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Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
Impact of Accurate Velocities from Signal Fidelity Enhancement for Reliable Seismic Interpretation - Example from Kuwait
(1) Exploration, Kuwait Oil Company, Kuwait, Kuwait.
In September 2008 Kuwait Oil Company (K.S.C.) acquired a 3D seismic survey across Arifjan area, S-E Kuwait. The primary objective of this survey is to image the Mid-Marrat Jurassic reservoir through maximizing the signal fidelity and the vertical resolution.
Following the processing of the seismic data, it was clearly recognized that the velocity analysis/picking, interpretation and velocity field modeling are the most crucial steps for enhancing the temporal resolution, needless, to say very challenging to achieve.
Accurate velocities have a great impact on flatting the gathers and consequently enhancing the frequency contents; the subtle changes in both RMS and interval velocities have shown a significant effect on some of the main processing stages such as residual statics calculation, de-multiple techniques, imaging and stacking, a special care of handling the velocity analysis and picking was considered.
In addition to the effective data preconditioning prior to the velocity analysis, different powerful velocity analysis tools were tested to identify the most suitable ones to use. Important processing steps were applied prior to velocity analysis to precondition the data for such as noise attenuation, multiple removal and inner trace mute.
Several rounds of interactive velocity picking have been run to fine tune the stacking velocities in order to achieve the best stacking response. Continuity and resolution of seismic horizons apparent anisotropic and high order moveout were tested. Finally the Spatial Continuous Velocity Analysis (SCVA) has been applied to achieve a much higher accuracy in the picking of stacking velocities. These refined velocities were then passed through a velocity model builder (VMB) to stack the final product ready for interpretation.
This case study will present the different velocity analysis techniques applied and will focus on the results achieved using these techniques and its impact on improving the seismic interpretation.