--> Abstract: Seismic Technologies for Unconventional Reservoir Characterization: Wamsutter Field Case Study, by Rosemarie T. Geetan, Brian Hornby, and Ricko Wardhana; #90124 (2011)

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Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA

Seismic Technologies for Unconventional Reservoir Characterization: Wamsutter Field Case Study

Rosemarie T. Geetan1; Brian Hornby2; Ricko Wardhana1

(1) North America Gas, BP America Inc., Houston, TX.

(2) E&P Technology, BP America Inc., Houston, TX.

As part of a significant seismic technology effort, the BP Wamsutter Seismic Integration team conducted two extensive field trials during 2006 and 2007- a surface seismic field trial and a borehole seismic field trial.

The surface seismic field trial consisted of a world’s-first deployment of cableless full-wavefield single-sensors in a 3D onshore survey. This acquisition delivered a unique high density, full azimuth, 3-component dataset for analysis. Very careful processing was applied to the full wavefield data to optimize resolution and retain robust amplitude and azimuthal information. In addition to conventional full stack seismic attributes, analysis of velocity anisotropy, AVO (Amplitude with Offset) and AVOAz (AVO with Azimuth) attributes calibrated to well data have greatly increased our understanding of this tight gas sandstone reservoir.

The borehole seismic field trial consisted of a 3D VSP (Vertical Seismic Profile), as well as a four-well crosswell seismic campaign. The 3D VSP was acquired to further our understanding of seismic technical limits within the field, demonstrate the value of enhanced temporal resolution to reservoir characterization, and to test the viability of borehole seismic as a development tool for infill planning. Pre-acquisition modeling allowed theoretical limits of vertical seismic resolution to be compared to existing seismic data. Processing of the field data demonstrated that significantly higher frequencies (double the bandwidth) were achieved with the 3D VSP, as compared to existing and newly acquired surface seismic data. Prestack depth migration of the 3D VSP yielded high quality imaging results, which have allowed enhanced stratigraphic description of a very complex, heterogeneous reservoir.

Analysis, interpretation and integration of the surface seismic and borehole seismic data have greatly progressed our understanding of the potential increase in the value of “designer” or fit-for-purpose seismic across the Wamsutter Field and beyond. Learnings from the field trial are already impacting the onshore seismic strategy both within the Wamsutter field and across BP’s tight gas business.