Summary
A mechanism for conveying logging tools inside drillpipe has been developed that reduces the risk and cost of acquiring openhole formation evaluation data in high-angle wells and bad hole conditions. The measurement string is housed inside drillpipe, where it is protected while running in, and pumped into open hole close to final depth. Wireline tools are used for data-quality reasons, but the wireline has been eliminated, giving time, access, and well-control advantages relative to wireline pipe-conveyed logging (PCL). It is an alternative to the formation evaluation element of logging while drilling (FE-LWD), where steering decisions do not rely on real-time petrophysical analysis, particularly when the risk to the bottomhole assembly (BHA) is high. The system's ability to acquire data while conditioning the hole contributes to its efficiency and is advantageous in bad hole conditions.
A 1.4-km horizontal test loop was constructed to help develop and prove the tool deployment and signaling mechanism. Insights gained during this process resulted in the development of novel payload delivery seals—key components in the system.
Formation evaluation data have been acquired in 220 wells; they include horizontal wells for which other logging solutions are unattractive for reasons of accessibility and/or cost. Knowledge gained from the interpretation of these data sets has influenced completions in some wellbores and guided remedial action in others.