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A Scaling Function to Predict Hydraulic Fracture Limits in Deep Shale and Tight Gas Formations

Flewelling, S. A.; Tymchak, Matthew P.; Sharma, M.

Recent advancements in directional drilling and hydraulic fracturing (HF) have led to increased hydrocarbon production in low permeability formations previously considered to be un-economical for oil and gas exploration. The widespread use of HF has raised concerns about potential environmental and human health effects. For example, several studies have hypothesized that induced fractures might be able to extend from low permeability target formations to overlying potable aquifers and lead to upward migration of HF fluid and brine [e.g., Myers, 2012; Rozell and Reaven, 2011]. On the other hand, others have shown that fracture height growth is limited to depths far below potable groundwater [e.g., Fisher and Warpinski, 2011; Davies et al., 2012]. To resolve this issue, we developed a simple scaling function that describes fracture height limit as a function of HF fluid volume. We compared the upper-bound theoretical fracture height to measurements collected from over 12,000 individual HF stimulations where the fracture network was mapped with down-hole microseismic sensor arrays in approximately 25 North American sedimentary basins. Our results indicate that fracture heights are generally bounded by our scaling function, and the vast majority of fracture heights lie far below the theoretical limit (i.e., maximum height is rarely attained). These findings demonstrate that HF fluid volume imposes a bulk limit on fracture height and that unbounded fracture growth to shallow depths is not physically plausible.

 

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013