Proceedings of SPE Annual Technical Conference and Exhibition · 1990 · 39 citations · 0 references
EngineeringPetroleum EngineeringDrillingDrilling EngineeringWell IntegrityBorehole StabilityDrilling MechanicsFailure CriteriaShear StrengthWellbore HydraulicsWellbore StabilityElastic AnalysisLinear Elastic AnalysisMud Weight DesignMud Weight ManagementWellbore Failure AnalysisWellbore Failure CriteriaWellbore Stability AnalysisWellbore Stability Assessment
Mechanical wellbore instability during drilling causes costly hole problems, and although linear‑elastic analysis is commonly used to predict failure and guide mud‑weight selection, there is no consensus on which compressive failure criterion to apply. The study evaluates how two common failure criteria affect mud‑weight recommendations for wellbore stability. The authors analyze the impact of two failure criteria on mud‑weight calculations and illustrate the results with field‑case examples that expose inconsistencies in criterion suitability. The choice of failure criterion dramatically alters the calculated safe mud weights, and field examples reveal inconsistencies that challenge the appropriateness of each criterion.
ABSTRACT Hole problems during the drilling phase of operations are often the consequence of mechanical wellbore instability. This leads to higher than necessary drilling costs. A linear-elastic analysis is frequently proposed for the prediction of the onset of failure, and consequently the mud weights required to prevent hole instability. However, there is no clear choice of which compressive failure criterion to use in the analysis. This paper assesses the influence of two commonly proposed failure criteria on mud weight selection. The failure criteria selected is shown to have an extremely significant effect on the computed 'safe’ mud weights. Examples related to field situations are presented which highlight the anomalies and contrary evidence relating to the suitability of failure criteria.