A laboratory study of microcracks variations in shale induced by temperature change

Li, Zhenglan; Duan, Yunlong; Peng, Yu; Wei, Mingqiang; Wang, Rong

doi:10.1016/j.fuel.2020.118636

Cited by 15 publications

(4 citation statements)

References 43 publications

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“…The temperature could positively influence the swelling volume of shales when the temperature was higher than 10 °C. Li et al [61] studied the effect of temperature change on fracture generation in water-shale interaction. They compared the CT images for the tests under 80 °C with those under 20 °C.…”

Section: Geofluidsmentioning

confidence: 99%

Review of the Generation of Fractures and Change of Permeability due to Water-Shale Interaction in Shales

et al. 2022

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In shale development, water-based liquids are injected into the formations. In this process, water can interact with shales, especially with clay content. The interaction can lead to some phenomena, including clay swelling, reduction of mechanical properties of shales and fractures, generation and propagation of fractures, particle detachment, and permeability change. All the phenomena can impact productivity during the development, thereby impacting our investment and return on investment (ROI). So far, many researchers have put their time and efforts into this topic, and many articles have been published. However, some discrepancies still exist in shale reservoirs regarding the role of the interaction between water and shale, especially the impact of clay swelling. Some believe that clay swelling causes formation damage, mainly impairing shale permeability. Others state that fractures can be induced because of clay swelling, leading to the enhancement of shale permeability. So far, few articles have reviewed the various views on this interaction. Additionally, the relationship between each phenomenon is not discussed. In this paper, we try to draw a clear picture of water-shale interaction by reviewing the published studies, mainly focusing on experimental methodology and experimental results. Based on the review, we summarized the influencing factors as well as the mechanisms about the formation of fractures and change of permeability due to water-shale interaction. In water-shale interaction, the induced fractures are generated by the combined effects from clay swelling, reduction of mechanical properties of shales and fractures, and stress anisotropy. Shale permeability can be enhanced if the generated fractures can form an effective flow channel. However, if the generated fractures cannot serve as an effective flow channel, shale permeability will be impaired by clay swelling, water blocking, stress-sensitive, etc.

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Section: Geofluidsmentioning

confidence: 99%

Review of the Generation of Fractures and Change of Permeability due to Water-Shale Interaction in Shales

et al. 2022

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“…China has large amount of unconventional oil and gas resources represented by tight gas, shale oil and gas reservoirs. In recent years, with the continuously in-depth oil & gas exploration and development, the unconventional resources have become increasingly important in China's petroleum industry system (Tong et al, 2018;Zou et al, 2018;Li et al, 2019a;Ji et al, 2019;Jiao, 2019;Li et al, 2020). After the successful development of marine reef and shoal facies reservoirs in Yuanba area of northeastern Sichuan, the tight sandstone gas reservoirs of the upper triassic Xujiahe formation also showed a great potential of resource (Zhang et al, 2016;Long et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

The investigation of microporous structure and fluid distribution mechanism in tight sandstone gas reservoirs: A case study on the second member of Xujiahe gas reservoirs in Yuanba area

Guo

Fu²,

Li³

et al. 2022

Front. Energy Res.

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Tight sandstone reservoir is characterized by ultra-low porosity, complex microporous structure and water residues, which shows different gas storage and transport mechanism from conventional reservoirs. Therefore, effective development of tight sandstone gas reservoirs is faced with technical challenges. Microporous structures, distribution mechanism of fluid is a basic issue in gas reservoir evaluation. In this work, we take gas reservoir in the 2nd member of Xujiahe Formation in Yuanba area as an example to analyze the microscopic feature of pore structure and fluid distribution. The three-dimensional digital core has been applied to represent the real microporous structure. Specifically, a digital core reconstruction method based on SEM and casting slice images has been proposed. Ultimately, the mechanism of distribution, mode of occurrence of water residues in tight sandstone reservoirs has been simulated and quantitatively analyzed. The results show that the water residues could been visualized and categorized into three modes, water mass in corner, water film on surface, and water column in throat. The water residues could cause dramatic influence on pore structures, active pore size could be decreased with rising residual water saturation, the magnitude falls by over 50%. In addition, grain size would affect the distribution of water residues, which shows different percentage in medium and fine sand. Pore connectivity is another characteristic factor to describe the microporous structures. In this study, cluster marking algorithm has been applied to obtain the pore connectivity in tight sandstone with different grain size. In medium sand, the pore connectivity is dramatically decreased with rising water saturation, the downward trend become slower when water saturation reaches to 60%. Compared to fine sand, the tendency variation appears when water saturation reaches to 40%. This paper provides an applicable method to reveal the micro-scale reservoir properties and fluid distribution mechanisms in tight sandstone gas reservoirs.

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“…At present, horizontal well technology combined with segmented multi-stage fracturing technology is commonly used worldwide to achieve efficient development of tight oil reservoirs (Jiang et al, 2017;Zhang, 2020;Guo et al, 2021;Zheng et al, 2021), and the recovery rate can be improved by increasing the stimulated reservoir volume. However, the fracture expansion of tight oil reservoirs is influenced by their own geological conditions with diverse situations (Zhao et al, 2015;Peng et al, 2016;Zhao et al, 2017;Li et al, 2020;Peng et al, 2020), some reservoirs are strongly heterogeneity with positive and reverse rhythm in the vertical direction (Li et al, 2019a;Zhang et al, 2022b), and the two-phase or even three-phase seepage is superimposed on the influence of engineering factors on the development process (Ma et al, 2021;Shen et al, 2022), which makes the seepage mechanism and development law of tight reservoirs very complex (Zafar et al, 2020;Zhao et al, 2021), and the dominant seepage channel is not clear (Li et al, 2019b). At present, the relevant research is still at the core scale (Jing et al, 2021)…”

Section: Introductionmentioning

confidence: 99%

Study on the development options of tight sandstone oil reservoirs and their influencing factors

Huang

et al. 2022

Front. Energy Res.

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The research area of tight sandstone oil reservoirs was selected, a numerical model of the oil reservoir was developed, and a study of the development options and influencing factors was carried out to analyze the influence of different development methods, physical and engineering parameters on the development dynamics. Study shows that the two main factors limiting the efficient development of tight sandstone reservoirs are reservoir properties and formation energy. Fractured horizontal well injection huff and puff development can effectively improve reservoir physical properties and timely replenish formation energy, which is suitable for the development of such oil reservoirs. In dense sandstone reservoirs, its impact on production capacity is also relatively small when the permeability ratio is small. Due to both gravity and reservoir physical properties, the permeability ratio increases, the cumulative oil production of positive rhythm reservoirs decreases and that of reverse rhythm reservoirs increases, and the location of high-quality reservoirs in the upper part of producing wells is conducive to increasing the final recovery rate. A lower oil to water viscosity ratio can significantly increase the swept volume and improve development effect. Hydrophilic reservoirs can reduce the injection pressure and increase the spread range, effectively improving the problem of inability to inject, and improving reservoir hydrophilicity through surface activators can increase reservoir recovery. The water injection rate determines the recovery rate of formation energy. Generally, the faster the rate, the higher the cumulative oil production. Therefore, the rate of water injection should be increased as much as possible, taking into account construction conditions and economic evaluation. Additionally, the effect of water injection on the development effect is different at different stages, so the appropriate timing of water injection is very important to the water injection huff and puff development effect, and the use of early water injection in this research area is not conducive. Soaking can promote pressure and fluid redistribution and improve water injection huff and puff development effect, but soaking for a long time can lead to reservoir contamination and reduce crude oil production, so the preferred time for a soaking is about 20 days.

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A laboratory study of microcracks variations in shale induced by temperature change

Cited by 15 publications

References 43 publications

Review of the Generation of Fractures and Change of Permeability due to Water-Shale Interaction in Shales

Review of the Generation of Fractures and Change of Permeability due to Water-Shale Interaction in Shales

The investigation of microporous structure and fluid distribution mechanism in tight sandstone gas reservoirs: A case study on the second member of Xujiahe gas reservoirs in Yuanba area

Study on the development options of tight sandstone oil reservoirs and their influencing factors

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