TY - JOUR

T1 - Thermoporoelastic model for the cement sheath failure in a cased and cemented wellbore

AU - Valov, A. V.

AU - Golovin, S. V.

AU - Shcherbakov, V. V.

AU - Kuznetsov, D. S.

N1 - Funding Information:
The authors would like to thank Schlumberger for permission to publish the results. The work of the first two authors was supported by the Ministry of Science and Higher Education of the Russian Federation (Grant No. 14.W03.31.0002 ).
Publisher Copyright:
© 2021 Elsevier B.V.

PY - 2022/3

Y1 - 2022/3

N2 - In the paper, we analyze factors that can lead to a failure of the cement sheath of a cased wellbore. By using a fully coupled linear thermo-poro-elastic model, we describe mechanical compression of the casing by fluid pressure and inhomogeneous geological stresses together with heating or cooling of the casing relative to the reservoir temperature. Due to the characteristic small ratio of the well diameter to its length, we observe the 2D problem in the section perpendicular to the well axis by adopting the plane strain approximation. We model the construction of single- or double-casings of the well, at that, both casings can be non-centered relative to the well axis. The cement sheath can be loaded by a prestress appeared during the cement hydration. The model is implemented numerically using the finite element method (FEM). Although many articles consider individual factors of the cement sheath failure, in our paper all these factors are modeled in a complex. Among the triggering effects for the failure we distinguish the strong contrast of geological stresses, the prestress in the cement sheath coupled with the action of the temperature variation. We also found that the thermo-poro-elastic coupling may lead to the significant growth of the pore pressure due to temperature changes when the pore pressure cannot dissolve either in the case of the very low permeability of cement or for the double-cased wellbore. In many situations, it is a combination of various factors that causes the failure of the cement sheath of the well, and not each factor separately.

AB - In the paper, we analyze factors that can lead to a failure of the cement sheath of a cased wellbore. By using a fully coupled linear thermo-poro-elastic model, we describe mechanical compression of the casing by fluid pressure and inhomogeneous geological stresses together with heating or cooling of the casing relative to the reservoir temperature. Due to the characteristic small ratio of the well diameter to its length, we observe the 2D problem in the section perpendicular to the well axis by adopting the plane strain approximation. We model the construction of single- or double-casings of the well, at that, both casings can be non-centered relative to the well axis. The cement sheath can be loaded by a prestress appeared during the cement hydration. The model is implemented numerically using the finite element method (FEM). Although many articles consider individual factors of the cement sheath failure, in our paper all these factors are modeled in a complex. Among the triggering effects for the failure we distinguish the strong contrast of geological stresses, the prestress in the cement sheath coupled with the action of the temperature variation. We also found that the thermo-poro-elastic coupling may lead to the significant growth of the pore pressure due to temperature changes when the pore pressure cannot dissolve either in the case of the very low permeability of cement or for the double-cased wellbore. In many situations, it is a combination of various factors that causes the failure of the cement sheath of the well, and not each factor separately.

KW - Cased wellbore

KW - Cement sheath damage

KW - Linear thermoporoelastic model

KW - Prestress

UR - http://www.scopus.com/inward/record.url?scp=85121110797&partnerID=8YFLogxK

U2 - 10.1016/j.petrol.2021.109916

DO - 10.1016/j.petrol.2021.109916

M3 - Article

AN - SCOPUS:85121110797

VL - 210

JO - Journal of Petroleum Science and Engineering

JF - Journal of Petroleum Science and Engineering

SN - 0920-4105

M1 - 109916

ER -