Abstract

Accurate wellbore temperature prediction is essential in deepwater drilling and completion operations. The wellbore temperature profile is the most dominant factor to consider when the cement slurry properties are designed. These properties are critical to ensure the success of cement placement. Many wellbore temperature simulators described in the literature use a finite difference approach in transient temperature profile modeling. However, for deepwater drilling and completion, the process is more complex. Seawater currents and natural convection cannot be ignored in heat-transfer modeling, especially for subsea pipelines and risers. Also, there are few published results of thermal property correlations for non-Newtonian, high-viscosity cement slurry. Special treatments accounting for transient heat transfer for those cases are necessary.

Mud and cement slurry are typically pumped at lower flow rates for cementing operations. At these rates, apparent viscosity may be used in heat transfer coefficient calculations. However, rheology properties for non-Newtonian fluids are changed abruptly for different models, and so are simulation results. For high viscosity fluids, such as cement slurry, there is a general need for experimentally derived heat transfer correlations.

A novel heat transfer model has been introduced for deepwater cementing. Special considerations for non-Newtonian fluids are included based on theoretical analysis, real field data correlations, and transient heat transfer of deepwater subsea pipelines and risers.

The predictions of the wellbore temperature profiles from this model are validated through measured wellbore temperature profiles, both in offshore and onshore cases. The model has been successfully applied in deepwater circulating, cementing, and hydraulic fracturing. Cases will be presented in this paper.

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