Measurements, Modeling and Analysis of High Pressure Gas Sorption in Shale and Coal for Unconventional Gas Recovery and Carbon Sequestration
| dc.contributor.author | Tang, Xu | en |
| dc.contributor.committeechair | Ripepi, Nino S. | en |
| dc.contributor.committeemember | Luttrell, Gerald H. | en |
| dc.contributor.committeemember | Hall, Matthew Robert | en |
| dc.contributor.committeemember | Luxbacher, Kramer Davis | en |
| dc.contributor.committeemember | Chen, Cheng | en |
| dc.contributor.department | Mining and Minerals Engineering | en |
| dc.date.accessioned | 2017-01-11T09:00:43Z | en |
| dc.date.available | 2017-01-11T09:00:43Z | en |
| dc.date.issued | 2017-01-10 | en |
| dc.description.abstract | In order to exploit unconventional gas and estimate carbon dioxide storage potential in shale formations and coal seams, two key questions need to be initially answered: 1) What is the total gas-in-place (GIP) in the subsurface reservoirs? 2) What is the exact ratio between bulk gas content and adsorbed gas content? Both questions require precise estimation of adsorbed phase capacity of gases (methane and carbon dioxide) and their adsorption behavior in shale and coal. This dissertation therefore analyzes adsorption isotherms, thermodynamics, and kinetics properties of methane and carbon dioxide in shale and coal based on experimental results to provide preliminary answers to both questions. It was found that the dual-site Langmuir model can describe both methane and carbon dioxide adsorption isotherms in shale and coal under high pressure and high temperature conditions (up to 27 MPa and 355.15K). This allows for accurate estimation of the true methane and carbon dioxide GIP content and the relative quantity of adsorbed phases of gases at in situ temperatures and pressures representative of deep shale formations and coal seams. The concept of a deep shale gas reservoir is then proposed to optimize shale gas development methodology based on the successful application of the model for methane adsorption in shale. Based on the dual-site Langmuir model, the isosteric heat of adsorption is calculated analytically by considering both the real gas behavior and the adsorbed phase under high pressure, both of which are ignored in the classic Clausius–Clapeyron approximation. It was also found that the isosteric heat of adsorption in Henry's pressure region is independent of temperature and can serve as a quantified index to evaluate the methane adsorption affinity on coal. In order to understand the dynamic response of gas adsorption in coal for carbon sequestration, both gas adsorption kinetics and pore structure of coal are investigated. The pseudo-second order model is applied to simulate the adsorption kinetics of carbon dioxide in coals under different pressures. Coal particle size effects on pore characterization of coal and carbon dioxide and nitrogen ad/desorption behavior in coal was also investigated. | en |
| dc.description.abstractgeneral | Shale gas is natural gas that is found trapped within subsurface shale formations, and the in-situ pressure and temperature of shale formations can go up to 27MPa and 86℃. Shale gas, the main component of which is methane, mainly consists of adsorbed phase and free compressed gas in shale formations. The adsorbed phase accounts for 20-85% of the total gas-in-place resource. Thus, the estimation of amount of methane adsorbed in shale under in-situ conditions are extremely important for determining the total gas-in-place quantity and the working life of a shale gas production well and its economic viability. This work provides a method for accurate estimation of the shale gas-in-place resource under in-situ shale formation conditions. The method is based on laboratory methane adsorption test data in shale at high pressure (up to 27MPa) and high temperature (up to 82℃) conditions. According to this method, it was found that for depths greater than 1000 m (> 15 MPa) in the subsurface, the shale gas resources have historically been significantly overestimated. For Longmaxi shale (2500 – 3000 m in depth), classical approaches overestimate the GIP by up to 35%. The ratio of the adsorbed phase compared to the free gas has been significantly underestimated. Shale gas production follows pressure depletion of shale formations. The pressure depletion process allows methane in the adsorbed phase to become free gas, which is known as the physical desorption process. Desorption is an endothermic process while adsorption is an exothermic process, both of them are reversible. Thus, the heat transfer process during shale gas production requires a thermodynamic analysis of methane adsorption in shale. This work investigates the isosteric heat of adsorption for methane in shale by considering both the real gas behavior and the volume effect of the adsorbed phase, not previously considered for methane in shale. The temperature dependence as well as the uptake dependence of the isosteric heat can be readily investigated by the applied method. This study lays the foundation for future investigations of the thermodynamics and heat transfer characteristics of the interaction between high pressure methane and shale. This work also investigates gas adsorption kinetics properties in coal and the particle size effect on pore characterization of coal using the gas adsorption approach. Results show that particle size of coal samples can significantly influence the sorption behavior of gas in coal, which finally affects pore characterization of coal. It is difficult to characterize the pore structure of coal using only one coal particle size. Carbon dioxide adsorption kinetics in coal, which can be modelled by the pseudo-second order model, is a combination of both bulk diffusion-controlled and surface interaction-controlled processes; the former dominates the initial stage while the latter controls the majority of the overall process. | en |
| dc.description.degree | Ph. D. | en |
| dc.format.medium | ETD | en |
| dc.identifier.other | vt_gsexam:9308 | en |
| dc.identifier.uri | http://hdl.handle.net/10919/74237 | en |
| dc.publisher | Virginia Tech | en |
| dc.rights | In Copyright | en |
| dc.rights.uri | http://rightsstatements.org/vocab/InC/1.0/ | en |
| dc.subject | adsorption | en |
| dc.subject | shale | en |
| dc.subject | coal | en |
| dc.subject | high pressure | en |
| dc.subject | methane | en |
| dc.subject | carbon dioxide | en |
| dc.subject | thermodynamics | en |
| dc.subject | kinetics | en |
| dc.title | Measurements, Modeling and Analysis of High Pressure Gas Sorption in Shale and Coal for Unconventional Gas Recovery and Carbon Sequestration | en |
| dc.type | Dissertation | en |
| thesis.degree.discipline | Mining Engineering | en |
| thesis.degree.grantor | Virginia Polytechnic Institute and State University | en |
| thesis.degree.level | doctoral | en |
| thesis.degree.name | Ph. D. | en |
Files
Original bundle
1 - 1 of 1