Traditional casing point selection fails to reflect influx dynamics and leverage managed pressure drilling (MPD) advancements in the well design process, which often leads to over-engineering and increased expenditure. This study proposes a new approach that integrates MPD into the casing design process, employing a reduced drift-flux model (RDFM) to account for complexity. The methodology aims to optimize casing design and enable real-time assessment of kick tolerance (KT) while drilling, exploiting opportunities for optimization.

In this study, we present a comprehensive approach for determining kick tolerance thresholds, considering current operating conditions and equipment limitations. Improving on industry-accepted rules of thumb for kick volume (25 bbl) and kick intensity (0.5 ppg), this work delivers a fit-for-purpose kick tolerance criterion. The research indicates that casing point selection can be significantly influenced by previously overlooked factors, such as the impact of temperature on formation stress, kick dilution in drilling fluid and annular distribution, as well as pressure and temperature effects and rig kick detection capabilities. Including these in the design criteria yields more accurate and efficient well construction planning and reduced well control risks. Practical case history results demonstrate the potential to extend critical sections by up to 60% while increasing the manageable kick volume, consequently eliminating at least 2 casing strings out of a 7 string well design.

The proposed methodology is shown to be suitable for real-time implementation, allowing drillers to make more informed decisions about casing point selection and section length extension while still ensuring safe well operations. This enhances the flexibility of the drilling process and leads to the reduction and simplification of over-engineered well schematics and excess number of casing strings, resulting in significant well construction cost savings.

This work presents a novel approach for MPD well design and casing point selection, considering overlooked factors such as case-specific defined thresholds for kick volume and intensity, complex gas behavior, and temperature-dependent formation stresses for pressure evaluation. Furthermore, it extends the scope to the drilling process by introducing the real-time assessment of KT, generating additional opportunities for optimization, and improving well control safety. In addition, it proves the suitability of an RDFM model for KT assessment.

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