The operation replaced logging-while-drilling (LWD) when the well encountered difficult drilling conditions above the target interval. The Well Shuttle returned quality data from the full open hole interval, including a secondary target that had not previously been evaluated.
BP operated Mungo is in the central North Sea, 150 miles east of Aberdeen. The 22/20 A-16 well was drilled to 11,077 ft measured depth with a maximum deviation of 70 degrees targeting oil in Palaeocene sands.
Severe losses of drilling fluids to chalk fractures prevented the inclusion of LWD because of the probability of plugging the drilling assembly and the risk of losing a neutron radiation source. Other conventional open hole logging options - wireline and pipe-conveyed-logging (PCL) - were ruled out because of the deviation, bad hole conditions and the inability to circulate & rotate the PCL string to bottom. The possibility of evaluating the well using cased hole data was rejected because interpretation uncertainty would have been too high.
"Reeves' Well Shuttle was the only technology able to deliver open hole data in such severe hole conditions," said Iain McBain, Senior Drilling Engineer for the Mungo asset. "We would not have obtained open hole logs without Reeves." The Well Shuttle acquired data concurrently with a full wiper trip, and so eliminated the need for a dedicated logging run.
The technology conveys Reeves Compact logging tools inside drill pipe. They are protected while running-in, and are pumped into open hole after reaching total depth. In contrast to conventional PCL the drill pipe can be rotated and mud circulated throughout the operation to reduce sticking risk. The Shuttle includes an open-ended reamer shoe and hole opening reamer that provide the ability to wipe and clean the hole prior to deploying the logging tools and pulling out.
The Mungo operation delivered array induction, photo-density, gamma ray, neutron porosity and acoustic velocity data from total depth to surface.
Operations Geologist Guy Phillips commented: "The Shuttle gave us wireline quality data over the target, and the only continuous set of open hole data we have over the chalk."
Reeves Director of Corporate Development, John Boyes, commented: "We developed Shuttle to be a lower cost and safer alternative to PCL and LWD, but what we saw here was Shuttle as the only realistic open hole logging option. Saving money was a bonus for this client."
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