Choosing an Intermediate Statics Datum in Dune and Sabkha Topography
Faigle, Matthew *1; Hassan, Khaled 1
(1) Exploration Operations Department, Saudi Aramco, Dhahran, Saudi Arabia.
After the processing of many thousands of square kilometers (km^2) of Rub’al-Khali seismic data, an odd phenomenon became apparent on one of the more recent surveys. Artifacts (false time structure) not seen on the previous processing efforts began showing up during the pre-stack time migration (PSTM) step.
A review of the standard processing sequence began and the near surface was suspected of causing the problems. This was because it exhibited the most significant physical change from the previous surveys in the area. Specifically, an increase in frequency and amplitude (height) of the dune surface topography was dramatic in the new survey area as compared to the adjacent older surveys.
The impact of the floating statics datum was the first issue to be reviewed. The standard datum, used thus far, was a smoothed version of the surface topography. The smoothing used on the standard datum was on the order of one spread length with a two km radius. Testing of the radii of the smoothers included a four km radius, six km radius, and finally a complete stripping of the dune sand to the base of the sand (BOS).
The artifacts were still seen on the sections using the floating datum statics calculated with the four km smoother, but not on the data with the six km smoother or the data with the BOS approach. Subsequently, the BOS floating datum approach showed better data quality after revisiting the velocities and residual statics as compared to the six km smoother.
The BOS floating datum was selected as the intermediate datum for the PSTM and there were no artifacts in the resultant volume.
AAPG Search and Discovery Article #90141©2012, GEO-2012, 10th Middle East Geosciences Conference and Exhibition, 4-7 March 2012, Manama, Bahrain