GM) survey at Dibrugarh heralding another milestone in G&G appraisal in Upper Assam Shelf.

Joint secretary (exploration) of the Ministry of Petroleum and Natural Gas (MoPNG), Amar Nath recently flagged off the AGG & GM survey in presence of the chairman and managing director of OIL, SC Mishra, director (HR & BD) Biswajit Roy and RCE, DK Das.

Earlier, director (E&D) Dr P Chandrasekaran and director (Operations) PK Goswami visited the aircraft and had discussions with OIL and Bellgeo teams at Dibrugarh on November 21, 2020.

To keep abreast with the latest technological developments, a technology induction initiative ‘TECHNOTHON” was institutionalized by OIL.

Induction of AGG & GM survey is an outcome of the inaugural session, Technothon-1 held in December 2017.

A total of 21000 LKM over an area of 9000 km2 is planned to be covered by the AGG & GM survey.

The data will be acquired in seven OALP Round-I blocks, three PELs and two PMLs in the logistically inaccessible terrains of the Northeast, including Dibru-Saikhowa National Park (DSNP), Brahmaputra River Bed (BRB) and geologically complex Thrust-Belt Areas in Assam and Arunachal Pradesh.

“The study is expected to provide understanding of the Sedimentary Structure & Basement Configuration, add value in understanding the ‘Regional Hydrocarbon Prospectivity’, better assess hydrocarbon prospectively in inaccessible areas and reduce ambiguity in geologically complex thrust belt areas,” an OIL press release stated.

AGG survey measures the spatial rate of change of gravitational acceleration. The sensors in the survey-aircraft measures five independent components of gravity field and provides high resolution image of various constituents of density contrast. Magnetics is a measure of the variation in the intensity of the earth’s magnetic field caused by sub-surface geology.

The technique is efficient and a non-invasive exploration tool with quick turnaround time enabling coverage of wide area in the shortest possible time and provides value addition to overall appraisal of the area.

The Acquisition, Processing & Interpretation of AGG & GM data is being done by the pioneer of the technology viz. ‘M/s Bellgeo Enterprises Limited, U.K. After obtaining the statutory clearances, the acquisition of AGG & GM data commenced on November 29, 2020.

Avik Chakraborty

Avik Chakraborty is Northeast Now Correspondent in Dibrugarh. He can be reached at: