Abstract:

Analysis of 3D seismic data in the area of 1500 km2 offshore Cameroon reveals a large area of BSR occurrence, c. 350 km2 in water depths ranging from 940 m - 1750 m. The BSR is associated with the amplitude anomalies which are bright spots above the BSR and pull-up BSR. The areas of bright spots have been mapped in three zones, from zone 1 to zone 3, with the area of 60 km2, 8 km2 and 84 km2, respectively. The appearance of bright spots in the blanking zone is supposed to be caused by the development of porous sandstone of channel-fan complex in those areas, from Pliocene to Pleistocene. The porous sandstone layers will store more free gas thus have higher concentration of gas hydrate compared to the surrounding areas. Due to the higher concentration of gas hydrate, the Vp of seismic velocity will increase incredibly, creating the bright spots in the blanking zones. The pull-up BSR phenomena is observed within the pipe and beneath the pockmark depression proved for the local positive heat flow anomaly in the study area. There are number of pipes and pockmarks observed in the study area possibly suggesting for the slightly rise the thermal gradient of the study area.