Where deep reservoirs of oil and natural gas occur, unusual underwater ecosystems may form on the seafloor above. As hydrocarbon-rich fluids seep through fissures in the earth’s crust, you can find thriving communities which have evolved independently of sunlight.
Seep life relies on a process called chemosynthesis, rather than photosynthesis. While most life on the surface of the earth gains energy from sunlight, specialised microorganisms associated with seeps metabolise methane and hydrogen sulphide released through the seabed, forming the base of the food chain upon which seep communities develop.
In the quest to discover and further understand deep oil and gas reserves, Fugro have led various seep-hunting surveys – last year off the coasts of Myanmar, Vietnam, USA, Mexico, and Belize in waters between 100 and 4,700 metres deep.
As part of these surveys, Fugro’s environmental team, in Edinburgh, document the unique communities associated with these seeps. Analysis of the footage collected from drop-down cameras revealed microbial mats – multi-layered sheets of micro-organisms – dense mussel beds and carbonate rock outcrops, which form as the emanating hydrocarbons react with sulphate-rich fluids close to the surface of the sediment. This complex mosaic of habitats provides both food and shelter, and attracts a variety of different species, including the tube worms, clams, gastropods, crabs, and brittle stars.
This year, Fugro continues to conduct the world’s largest offshore seep-hunting survey, an 18-month campaign covering an area of over 800,000 km2 off the coast of Mexico and the Southern United States of America. The survey uses hull-mounted multibeam echosounder (MBES) and sub-bottom profiler systems to map the deep waters.
The data acquired will be used to identify sites where deep hydrocarbon-rich fluids are escaping to the seafloor and to target hundreds of sites for coring and geochemical analysis.
Fugro’s Global Centre of Excellence for Seep Studies, in Houston, ensures every seep-hunting project is consistent, no matter the location. Its pioneering data acquisition technology and interpretation methods help innovative oil companies to maximise their deepwater exploration success.
Oil ‘seeps’ on the seabed were discovered less than 40 years ago, and since then have been found in every ocean on the planet.
Our seep hunting and geochemical campaigns are an innovative method for economical and effective exploration, especially in frontier regions where prospectivity is uncertain.