Progress and development of volume stimulation techniques

Xu, Yizhuang; Lei, Qun; Chen, Ming; Wu, Qi; Yang, Nengyu; Weng, Dingwei; Li, Deqi; Jiang, Hao

doi:10.1016/s1876-3804(18)30097-1

Cited by 54 publications

(9 citation statements)

References 66 publications

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“…It is found that the fracturing process seriously affects the effective sealing of cement sheath. However, scholars have proposed the tight spacing fracturing technology of reducing cluster spacing in recent years, the cluster spacing of horizontal wells in unconventional reservoirs in North America has been reduced from 20~30 m to 5~10 m [72]. This means that the interface cracks are prone to channeling, after the interface cracks between clusters are connected, they may continue to expand along the wellbore to the unfractured area and connect the whole horizontal section area.…”

Section: Conclusion and Suggestionsmentioning

confidence: 99%

Study on Synchronous Propagation Behavior of Hydraulic Fractures and Cementing Interfacial Cracks during Fracturing of Shale Horizontal Wells

et al. 2021

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Large-scale staged hydraulic fracturing stimulation technology is an effective method to increase shale oil and gas recovery. However, cracks will appear along with the cementing interface and expand under the drive of fluid while hydraulic fracturing, failing wellbore sealing. To solve this problem, the synchronous propagation model of hydraulic fractures and cementing interfacial cracks in hydraulic fracturing is established. The Newton iteration method and displacement discontinuity method are used to solve the propagation length of each fracture, and the effects of cement sheath parameters and fracture parameters on the interface failure range are studied. The results show that when multiple hydraulic fractures expand, the interfacial cracks are also affected by “stress shadow,” offering an asymmetric expansion, and the cementing interfacial cracks in the area between hydraulic fractures are easier to expand. The failure range of interface between the hydraulic fractures expands rapidly if the cement elastic modulus increases from 5 GPa to 10 GPa; while the cement elastic modulus is higher than 10 GPa, the failure area is mainly affected by the number of hydraulic fractures; the failure range is not affected by the number of hydraulic fractures if the hydraulic fracture spacing is less than 10 m or more than 30 m; while the crack spacing is between 10 m and 30 m, the more the number of hydraulic fractures, the easier it is to cause the interface failure range to increase and connect. The research results can provide a theoretical basis for the optimization of cement slurry systems and fracturing parameters.

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Section: Conclusion and Suggestionsmentioning

confidence: 99%

Study on Synchronous Propagation Behavior of Hydraulic Fractures and Cementing Interfacial Cracks during Fracturing of Shale Horizontal Wells

et al. 2021

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“…The fluid loss effect of the fracturing fluid causes the liquid water to enter the coal body through the fracture or pore [13], which affects coal volume and permeability. Previous studies have mainly focused on fracture expansion direction, formation stress, influencing factors and numerical method modeling [6]. In addition, researches were also focused on the gas flow behavior in the gas extraction process [1,[7][8][9][10], from the early single-phase gas flow model to the later two-phase water-gas flow model [11].…”

Section: Model Conceptmentioning

confidence: 99%

The Influence of the Injected Water on the Underground Coalbed Methane Extraction

et al. 2020

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The increasing demand on coal production has led to the gradually increase of mining depth and more high methane mines, which bring difficulties in terms of coalbed methane (CBM) extraction. Hydraulic fracturing is widely applied to improve the production of CBM, control mine gas, and prevent gas outbursts. It improves coal bed permeability and accelerate desorption and migration of CBM. Even though the impacts of hydraulic fracturing treatment on the coal reservoirs are rare, negative effects could not be totally ignored. To defend this defect, the presented work aims to study the influence of water filtration on coal body deformation and permeability evolution. For this purpose, a simulation based finite element method was developed to build a solid-fluid coupled two-phase flow model using commercial software (COMSOL Multiphysics 5.4). The model was verified using production data from a long strike borehole from Wangpo coal mine in Shanxi Province, China. Several simulation scenarios were designed to investigate the adverse impacts of hydraulic fracturing on gas flow behaviors. The mechanisms of both relative and intrinsic permeability evolutions were analyzed, and simulation results were presented. Results show that the intrinsic permeability of the fracture system increases in the water injection process. The impacts of water imitation were addressed that a critical time was observed beyond which water cannot go further and also a critical pressure exists above which the hydraulic pressure would impair the gas flow. Sensitivity analysis also showed that a suitable time and pressure combination could be observed to maximize gas extraction. This work provides an efficient approach to guide the coal bed methane exploitation and other unconventional gas reservoirs.

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“…In view of the fact that the porosity and permeability of shale reservoirs are extremely low, hydraulic fracturing is an effective technology to achieve commercial development (Zou et al, 2017). Ideally, hydraulic fractures initiate from the borehole at an acceptable breakdown pressure and propagate into the reservoir, fully activating natural fractures and bedding and forming a complex fracture network (Xu et al, 2018). The fracturing effects are controlled by various factors, which can be roughly divided into geological and engineering categories.…”

Section: Introductionmentioning

confidence: 99%

Laboratory investigation and evaluation of the hydraulic fracturing of marine shale considering multiple geological and engineering factors

Wang

Zhou²,

Guo³

et al. 2022

Front. Earth Sci.

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Hydraulic fracturing is widely implemented in the exploration of marine shale gas. Affected by various geological and engineering factors, gas production after stimulation is not always satisfactory. To reveal the influential effect of multiple factors, laboratory hydraulic fracturing experiments are performed on Longmaxi marine shales by considering key parameters (deviatoric stress, confining pressure, pumping rate, fracturing fluid type, and bedding angle). The variation of breakdown pressures and the characteristics of hydraulic fractures are recorded and analyzed. The results show that the breakdown pressure increases with increasing deviatoric stress, confining pressure, pumping rate, and viscosity of the fracturing fluid. As the bedding angle varies from 0° to 90°, the breakdown pressure declines first and increases again. Furthermore, parameter sensitivity analysis indicates that geological factors (confining pressure, bedding angle, and deviatoric stress) would largely determine the breakdown pressure, while engineering factors (pumping rate, fracturing fluid type) could only affect it to a lesser extent. Computed tomography measurements show that natural fractures, originating from tectonic shear failure, could possess greater width than tension-dominated hydraulic and bedding fractures. Statistical analysis shows that the length of the hydraulic fractures alone is only approximately 150 mm. However, the fully activated natural and/or bedding fractures could help substantially increase the total fracture length to 600 mm. Low deviatoric stress, low confining pressure, low viscous slick-water, and high bedding angle are conducive to activating natural and bedding fractures and forming a complex fracture network. The aforementioned findings are valuable for the optimal design of field hydraulic fracturing.

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Progress and development of volume stimulation techniques

Cited by 54 publications

References 66 publications

Study on Synchronous Propagation Behavior of Hydraulic Fractures and Cementing Interfacial Cracks during Fracturing of Shale Horizontal Wells

Study on Synchronous Propagation Behavior of Hydraulic Fractures and Cementing Interfacial Cracks during Fracturing of Shale Horizontal Wells

The Influence of the Injected Water on the Underground Coalbed Methane Extraction

Laboratory investigation and evaluation of the hydraulic fracturing of marine shale considering multiple geological and engineering factors

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