Impact of CO2 injection on wettability of coal at elevated pressure and temperature

CO 2 -enhanced coalbed methane (CO 2 -ECBM) technology helps to store CO 2 while producing a clean source of energy (CH 4 ) through the sorption process. This technique can sequester much CO 2 at low temperatures and pressures while recovering CH 4 , which will help offset the associated costs, such as capturing injection gases, drilling and completion infrastructure, compression, and injection expenses. This review paper critically analyzes the CO 2 sequestration potentiality in deep unmineable coal seams. The results revealed that, despite several researchers' insights from proposed concepts, experimental data, modeling and simulations, and pilot tests, there are no reported full field CO 2 -ECBM technology applications for CO 2 sequestration and CH 4 recovery because implementing the projects is uneconomical. Also, CO 2 sequestration and CH 4 recovery effectiveness on coal seams depend on wettability changes of the CO 2 −H 2 O−coal system. The identified research gaps and challenges in this paper are going to help various researchers and shareholders in conducting extra investigations toward full field application of CO 2 sequestration while simultaneously producing a clean source of energy (CH 4 ) in deep unmineable coal seams to meet the Paris climate summit agreement to achieve net zero emissions by 2050 and a maximum global temperature rise of 1.5 °C.

Section: Wettability Alteration During Co2-ecbm Technology Applicationsupporting

confidence: 89%

Recent Advances in Carbon Dioxide Sequestration in Deep Unmineable Coal Seams Using CO₂-ECBM Technology: Experimental Studies, Simulation, and Field Applications

Mwakipunda,

Wang,

Mgimba

et al. 2023

“…36 Therefore, the irreducible water saturation in the CO 2 −water system was smaller than that in the He/CH 4 −water system. In addition, the previous study found that the CO 2 /water/coal contact angles increased slightly with pressure, 37 which indicated that the water mobility was enhanced as the pressure increased. Thus, the irreducible water saturation in the CO 2 −water system decreased with an increase in displacement pressure.…”

Section: Effect Of Displacement Pressure and Gas Type On The Relative...mentioning

confidence: 96%

Experiment on the Gas Permeability and Gas–Water Relative Permeability in High-Rank Coal with a Self-Developed Device

Shen

Fang

et al. 2023

Water saturation, displacement pressure, and gas type are essential factors affecting the seepage characteristic of fluid in coal due to the swelling induced by gas adsorption. However, the understanding of the seepage behavior of water, CH 4 , and CO 2 in coal seams is still poor owing to the lack of research. In this work, a series of gas permeability and gas−water relative permeability experiments were conducted by our self-developed device. The results can be summarized as follows: (1) with the increase in water saturation, the gas permeability decreased rapidly at first and then reduced sharply again after a period of slow decline; (2) the two-phase flow span showed no significant difference for He−water and CH 4 −water systems under different displacement pressures, but it increased for CO 2 -water system. The different behaviors of the two-phase flow span suggested that the effect of displacement pressure on relative permeability properties is dependent on the gas type. (3) The CO 2 −water relative permeability showed a sizeable two-phase flow span compared to the He−water or CH 4 −water system under the same displacement pressure, and the gas relative permeability decreased obviously in the following sequence: He > CH 4 > CO 2 . The concept of relative permeability surface was proposed based on the experimental results. A parametric interpolation method was applied to determine the relative permeability surface, which could be used to accurately describe the flow characteristics of fluids in a mixed gas−water system.

“…Detailed experimental procedures are mentioned in our previous work. 45,46 2.3.3. Bubble Image Analysis.…”

Section: Contact Angle Measurement Proceduresmentioning

confidence: 99%

“…45 and 60 °C were 8.65 and 4.77, respectively. The static contact angles were greater at low temperatures and more significantly affected by pressure according to the filled area.…”

mentioning

confidence: 95%

Wetting Behavior of CO₂–H₂O–coal with Different Metamorphic Degrees under In Situ Thermophysical Conditions

Li,

Zhu,

Zhang

et al. 2024

Self Cite

Wettability in CO2–H2O–coal directly determines pore-scale configuration and further affects practice projects on the hectometer scale; however, coal rank and thermophysical condition dependences of wettability and their underlying mechanisms are inadequate. Potential candidate coal beds (hvBb, hvAb, mvb, sa) were considered, and wettability reflected by static/dynamic contact angles was evaluated under in situ reservoir conditions (temperature and pressure) by the captive bubble method. Physicochemical properties with potential effects on wetting behavior were characterized via SEM-EDS, FTIR, and XRD. Static/dynamic contact angles increased with pressure and coal rank, while they decreased with temperature, typically showing intermediate- or CO2-wetting in deep reservoirs. Advancing contact angles depended less on temperature and coal rank than static/receding contact angles. At a low temperature (T = 25 °C), CO2-wetting was stronger and was more significantly affected by coal rank and pressure. The curves of contact angles and CO2 density as a function of pressure almost coincided and increased steeply at pressures between 60 and 90 bar (∼64.3 bar). With increasing metamorphic degrees, defects, oxygen content, and polar oxygen-containing functional groups (hydroxyl, etc.) on the surface decreased, while C/O (the ratio of carbon to oxygen), C, and aromatic hydrocarbons increased. The results of the gray relational model indicate that C/O and hydroxyl are the primary factors affecting wettability in chemical properties. With coal rank, the degree of aromatic ring condensation increased and inorganic minerals (e.g., clay minerals and calcite) reduced; the crystallite structure tended to grow and become graphite-like. Measurement data and an understanding of wetting behavior have implications for project site selection and provide input parameters for field-scale reservoir modeling.