TDI-Brooks International Inc. has completed the offshore multibeam phase for TGS offshore the Niger Delta, the company said on May 15. This survey took place in water depths of 750 m to 3,500 m and is Nigeria’s first regional multiclient, multibeam and seafloor sampling (MB&SS) study.

TDI-Brooks’ R/V Gyre acquired 82,000 sq km (31,660 sq miles) of high-resolution hull-mounted multibeam echo sounder data. During the multibeam data collection, 1,223 active hydrocarbon seeps were detected in the multibeam water column data. Onboard hydrocarbon seep analysis was conducted in near real-time onboard the vessel to expedite the process of core selection.

TGS Nigeria gas plume. (Source: TGS)

The R/V Proteus is scheduled to begin acquisition of the follow-up surface geochemical exploration (SGE) coring campaign in July 2020, where approximately 245 piston core samples targeting suspected seep features selected from the MBES dataset will be collected, along with an additional 45 additional piston core samples for geotechnical and biostratigraphic studies. An additional 17 surface heat flow measurements will also be collected as part of the program.

SGE is a petroleum prospecting tool based that traces upward migrated petroleum from deep source rocks and reservoirs in targeted seabed sediments and is used to evaluate exploration potential.

Modern SGE campaigns utilize an integrated approach to identify seepage on the seafloor, pinpoint core locations, and accurately characterize geochemical results. The science and art of this seep hunting involves proper selection of core sites from the geophysical records, safe and skilled acquisition of seabed cores at these exact sites, analytically distinguishing promising samples from samples with varying levels of natural background concentrations, and properly interpreting the geochemical results in a geologic context.

SGE campaigns are a low-cost exploration tool that provides insight into reservoirs at depth before a well is ever drilled.