Processing of Full Azimuth, High-density Land Acquisition - 3D Irharen, Algeria

Using a square spread of closely-spaced receiver stations, a full azimuth dense 3D survey was recorded in 2005-06 over the Irharen gas discovery in Algeria. A basic square-spread geometry was chosen for reasons of azimuthal coverage. The processing had to deal with a huge amount of data and encountered the classical land processing issues of statics and amplitudes. An innovative processing sequence was developed to take into account the multi-azimuth distribution. The high density acquisition provided a good spatial sampling of the subsurface and allowed high density velocity picking to determine 2nd and 4th order velocity fields. The parallel processing and interpretation saved considerable time by producing several fast-track products and intermediate inversion cubes, necessary to answer operational constraints. This approach gave very encouraging qualitative results in terms of fractured reservoir definition.