Numerical simulations of wellbore cement sheath microannuli leakage in Gulf of Mexico wells

Wise, Jarrett

Numerical simulations of wellbore cement sheath microannuli leakage in Gulf of Mexico wells

dc.contributor.advisor	Nygaard, Runar
dc.contributor.author	Wise, Jarrett
dc.contributor.committeeMember	Stalford, Harold
dc.contributor.committeeMember	Salehi, Saeed
dc.contributor.committeeMember	Karami, Hamidreza
dc.date.accessioned	2021-04-01T20:52:24Z
dc.date.available	2021-04-01T20:52:24Z
dc.date.issued	2021-02-25
dc.date.manuscript	2021
dc.description.abstract	The Gulf of Mexico (GoM) is home to more than 50,000 oil and gas wells with approximately 30,000 wells that are plugged and abandoned leading to concerns of oil and gas leakage where currently, little to no monitoring is performed. The cement used when completing and eventually plugging wells are subject to harsh conditions leading to failure of the cement due to debonding of the cement to the formation and/or casing, shrinkage of the cement, and chemical degradation in the cement. Due to the complicated mechanical and chemical nature of cement, researchers have turned to numerical simulations to model cement failure and predict potential leakage rates. However, the numerical models in previous studies either predict leakage mechanisms but fail to provide comprehensive quantification of the fracture magnitudes. Or the models assume a fracture value and quantify leakage assuming water as the leaking fluid. The goal of this study is to determine if leakage is occurring through the cement sheath in GoM wells. This study develops a realistic finite element analysis (FEA) model coupled with fluid flow to determine if hydraulic propagation occurs providing a continuous leakage pathway. An analytical gas flow model is developed and used in conjunction with the FEA fracture volume to provide accurate fluid leakage rates within the pathways. The results of this work show that FEA models coupled with fluid flow can accurately quantify microannuli magnitude and predict if the microannuli propagate up the wellbore to the environment. The fluid flow models show that assuming wellbore water leakage versus gas leakage has an order of magnitude difference in leakage rates, cement shrinkage occurs in conventional cements causing continuous leakage pathways, and cement additives that change the mechanical properties of the cement are not required to achieve wellbore integrity.	en_US
dc.identifier.uri	https://hdl.handle.net/11244/329088
dc.language	en_US	en_US
dc.subject	Engineering, Petroleum	en_US
dc.subject	Wellbore Integrity	en_US
dc.subject	Microannuli	en_US
dc.subject	Gas Flow	en_US
dc.thesis.degree	Ph.D.	en_US
dc.title	Numerical simulations of wellbore cement sheath microannuli leakage in Gulf of Mexico wells	en_US
ou.group	Mewbourne College of Earth and Energy::Mewbourne School of Petroleum and Geological Engineering	en_US