Abstract
In oil and gas drilling, consistency of performance delivery heavily depends upon rig capability and its ability to maintain performance assurance through its execution cycle. It's not an uncommon occurrence that a rig is found with an underperforming top drive, one such scenario was observed in an in-fill oil well drilling project. This project was essentially drilling horizontal wells with bottom hole assemblies which had primary drive mechanism as a top drive. The rig in question was struggling to provide not only the requisite RPM but also not been able to deliver consistent torque needed to drill the well. This study analyzes how severe rig limitations were overcome through an optimization plan in which most optimal BHA was designed and drilling practices were customized for safe and successful execution of wells.
In order to understand root cause of the challenge, an offset well analysis was conducted, it identified that high torque was mostly generated while drilling through inter-bedded formations which typically caused top drive to stall. In addition, multiple tool failures were encountered due to the high stick slip which rig couldn't mitigate due to the low RPM yield of the top drive. To manage the rpm and torque limitations, a motorized RSS BHA was designed as a solution. Further, based on micro-stall events of motor only BHA's across the inter-bedded formations in the field, a stick slip management tool was placed below the motor so that a potential twist-off and/or motor damages can be avoided. Also, different bottom hole assembly's drilling dynamics response were analyzed to come up with optimal stabilization and connection practices to avoid back reaming while trip outs.
This paper would showcase actual results which highlight improvements achieved in stagnant drilling performance of the project. The analysis would demonstrate how multiple wells were drilled in one run following the risk assessment developed from the optimization study and subsequent real time monitoring of mitigating actions while execution.
The comprehensive bottoms-up drilling optimization approach helped save 4 planned days for each well, this really paves way to pursue applied-engineering solutions to achieve step change in drilling performances, especially on rigs which are severely limited either due to capacity or malperformance issues. The bottoms up approach taken to understand the drilling challenges followed by a methodical approach to address each of the challenges demonstrate importance of effective pre-job planning. Learnings from this study can be adopted as a template to mitigate similar drilling challenges.
A Real-Time Decision Support System for High Cost Oil-Well Drilling Operations