High ROP turbodrilling with drillbit durability required
An operator working in the Yidma/Alamein field in Egypt's Western Desert
was trying to complete two 8 1⁄2-in hole sections through interbedded
sandstone and shales of the Alam El Bueib (AEB) and the
sandstone/shale/limestone of the Khatatba formation. Results were marked by
short-run lengths and low ROPs—produced by tungsten carbide insert (TCI)
bits—forcing numerous unplanned trips. Additionally, another
manufacture's high-speed motor was lost downhole, which put the operation 19
days behind schedule. Going forward, the operator wanted to minimize the number
of trips to section TD, while maintaining verticality and wellbore quality in
each.
For the first run, the BHA consisted of a Neyrfor 6 5⁄8-in TSXL
turbodrill and Smith Bits 8 1⁄2-in K503 Kinetic diamond-impregnated bit.
The bit profile called for initially drilling with low weight on bit (WOB);
parameters were then increased to full drilling rate. Maximum penetration rate
was sustained with excellent ROP through the AEB formation to 14,065 ft. The
drillstring was pulled out of hole (POOH) to inside the casing shoe for pump
repairs. The assembly was run back to bottom and drilled through the AEB and
Khatatba formation to 16,067 ft; an ROP of 8.8 ft/h was maintained totaling
2,340 ft drilled.
For the second run, a second Neyrfor turbodrill and 8 1⁄2-in K507
Kinetic bit were made up and RIH to shoe. Adhering to the bit profile
requirements, drilling was once again started with low WOB and then increased
to full drilling parameters. The Khatatba formation was drilled from 16,067 ft
to TD of 17,000 ft at a penetration rate of 8.72 ft/h, totaling 933 ft
drilled.
