Effect of advective flow in fractures and matrix diffusion on natural gas production. Issue 10 (12th October 2015)

• Record Type: Journal Article
• Authors: Karra, Satish; Makedonska, Nataliia; Viswanathan, Hari S.; Painter, Scott L.; Hyman, Jeffrey D.
• Is Part Of: Water resources research. Volume 51:Issue 10(2015:Oct.)
• Page Start: 8646
• Page End: 8657
• Publication Date: 2015-10-12
• Subjects: simulation -- natural gas -- fracture flow -- diffusion; Hydrology -- Periodicals; 333.91
• DOI: 10.1002/2014WR016829
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: Although hydraulic fracturing has been used for natural gas production for the past couple of decades, there are significant uncertainties about the underlying mechanisms behind the production curves that are seen in the field. A discrete fracture network‐based reservoir‐scale work flow is used to identify the relative effect of flow of gas in fractures and matrix diffusion on the production curve. With realistic three‐dimensional representations of fracture network geometry and aperture variability, simulated production decline curves qualitatively resemble observed production decline curves. The high initial peak of the production curve is controlled by advective fracture flow of free gas within the network and is sensitive to the fracture aperture variability. Matrix diffusion does not significantly affect the production decline curve in the first few years, but contributes to production after approximately 10 years. These results suggest that the initial flushing of gas‐filled background fractures combined with highly heterogeneous flow paths to the production well are sufficient to explain observed initial production decline. These results also suggest that matrix diffusion may support reduced production over longer time frames. Key Points: Initial fast decline in gas production is due to flushing of gas from fractures Production curve is insensitive to local aperture variability within a fracture Matrix diffusion can improve gas production at later times