The client wanted to define the evaporite cap of a gas reservoir in order to decide the location of 3 planed wells after constructing 2 dry wells . A 2D seismic survey that was contacted in the area provided no results due to heavy seismic penetration problems caused by the heavily weathered surface limestone and an extensive layer of evapoorites. From sonic measurements within the existing wells and core measurements it was found that the evaporites were characterized by values of Vp/Vs less than 1,739.

LandTech installed a 64 stations passive network and operated it for a period of six months. Isolating the formations with Vp/Vs values less than 1.739 a general view of the evaporitic cap was obtained (see figure below).

Passive seismic case study