Cement Sheath Failure Mechanisms: Numerical Estimates to Design for Long-Term Well Integrity

Andrade, Jesús de; Sangesland, Sigbjørn

doi:10.1016/j.petrol.2016.08.032

Cited by 139 publications

(34 citation statements)

References 22 publications

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“…Under confining pressure, the formation behaves as elastic-plastic cement stone. e material parameters of the casing, the cement, and the formation are given in Table 2 based on literature values [24,25].…”

Section: Finite Element Methods To Calculate Microannulus Size Under Ementioning

confidence: 99%

Microannulus Formation Mechanism at the Cementing Interface of a Thermal Recovery Well during Cyclic Steam Injection

Wang

Song

et al. 2020

Advances in Civil Engineering

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During the thermal recovery of heavy oil when using cyclic steam injection technology, a microannulus tends to form at the cementing interface subjected to high temperature and pressure during steam injection, and large temperature and pressure differences after injection can lead to wellbore integrity failure. In this study, a thermomechanical coupled finite element casing-cement-formation model of a thermal recovery wellbore is established. The deformation of the wellbore during both the steam injection stage and the steam shutdown stage is analyzed. The microannulus formation mechanism at the cementing interface of the wellbore is studied. During steam injection, under the large thermomechanical coupling load, the wellbore generates a high stress that leads to elastic-plastic deformation. In the steam shutdown stage, with the load on the wellbore decreasing, elastic deformation recovers mostly, while plastic deformation continues. If the plastic deformation is large enough, a microannulus will form at the cementing interface. Increasing the elastic moduli of the casing, cement, and the formation can enlarge their plastic deformation during steam injection. The increase of plastic deformation of the cement or formation can enlarge the microannulus of the casing-cement interface or the cement-formation interface correspondingly in the steam shutdown stage.

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Section: Finite Element Methods To Calculate Microannulus Size Under Ementioning

confidence: 99%

Microannulus Formation Mechanism at the Cementing Interface of a Thermal Recovery Well during Cyclic Steam Injection

Wang

Song

et al. 2020

Advances in Civil Engineering

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“…Compressive strength analysis is critical in ascertaining the integrity and long-term bearing capacity of cement [21]. Cement with higher compressive strength usually means lower porosity and increased durability [50].…”

Section: Compressive Strength Analysismentioning

confidence: 99%

Experimental Evaluation of the Performance of Fresh Nano Zeolite as an Oil Well Cement Additive

Broni-Bediako¹,

Naatu²

2021

PSE

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Cementing oil and gas wells require materials that, not only meet performance standards but also fairly different from those encountered in conventional processes. The search for alternative materials for cementing oil wells has increased worldwide. It is desirable that these alternative materials make cement sheath stronger, durable, flexible, cost-effective and more resistant to shocks. This research aimed at evaluating the performance of fresh nano zeolite as an additive for shallow oil well cementing operations. Laboratory tests were conducted on a base cement slurry mixed with different concentrations of fresh nano zeolite from 1% bwoc to 3% bwoc at a Bottomhole Circulating Temperature (BHCT) of 80°F (27°C) to determine physical properties such as compressive strength, thickening time, rheology, free fluid, and fluid loss. The results showed that the compressive strength of the cement slurries improved significantly at 12 hours than 24 hours curing period at 87°F (31°C). As the concentration of fresh nano zeolite increases less time was required to reach 50 psi, 100 psi and most importantly 500 psi which is needed to resume drilling operations. An increase in concentration of fresh nano zeolite at 80°F (27°C) resulted in an increase in the thickening time of all the cement slurries. This shows that fresh nano zeolite has a high retardation effect. Generally, the addition of fresh nano zeolite from 1% bwoc to 3% bwoc improved the carrying capacity of all the cement slurries. Test results also showed that increasing the fresh nano zeolite concentrations resulted in a decrease in rheological values which is a characteristic of a dispersant. Plastic viscosity values were observed to have an increasing trend generally with an increasing concentration of fresh nano zeolites. All the cement slurries were below 100 cP and therefore pumpable. The addition of fresh nano zeolite to the base cement slurry increased the free fluid of the cement slurries. The fresh nano zeolite didn't have any effect on fluid loss and therefore does not exhibit characteristics of a fluid loss agent.

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Section: Whole Wellbore Cement Sheath Stress Calculation Modelmentioning

confidence: 99%

Sealing Failure Mechanism and Control Method for Cement Sheath during Hydraulic Fracturing

Lian

Qian

et al. 2020

ACS Omega

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This study focused on the sealing failure mechanism and control method for a cement sheath during hydraulic fracturing. Taking a shale gas well as an example, whole wellbore numerical models of the casing-cement sheath-formation assembly were established, failure modes of the cement sheath at different depths were clarified, and control methods were proposed based on the calculation results. The following conclusions were drawn. (1) The maximum radial/tangential stress of the cement sheath increased/decreased with an increase in the depth, and the cement sheath above the intermediate casing shoe posed the risk of tangential tensile failure, resulting in tensile cracks. The cement sheath below the intermediate casing shoe produced a micro-annulus under a cyclic casing pressure, and the tensile cracks and micro-annulus constituted passages for the sustained casing pressure. (2) The swelling stress of the expansion cement slurry could offset the circumferential tensile stress and increase the radial compressive stress. Because a cement sheath with a high Young’s modulus usually exhibits high tensile and compressive strengths, it is recommended to use a high Young’s modulus cement slurry system above the intermediate casing shoe and optimize the free expansion ratio. (3) In comparison with ordinary cement stone, low residual strain cement stone exhibited a larger elastic deformation interval. The cumulative residual strain caused by cyclic loading was smaller, and the Young’s modulus demonstrated a lesser decrease. The results of an equivalent physical experiment demonstrated that an ordinary cement sheath lost its integrity after 13 loading cycles with a maximum casing pressure of 60 MPa. A low residual strain cement sheath could guarantee integrity after 30 loading cycles when the maximum casing pressure was 90 MPa, and sealing failure occurred after 11 loading cycles when the maximum casing pressure was 130 MPa. It is recommended to use a low residual strain cement slurry below the intermediate casing shoe to prevent a micro-annulus.

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Cement Sheath Failure Mechanisms: Numerical Estimates to Design for Long-Term Well Integrity

Cited by 139 publications

References 22 publications

Microannulus Formation Mechanism at the Cementing Interface of a Thermal Recovery Well during Cyclic Steam Injection

Microannulus Formation Mechanism at the Cementing Interface of a Thermal Recovery Well during Cyclic Steam Injection

Experimental Evaluation of the Performance of Fresh Nano Zeolite as an Oil Well Cement Additive

Sealing Failure Mechanism and Control Method for Cement Sheath during Hydraulic Fracturing

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