Long term zonal isolation is critical for Enhanced Oil Recovery (EOR) wells. The paper will present placement techniques along with the use of mechanical properties characterization and modeling software used to optimize the cement design ensuring well life integrity and longevity for thermal EOR wells in particular. Results and supporting data will also be compared to field performance.

The approach taken incorporates slurry design and mechanical properties characterization of typical standard cements compared to modern slurry design. Cement properties and well operating procedures are simulated using software to model potential failure points during well life. Multiple design and model iterations were performed by adjusting mechanical properties required to withstand well life operating procedures. This method was used to develop an optimized cement design. Field operations and placement technique processes were also developed to enhance proper placement and support overall slurry performance.

Data showing typical mechanical properties required to withstand the simulated wellbore stresses over the life of the well will be compared. This will demonstrate that enhanced mechanical properties are necessary. Standard/conventional slurry design data such as Youngs Modulus, Poissons Ratio, Long term expansion data and tensile data is compared and simulated to show how different types of cements may fail or survive under the same imposed wellbore stresses. Interesting findings demonstrated by software model simulations also show that certain properties, like expansion, are critical to the integrity of the cement sheath. Another observation shows that optimized placement techniques designed for large annulus thermal wells can result in the removal of potentially detrimental accelerating additives, which are typically used. This allows for improved slurry design and performance by reducing the potential for corrosion, shrinkage and increased permeability.

Utilizing tools such as complex well integrity software to simulate well operations can be valuable in evaluating your well life performance to develop novel cement blends and placement techniques. It can be used to determine the desired cement performance properties required to maintain long term wellbore isolation and integrity.

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