oa Impact of Accurate Velocities from Signal Fidelity Enhancement for Reliable Seismic Interpretation - Example from Kuwait

In September 2008 Kuwait Oil Company (K.S.C.) acquired a 3D seismic survey across Arifjan area, S-E<br>Kuwait. The primary objective of this survey is to image the Mid-Marrat Jurassic reservoir through<br>maximizing the signal fidelity and the vertical resolution.<br>Following the processing of the seismic data, it was clearly recognized that the velocity<br>analysis/picking, interpretation and velocity field modeling are the most crucial steps for enhancing the<br>temporal resolution, needless, to say very challenging to achieve.<br>Accurate velocities have a great impact on flatting the gathers and consequently enhancing the<br>frequency contents; the subtle changes in both RMS and interval velocities have shown a significant<br>effect on some of the main processing stages such as residual statics calculation, de-multiple<br>techniques, imaging and stacking, a special care of handling the velocity analysis and picking was considered.<br>In addition to the effective data preconditioning prior to the velocity analysis, different powerful<br>velocity analysis tools were tested to identify the most suitable ones to use. Important processing<br>steps were applied prior to velocity analysis to precondition the data for such as noise attenuation,<br>multiple removal and inner trace mute.<br>Several rounds of interactive velocity picking have been run to fine tune the stacking velocities in order<br>to achieve the best stacking response. Continuity and resolution of seismic horizons apparent<br>anisotropic and high order moveout were tested. Finally the Spatial Continuous Velocity Analysis<br>(SCVA) has been applied to achieve a much higher accuracy in the picking of stacking velocities. These<br>refined velocities were then passed through a velocity model builder (VMB) to stack the final product<br>ready for interpretation.<br>This case study will present the different velocity analysis techniques applied and will focus on the<br>results achieved using these techniques and its impact on improving the seismic interpretation.