Experimental Study on Hydraulic Fracturing of Bedding Shale Considering Anisotropy Effects

Liu, Qi; Li, Bing; Sun, Weiji; Zhao, Hang; Hao, Jianfeng; Hou, Mengru

doi:10.1021/acsomega.2c02157

Cited by 5 publications

(7 citation statements)

References 47 publications

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“…Moreover, the initiation angles of both elliptical and circular boreholes decrease with increasing v 12 /v 13 , and the initiation angle of elliptical boreholes is consistently smaller than that of circular boreholes. This finding suggests that borehole deformation brings the direction of fracture initiation closer to the direction of the maximum principal stress, consistent with existing experimental results (Heng et al, 2019;Liu et al, 2022).…”

Section: Effect Of Poisson's Ratio Anisotropysupporting

confidence: 91%

“…The initiation angle of the elliptical borehole is smaller than that of the circular borehole. The difference gradually decreases with increasing σ h , which implies that considering the deformation of the boreholes in the calculations yields fracture initiation directions that are closer to the direction of the maximum principal stresses, which is more consistent with the existing experimental results (Heng et al, 2019;Liu et al, 2022).…”

Section: Effect Of the In Situ Stresssupporting

confidence: 85%

“…We have developed an improved FIP prediction model based on the forecasted borehole deformation and validated its accuracy by comparing it with the models of Aadnoy and Angell-olsen (1995) and Ge et al (2019). Zang et al (2023) observed, through digital image correlation during SC-CO 2 fracturing in the laboratory, that there is a strain concentration near the borehole before fracturing, which can cause borehole deformation, which suggests that our proposed model can also be used to predict the FIP of bedding shales for hydraulic fracturing in laboratory experiments (Liu et al, 2022). Based on the experimental findings by Liu et al (2022), we have conducted a comparative analysis of our model and that of Ma et al (2022).…”

Section: Discussionmentioning

confidence: 68%

“…To validate the dependability of the proposed model, we substituted the experimental conditions and mechanical parameters from the literature (Liu et al, 2022) into our proposed model and Ma et al's model. (Ma et al, 2022).…”

Section: Model Validation By Experimental Datamentioning

confidence: 99%

“…As a result, these reservoirs typically be simplified as transverse isotropic mediums (Espinoza et al, 2013;Ma et al, 2021). Existing laboratory experiments on fracturing have shown that the FIP of hydraulic fracturing varies as the angle between the bedding plane and the borehole changes, highlighting the significant impact of rock anisotropy, a factor acknowledged by numerous scholars (Qu et al, 2022a;Liu et al, 2022;Zhang et al, 2023). Numerous researchers have conducted theoretical examinations on the influence of rock anisotropy.…”

Section: Introductionmentioning

confidence: 99%

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Fracture initiation pressure prediction of hydraulic fracturing for layered reservoirs considering borehole deformation

Wang,

Niu

et al. 2024

Front. Earth Sci.

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Accurately predicting fracture initiation pressure is crucial for successfully applying hydraulic fracturing technology in layered reservoirs. However, existing models overlook the effects of rock anisotropy and borehole deformation. In this study, we simplified the layered reservoir to a transversely isotropic medium and developed a model to estimate borehole deformation precisely. Based on this estimated deformation, we created a model to predict fracture initiation pressure in hydraulic fracturing. By comparing previous models and experimental data, we validated the effectiveness of these proposed models. We examined the impacts of various factors on borehole deformation, fracture initiation pressure, and initiation angle. The results revealed that circular boreholes in layered reservoirs deform into elliptical boreholes under in situ stress, with the major axis not aligning with the principal stress direction, which highlights the significant impact of rock anisotropy on borehole deformation. Furthermore, the fracture initiation pressure of hydraulic fracturing either increases or decreases following borehole deformation, depending on specific geological parameters. The calculated initiation angle after borehole deformation is within 10°, closer to previous experimental results, underscoring the notable effect of borehole deformation on hydraulic fracturing. Our research indicates that the impact of borehole deformation on hydraulic fracturing is significant and should not be overlooked. This finding will offer fresh avenues for further study in the field of hydraulic fracturing.

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Section: Effect Of Poisson's Ratio Anisotropysupporting

confidence: 91%

Section: Effect Of the In Situ Stresssupporting

confidence: 85%

Section: Discussionmentioning

confidence: 68%

Section: Model Validation By Experimental Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Fracture initiation pressure prediction of hydraulic fracturing for layered reservoirs considering borehole deformation

Wang,

Niu

et al. 2024

Front. Earth Sci.

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Vertical height growth mechanism of hydraulic fractures in laminated shale oil reservoirs based on 3D discrete lattice modeling

Chang,

Wang,

Yang

et al. 2023

J Petrol Explor Prod Technol

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Bedding planes are abundant in shale oil reservoirs, but the intrinsic mechanism of fracture-height containment by these weak interfaces remains unclear. To investigate the effects of interface properties, stress conditions, and fracturing fluid viscosity on the vertical propagation of fracture heights in laminated shale oil reservoirs, a three-dimensional hydro-mechanical coupling numerical model was developed. The model is based on the 3D discrete lattice algorithm (DLA), which replaces the balls and contacts in the conventional synthetic rock mass model (SRM) with a lattice consisting of spring-connected nodes, resulting in improved computational efficiency. Additionally, the interaction between hydraulic fractures and bedding planes is automatically computed using a smooth joint model (SJM), without making any assumptions about fracture trajectories or interaction conditions. The results indicate that a higher adhesive strength of the laminated surface promotes hydraulic fracture propagation across the interface. Increasing the friction coefficient of the laminated surface from 0.15 to 0.91 resulted in a twofold increase in the fracture height. Furthermore, as the difference between vertical and horizontal principal stresses increased, the longitudinal extension distance of the fracture height significantly increased, while the activated area of the laminar surface decreased dramatically. Moreover, increasing the viscosity of the fracturing fluid led to a decrease in filtration loss along the laminar surface of the fracture and a rapid increase in net pressure, making the hydraulic fracture more likely to cross the laminar surface directly. Therefore, for heterogeneous shale oil reservoirs, a reverse-sequence fracturing technique has been proposed to enhance the length and height of the fracture. This technique involves using a high-viscosity fracturing fluid to increase the fracture height before the main construction phase, followed by a low-viscosity slickwater fracturing fluid to activate the bedding planes and promote fracture complexity. To validate the numerical modeling results, five sets of laboratory hydraulic fracturing physical simulations were conducted in Jurassic terrestrial shale. The findings revealed that as the vertical stress difference ratio increased from 0.25 to 0.6, the vertical fracture area increased by 1.98 times. Additionally, increasing both the injection displacement and the viscosity of the fracturing fluid aided in fracture height crossing of the laminar facies. These results from numerical simulation and experimental studies offer valuable insights for hydraulic fracturing design in laminated shale oil reservoirs.

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Impacts of wellbore orientation with respect to bedding inclination and injection rate on laboratory hydraulic fracturing characteristics of Lushan shale

Zhang

Long

Zhao

et al. 2023

Fuel

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Experimental Study on Hydraulic Fracturing of Bedding Shale Considering Anisotropy Effects

Cited by 5 publications

References 47 publications

Fracture initiation pressure prediction of hydraulic fracturing for layered reservoirs considering borehole deformation

Fracture initiation pressure prediction of hydraulic fracturing for layered reservoirs considering borehole deformation

Vertical height growth mechanism of hydraulic fractures in laminated shale oil reservoirs based on 3D discrete lattice modeling

Impacts of wellbore orientation with respect to bedding inclination and injection rate on laboratory hydraulic fracturing characteristics of Lushan shale

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