Development of drilling non-productive time reduction framework using lean six sigma methodology for buntal exploration wells

Abstract

Drilling Non-Productive Time (NPT) is loss time incurred when drilling activity has to be stopped or rate of penetration is very low during a drilling operation. Drilling NPT results in drilling cost overruns and delay in drilling schedule. Presently, there are several methods which are being deployed to mitigate drilling NPT and these methods would fall into either the anticipative or targeted category. Anticipative category focuses on development of model, database, and risk management framework to enhance information sharing and decision-making among drilling operation stakeholder while the targeted category revolves around deployment of surgical solutions which focus on one or a handful of drilling NPT categories such as wellbore instability, equipment failure etc. Both categories generally lack Drilling NPT severity assessment, validation of Root Causes and derivation of Root Cause Analysis-centric solutions, resulting in knee-jerk reactions to Drilling NPT mitigation. This study, therefore, aims to develop a Drilling NPT reduction framework using Lean Six Sigma (a process improvement methodology) based on retrospective drilling data from Buntal Exploration Wells. Lean Six Sigma advocates data-driven analytics and decision-making in solving operational problems. The drilling NPT reduction framework will follow the DMAIC (Define, Measure, Analyse, Improve and Control) stage-gate model of Lean Six Sigma. In the case of Buntal Exploration Wells, it is observed that the drilling process is not capable from operational and financial standpoints in meeting the Drilling Plan requirements (as illustrated by Process Capability Indexes which are lower than 1.0). In view of retrospective nature of the available drilling data, root causes are validated graphically and qualitatively with equipment failure appearing as the leading contributor of Drilling NPT. Potential solutions are then ideated based on the validated root causes or Vital Few Factors. It is expected that the Drilling NPT reduction framework will pave way for future research through capitalization on quantitative data and continuous feedback from the drilling fraternity.