PSI - Issue 22

Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000

www.elsevier.com/locate/procedia

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 22 (2019) 84–92

© 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the First International Symposium on Risk and Safety of Complex Structures and Components organizers © 2019 The Authors. Published by Elsevier B.V.This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the First International Symposium on Risk and Safety of Complex Structures and Components organizers Keywords: Collapse strength; Curved casing; Uniform load; Wellbore curvature; Finite element method (FEM); Lame theory; Distortion energy theory Abst act In horizontal wells or directional wells, a casing bends to be in ccordance with the w llbor curvature of the wells. The ollapse strength of a curv d casing correspondingly decreases, which may cause well failure if neg ected. Herein, a curv c ing is taken as a bending be m under uniform load according to mater al mechani s. The differential quation of the defl ction is established. The relationships among axial s r ss, hoop tress, radial stress of casing, and wellbore dogl g is obtained b ed o Lame th ory. The equation of collapse stre gth of the curved casing is deduced using distortion- nergy theory. To verify theoretical result, a finite-element model of the casing is stablished with ANSYS software. The collapse strengths of casing in four cases are analyzed using theoretical and finite-ele ent method. Results show that the theoretical results well match the numerical ones. The collapse strength of the casing decreas s nonlinearly with creased curvature. Fo th casi g with outer diamet r (OD) of 139.7 mm and thickn ss of 10.54 mm, collapse str ngth decre ses from 104.74 MPa to 99.30 MPa with increased wellbore curvature from 2°/30 to 12°/30 m. The relative reduction in collapse trength incre ses no linea ly with increased wellbore curvature. OD has a greater influence on the relative reduction than thickness. The maximum value of relative reduction is 6.099% when OD is 139.7 mm but only 4.039% when OD is 114.3 mm. These results provide a reference for casing selection in production or ot r cases. © 2019 The Authors. Publ shed by Elsev er B.V.This is an open access article u er th CC BY-NC-ND li ense (http://cr a ivecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the First International Symposium on Risk and Safety of Complex Structures and Components organiz rs Keywords: Collapse strength; Curved casing; Uniform load; Wellbore curvature; Finite element method (FEM); Lame theory; Distortion energy theory 2452-3216 © 2019 The Authors. Published by Elsevier B.V.This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review statement: Peer-review under responsibility of the First International Symposium on Risk and Safety of Complex Structures and Components organizers 2452 3216 © 2019 The Autho s. Published by Elsevier B.V.This is an open acc ss rticle under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review statement: Peer-review under responsibility of the First International Symposium on Risk and Safety of Complex Structures and Components organizers * Corresponding author. Tel.: +86-139-0918-3925; fax: +86-029-88382126 E mail address: y do @vip sina.com Abstract In horizontal wells or directional wells, a casing bends to be in accordance with the wellbore curvature of the wells. The collapse strength of a curved casing correspondingly decreases, which may cause well failure if neglected. Herein, a curved casing is taken as a bending beam under uniform load according to material mechanics. The differential equation of the deflection is established. The relationships among axial stress, hoop stress, radial stress of casing, and wellbore dogleg is obtained based on Lame theory. The equation of collapse strength of the curved casing is deduced using distortion-energy theory. To verify the theoretical result, a finite-element model of the casing is established with ANSYS software. The collapse strengths of casing in four cases are analyzed using theoretical and finite-element method. Results show that the theoretical results well match the numerical ones. The collapse strength of the casing decreases nonlinearly with increased curvature. For the casing with outer diameter (OD) of 139.7 mm and thickness of 10.54 mm, collapse strength decreases from 104.74 MPa to 99.30 MPa with increased wellbore curvature from 2°/30 m to 12°/30 m. The relative reduction in collapse strength increases nonlinearly with increased wellbore curvature. OD has a greater influence on the relative reduction than thickness. The maximum value of relative reduction is 6.099% when OD is 139.7 mm but only 4.039% when OD is 114.3 mm. These results provide a reference for casing selection in production or other cases. * Corresponding author. Tel.: +86-139-0918-3925; fax: +86-029-88382126 E-mail address: yhdou@vip.sina.com First International Symposium on Risk and Safety of Complex Structures and Components Theoretical and Simulation Study on the Collapse Strength of a Curved Casing in Horizontal Wells First International Symposium on Risk and Safety of Complex Structures and Components Theoretical and Simulatio Study n the Collapse Strength of a Curved Casing in Horizontal Wells Yinping Cao a , YiHua Dou a, * , MingFei Li a , HongJuan Suo a a Mechanical Engineering College, Xi’an Shiyou University, Xi’an , Shaan xi, 710065, China Yinping Cao a , YiHua Dou a, * , MingFei Li a , HongJuan Suo a a Mechanical Engineering College, Xi’an Shiyou University, Xi’an , Shaan xi, 710065, China

2452-3216 © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the First International Symposium on Risk and Safety of Complex Structures and Components organizers 10.1016/j.prostr.2020.01.012