Experimental study of physical‐chemical properties modification of coal after CO₂ sequestration in deep unmineable coal seams

Abstract

An initial investigation into the impacts of CO2 storage in unmineable coal seams, with or without enhanced coal‐bed methane recovery (CO2‐ECBM), was conducted, focusing on changes in the chemical and physical properties of coal. A high metamorphic grade anthracite was obtained from Qinshui Basin in China. Powdered coal was reacted with deionized water and carbon dioxide at temperatures of 25–35 °C and pressures of 5–11 MPa, in seven custom‐built batch reactors – conditions similar to the in situ formation conditions for the coal samples. An experiment with N2 saturated‐water to compare CO2‐free‐water mobilization with CO2‐water was also performed. It was observed that the supercritical CO2‐H2O‐coal reaction had a more significant influence on the micropores than mesopores. The micropore increase was reflected directly in the specific surface area and pore volume, which increased sharply. The true density also increased accordingly. The changes to the pore structure in the coal may affect the storage capacity of CO2 and can modify the fluid flow pattern in the process of CO2‐ECBM. Meanwhile, after exposing the coal samples to supercritical CO2, most of the trace‐element content in the reaction solutions was very low; only the Se and Mn content was beyond acceptable drinking water quality, but not enough to produce a serious influence on shallow aquifers. Nonetheless, the potential for mobilizing toxic trace elements from the coalbed is an important factor to be considered when evaluating CO2 sequestration in deep unmineable coal seams. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

Numerical Simulation of the Influence of Geological CO2 Storage on the Hydrodynamic Field of a Reservoir

“…The storage mechanism includes structural storage, residual storage, dissolution storage, and mineral storage. The geological storage of CO 2 is a complex process and is therefore affected by many factors, such as the reservoir conditions, rock heterogeneity, faults, minerals, relative permeability hysteresis, and dip angle of the reservoir [6][7][8][9]. Because deep saline aquifers can be found in widespread areas, these aquifers are considered to have enormous potential for CO 2 storage [1].…”

Influence of supercritical, liquid, and gaseous CO2 on fracture behavior in sandstone

“…Gibbs 65 proposed that when a porous dielectric material adsorbs a liquid or gas, its surface energy changes. These two theories can be expressed by Equations (5) and (6), respectively:…”

“…Effective CO 2 underground reservoirs primarily include oil and gas reservoirs, abandoned oil and gas reservoirs, unrecoverable coal seams, and deep saline aquifers. [5][6][7][8] The exploitation of oil and gas by injecting CO 2 , such as CO 2 -EOR, CO 2 -EGR, and CO 2 -ECBM, not only promotes energy development but also effectively sequesters CO 2 . CCS technology has been utilized in Norway, the United States, Japan, Australia, Canada, and other countries.…”

“…Geological sequestration involves long‐term CO 2 storage in natural underground reservoirs and is one of the most economical and reliable practical methods. Effective CO 2 underground reservoirs primarily include oil and gas reservoirs, abandoned oil and gas reservoirs, unrecoverable coal seams, and deep saline aquifers 5‐8 . The exploitation of oil and gas by injecting CO 2 , such as CO 2 ‐EOR, CO 2 ‐EGR, and CO 2 ‐ECBM, not only promotes energy development but also effectively sequesters CO 2 .…”

Kinetic analysis about the CO2 capture capacity of lime mud from paper mill in calcium looping process

“…Since fossil fuel fired power plants are the major sources of CO 2 emission, how to capture the CO 2 from flue gas in power plant has drawn public attentions. [8][9][10] The reuse of the lime mud in environmentally friendly way and CO 2 capture from flue gas can be simultaneously realized if lime mud can be used as CO 2 sorbent in carbon capture system. Calcium looping process is widely considered as one of the most potential methods that can achieve deep CO 2 emission reduction in view of its advantages including low-cost CO 2 sorbent 11 and proven CFB technology.…”