An Analytical Model for Fracture Initiation from a Particular Radial Borehole in Hydraulic Fracturing Guided by Multiradial Boreholes

Chen, Yuxin; Ding, Yunhong; Liang, Chong; Zhu, Deqing; Bai, Yu; Zou, Chunmei

doi:10.1155/2021/6657788

Cited by 4 publications

(3 citation statements)

References 21 publications

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“…Liu et al 28 verified the guiding effect of radial holes on directional propagation of hydraulic fracture by the extended finite element method and true triaxial experiments. On the basis of Liu's model, Chen et al 29 analytically studied the interference between radial boreholes by analyzing the varieties of FIP with different borehole parameters.…”

Section: Introductionmentioning

confidence: 99%

Initiation mechanisms of radial drilling‐fracturing considering shale hydration and reservoir dip

Chen

Ding

Liang

et al. 2021

Energy Science & Engineering

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Section: Introductionmentioning

confidence: 99%

Initiation mechanisms of radial drilling‐fracturing considering shale hydration and reservoir dip

Chen

Ding

Liang

et al. 2021

Energy Science & Engineering

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“…To prevent single radial borehole not efficiently guiding the fracture propagation, researchers proposed multibranched radialdrilling fracturing. The fracture initiation mechanism of multibranched radial-drilling fracturing has been investigated by many researchers through numerical simulation [15][16][17][18][19], experiments [20][21][22][23], and establishing mathematical models [24][25][26][27]. Haimson and Fairhurst [28] established a calculation model of stress distribution surrounding the vertical wellbore under the circumstance of open-hole completion, expounded the mechanism of vertical fracture initiation, and deduced the equation of vertical fracture initiation pressure.…”

Section: Introductionmentioning

confidence: 99%

Fracture Initiation Mechanisms of Multibranched Radial-Drilling Fracturing

et al. 2021

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Compared with conventional hydraulic fracturing, radial-drilling fracturing presents remarkable advantages and can effectively develop low-permeability reservoirs. The radial borehole can reduce formation fracture pressure and guide the fracture initiation and propagation. Due to the large radial borehole azimuth or the strong anisotropy of the reservoir, the single radial borehole may not efficiently guide the fracture propagation. The researchers proposed multibranched radial-drilling fracturing. However, the research on fracture initiation of multibranched radial-drilling fracturing is inadequate. Radial boreholes usually need certain dip angles to avoid penetrating the interlayer, but the effect of dip angle on the stress field has never been considered before. In this paper, an analytical model for predicting stress distribution around the main wellbore with multiradial boreholes of arbitrary dip angle, azimuth angle, and phase angle is established for the first time, taking full account of the influences of in situ stress, internal pressure, and fracture fluid infiltration on the stress field. The model is utilized to calculate the fracture initiation pressure (FIP) and point out the specific fracture initiation location (FIL). The influences of azimuth angle, dip angle, phase angle, depth difference, and the stress profile radius on fracture initiation pressure, fracture initiation location, and maximum tensile stress distribution are investigated, and a series of sensitivity analyses are carried out. The results show that the areas between the radial boreholes and closer to the walls of radial boreholes are more prone to tensile failure, which provides a theoretical basis for radial boreholes guiding fracture initiation. The reduction of phase angle and depth difference enhances the interference between radial wells, which is conductive to the formation of hydraulic fracture networks between them. As the dip angle increases, the stress becomes increasingly concentrated, and the preferential rock tensile failure becomes increasingly easy. The farther the stress profile is from the main wellbore axis, the smaller it will be influenced by the main wellbore. When the distance exceeds 2R, the maximum tensile stress distribution on the profile remains constant. The research enriches the fracture initiation mechanism of multibranched radial-drilling fracturing and provides guidance for optimizing radial borehole layout parameters of hydraulic fracturing directed by multiradial boreholes.

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“…Liu et al [27] built a general analytical model to predict fracture initiation from the radial borehole based on the maximum tensile criterion and conducted a series of sensitivity analyses by discussing different effects, including in situ stress statues, radial borehole azimuth, radial borehole length, and radial borehole diameter. Chen et al [28] developed an analytical model to study the fracture initiation under the guidance of multiradial boreholes and analyzed the interference between radial boreholes.…”

Section: Introductionmentioning

confidence: 99%

An Analytical Model for Fracture Initiation of Radial Drilling-Fracturing in Shale Formations

et al. 2021

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Radial drilling-fracturing, the combination of radial drilling and hydraulic fracturing, can guide fractures toward the target area and effectively enhance the recovery of the low permeable reservoir. In this paper, based on the stress superposition principle, we establish an analytical model to predict fracture initiation pressure (FIP) and the shale failure mode for radial drilling-fracturing applied in shale formations. In contrast with the former studies, this model can additionally consider the failure from shale beddings and is more applicable in the shale reservoir. The model classifies the shale failure into three modes and, respectively, gives the criterion for each failure mode. Then, a series of sensitivity analyses is conducted by examining effects of various parameters. By analyzing the variation characteristic of the initiation pressures required for three failure modes, the main conclusions are as follows. Firstly, matrix failure and shear failure along bedding tend to take place when the azimuth of radial borehole is moderate. Small and large azimuths are favorable for the occurrence of tensile failure along bedding. Secondly, a high ratio of horizontal in situ stress predisposes shale to generate matrix failure, and bedding tensile failure and bedding shear failure are apt to occur when the ratio of horizontal in situ stress is low. Thirdly, with the increasing intersection angle of the radial borehole wall and bedding plane, the failure mode apt to occur changes from bedding tensile failure to bedding shear failure and then to matrix failure. Fourthly, shale prefers to yield bedding shear failure under a small Biot coefficient and generate the other two failure modes when Biot coefficient is large. Fifthly, permeability coefficient virtually has no influence on the failure mode of shale. The research clarifies the fracture initiation characteristics of radial drilling-fracturing in shale formations and provides a reference for the field application of radial drilling-fracturing.

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An Analytical Model for Fracture Initiation from a Particular Radial Borehole in Hydraulic Fracturing Guided by Multiradial Boreholes

Cited by 4 publications

References 21 publications

Initiation mechanisms of radial drilling‐fracturing considering shale hydration and reservoir dip

Initiation mechanisms of radial drilling‐fracturing considering shale hydration and reservoir dip

Fracture Initiation Mechanisms of Multibranched Radial-Drilling Fracturing

An Analytical Model for Fracture Initiation of Radial Drilling-Fracturing in Shale Formations

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