The client was operating a gas and oil producing block and wanted to delineate farther the distribution of the gas and oil reservoir in order to extend its drilling program. The conventional seismic provided no information and were rather useless due to a heavy limestone weathering zone extremely rough topography and severe seismic penetration problems due the existence of an evaporitic layer.

A high resolution passive seismic tomography using 90 LandTech’s passive seismometers was contacted over the area of interest. Two 3D velocity and Vp/Vs cubes were obtained bellow the entire block and revealed unknown structural details and even more delineated the hydrocarbon reservoir with surprising accuracy. Below we depict to Vp and Vp/Vs sections cut from the 3D volumes.

Passive seismic case study

Although the Vp results show structural details which can justify the location of the reservoir if one looks at the Vp/Vs results can clearly see the extend of the gas reservoir. We remind again that conventional seismic were totally useless.

Passive seismic case study