AAPG ACE 2018

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Geological Controls on Fluid Distribution in Unconventional Hybrid Plays: Example From the Montney Formation of Western Canada

Abstract

The amount of liquids produced from individual wells has major technical and economic implications on the development of unconventional resources. Understanding the mechanisms and geological heterogeneity that control the present-day distribution of in situ fluids, provides a way to better predict spatial variations of well productivity and liquids/gas ratio. In the Montney resource play of western Canada, a regional maturity trend has long been recognized, as operators moved up dip from the overmature to the liquid-rich part of the play. However, the highly variable condensate-gas ratio from production data suggests a much more complex fluid distribution at sub-regional and local scales.

Mapping produced gas composition within a well-defined stratigraphic framework provides a powerful tool to identify geological controls that influenced hydrocarbon fluids distribution. Our analysis of over 1,500 producing wells in the Regional Heritage area of the Montney Play reveals complex local trends in gas composition and condensate-gas ratio. These trends suggest that stratigraphic and structural discontinuities influenced fluids retention, migration and trapping in the Montney Formation. Fluid compositions produced from different stratigraphic intervals show distinct spatial trends, highlighting the need for analyzing compositional variations within the stratigraphic framework. Within a single stratigraphic unit, both gas wetness and iC4/nC4 ratio show local departure from the regional maturity trend and the influence of linear discontinuities interpreted as faults. Finally, gas-enriched elongated areas consistent with regional gas migration pathways suggested by Wood and Sanei (2016) are also observed.

With a well-defined stratigraphic architecture and a huge amount of production data available, the Montney resource play offers a unique opportunity to better understand fluid compositional variations in hybrid unconventional plays.

Ref:

Wood, J. M., & Sanei, H. (2016). Secondary migration and leakage of methane from a major tight-gas system. Nature Communications, 7(May), 13614. http://doi.org/10.1038/ncomms13614