Extracting Hydrocarbon From Shale: An Investigation of the Factors That Influence the Decline and the Tail of the Production Curve

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.

Characterizing the Impact of Fractured Caprock Heterogeneity on Supercritical CO$$_2$$ Injection

“…FEHM has been used for numerous studies addressing CO 2 sequestration [11,15,32,40,41]. DFNWORKS has been previously used to study flow and transport in fractured media in a variety of other physical scenarios including hydraulic fracturing operations [31,34,23], inversion of micro-seismicity data for characterization of fracture properties [38], and the long term storage of spent civilian nuclear fuel [22], but this study marks the first time DFNWORKS has been used in problems related to CO 2 sequestration.…”

Impact of Acid–Base Stimulation Sequence on Mineral Stability for Tight/Impermeable Unconventional Carbonate-Rich Rocks: A Delaware Basin Case Study

“…Hydraulic fracturing of ultra-low permeability shale and other tight/impermeable formations is an important technique for recovering oil and natural gas. Although hydrocarbon production from these unconventional resources has significantly increased U.S. oil and natural gas supply, production curves decline significantly after the first year and valuable hydrocarbons are left in the subsurface. , Thus, an improved understanding of reservoir geochemical processes is needed to increase recoverable reserves.…”

In-situ synchrotron characterisation of fracture initiation and propagation in shales during indentation

“…These relationships between microstructure and strains are difficult to quantify in the laboratory (Fauchille et al, 2019). Advanced mechanical tests can characterise fracture propagation measured by pressure curves, through optical and electron microscopy (nm to mm) techniques on the 2D surface of the material (Chandler et al, 2018), or postexperimentally in 3D by X-ray Computed Tomography (XCT) (Lovell et al, 2018). Despite great progress, the spatial and temporal development of the fracture still cannot be determined in 3D using these techniques, and this information is critical to understand the natural and anthropogenic fracture propagation.…”