Summary
In an attempt to enhance the understanding of fracture growth in fluvial
systems, this paper provides an analysis of the impact of depositional
environments and associated heterogeneities on hydraulic fracturing growth in
fluvial tight gas reservoirs. A 3D geostatistical reservoir model, representing
a 160-acre field area, was created based on a 3D meandering fluvial tight gas
geologic model developed from outcrop. This detailed geologic model
differentiates between sandstone-dominated channel-belt environments including
point bars, crevasse channels, and crevasse splays, as well as the intervening
overbank environments consisting of mudstone and coal deposits. Petrophysical
properties and reservoir conditions used in the reservoir model were based on
subsurface data from nearby producing fields with comparable fluvial
systems.
Two different well locations were then chosen within the 3D model in an
effort to capture various sandstone body distributions. A range of hydraulic
fracture orientation planes, associated with the two well locations, were
selected and loaded into a 3D hydraulic fracture modeling package. Eight cases,
representing various stimulation-treatment sensitivities, were studied.
Results show that consideration of both vertical and lateral reservoir
changes is critical to understanding fracture growth in fluvial systems. When
comparing a layered system with no lateral variation to a system with lateral
variation, 1-year cumulative production can vary by as much as 25%. Subtle
lithofacies variations, present in significant quantities in these complex
depositional systems, affect fracture growth and can affect well production by
25 to 50%. Additionally, how depletion is treated in the fracturing model
(i.e., whether the entire interval is considered depleted or just a single sand
body) can also have a significant effect on fracture propagation.
© 2013. Society of Petroleum Engineers
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History
- Original manuscript received:
15 November 2010
- Meeting paper published:
24 January 2011
- Revised manuscript received:
7 September 2012
- Manuscript approved:
11 September 2012
- Published online:
31 January 2013
- Version of record:
26 February 2013
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