CO2 Sequestration effect on outburst in coal mining

Coal mass has the potential to store substantial amounts of CO2 in the coal matrix and that CO2 has the ability to move through the coal seam pore and fracture systems, which influences the release of gases during coal mining and the CO2 sequestration process. In addition, the reduction of coal mass strength due to CO2 adsorption greatly affects the outburst process. The sudden and violent failure of coal seam with releasing large amount of gas is called outburst in coal mining. Up to date only few have been conducted to investigate the effect of CO2 adsorption induces strength reduction on the outburst process. The main objective of this study is to investigate the effect of CO2 injection on outburst in coal mining. Uniaxial Compressive Strength (UCS) experiments were therefore conducted on black coal samples, which have been saturated with CO2 and N2 at various pressures at 33 ºC. According to the results CO2 adsorption causes the UCS strength of coal to be reduced by up to 53 % and this higher strength reduction is due to the CO2 adsorption induce coal matrix swelling. However, N2 saturation causes the coal strength to be slightly increased. According to these observations, there is a high risk associated with CO2 sequestration process in coal seam as it significantly reduces the coal seam strength, which has direct influence on outburst process in coal

Development of a 3d model to study the co2 sequestration Process in deep unmineable coal seams.

This paper presents a numerical model to study the carbon dioxide (CO2) sequestration process in deep coal seams and to investigate the factors that affect this process. A coal seam lying 1000 m below the ground surface was considered for the simulation. One injecting well was first inserted at the middle of the area under consideration and CO2 was injected for a 10 year period. With one injection well, the storage capacity was calculated as 13´107 m3. The number of injecting wells was then increased to 4. It was found that the maximum storage capacity was observed at two well conditions (an increment of 130% of the single well condition). However, further increasing the number of wells (up to 4) reduced the storage capacity to 12.5´107 m3. According to the model results, it is clear that CO2 storage capacity in deep unmineable coal seams is dependent on the number of injecting wells and their location and porosity, the permeability of the coal seams, coal bed moisture content and temperature

Effect of supercritical-CO2 interaction time on the alterations in coal pore structure

International audienc

Data from: Assessment of dynamic material properties of intact rocks using seismic wave attenuation: an experimental study

The mechanical properties of any substance are essential facts to understand its behaviour and make the maximum use of the particular substance. Rocks are indeed an important substance, as they are of significant use in the energy industry, specifically for fossil fuels and geothermal energy. Attenuation of seismic waves is a non-destructive technique to investigate mechanical properties of reservoir rocks under different conditions. The attenuation characteristics of five different rock types, siltstone, shale, Australian sandstone, Indian sandstone and granite, were investigated in the laboratory using ultrasonic and acoustic emission instruments in a frequency range of 0.1–1 MHz. The pulse transmission technique and spectral ratios were used to calculate the attenuation coefficient (α) and quality factor (Q) values for the five selected rock types for both primary (P) and secondary (S) waves, relative to the reference steel sample. For all the rock types, the attenuation coefficient was linearly proportional to the frequency of both the P and S waves. Interestingly, the attenuation coefficient of granite is more than 22% higher than that of siltstone, sandstone and shale for both P and S waves. The P and S wave velocities were calculated based on their recorded travel time, and these velocities were then used to calculate the dynamic mechanical properties including elastic modulus (E), bulk modulus (K), shear modulus (µ) and Poisson's ratio (ν). The P and S wave velocities for the selected rock types varied in the ranges of 2.43–4.61 km s−1 and 1.43–2.41 km h−1, respectively. Furthermore, it was observed that the P wave velocity was always greater than the S wave velocity, and this confirmed the first arrival of P waves to the sensor. According to the experimental results, the dynamic E value is generally higher than the static E value obtained by unconfined compressive strength tests

Microwave-assisted damage and fracturing of hard rocks and its implications for effective mineral resources recovery

International audienc