Evaluation of the injection and plugging ability of a novel epoxy resin in cement cracks

Sustained casing pressure (SCP) is a crucial issue in the oil and gas production lifecycle. Epoxy resins, exhibiting exceptional compressive strength, ductility, and shear bonding strength, have the potential to form reliable barriers. The injectivity and sealing capacity of the epoxy resin is cruci...

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Bibliographic Details
Published in:Petroleum science 2024-04, Vol.21 (2), p.1211-1220
Main Authors: Leng, Guang-Yao, Yan, Wei, Ye, Hai-Mu, Yao, Er-Dong, Duan, Ji-Bin, Xu, Zheng-Xian, Li, Ke-Pei, Zhang, Jing-Ru, Li, Zhong
Format: Article
Language:English
Subjects:
Bonding strength
Brittleness
Cement
Composite materials
Compressive strength
Concrete
Crack sealing
Cracks
Curing
Curing (processing)
Curing agent
Curing agents
Ductility
Efficiency
Epoxy compounds
Epoxy resin sealant
Epoxy resins
Flow characteristics
Gas production
Injection
Mechanical properties
Modulus of elasticity
Oil and gas production
Permeability
Plugging
Polymers
Portland cement
Portland cements
Pressure
Sealants
Sealing
Sealing compounds
Shear strength
Success
Sustained casing pressure
Viscosity
Viscosity reducer
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Summary:Sustained casing pressure (SCP) is a crucial issue in the oil and gas production lifecycle. Epoxy resins, exhibiting exceptional compressive strength, ductility, and shear bonding strength, have the potential to form reliable barriers. The injectivity and sealing capacity of the epoxy resin is crucial parameters for the success of shallow remediation operations. This study aimed to develop and assess a novel solid-free resin sealant as an alternative to Portland cement for mitigating fluid leakage. The investigation evaluated the viscosity, compressive strength, and brittleness index of the epoxy resin sealant, as well as its tangential and normal shear strengths in conjunction with casing steel. The flow characteristics and sealing abilities of conventional cement and epoxy resin were comparatively analyzed in cracks. The results showed that the application of a viscosity reducer facilitated control over the curing time of the epoxy resin, ranging from 1.5 to 6 h, and reduced the initial viscosity from 865.53 to 118.71 mPa⋅s. The mechanical properties of the epoxy resin initially increased with a rise in curing agent content before experiencing a minor decrease. The epoxy resin containing 30% curing agent exhibited optimal mechanical properties. After a 14-day curing period, the epoxy resin's compressive strength reached 81.37 MPa, 2.12 times higher than that of cement, whereas the elastic modulus of cement was 2.99 times greater than that of the epoxy resin. The brittleness index of epoxy resin is only 3.42, demonstrating high flexibility and toughness. The tangential and normal shear strengths of the epoxy resin exceeded those of cement by 3.17 and 2.82 times, respectively. In a 0.5 mm-wide crack, the injection pressure of the epoxy resin remained below 0.075 MPa, indicating superior injection and flow capabilities. Conversely, the injection pressure of cement surged dramatically to 2.61 MPa within 5 min. The breakthrough pressure of 0.5 PV epoxy resin reached 7.53 MPa, decreasing the crack's permeability to 0.02 D, a mere 9.49% of the permeability observed following cement plugging. Upon sealing a 2 mm-wide crack using epoxy resin, the maximum breakthrough pressure attained 5.47 MPa, 3.48 times of cement. These results suggest that epoxy resin sealant can be employed safely and effectively to seal cracks in the cement.
ISSN:1995-8226
1672-5107
1995-8226
DOI:10.1016/j.petsci.2023.10.014