This paper outlines the R&D methodology of an innovative Smart Reamer Calliper for measurement while drilling. The concept was progressed from design to prototype with long hours downhole drilling qualification completed in 3 years. Existing calliper measurement technology is limited for numerous reasons not least BHA placement and erroneous readings due to changes in fluid density. The prototype tool overcame these limitations by building on-board proper calibration and multiple sensors that allow 360 degree mapping of the wellbore shape. Further optional Measurement While Drilling (MWD), magnetic, vibration and underreamer position sensors can be added.

A R&D project was established with incremental tests identifying root-cause failures/design issues before moving to the next stage. This iterative process ensured proper prototype manufacturing and minimised risk at critical test points. At the same time parallel activities enabled the project to reduce overall time associated with common project tasks. The whole R&D consisted of 4 stages: design and FEA, small scale testing, full scale testing and long hours field test drilling.

The prototype tool was first tested in sliding, rotating and underreaming BHAs for actually drilling a total of 900 m in chalk, clay and sands. Small scale lab tests including high pressure and temperature at 13,053 psi and 150°C for 100 hours were conducted in England. Full scale under-reaming testing occurred in Norway with a wireline calliper for cross-check of the wellbore diameter measurement, and finally another qualification test in England comprising 59 hours on bottom drilling. Lastly, MWD integration was performed using standard MWD pulsers. The new Smart Calliper tool is being developed to accurately measure and provide both memory and real-time data of the 3-D wellbore allowing the drilling team at rig-site to:

  • Pinpoint narrow or under-gauge wellbore sections, verifying underreamer performance and measuring wellbore diameter above the reamer allowing for corrective reaming trip to be performed while drilling BHA is still in hole.

  • Offer better cement volume estimate to minimise excess.

  • Eliminate wireline calliper deployment.

  • Eliminate a wiper trip typically carried out prior to running long casing string.

  • Offer monitoring of downhole tool vibration and separate directional survey if required.

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