--> Abstract: A Dynamic Approach to Evolution of Low Permeability Gas Accumulations in the Greater Green and Wind River Basins, Wyoming, by Randal L. Billingsley and Maria Wood Henry; #90039 (2005)

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A Dynamic Approach to Evolution of Low Permeability Gas Accumulations in the Greater Green and Wind River Basins, Wyoming

Randal L. Billingsley1 and Maria Wood Henry2
1Advanced Resources International, Inc, Denver, CO
2 Henry GeoConsulting Services, Englewood, CO

Preliminary conclusions from a produced water database study were used to develop a conceptual model for movement of gas and water through low permeability basins using a basin history framework. This work is supported by the Department of Energy (DE-FC-02NT41437).

Basin history is key to understanding changes in reservoir fabric and fluid movements, because it records the input and release of thermal and mechanical energy during basin burial and uplift cycles. These cycles of energy input and release control mechanical and chemical diagenesis of sediments through time. The diagenesis of porosity and permeability destruction in clastic sediments with increasing burial is well described. There has been less focus on describing diagenesis during an uplift (energy release) phase. The impact of stress reduction on reservoirs during uplift may be an important, underestimated mechanism for permeability enhancement of tight reservoirs.

Water chemistry, geomechanics, stratigraphy, and reservoir engineering were used to constrain our concept of tight gas reservoir development through time. The influence of lithology, stratigraphy and basin history (particularly uplift) in the development of these reservoirs was recognized. Natural fracturing plays a significant role in tight gas reservoir development at a wide range of scales and may be either lithology or basement controlled. The contribution of interbedded organic-rich shales and coals to reservoir storage and flow is poorly understood. Tight gas reservoirs are complex and can only be truly understood by thorough integration of all available lines of data.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005