Adsorption Behavior of CH₄ and C₂H₆ on Shale under the Influence of CO₂ and Flue Gas

Abstract

CO 2 injection has been accepted as a suitable method for enhancing shale hydrocarbon recovery as well as achieving CO 2 storage in shale reservoirs. In this study, flue gas is proposed as a better injection gas for shale resource recovery. The objective of this work is conducted to investigate how introduced CO 2 and flue gas affect the adsorption behavior of CH 4 and C 2 H 6 , which are two main components in shale gas, on shale, which is critical for understanding the fundamental mechanism of shale gas recovery. In this work, the adsorption isotherms are first measured to evaluate the relative adsorption capacity of CO 2 , flue gas, CH 4 , and C 2 H 6 on typical shale samples. The low-field nuclear magnetic resonance technique is consequently applied to study the influence of injected CO 2 and flue gas on the adsorption behavior of CH 4 and C 2 H 6 at the reservoir pressure and temperature conditions. Test results show that flue gas presents the highest adsorption capacity on shale, which is followed by C 2 H 6 , CO 2 , and CH 4 , respectively. On the basis of the measured T 2 signals, CH 4 and C 2 H 6 exist in shale within the two patterns, i.e., the adsorbed pattern in pores and the free-state pattern at the pore center. After injection of CO 2 and flue gas, the amount of adsorbed CH 4 is reduced, accompanying with the increase of the quantity of free gas state that appeared at the pore center. In comparison to CO 2 , flue gas can further replace adsorbed CH 4 and C 2 H 6 from the shale surface, suggesting more feasibility of flue gas for enhancing CH 4 and C 2 H 6 recovery. This study may inspire new strategies that can be applied for shale reservoir development; more importantly, it may provide a new way for the usage of flue gas for energy supply while reducing the possibility for environmental pollution.

Experimental setup for CO2 injection for Enhance Shale Gas Recovery (ESGR) - A Review

“…Give a brief idea of shrinkage effect because of N2 increasing permeability and swelling because of CO2 injection closing fracture decreasing permeability. Low field Nuclear Magnetic Resonance Technique (LF NMR) is used to determine that apart from the affinity of CO2 to get adsorb at shale surface what other changes take place [5]. To understand the flow of CO2 in the shale matrix instrument is provided with a pressure pulse transmission test.…”

“…Schematic experimental model to estimate changes in shale samples after subjecting it to different gases (Huang, Xue & Li, 2020). …”

Quantitative Analysis of Crude Oil Mobilization in Microscopic Pores during the Spontaneous Imbibition of CO2-Enhanced Fracturing Fluids in Shale Oil Reservoirs

“…Expanding on the research by Xiao et al, Zhang et al determined effective porosity initiation times for two tight sandstones, recorded at 1 and 2.8 ms, respectively. Gao et al classified shale pores into three types: inorganic intergranular pores, inorganic intragranular pores, and organic pores. − …”

Progress and Prospects of Supercritical CO2 Application in the Exploitation of Shale Gas Reservoirs

“…Additionally, the CH 4 recovery enhanced by CO 2 injection in shale gas reservoir is deemed one of the best potential development schemes due to the high adsorption capacity and preference of CO 2 in shale, and the geological storage of CO 2 is realized from the excellent self-sealing capacity of shale reservoirs. − From coalbed methane (CBM) production, this scheme proposes CO 2 injection into the coal seam to enhance CBM recovery and realize geological storage (CO 2 -ECBM). CO 2 -ECBM has achieved promising field test results in the United States, Canada, China, and other countries.…”