An experimental study on the CO2/sand dry-frac process

Song, Zhiyong; Weidong, Su; Yanzeng, Yang; Li, Yong; Li, Zhihang; Wang, Xiaoyu; Li, Qianchun; Dongzhe, Zhang; Wang, Yu

doi:10.1016/j.ngib.2014.11.011

Cited by 15 publications

(5 citation statements)

References 4 publications

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“…In the early stage of CO 2 sand fracturing operation, due to the limitation of technical parameters of sand mixing equipment, the amount of sand added was limited, which significantly affected the productivity improvement. In the first China's field test of CO 2 dry sand fracturing conducted in Sulige Gas Field, the volume of sand mixing equipment used was 10 m 3 , the working pressure was 2.5 MPa, the maximum sand transport rate was only 0.5 m 3 /min, and the final sand amount was only 2.8 m 3 [10]. Jilin Oilfield and Changqing Oilfield have made many design improvements and filed tests on CO 2 special closed sand mixing equipment [11,12].…”

Section: Supercritical Co 2 Fracturing Equipmentmentioning

confidence: 99%

Analysis of Supercritical CO<sub>2</sub> Coiled Tubing Fracturing Technology for Shale Gas Formation

Zhang¹

2022

AJCHE

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Hydraulic fracturing of shale formations has led to energy boom both in China and abroad. Currently, water is regularly used as fracturing fluid in commercial shale gas and oil production, but it has raised concerns in many aspects such as environment and reservoir protection. Supercritical CO 2 , as a non-aqueous fracturing fluid, combined with coiled tubing fracturing technology, can effectively increase shale gas production, shorten operation period, reduce cost, conserve water resources, and minimize environmental impacts. Firstly, the process of supercritical CO 2 fracturing with coiled tubing of shale gas formation was introduced, and the potential advantages of using CO 2 as working fluid in coiled tubing fracturing of shale gas formation were analyzed, including enhanced fracturing and fracture propagation, reduction of flow-blocking, increased desorption of methane adsorbed in organic-rich parts of the shale, and a reduction or elimination of the deep re-injection of flow-back water that has been linked to induced seismicity and other environmental concerns. In addition, shale gas formations may also become a major utilization option for carbon sequestration. Then, the computational fluid dynamics were applied to simulate the flow fields inside cavity of supercritical CO 2 fracturing with coiled tubing, and the pressure boost capability was verified. By comparing the pressure boost effects of water fracturing and supercritical CO 2 fracturing, it could be concluded that supercritical CO 2 fracturing with coiled tubing has stronger pressure boost effect than water fracturing under the same conditions. The research and development status of supercritical CO 2 fracturing equipment and field test were also analyzed. The research results can provide references for the application of supercritical CO 2 fracturing with coiled tubing in shale gas formations and the development of related tools.

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Section: Supercritical Co 2 Fracturing Equipmentmentioning

confidence: 99%

Analysis of Supercritical CO<sub>2</sub> Coiled Tubing Fracturing Technology for Shale Gas Formation

Zhang¹

2022

AJCHE

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“…The success in developing shale formations in recent decades has shifted attention towards shale reservoirs, and considered them as promising candidates to store CO 2 for extended periods [9], mainly because shales with their ultralow permeability play a major role as barriers or seals in a petroleum reservoir system, and also due to their wide availability worldwide [7,[10][11][12][13][14][15]. The breakthrough made in technology to utilize CO 2 (instead of slick-water) in developing shale formation during drilling, fracturing, and enhanced shale gas recovery (ESGR) processes leads to minimizing many environmental issues during the operations, i.e., minimizing the amount of produced wastewater and increasing the production efficiency of gas while sequestering the adsorbed CO 2 simultaneously [16][17][18]. These developed technologies, including hydraulic fracturing and horizontal drilling make commercial development of shale formations possible.…”

Section: Development Of Shale Formationsmentioning

confidence: 99%

A Review on the Influence of CO2/Shale Interaction on Shale Properties: Implications of CCS in Shales

et al. 2020

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Carbon capture and storage (CCS) is a developed technology to minimize CO2 emissions and reduce global climate change. Currently, shale gas formations are considered as a suitable target for CO2 sequestration projects predominantly due to their wide availability. Compared to conventional geological formations including saline aquifers and coal seams, depleted shale formations provide larger storage potential due to the high adsorption capacity of CO2 compared to methane in the shale formation. However, the injected CO2 causes possible geochemical interactions with the shale formation during storage applications and CO2 enhanced shale gas recovery (ESGR) processes. The CO2/shale interaction is a key factor for the efficiency of CO2 storage in shale formations, as it can significantly alter the shale properties. The formation of carbonic acid from CO2 dissolution is the main cause for the alterations in the physical, chemical and mechanical properties of the shale, which in return affects the storage capacity, pore properties, and fluid transport. Therefore, in this paper, the effect of CO2 exposure on shale properties is comprehensively reviewed, to gain an in-depth understanding of the impact of CO2/shale interaction on shale properties. This paper reviews the current knowledge of the CO2/shale interactions and describes the results achieved to date. The pore structure is one of the most affected properties by CO2/shale interactions; several scholars indicated that the differences in mineral composition for shales would result in wide variations in pore structure system. A noticeable reduction in specific surface area of shales was observed after CO2 treatment, which in the long-term could decrease CO2 adsorption capacity, affecting the CO2 storage efficiency. Other factors including shale sedimentary, pressure and temperature can also alter the pore system and decrease the shale “caprock” seal efficiency. Similarly, the alteration in shales’ surface chemistry and functional species after CO2 treatment may increase the adsorption capacity of CO2, impacting the overall storage potential in shales. Furthermore, the injection of CO2 into shales may also influence the wetting behavior. Surface wettability is mainly affected by the presented minerals in shale, and less affected by brine salinity, temperature, organic content, and thermal maturity. Mainly, shales have strong water-wetting behavior in the presence of hydrocarbons, however, the alteration in shale’s wettability towards CO2-wet will significantly minimize CO2 storage capacities, and affect the sealing efficiency of caprock. The CO2/shale interactions were also found to cause noticeable degradation in shales’ mechanical properties. CO2 injection can weaken shale, decrease its brittleness and increases its plasticity and toughness. Various reductions in tri-axial compressive strength, tensile strength, and the elastic modulus of shales were observed after CO2 injection, due to the dissolution effect and adsorption strain within the pores. Based on this review, we conclude that CO2/shale interaction is a significant factor for the efficiency of CCS. However, due to the heterogeneity of shales, further studies are needed to include various shale formations and identify how different shales’ mineralogy could affect the CO2 storage capacity in the long-term.

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“…In recent years, studies have been conducted to evaluate various types of CO 2 storage such as geological storage of CO 2 in the forms of hydrates − and underlying depleted oil and gas reservoirs with caprock seals. − Understanding the role of sealing caprocks during carbon capture and storage (CCS) application is crucial to ensure the safe containment of the stored CO 2 . , Due to the low density of CO 2 compared to formation brine, CO 2 tends to migrate upward and penetrate through the sealing layers resulting in CO 2 breakthrough. − Shale caprocks play a major role in a petroleum reservoir system, as they are considered effective sealing layers due to their ultralow permeability and high capillary pressures, which can either prevent CO 2 leakage or significantly reduce CO 2 migration rate. Previous studies reported that CO 2 /brine injection can be beneficial for enhanced oil recovery (EOR) applications, as CO 2 can generate complex fractures with high conductivity, prevent formation damage, reduce the amount of produced wastewater, , and provide better displacement of the natural preadsorbed methane during fracturing. , However, during storage, CO 2 can cause major changes in the petrophysical and chemical properties of rocks and affect the storage capacity. − Considerable accomplishments were achieved in studying the sealing integrity of shales during CO 2 storage. − Seal integrity of shales is mainly affected by the geochemical interactions between CO 2 –brine and shale mineralogy, which can alter the wetting behavior, pore structure, and surface chemistry.…”

Section: Introductionmentioning

confidence: 99%

“…11−14 Shale caprocks play a major role in a petroleum reservoir system, as they are considered effective sealing layers due to their ultralow permeability and high capillary pressures, which can either prevent CO 2 leakage or significantly reduce CO 2 migration rate. Previous studies reported that CO 2 /brine injection can be beneficial for enhanced oil recovery (EOR) applications, as CO 2 can generate complex fractures with high conductivity, 15 prevent formation damage, 16 reduce the amount of produced wastewater, 17,18 and provide better displacement of the natural preadsorbed methane during fracturing. 19,20 However, during storage, CO 2 can cause major changes in the petrophysical and chemical properties of rocks and affect the storage capacity.…”

Section: Introductionmentioning

confidence: 99%

Surface Chemistry and Chemical Structure of Shale Caprocks Exposed to CO₂: Implication for Sealing Integrity

Fatah,

Norrman,

Al-Yaseri

2024

Energy Fuels

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Subsurface carbon dioxide storage is being widely studied as an effective solution for minimizing greenhouse gas emissions. Shale caprocks are regarded as effective seals during CO 2 storage that provide safe CO 2 conditions and prevent possible CO 2 leakage. However, the geochemical CO 2 /shale reactions remain a key challenge that can affect the sealing integrity. Despite the extensive studies on CO 2 /shale geochemical reactions, the impact of CO 2 on the surface chemistry and chemical structure of shale caprocks has rarely been addressed. In this work, we provide a detailed experimental analysis of the impact of CO 2 exposure on the chemical structure of shale caprocks and the potential implications for seal integrity. A real reservoir subsurface shale sample was treated with CO 2 at 75 °C at 1400 psi for 35 days and examined using chemical characterization techniques X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Based on the XPS results, no detectable reaction between CO 2 and the shale surface was observed, and the composition of the carbon functionalities appeared to be unaffected by the CO 2 exposure. The elemental composition showed insignificant changes, and no major chemical alterations occurred on the surface as a result of CO 2 exposure. TOF-SIMS analysis revealed that the saturated hydrocarbons accumulated on the surface, which consequently reduces the occurrence of inorganic and aromatic components since these get partly covered by the saturated hydrocarbons. This process is presumably a result of the experimental conditions (75 °C, 1400 psi, 35 days) rather than the presence of CO 2 . No direct evidence was found for any reaction involving CO 2 . This suggests a high sealing integrity of shales with low risks of CO 2 leakage. Future work can build on the findings in this work and consider it as a suitable experimental framework to assist in evaluating the reactivity of CO 2 to shale caprocks.

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An experimental study on the CO2/sand dry-frac process

Cited by 15 publications

References 4 publications

Analysis of Supercritical CO<sub>2</sub> Coiled Tubing Fracturing Technology for Shale Gas Formation

Analysis of Supercritical CO<sub>2</sub> Coiled Tubing Fracturing Technology for Shale Gas Formation

A Review on the Influence of CO2/Shale Interaction on Shale Properties: Implications of CCS in Shales

Surface Chemistry and Chemical Structure of Shale Caprocks Exposed to CO₂: Implication for Sealing Integrity

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An experimental study on the CO2/sand dry-frac process

Cited by 15 publications

References 4 publications

Analysis of Supercritical CO&lt;sub&gt;2&lt;/sub&gt; Coiled Tubing Fracturing Technology for Shale Gas Formation

Analysis of Supercritical CO&lt;sub&gt;2&lt;/sub&gt; Coiled Tubing Fracturing Technology for Shale Gas Formation

A Review on the Influence of CO2/Shale Interaction on Shale Properties: Implications of CCS in Shales

Surface Chemistry and Chemical Structure of Shale Caprocks Exposed to CO2: Implication for Sealing Integrity

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Analysis of Supercritical CO<sub>2</sub> Coiled Tubing Fracturing Technology for Shale Gas Formation

Analysis of Supercritical CO<sub>2</sub> Coiled Tubing Fracturing Technology for Shale Gas Formation

Surface Chemistry and Chemical Structure of Shale Caprocks Exposed to CO₂: Implication for Sealing Integrity