Impact of Casing Eccentricity on Cement Sheath

Liu, Kui; Gao, Deli; Taleghani, Arash Dahi

doi:10.3390/en11102557

Cited by 11 publications

(4 citation statements)

References 15 publications

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“…In addition, casing eccentricity is ignored during the experimental process. At the same time, existing studies show that casing centralization has a great influence on the stress state of cement sheaths (Liu et al, 2018). As such, a set of full-scale devices for cement sheath seal integrity evaluation at high temperature and high pressure returns and eccentric casing is developed.…”

Section: Introductionmentioning

confidence: 99%

Influence of the Casing Eccentricity on the Cement Sheath Sealing Integrity in the Tie-Back Interval Under the Complex Temperature and Pressure Conditions of Deep-Water Oil and Gas Wells

Zhong¹,

Wu²,

Xie³

et al. 2022

Front. Energy Res.

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The integrity of cement sheath seals in casing connection sections is an important part of preventing air channelization. It is of great significance to evaluate the failure mechanism of cement sheath seals in casing connection sections under complex temperatures, pressures, and casing eccentricities. Based on the self-developed high-temperature and high-pressure full-size casing connection period of the cement sheath seal integrity evaluation device and the casing loading/unloading casing eccentricity influence on the cement sheath seal failure under the experimental conditions, it is concluded that the casing pressure changes, annulus preset pressure, and casing eccentricity influence the law of cement sheath seal integrity. The results show that the following: ① Casing eccentricity has an important influence on the failure of the cement sheath seal when the casing is loaded, and to ensure the integrity of the cement sheath seal the casing should be greater than 75%; ② in the case that the annular pressure is not set, casing eccentricity has little influence on the integrity of the cement annular seal during casing unloading, and sealing failure occurs when pressure unloading is 15–20 MPa; ③ when there is a preset pressure in the annulus, casing eccentricity has a great influence on seal failure during unloading. The greater the preset pressure in the annulus is, the better the seal integrity of the cement annulus. The research results provide an important basis for ensuring the integrity of cement sheath seals in casing connection sections.

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Section: Introductionmentioning

confidence: 99%

Influence of the Casing Eccentricity on the Cement Sheath Sealing Integrity in the Tie-Back Interval Under the Complex Temperature and Pressure Conditions of Deep-Water Oil and Gas Wells

Zhong¹,

Wu²,

Xie³

et al. 2022

Front. Energy Res.

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“…Liu et al established the calculation model of a cement sheath stress under casing eccentricity and pointed out that casing eccentricity would significantly increase the stress of a cement sheath, thus leading to yield failure of the cement sheath. − Han analyzed the influence of casing eccentricity on the loading capacity of a cement sheath using the finite element model . Wei studied the unloading effect of a cement sheath on external extruding load under different casing eccentricity conditions using theoretical calculation, finite element analysis, and experimental investigation; he pointed out that casing eccentricity would reduce the unloading capacity of the cement sheath .…”

Section: Introductionmentioning

confidence: 99%

Influence of Casing Eccentricity on the Mechanical Integrity of Cement Sheaths in Fractured Wells

Zheng

Wang

et al. 2021

ACS Omega

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During the fracturing process of oil and gas wells, casing eccentricity directly affects the mechanical integrity of cement sheaths, but the law and degree of influence are not clear at present, and there are no measures to address the influence of casing eccentricity on the mechanical integrity of cement sheaths. This paper took the lead in developing a set of experimental devices for cement sheath integrity. A comparative experimental study on the mechanical integrity of cement sheaths was carried out for the first time under casing concentric and eccentric conditions, and the influence of casing eccentricity on the mechanical integrity of cement sheaths in fractured wells of the Wushi 17-2 oilfield was also investigated. The numerical simulation method was used to perform stress analysis on cement sheaths of fractured wells under casing concentric and eccentric conditions. The influences of casing wall thickness, cement sheath thickness, the elastic modulus of cement sheath, and formation on radial stress of the cement sheath were analyzed, and the mechanical integrity safeguard or remedy measures of the cement sheath under the casing eccentric condition were proposed for the first time. The results show that casing eccentricity can easily lead to stress concentration at the narrow edge of the cement sheath. Under the condition of the same strength of the cement sheath, the integrity of the cement sheath is more likely to fail under the casing eccentric condition. The tensile failure cracks are concentrated at the narrow edge of the cement sheath. With the increase in casing eccentricity, the stress at the narrow edge of the cement sheath increased, the critical failure pressure of the cement sheath decreased, and the failure pressure of cement sheath integrity decreased by 17.72% at a casing eccentricity of 33% compared within a casing eccentricity of 0%. Improving the casing center degree, increasing the casing wall thickness and cement sheath thickness, and reducing the elastic modulus of the cement sheath can minimize the stress of the cement sheath and prevent mechanical integrity failure. This study is helpful to evaluate the mechanical integrity of the cement sheath in fractured wells accurately and can provide a technical reference for optimizing the casing center degree.

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“…According to research on the effect of the casing eccentricity on the integrity of the cement sheath, poorly cementing increases this effect seriously. Therefore the risk of cement failure is reduced by setting thick and centralized casing strings [12]. Salehabadi et al [16] investigated the effect of eccentricity in the gas hydrate bearing sediments under uniform and non-uniform loadings by the finite element method.…”

Section: Introductionmentioning

confidence: 99%

Solid-geo-mechanical investigation of the effect of salt creep on casing stability using finite element method: a case study

2020

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The salt formation creeping can significantly affect the casing stability, because of the changes in mechanical and geomechanical parameters. The creeping of Gachsaran salty formation in the south part of Iran has influences on wells drilled in the region, which should be carefully considered in the casing design process. In this study, the finite element analysis technique was applied to study the alteration in mechanical/geomechanical parameters of a well in this formation. The accuracy of the methodology was validated by data available from the reduction in wellbore diameter of another well in the formation. Different scenarios were studied to analyze the effect of geomechanical parameters on stress, plastic strain, and casing diameter for a cased cemented well and a well completed with two casings. The effect of mechanical parameters on casing collapse was studied, where casing eccentricity, ovality, and slenderness ratio were also considered. Our simulation studies showed that casing stability in salty formations is strongly affected by geomechanical and pipe mechanical parameters. To reduce the severity of the casing collapse in salty formation, it is recommended to complete the well with two casings. Our study showed that, this arrangement reduces the plastic strain and the change in casing diameter significantly For a safe casing design, effect of mechanical parameters should be also considered. Effects of parameters such as ovality, eccentricity, and slenderness ratio are noticeable, for example, 2% ovality and 2% eccentricity in L-80 casing, lead to increase in the plastic strain from 0.112 to 0.31 and 0.3, and the overall diameter reduction from 0.455″ to 0.685″ and 0.535″, respectively.

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Impact of Casing Eccentricity on Cement Sheath

Cited by 11 publications

References 15 publications

Influence of the Casing Eccentricity on the Cement Sheath Sealing Integrity in the Tie-Back Interval Under the Complex Temperature and Pressure Conditions of Deep-Water Oil and Gas Wells

Influence of the Casing Eccentricity on the Cement Sheath Sealing Integrity in the Tie-Back Interval Under the Complex Temperature and Pressure Conditions of Deep-Water Oil and Gas Wells

Influence of Casing Eccentricity on the Mechanical Integrity of Cement Sheaths in Fractured Wells

Solid-geo-mechanical investigation of the effect of salt creep on casing stability using finite element method: a case study

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