Structural integrity of liner cement in oil &amp; gas wells: Parametric study, sensitivity analysis, and risk assessment

Patel, Harshkumar; Salehi, Saeed

doi:10.1016/j.engfailanal.2020.105203

Cited by 16 publications

(9 citation statements)

References 27 publications

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“…Specifically, this curve is constructed by changing the value of one variable and maintaining the base value of the other variables. Subsequently, the value of each variable is divided by its base value to obtain the normalized value [19,20]. Using model A as an example, we plotted the sensitivity response curves of various variables to the maximum CS and MS of the cement sheath and then evaluated the sensitivity of each variable to the stress of the cement sheath.…”

Section: Sensitivity Of Cement Sheath Integrity and Engineering Count...mentioning

confidence: 99%

“…Wang et al [17] analyzed wellbore integrity during the fracturing process of shale gas horizontal wells and reported that increasing the casing wall thickness and Poisson's ratio of the cement sheath, reducing the EM of the cement sheath, and selecting an appropriate cement sheath thickness can ensure the integrity of the wellbore. Patel et al [18][19][20] investigated the effects of the load, material properties, and cement sheath size on the cement sheath integrity of a liner-casing overlapping section of offshore oil and gas wells. A sensitivity response curve was constructed to evaluate the effects of different operating and design parameters on the stress of the cement sheath.…”

Section: Introductionmentioning

confidence: 99%

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Integrity and Failure Analysis of Cement Sheath Subjected to Coalbed Methane Fracturing

Zhao¹,

Yang²,

Wei³

et al. 2023

Fluid Dynamics &Amp; Materials Processing

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Perforation and fracturing are typically associated with the development of coalbed methane wells. As the cement sheath is prone to failure during this process, in this work, the effects of the casing pressure, elastic modulus of the cement, elastic modulus of the formation, and casing eccentricity on the resulting stresses are analyzed in the frame of a finite element method. Subsequently, sensitivity response curves of the cement sheath stress are plotted by normalizing all factors. The results show that the maximum circumferential stress and Mises stress of the cement sheath increase with the casing internal pressure, elastic modulus of the cement and casing eccentricity. As the elastic modulus of the formation increases, the maximum circumferential stress of the cement sheath decreases, and its maximum Mises stress increases slightly. The cement sheath undergoes tensile failure during coalbed methane fracturing. The stress sensitivity of the cement sheath to the influential parameters is in the following order: casing internal pressure > elastic modulus of cement sheath > casing eccentricity > elastic modulus of formation. KEYWORDSCoalbed methane fracturing; finite element method; cement sheath integrity; sensitivity analysis; failure analysis Nomenclature a casing eccentricity rate Δl casing eccentricity distance, mm r b borehole radius, mm r c outer radius of casing, mm Abbreviations CCFC casing-cement sheath-formation combination CIP casing internal pressure CS circumferential stress This work is licensed under a Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Section: Sensitivity Of Cement Sheath Integrity and Engineering Count...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Integrity and Failure Analysis of Cement Sheath Subjected to Coalbed Methane Fracturing

Zhao¹,

Yang²,

Wei³

et al. 2023

Fluid Dynamics &Amp; Materials Processing

View full text Add to dashboard Cite

show abstract

“… 3 − 5 Maintaining the sealing integrity of the cement sheath is the key to ensuring the long-term safe production of oil and gas wells, and how effectively evaluating the sealing performance of the cement sheath is a basic problem that needs to be solved urgently. 6 At present, the direct way is to evaluate the damage and failure mode of the cement sheath through annulus isolation simulation experiments.…”

Section: Introductionmentioning

confidence: 99%

“…Portland cement stone is a brittle material with congenital defects. During the drilling and production of oil and gas wells, under the action of the surrounding rock stress and wellbore stress, , the cement sheath is easily broken to form macroscopic cracks, which become gas channeling paths and cause sustained casing pressure. − Maintaining the sealing integrity of the cement sheath is the key to ensuring the long-term safe production of oil and gas wells, and how effectively evaluating the sealing performance of the cement sheath is a basic problem that needs to be solved urgently . At present, the direct way is to evaluate the damage and failure mode of the cement sheath through annulus isolation simulation experiments.…”

Section: Introductionmentioning

confidence: 99%

Failure Analysis of Cement Sheath Mechanical Integrity Based on the Statistical Damage Variable

Liu

et al. 2023

ACS Omega

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Maintaining the cement sheath mechanical integrity is the key to ensuring the benefit and safety of oil and gas well drilling and production. The main function of the cement sheath is to isolate oil and gas from water layers, which prevents the formation fluid from channeling to other layers. At present, how to effectively evaluate the cement sheath sealing performance is the fundamental problem to be solved urgently. This paper first carried out the cement sheath annulus isolation experiment and analyzed the main forms of cement sheath seal failure. Then, the interaction of the cement sheath, casing, and surrounding rock in the initial state and subsequent wellbore operations was explained. An analysis model for the cement sheath mechanical integrity incorporating the nonlinear elastic constitutive equation was proposed. Based on the statistical damage variable in continuum mechanics theory, a damage variable was established. The results show that the main form of cement sheath integrity failure is tensile crack damage and micro-annulus caused by plastic yielding. The damage variable can quantitatively describe the cement sheath mechanical integrity. The field case analysis shows that the damage variable is highly correlated with wellbore pressure and also verifies the applicability of the variable. Reducing wellbore pressure will help maintain the mechanical integrity of the cement sheath, providing sealing performance. This research can provide a reference for designing the mechanical properties of the cement sheath and improving the sealing ability of the cement sheath.

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“…The results indicate that the effect of a high temperature on concrete involves cement paste and aggregates, as well as the interaction of these two constituents. Patel [26] studied the effect of pressure, mechanical properties, and sheath size on the integrity of sheath. Results indicate that flexible and expanding cement tend to be reliable for the structure versus brittle and nonexpanding cement.…”

Section: Introductionmentioning

confidence: 99%

Integrity Analysis of the Sheath Considering Temperature Effect under Deep and Large-Scale Multi-Section Hydraulic Fracturing

et al. 2021

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Different operations make the borehole temperature change and cause periodic stresses, which often cause variations in the stress state of the sheath or damage. In this paper, the effect of temperature on sheath integrity is investigated. First, the mechanical model of sheath is established and analyzed by shakedown theory. Then, compression experiments of well cement at different temperatures are carried out, and the law of mechanical properties with temperature is obtained. Finally, combining the theoretical analysis and mechanical experiments, the results show that (1) when only the temperature inside the sheath cyclically varies, the negative influence of temperature caused by the practical operations can be negligible. (2) When the internal pressure and temperature act together, the effect of temperature on the sheath is reflected in temperature stress and the change of the cement properties. (3) With the increase of temperature difference (∆T), the cohesion of cement decreases while the internal friction angle increases, and the plasticity characteristics of the cement are enhanced, and the negative effect on the Pmax ascends slowly. (4) The temperature stress is in a positive relationship with the ∆T, and its weakening on the Pmax is about 6% to 7%. (5) Combining the temperature stress and the change of the cement properties, total negative effect of temperature on the sheath accounts for 10% to 12%, when ∆T ranges from 60 to 110 °C.

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Structural integrity of liner cement in oil & gas wells: Parametric study, sensitivity analysis, and risk assessment

Cited by 16 publications

References 27 publications

Integrity and Failure Analysis of Cement Sheath Subjected to Coalbed Methane Fracturing

Integrity and Failure Analysis of Cement Sheath Subjected to Coalbed Methane Fracturing

Failure Analysis of Cement Sheath Mechanical Integrity Based on the Statistical Damage Variable

Integrity Analysis of the Sheath Considering Temperature Effect under Deep and Large-Scale Multi-Section Hydraulic Fracturing

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