Investigation on the physics structure and chemical properties of the shale treated by supercritical CO 2

Ao, Xiang; Lu, Yiyu; Tang, Jiren; Chen, Yuting; Li, Honglian

doi:10.1016/j.jcou.2017.05.028

Cited by 144 publications

(66 citation statements)

References 35 publications

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“…Energies 2020, 13, 1167 21 of 30 decrease of tensile strength with exposure time, and little effect of bedding orientation was found. These results are similar to those found by other authors [171], as presented in Figure 6. The normalized values, also presented in previous figures, were obtained by dividing the value at a given age of exposure over the initial value (without CO2).…”

Section: Tensile Strength and Surface Energysupporting

confidence: 93%

“…The normalized values, also presented in previous figures, were obtained by dividing the value at a given age of exposure over the initial value (without CO 2 ). The results of Ao et al [171] demonstrate a reduction of around 30% for tensile strength after only 5 days of exposure, while the results of Feng et al [24] show a reduction of around 8% and 45% after 10 and 60 days, respectively. The shale samples of these two investigations were from the same basin but with different total organic content (TOC).…”

Section: Tensile Strength and Surface Energymentioning

confidence: 92%

“…CO 2 -brine-caprock interactions can therefore cause changes in the mechanical properties of rocks, in terms of their strength, stiffness, and fracture thresholds, which can increase the risk of CO 2 leaking from the reservoir [163][164][165]. These effects have been experimentally investigated on various shale formations and under different exposure conditions in terms of temperature and pressure [24,70,72,[166][167][168][169][170][171][172][173][174]. The investigated parameters affected by CO 2 exposure include volume change (swelling), strength, stiffness, Poisson's ratio, stress thresholds for crack initiation, and crack damage, as well as the brittleness index.…”

Section: The Effect Of Co 2 On the Mechanical Properties Of Shale Rockmentioning

confidence: 99%

“…After exposure to dry sub-and supercritical CO 2 , the experiments show a gradual decrease in the UCS and static Young's modulus with saturation time [168,171,173]; they also show a decrease in the dynamic Young's modulus [172]. An outcrop anisotropic shale from the Sichuan basin in China was exposed for 10 and 20 days to CO 2 and CO 2 -water at a temperature of 40 • C under a pressure of 9 MPa.…”

Section: Exposure To Dry Comentioning

confidence: 99%

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Micro- and Macroscale Consequences of Interactions between CO2 and Shale Rocks

et al. 2020

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In carbon storage activities, and in shale oil and gas extraction (SOGE) with carbon dioxide (CO2) as stimulation fluid, CO2 comes into contact with shale rock and its pore fluid. As a reactive fluid, the injected CO2 displays a large potential to modify the shale’s chemical, physical, and mechanical properties, which need to be well studied and documented. The state of the art on shale–CO2 interactions published in several review articles does not exhaust all aspects of these interactions, such as changes in the mechanical, petrophysical, or petrochemical properties of shales. This review paper presents a characterization of shale rocks and reviews their possible interaction mechanisms with different phases of CO2. The effects of these interactions on petrophysical, chemical and mechanical properties are highlighted. In addition, a novel experimental approach is presented, developed and used by our team to investigate mechanical properties by exposing shale to different saturation fluids under controlled temperatures and pressures, without modifying the test exposure conditions prior to mechanical and acoustic measurements. This paper also underlines the major knowledge gaps that need to be filled in order to improve the safety and efficiency of SOGE and CO2 storage.

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Section: Tensile Strength and Surface Energysupporting

confidence: 93%

Section: Tensile Strength and Surface Energymentioning

confidence: 92%

Section: The Effect Of Co 2 On the Mechanical Properties Of Shale Rockmentioning

confidence: 99%

Section: Exposure To Dry Comentioning

confidence: 99%

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Micro- and Macroscale Consequences of Interactions between CO2 and Shale Rocks

et al. 2020

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“…They identified that the temperature will have the positive effect on the specific surface area increment of shale under the Sc-CO 2 environment. Xiang et al [18] studied the structural and chemical properties of the shale by conducting four types of instrumental analysis after the Sc-CO 2 soaking procedure. They believed that the Sc-CO 2 treatment reduced the shale strength and altered the mineral content of the shale.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Properties Alternation during Super-Critical CO2 Injection in Shale

et al. 2019

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The low recovery of oil from tight liquid-rich formations is still a major challenge for a tight reservoir. Thus, supercritical CO2 flooding was proposed as an immense potential recovery method for production improvement. While up to date, there have been few studies to account for the formation properties’ variation during the CO2 Enhanced Oil Recovery (EOR) process, especially investigation at the micro-scale. This work conducted a series of measurements to evaluate the rock mechanical change, mineral alteration and the pore structure properties’ variation through the supercritical CO2 (Sc-CO2) injection process. Corresponding to the time variation (0 days, 10 days, 20 days, 30 days and 40 days), the rock mechanical properties were analyzed properly through the nano-indentation test, and the mineralogical alterations were quantified through X-ray diffraction (XRD). In addition, pore structures of the samples were measured through the low-temperature N2 adsorption tests. The results showed that, after Sc-CO2 injection, Young’s modulus of the samples decreases. The nitrogen adsorption results demonstrated that, after the CO2 injection, the mesopore volume of the sample would change as well as the specific Brunauer–Emmett–Teller (BET) surface area which could be aroused from the chemical reactions between the CO2 and some authigenic minerals. XRD analysis results also indicated that mesopore were altered due to the chemical reaction between the injected Sc-CO2 and the minerals.

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