Modeling Storage and Flow of Fluids in Shale Reservoirs

Date
2017
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Abstract
Recent development of shale gas reservoirs has led to a revolution in the global energy market. The shale gas industry has expanded rapidly through the application of new drilling and completion technologies, particularly horizontal wells completed in multiple hydraulic fracture stages. While these technologies play a critical role enabling economical production from these resources, uncertainty in the understanding of basic shale gas reservoir properties, and methods used to characterize them, has led to inefficiencies in shale gas resource development. This thesis addresses uncertainties in the characterization of fluid storage and transport mechanisms in shales, and uses new methods for characterization in exploring enhanced recovery options for shale-hosted hydrocarbons. The primary gas storage mechanisms in organic-rich shales are free gas storage and adsorption; however, there is a significant amount of uncertainty in modeling these storage mechanisms in shale. Of the adsorption models tested, the simplified local density (SLD) model was found to be the most useful for shale gas storage estimation. The model was used not only for adsorption modeling, but also to rigorously correct free gas storage calculations for the presence of adsorbed phase volume. Further, the SLD model was used to predict changes in fluid behaviour within the confined pore space of shale reservoirs. An important contribution of this thesis is the estimation of gas storage and transport parameters from shale reservoir drill cuttings. Low-pressure (N2 and CO2) adsorption data was collected on “artificial” (crushed rock) shale cuttings, and used, in combination with the SLD model to predict high-pressure/high-temperature adsorption of hydrocarbons. Further, adsorption rate data, collected on small masses of artificial cuttings, combined with sophisticated numerical modeling which takes into account the physics of gas storage and transport through shale, was used to estimate shale gas diffusivity/permeability. Finally, the importance of hydrocarbon adsorption and diffusivity for predicting hydrocarbon liquid recovery after CO2 injection was investigated. A history-matched (flowback data) multi-fractured horizontal well completed in a tight liquid-rich reservoir was used as a starting point for sensitivities using CO2 injection. Unique to this study, fluid compositions as a function of depth in the reservoir were available. Simulation of CO2 huff-n-puff schemes using this calibrated model demonstrated that inclusion of adsorption/diffusion effects has an important impact on hydrocarbon liquid recovery.
Description
Keywords
Engineering--Petroleum
Citation
Haghshenas, B. (2017). Modeling Storage and Flow of Fluids in Shale Reservoirs (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/26951