Dual Inversion Applied to 2D Multi-Component Seismic Data Onshore Libya

In line with the theme of the conference 'Opportunities in Mature Areas' (Sirt basin onshore Libya), 2D3C (multi-component) surface seismic data have been acquired, processed and inverted on behalf of Wintershall Libya in concession C97-I. In this area, presence of non-reservoir is the main risk for new wells. Reservoir sandstone can be partly or fully missing because of shallow basement or intrusions of basalt or deposition of volcanoclastics. From integrated reservoir characterisation studies it was concluded that it is the ratio of compressional to shear wave velocity (Vp/Vs) that allows differentiating reservoir sandstone from non-reservoir. Vp/Vs can be estimated by simultaneous ("dual") inversion of multi-component surface seismic data. In areas of good seismic data quality, the Vp/Vs inversion results correlate very well with well data. In areas with medium to poor seismic quality, Vp/Vs sections can still be interpreted in a relative sense. Therefore, the technology has the potential to help reduce the risk of dry wells in this area.