Effect of supercritical CO2 treatment on physical properties and functional groups of shales

Fatah, Ahmed; Mahmud, Hisham Ben; Bennour, Ziad; Hossain, Mofazzal; Gholami, Raoof

doi:10.1016/j.fuel.2021.121310

Cited by 60 publications

(54 citation statements)

References 60 publications

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“…For claystone (NK), the SSA increased by 5.4% and D decreased by 5.1%, while for limestone (TR 4 ), the SSA increased by 23.1% and D decreased by 23.1%. These results were consistent with reported studies on carbonate and shale rocks that reported an increase in the SSA with decreasing D after their minerals (calcite and quartz) reacted with carbonated water. ,− …”

Section: Resultssupporting

confidence: 92%

“…Following eqs –, CO 2 dissolution results in carbonic acid (H 2 CO 3 ), which further decomposes to be bicarbonate (HCO 3 – ) and carbonate (CO 3 2– ) ions Carbonic acid in brine could then induce the dissolution of carbonate minerals, eq ; however, when exposed to kaolinite, the reaction might otherwise precipitate into some minerals, e.g., quartz, as shown in eq . , It is noted that such CO 2 –mineral interactions cause some changes in rock porosity (ϕ) and likely changes in the pore size ( R ). Nevertheless, previous studies have rarely paid attention to the pore size change effect (Δ R ) on the CO 2 column height ( h ), as expressed in eq .…”

Section: Introductionmentioning

confidence: 99%

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Relative CO₂Column Height for CO₂Geological Storage: A Non-Negligible Contribution from Reservoir Rock Characteristics

et al. 2022

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As one of the solutions to tackle climate change caused by excess carbon dioxide (CO2) emission, CO2 geological storage has been increasingly implemented globally to store CO2 securely and permanently in the subsurface. In the current study, structural trapping, which shows the potential of initial CO2 containment and integrity of the subsurface structure, is experimentally investigated with CO2 leakage assessed. CO2 containment is quantified by CO2 column height, which describes the amount of CO2 accumulated in the formation underneath seal rock and is controlled by a balance between capillary and gravitational forces acting on formation brine and invading CO2. While previous studies considered only contributions from seal rock (i.e., “nonrelative”), the current study examines a concurrent contribution from reservoir rock as a seal–reservoir “relative” column height since CO2 storage as an analogy to petroleum reservoir is a structural trap consisting of the reservoir and impermeable seal covered. A distinctive discrepancy was found between the resultant relative and nonrelative column heights. The nonrelative column heights were positive (∼3000 m), implying a high potential for CO2 storage. On the contrary, with reservoir rock contribution considered, the relative column heights were negative (∼−1800 m), suggesting CO2 leakage through the structural trap. This was attributed to a relatively larger reservoir pore size (5.72 nm) than that of seal rock (4.04 nm). Hence, the contribution from reservoir rock characteristics is non-negligible when analyzing CO2 storage potential. Owing to CO2 dissolution in formation brine, CO2-induced effects including a geochemical reaction between acidic carbonated brine and rocks were also investigated. Rock dissolutions in both seal (claystone) and reservoir (limestone) rocks were observed with changes in the pore size, leading to lower storage potential. Further attempts to improve the column height were made by hydrophobizing seal rock via surfactant adsorption, although the changes were slight and could only facilitate a possible leakage (less negative height column).

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Relative CO₂Column Height for CO₂Geological Storage: A Non-Negligible Contribution from Reservoir Rock Characteristics

et al. 2022

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“…Kaveh et al221 in their study evaluating CO 2 wettability of silty shale caprocks found that the contact angle between CO 2 and silty shale was low, indicating a strong water-wet caprock system, making it favorable for CO 2 storage. Fatah et al222 evaluated the wettability of two mineralogically distinct shales after SC-CO 2 treatment. The results obtained indicate that the shale/water contact angle alteration was mineralogy-dependent.…”

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confidence: 99%

Impact of Supercritical CO₂ on Shale Reservoirs and Its Implication for CO₂ Sequestration

et al. 2022

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Hydraulic fracturing has transformed the international energy landscape by becoming the go-to method for the exploitation of natural gas from unconventional shale reservoirs. However, in the recent years, the search for an alternative method of shale-gas exploration has intensified, because of various problems (e.g., contamination of ground and surface water, overexploitation of precious water resources, air pollution, etc.) associated with the usage of water-based fracturing techniques. The use of CO2 for shale gas exploitation has emerged as a better alternative to aqueous-based gas exploration techniques. CO2 when injected into deep shale reservoirs, transitions into supercritical CO2 (SC-CO2) when temperature and pressure condition exceeds the critical point, i.e., 31.1 °C and 7.38 MPa. In this paper, we comprehensively review the impact of SC-CO2 on shale gas reservoirs during the different stages of shale-gas exploration, i.e., (i) drilling, which involves the superiority of SC-CO2 over water-based drilling fluids, in terms of achieving under-balanced well condition, higher rates of penetration, and resistance to formation damage; (ii) fracturing, which involves factors affecting the tortuosity of fractures created by SC-CO2 fracturing, breakdown pressure, and proppant-carrying capacity; and (iii) injection, which involves the twin-headed benefit of enhanced recovery due to CO2/CH4 competitive adsorption and geological sequestration, CO2 vs CH4 excess sorption as a function of pressure, etc. Several research works have indicated discrepancies on how SC-CO2 impacts different shale properties. Some studies show low-pressure N2-gas-adsorption-derived surface area and total pore volume to be increasing with SC-CO2 imbibition, while others show a decreasing trend for the same. Similarly, for some shales, the quartz content, along with the clay mineral contents, decreased as the exposure to SC-CO2 increased, while in some other studies, with similar long-term exposure to SC-CO2, the quartz content was observed to increase along with the decrease in clay content and vice versa. Essentially, the increased exposure to SC-CO2 results in the dissolution of primary porous structures and fractures, and reformation of newer porous structure and conduits in shales. Nonetheless, these changes in the mineralogy weaken the microstructure of the rock bringing significant changes in the mechanical properties of the shales with implications on the wellbore stability and fracturing efficiency. The mechanical properties such as uniaxial compressive strength (UCS), Young’s modulus, and tensile strength decrease as the SC-CO2 saturation period increases. However, some studies have shown factors like bedding angle and phase-state of CO2 having varying effect on the strength behavior of the shales. Moreover, changes in the structure of shales caused by the creation of fractures and the reduction of their strength can also pose major risks, because of potential leakage of CO2 through these created pathways. How these processes would i...

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“…Core samples were prepared in various sizes to meet the test requirements. The bulk sample was crushed into powders, and then sieved into sizes of (<75 µm) to fulfil the sampling requirements for silica solubility tests (Fatah, Ben Mahmud, et al, 2021). Fragments of the core sample were polished with 1500 silicon carbide grit, and cleaned with ethanol to be used for SEM analysis.…”

Section: Samples and Materialsmentioning

confidence: 99%

The Effect of Silica Dissolution on Reservoir Properties during Alkaline-Surfactant-Polymer (ASP) Flooding

Fatah¹

2021

Preprint

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Chemical flooding is one of the effective methods to recover large volumes of oil from sandstone formations after primary depletion. However, silica dissolution often occurs during Alkaline-Surfactant-Polymer (ASP) flooding, affecting the petro-physical properties of the formation. To address this issue, samples from Berea sandstone formations were treated with various brine solutions, through static tube tests and core flooding experiments. Analytical tests such as DR/2800 spectrophotometer and scanning electron microscope were used to evaluate the silica solubility and the alteration in mineral content. The results indicated that the silicate contents decreased after the saturation due to silica solubility in the solution. Increasing brine salinity to 40,000ppm and introducing Magnesium and Calcium ions to the solution, reduces the silicate contents by 5.03 % and 7.32 %. Moreover, saturating the samples with ASP solution, further reduced the silicate contents by 14.86 %. This reduction is associated with a relative increase in silica solubility and pH of the solution. Silica dissolution affects the pore microstructure, which resulted in increasing the porosity and pore volume after the core flooding. The injection of the ASP solution increased the porosity by 5.83%, thus the pore volume increased from 17.72 to 18.76cc. This is associated with the high silica solubility and the increase of solution pH in the ASP solution. The permeability of the samples generally reduced after the core flooding, due to the silica solubility. However, injecting the ASP solution, resulted in a major reduction of the permeability by more than 75%. These changes in the petro-physical properties can lead to severe formation damage, and affect hydrocarbon production. This study assists in understanding the impact of silica dissolution during ASP treatment and addresses the factors involved. Efficient utilization of chemical flooding can help mitigating silicate scaling within the formation, and extend field productivity.

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Effect of supercritical CO2 treatment on physical properties and functional groups of shales

Cited by 60 publications

References 60 publications

Relative CO₂Column Height for CO₂Geological Storage: A Non-Negligible Contribution from Reservoir Rock Characteristics

Relative CO₂Column Height for CO₂Geological Storage: A Non-Negligible Contribution from Reservoir Rock Characteristics

Impact of Supercritical CO₂ on Shale Reservoirs and Its Implication for CO₂ Sequestration

The Effect of Silica Dissolution on Reservoir Properties during Alkaline-Surfactant-Polymer (ASP) Flooding

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Effect of supercritical CO2 treatment on physical properties and functional groups of shales

Cited by 60 publications

References 60 publications

Relative CO2Column Height for CO2Geological Storage: A Non-Negligible Contribution from Reservoir Rock Characteristics

Relative CO2Column Height for CO2Geological Storage: A Non-Negligible Contribution from Reservoir Rock Characteristics

Impact of Supercritical CO2 on Shale Reservoirs and Its Implication for CO2 Sequestration

The Effect of Silica Dissolution on Reservoir Properties during Alkaline-Surfactant-Polymer (ASP) Flooding

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Product

Resources

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Relative CO₂Column Height for CO₂Geological Storage: A Non-Negligible Contribution from Reservoir Rock Characteristics

Relative CO₂Column Height for CO₂Geological Storage: A Non-Negligible Contribution from Reservoir Rock Characteristics

Impact of Supercritical CO₂ on Shale Reservoirs and Its Implication for CO₂ Sequestration