Rajive Kumar

Seismic Source Comparison For Shallow Targets In North Kuwait Field

A 2D seismic reflection line for shallow targets in north Kuwait was acquired in December of 2010 with varying source types: explosives, accelerated weight drop, small (15,000 lb) vibrator, and heavy (80,000 lb) vibrator. The exploration target is shallow at around 100 ms to 400 ms two-way time (TWT). The objective of the study was to establish the optimal source effort for a planned 3D survey. The accelerated weight drop proved to be inferior to the other source types because the data lacked high-frequency content. Explosive data benefit from the absence of engine noise and less surface-wave noise compared to the other source types used; yet, the overall energy penetration was not as good as expected. The best data were achieved with vibrators. The small 15,000 lb vibrator produced less engine noise, but fell somewhat short with the observed frequency bandwidth compared to the heavy 80,000 lb vibrator because of vibrator design and energy penetration. The final stacked sections of the two vibrator data are very comparable, however, in the overall imaging of the subsurface. In addition, we acquired the 2D line a second time with the heavy vibrator refitted with an exhaust silencer kit that reduced the engine noise and air wave in prestack data. This has improved the signal-to-noise (S/N) ratio in the stacked data by 2 dB.

Fracture characterization using seismic data in a West Kuwait field

Summary This paper describes a multi-scale seismic approach for characterizing reservoirs affected by large scale fracture corridors (close to seismic resolution) as well as diffuse fractures (far below seismic resolution). To reach such objective, the method is based on joint use of three approaches: (1) post-stack discontinuity analysis, (2) azimuthal inversion and (3) lithology prediction using prestack inversion and characterization. This paper illustrates how these known approaches can be used simultaneously to provide a comprehensive description of the fracture network, calibrated at wells and validated against the conceptual fracture models.