This paper will present an innovative new methodology for realtime monitoring of bit condition – and hence drilling efficiency - using surface measurement of alkene gases artificially created at-bit by the bit as its condition deteriorates.

A drop in ROP can be an effect of a variety of causes, often disparate in nature. Can performance be improved by a change in drilling parameters and, if so, for how much further will these parameters remain effective? Is there some form of drilling dysfunction that is resulting in inefficient transfer of energy into drilling action? Is there a change in lithology and, if so, is the bit still appropriate and viable in this new formation? Or is the bit simply approaching the end of its useful life through wear earlier than anticipated, in which case at what point does it become less economic to continue drilling at low ROP and POOH instead?

The decision to POOH to change a bit that is perceived to be under-performing can be costly if the bit is found to be in workable condition and the trip is therefore premature. Unnecessary trips are a major source of non-productive time (NPT) so any trusted source of indicative information on bit condition adds valuable context and confidence to operational decision-making.

Realtime monitoring of contaminant alkenes provides timely indications to drillers of the degree of bit wear, mitigating invisible lost time (ILT) through excessive prolongation of an ineffectual dulled bit run, and reducing the risk of its potentially catastrophic failure. Field-based case histories are presented supporting the complementary relationship of alkene generation to other indicators of inefficient drilling, how alkene presence can assist in drilling dysfunction diagnosis, and a prototype of a software application based on alkene levels that informs decision-makers of the ‘tipping point’ at which objective commercial factors support pulling a dull bit.

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