A Review of Conventionally Undrillable Wells with Ultra-Narrow Pressure Windows Successfully Drilled Utilizing MPD Over the Last Five Years in USA and Canada

Abstract

Abstract Managed Pressure Drilling (MPD) has been used on multiple projects by several operators in different regions of North America to drill through formations that had ultra-narrow (or conventionally undrillable) pressure windows. As illustrated by the case studies discussed here, a combination of Constant Bottomhole Pressure (CBHP) MPD, Anchor Point MPD, and Pressurized MudCap Drilling (PMCD) MPD variations helped drill through several of these formations, trip in and out safely, log and core hole-sections, and run liner or casing to the target depth and cement it in place. Thus, MPD successfully enabled the operators to tap into these otherwise unattainable reserves. Typical challenges include formation/wellbore instability, shallow-water flows, over-pressured formations, low FIT/LOT, fracture pressure/wellbore strength regression, and moderate to severe losses. A few anomalous formations with uncertain pressure regimes resulted in severe to total losses on one well, while an adjacent well drilled at similar depths resulted in high-pressure influxes with ensuing well-control consequences. A detailed evaluation of historical data, comprehensive hydraulic analysis, appropriate MPD design and planning, and use of technologically advanced, reliable, efficient, and well-maintained equipment were critical factors that led to the success of these MPD projects. Above all, utilizing knowledgeable, experienced, and well-trained MPD personnel helped integrate MPD with the existing rig systems and teams and consistently solve the seemingly insurmountable drilling challenges safely and reliably.