The value of reprocessing legacy data : a case study of Bois d'Arc, a Mississippi play in northeastern Oklahoma

Abstract

Exploration companies have been producing the Mississippi Lime and overlying Redfork for almost 100 years, such that legacy 3D surveys cover significant parts of northern Oklahoma. Early 3D seismic surveys were acquired and processed to image conventional structural and stratigraphic plays that would be drilled by vertical wells. Modern adoption of horizontal drilling, acidation, and hydraulic fracturing have resulted in the Mississippi Limestone of Northern Oklahoma/Southern Kansas moving from marginal production to becoming one of the newest "unconventional" plays. With advances in processing algorithms and workflows, improved computing power, the desire to not only map structure but also to map rock properties such as density, porosity , lithology, P-wave velocity, S-wave velocity and the need to accurately land and guide horizontal wells, seismic data once thought to be sufficiently processed need to be re-examined.

I illustrate the value of reprocessing a legacy seismic data volume acquired in 1999 in Kay County, OK by applying a modern workflow including surface consistent gain recovery and balancing, advanced phase match filtering of merged datasets, 3D FKK for ground roll attenuation, wavelet processing of vibroseis data in order to minimum phase convert for Wiener-Levinson spiking deconvolution. Final steps include Kirchhoff Prestack Time Migration followed by modern spectral enhancement. Each step adds incremental improvements to vertical and lateral resolution. I use both geometric attributes and impedance inversion to quantify the interpretational impact of reprocessing and find an improvement on vertical resolution from 20 m to 15 m. Coherence and curvature techniques show more detailed faulting and folding while ties to blind impedance wells increase from R=0.6 to R=0.7. Prestack acoustic impedance inversion indicates lateral changes in density and impedance that are consistent with tripolitic chert sweet spots.