Summary
Vibration measurements have traditionally targeted the improvement of
downhole-tool reliability. This paper targets the effects of vibration on the
complete drillstring. Failures associated with drillstring vibration continue
to happen despite the sophistication of today's measurements. These failures
represent a very significant amount of lost time, which we target to
improve.
The industry has a very limited database for evaluating indices to manage or
quantify risks of vibration to the complete drillstring. This fact makes the
use of the methods in the field heavily depend on the past experience of the
drillers and on the rig types. Operators are faced with an unknown
quantification of the risk severity when attempting to mitigate vibration. By
quantifying the risk, this work demonstrates how the prevention of incidents
can be achieved. These incidents include but are not limited to, twistoffs,
backoffs, and bottomhole-assembly (BHA) component failures.
The proposed solution is based on real-time measurements of drillstring
vibration to estimate an ongoing drillstring-integrity risk, which is used as a
guideline to improve decisions while drilling the well. This solution has been
developed through use of advanced vibration sensors to discriminate between
different types of vibration. This was critical to estimating realistic
cumulative damage to the drillstring, which is highly dependent on the type of
vibration suffered by the assembly and the onset of vibration-mode
coupling.
This paper shows that approximately 80% of drillstring-integrity failures
analyzed can be identified and prevented through use of the proposed
risk-quantification solution. This result has been obtained despite unknown
fatigue or wear of drillstring components before a run, and vibration sensors
were located at a single position in the drillstring. This indicates that the
primary contributor to drillstring failures is the drilling conditions for any
given run.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
12 June 2011
- Meeting paper published:
21 September 2011
- Revised manuscript received:
25 November 2011
- Manuscript approved:
24 January 2012
- Published online:
30 May 2012
- Version of record:
11 June 2012
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