Investigation of casing deformation during hydraulic fracturing in high geo-stress shale gas play

Yan, Wei; Zou, Lingzhan; Li, Hong; Deng, Jingen; Ge, Hongkui; Wang, Haige

doi:10.1016/j.petrol.2016.11.007

Cited by 95 publications

(53 citation statements)

References 14 publications

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“…In the principal stress coordinate system, the principal horizontal stress matrix is σ 0 , whose components are maximum principal stress, σ H ; the minimum principal stress, σ h ; and the overburden pressure, σ v , shown in equation (2). e stress matrix in the wellbore coordinate system is σ.…”

Section: New Methodmentioning

confidence: 99%

“…Substituting the initial and boundary conditions into equations (7) and (8), the displacement and stress in formation were obtained as shown below. Because R 4 approached to infinity, A 3 ′ � 0 and C 3 ′ � R 2 3 were obtained:…”

Section: Formation Stressmentioning

confidence: 99%

“…ere were over 36 wells with casing deformation (including 112 horizontal wells by 2017) during fracturing process in some shale gas plays. Drilling tools were blocked, and serious deformation sections were abandoned before fracturing operation completion [2][3][4]. erefore, casing integrity has always been the main issue in designing shale gas wells under harsh conditions, and accurately calculating casing stress becomes primary to guarantee the casing safety.…”

Section: Introductionmentioning

confidence: 99%

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New Analytical Method to Evaluate Casing Integrity during Hydraulic Fracturing of Shale Gas Wells

Guo

Liu

et al. 2019

Shock and Vibration

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An accurate analysis of casing stress distribution and its variation regularities present several challenges during hydraulic fracturing of shale gas wells. In this paper, a new analytical mechanical-thermal coupling method was provided to evaluate casing stress. For this new method, the casing, cement sheath, and formation (CCF) system was divided into three parts such as initial stress field, wellbore disturbance field, and thermal stress field to simulate the processes of drilling, casing, cementing, and fracturing. The analytical results reached a good agreement with a numerical approach and were in-line with the actual boundary condition of shale gas wells. Based on this new model, the parametric sensitivity analyses of casing stress such as mechanical and geometry properties, operation parameters, and geostress were conducted during multifracturing. Conclusions were drawn from the comparison between new and existing models. The results indicated that the existing model underestimated casing stress under the conditions of the geostress heterogeneity index at the range of 0.5–2.25, the fracturing pressure larger than 25 MPa, and a formation with large elastic modulus or small Poisson’s ratio. The casing stress increased dramatically with the increase of in situ stress nonuniformity degree. The stress decreased first and then increased with the increase of fracturing pressure. Thicker casing, higher fluid temperature, and cement sheath with small modulus, large Poisson’s ratio, and thinner wall were effective to decrease the casing stress. This new method was able to accurately predict casing stress, which can become an alternative approach of casing integrity evaluation for shale gas wells.

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Section: New Methodmentioning

confidence: 99%

Section: Formation Stressmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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New Analytical Method to Evaluate Casing Integrity during Hydraulic Fracturing of Shale Gas Wells

Guo

Liu

et al. 2019

Shock and Vibration

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“…A lack of well stability has led to low production and significant implications in terms of the costs, safety and environmental issues. To reduce the probability of borehole failure, previous studies on borehole failure mainly focused on the evaluation of drilling design, including borehole construction and trajectory, casing material and drilling fluid, generally assumed that rock materials are isotropic and linear elastic in deformability and strength (Bradely, 1979;Kiran et al, 2017), and extended the analysis of the homogeneous or anisotropic strength (Ajalloeian and Lashkaripour, 2000;Lee et al, 2012;Mohammed et al, 2019;Pe´rie´, 1990;Tien et al, 2006) and geostress of the lithology (Song, 1998;Yan et al, 2017). The chemical-mechanical or physical-mechanical interactions between drilling fluids and clay minerals as well as groundwater also affect drilling damage (Haimson and Song, 1993;Liang et al, 2015;Zeynali, 2012), but these effects may be applied to improve drilling methods and maximize the effectiveness of drilling (Bennion et al, 1996;Clancey et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Analysis of the shear failure of surface methane capture boreholes for improving the drainage period efficiency: A lithological perspective

Fang

Sang

et al. 2019

Energy Exploration & Exploitation

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The shear failure of surface methane capture boreholes (SMCBs) is the main reason for the life cycle shortening of surface methane capture boreholes but lacks a comprehensive lithological analysis. To improve the surface methane capture borehole stability and drainage period efficiency, it is of great importance to investigate the influence of lithology on the shear failure of surface methane capture boreholes. The results of direct shear tests and geological investigations show that the shear displacement increases as the grain size decreases. A jump in mechanical properties occurs at the lithological boundaries and is mainly controlled by the composition of the rock specimens. The change in cohesion is the main possible reason for the step change of the shear strength. High quartz and low clay contents may effectively improve the shear strength and failure resistance of rock. Boreholes may potentially experience preferential casing failure in the section of the weaker mudstone and siltstone due to larger shear displacements and lower shear strengths of those rock types. Protective measures at these sections may improve the stability of the borehole casing. The detection results at the close of the borehole verify the prediction.

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“…For example, 12 of 22 SBCMs in the Huainan coal field ceased to produce gas as a result of borehole failure, adversely affecting the extraction efficiency [6]. To reduce the probability of borehole failure, previous researches on borehole failure mainly focused on evaluating drilling design, including the well construction and trajectory, casing material, drilling fluid and typically assuming that the rock material is isotropic, linear elastic and homogeneous in deformability and strength [7][8][9], and extending analyses to anisotropic strength of lithology [10][11][12][13] and geostress [14][15][16].Borehole failure is also influenced by the chemical-mechanical or physical-mechanical interactions between clay minerals and drilling fluids as well as groundwater [17,18], but these effects may be applied to improve drilling methods and maximize the effectiveness of drilling [19][20][21].…”

mentioning

confidence: 99%

Analysis of Shear Failure of Surface Methane Capture Boreholes for Improving Efficient Drainage Period–A Lithology Perspective

Xu¹,

Fang²,

Sang³

et al. 2019

Preprint

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The shear failure of surface methane capture borehole (SMCB) is the main cause of shortening life cycle of SMCB but lack of lithological analysis. In order to improve the stability of SMCB and improve efficient drainage period, it is of great significance to investigate the lithology performances for shear failure of SMCB. Based on the direct shear tests and geological method, the results shows that the shear displacement increases as the grain size decreases. Mechanical jump occurs at the lithological boundaries, which is mainly determined by the composition of rock specimens. The cohesion is the mainly possible reason for the step change of shear strength. Lithology with high quartz and low clay may effectively improve shear strength and failure resistance. Boreholes drilled into the weaker siltstone and mudstone sections may potentially experience preferential damage due to the larger shear displacement and shear strength. Protective measures at these sections may improve the stability of the borehole casing. The probing data where it was found that boreholes closure validated the prediction.

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Investigation of casing deformation during hydraulic fracturing in high geo-stress shale gas play

Cited by 95 publications

References 14 publications

New Analytical Method to Evaluate Casing Integrity during Hydraulic Fracturing of Shale Gas Wells

New Analytical Method to Evaluate Casing Integrity during Hydraulic Fracturing of Shale Gas Wells

Analysis of the shear failure of surface methane capture boreholes for improving the drainage period efficiency: A lithological perspective

Analysis of Shear Failure of Surface Methane Capture Boreholes for Improving Efficient Drainage Period–A Lithology Perspective

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Investigation of casing deformation during hydraulic fracturing in high geo-stress shale gas play

Cited by 95 publications

References 14 publications

New Analytical Method to Evaluate Casing Integrity during Hydraulic Fracturing of Shale Gas Wells

New Analytical Method to Evaluate Casing Integrity during Hydraulic Fracturing of Shale Gas Wells

Analysis of the shear failure of surface methane capture boreholes for improving the drainage period efficiency: A lithological perspective

Analysis of Shear Failure of Surface Methane Capture Boreholes for Improving Efficient Drainage Period&ndash;A Lithology Perspective

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Analysis of Shear Failure of Surface Methane Capture Boreholes for Improving Efficient Drainage Period–A Lithology Perspective