--> ABSTRACT: Evolution and Development of the WolfBone Play, Southern Delaware Basin, West Texas: An Emerging Frontier; An Oil-Rich Unconventional Resource, by Fairhurst, Bill; Hanson, Mary Lisbeth; #90142 (2012)
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Evolution and Development of the WolfBone Play, Southern Delaware Basin, West Texas: An Emerging Frontier; An Oil-Rich Unconventional Resource

Fairhurst, Bill *1; Hanson, Mary Lisbeth 1
(1) Eagle Oil & Gas, Co., Dallas, TX.

The WolfBone play is an emerging unconventional oil-resource in the southern Delaware Basin. Exploration and development has been a systematic, progressive evolution from geologic concept to drilling, production, evaluation and revision of targets. Originally exploration focused on Wolfcamp sandstone reservoirs below and Third Bone Springs sandstone reservoirs above to current focus on the 1,000’ thick, oil-rich, unconventional Wolfcamp shale.

The Wolfcamp is an ideal heterogenitic resource consisting of quartz, carbonate and kerogen. Exploration and field development will be successful over a large area. However, the geologic and economic sweet spot is limited to the proximal basin floor on the gently-dipping western flank. In this setting quartz and kerogen accumulated in the quiet deep-basin interrupted by episodic deposition of shelf to basin floor carbonate debris flows that settled at the de-acceleration boundary between the slope and basin floor. These depositional processes resulted in compositional and grain-size heterogeneities and accumulation of the thick organic-rich, technically and economically exploitable targets.

During maturation large volumes of oil were sealed in place (108 MMBOIP per Section). Expansion from kerogen to oil in a sealed system resulted in overpressure. Individual wells have flowed 45 MBO from 11,000’ prior to initiating Previous HitartificialNext Hit Previous HitliftTop; atypical of Permian Basin reservoirs. Farther into the basin and upslope these conditions do not exist and are outside the economic sweet spot. Basinward the unit is consistently thick, however, there is more shale and is starved of siltstones and carbonates. Upslope the unit thins is gas-prone and the mixture of coarser-grained shelf carbonates and sandstones provided migration pathways breaching the closed system, limiting productivity and ultimate economic recoveries.

Since 2009, this play has been developed with vertical wells co-mingling the oil-resource with conventional reservoirs. Interpretation of imaging logs has identified the primary fracture orientation and zones with conjugate fractures systems. Integration with production logs has optimized horizontal target identification and horizontal drilling has begun. The Avalon, being exploited in New Mexico, is also present. The Avalon sweet spots occur at similar depositional setting as the Wolfcampian resource and the same geographic position in this portion of the basin. The Avalon is estimated to have 103 MMBOIP per Section.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California