Extracting Hydrocarbon From Shale: An Investigation of the Factors That Influence the Decline and the Tail of the Production Curve. Issue 5 (24th May 2018)

• Record Type: Journal Article
• Authors: Lovell, A. E.; Srinivasan, S.; Karra, S.; O'Malley, D.; Makedonska, N.; Viswanathan, H. S.; Srinivasan, G.; Carey, J. W.; Frash, L. P.
• Is Part Of: Water resources research. Volume 54:Issue 5(2018)
• Page Start: 3748
• Page End: 3757
• Publication Date: 2018-05-24
• Subjects: discrete fracture network -- transport -- hydrocarbon -- production -- hydraulic fracturing -- matrix; Hydrology -- Periodicals; 333.91
• DOI: 10.1029/2017WR022180
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: Understanding physical processes that control the long‐term production of hydrocarbon from shale formations is important for both predicting the yield and increasing it. In this work, we explore the processes that could control the tail of the production curve by using a discrete fracture network method to calculate the total travel time from the rock matrix to small‐scale fractures to the primary hydraulic fracture network. The factors investigated include matrix diffusion, extent of the small‐scale fracture zone (or tributary fracture zone/TFZ) consisting of natural, reactivated and induced fractures, and the percentage of free hydrocarbon in the primary fracture network. Individual and combined parameter spaces are explored for each of these to understand the limits of these parameters as well as any systematic correlations between pairs of parameters. Although recent studies have shown that the matrix diffusion in virgin shale influences the production tail only after nearly 20 years, we demonstrate that matrix diffusion in the region of the TFZ significantly impacts production within the first year itself. Additionally, we found that the depth of TFZ fracturing region had no effect on the shape of the production curves although the total mass of the hydrocarbon produced increases with the depth. We also show that one can fit the production data using a site‐specific set of parameters representing the diffusion in the TFZ, depth of the TFZ, and the free hydrocarbon in the large‐scale fractures. Key Points: A DFN method is used to calculate hydrocarbon travel times for transport from the matrix to small‐scale fractures to the primary fractures Diffusion from the matrix to small‐scale fractures control both peak and the shape of late stages of the production curve Depth of small‐scale fracture region has no effect on the shape of the production curve although total mass produced increases with depth