Drillpipe and casing can become stuck while running into a wellbore or pulling out of a wellbore which can lead to significant non-productive time (NPT) events and cause costly remediation and lost production. These sticking events can be caused by wellbore quality issues, also called mechanical sticking, or differential sticking due to the pressure differential between the wellbore and formation pressure which creates normal force on the tubular. Pipe running friction is traditionally monitored by viewing trends for average hookload and torque values while picking up, slacking off, or rotating off-bottom. These average hookload and torque values only apply to dynamic friction factors and do not differentiate the cause of friction.
Static friction correlates with differential sticking whereas dynamic friction can be caused by mechanical sticking. This paper discusses a sticking advisory system for detecting both static and dynamic sticking as friction increases while running into or pulling out of the wellbore. The system uses one-second surface drilling data to identify friction indicators in the axial and rotational directions based on data-driven analysis of time series data trends. The system can create these trends in near-real-time to enable a team to monitor ongoing operations and make proactive decisions. The system trends may also be used in hindcasting mode to identify thresholds for friction indicators based on historical events. The friction indicators are validated by comparing data trends from wells with and without known sticking events and correlating trends with operational activities. Two indicators, Static Sticking Index and Dynamic Sticking Index, are introduced to provide useful surveillance parameters during pipe running operations.
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Kucs, R., Sporker, H.F., Thonhauser, G., Zoellner, P. 2008. Automated Real-Time Hookload and Torque Monitoring. IADC/SPE-112565
Mason C., Lopez, J., Meling, S., Munger, R., Fraser, B. 2003. Casing Running Challenges for Extended - Reach Wells. SPE-84447
Samuel, R. 2010. Friction factors: What are they for torque, drag, vibration, bottom home assembly and transient surge/swab analyses? Journal of Petroleum Science and Engineering, 73, 258-266. doi: 10.1016/j/petrol.2010.07.007
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