3D seismic proves its value in Bakken geosteering

Abstract

Improved geosteering performance has been hailed publicly by WPX Energy management as a key driver in achieving lower well costs in the Williston Basin. Geosteering errors in the basin were reduced by 90% from mid 2012 to early 2013. This impressive improvement is in part attributable to the use of advanced processing of 3D seismic data. Using 3D seismic for geosteering applications requires (1) resolving the Bakken interval, a well documented challenge in the Williston Basin, and (2) accurately converting seismic surfaces to depth, an easy task filled with hidden problems. Resolving the Bakken interval is the most critical and arguably the most difficult objective for 3D seismic data in the Williston Basin today. 130 square miles of 3D data were reprocessed rigorously at the front end so that high frequency “extender” (HFE) approaches had a chance to produce stable and geologically plausible results. Upper Bakken, Lower Bakken and Three Forks horizons were mapped using the HFE volume, providing higher confidence geosteering surfaces. Converting to depth with HFE 3D seismic shed light on another important challenge with creating accurate geosteering surfaces: well tops and their accuracy. Careful examination of both logging procedures and depth calibration of wire line versus MWD/LWD tools must be performed. Examples can be shown that this issue is more the culprit for depth conversion inaccuracies than uncertainty in seismic velocities. Additionally PSDM comparisons are available to take advantage of carefully vetted well tops and meticulous seismic velocity determinations. WPX Energy has demonstrated bottom-line value in applying 3D seismic data as a geosteering tool when proper attention has been paid to seismic processing and depth conversion.

AAPG Datapages/Search and Discovery Article #90193 © 2014 Rocky Mountain Section AAPG Annual Meeting, Denver, Colorado, July 20-22, 2014