Wavelet-Consistent Reprocessing of Multi-Environment 3D Seismic from Abu Dhabi

By

 Michael P. West¹, Erik Kleiss², Abu Baker Al Jeelani², Mohamad Samir Al Nahhas², Constantine Tsingas¹

(1) Petroleum Geosciences Services, Cairo, Egypt (2) Abu Dhabi Company for Onshore Oil Operations (ADCO), Abu Dhabi, United Arab Emirates

 A vibroseis survey was reprocessed jointly with an adjacent transition zone survey. Data of high temporal and lateral resolution, and of good structural and stratigraphic accuracy is required here for mapping of subtle faults and improved reservoir characterization. Accurate statics solutions and reliable wavelets are critical - here 6ms false structure can make the difference of an oil well or one in the water. The older data has laterally variable bandwidth, phase and structural errors, resulting from inadequate statics and from unsatisfactory matching of source- and receiver types.

Consistent data character requires good wavelet corrections for the various source-receiver combinations. In our reprocessing, partly-deterministic and partly-statistical (PDPA) zero-phasing dealt with these issues. Well-proven deterministic phase corrections were applied to the vibroseis data. A statistical deconvolution ("PSW designature") was used for zerophasing the impulsive-source data and removing the hydrophone ghosts. This route avoids ad-hoc phase matching of overlapping parts of the data. Our method was validated using numerous comparisons of pre-stack and stacked data.

All data were zero-phased before first-arrival picking and refraction statics, ensuring consistency between statics-related and zerophasing-related time shifts. This avoids structural errors resulting from lateral phase variability. Phase-corrected impulsive-source first arrivals were found consistent with those for zero-phased vibroseis.

This approach for matching the various data types yields a consistent data character across the combined surveys. The easier correlation of first-arrival data and absence of any post-statics space-variant phase corrections is expected to improve the structural accuracy.