Published: 07/09/2015
Published: 07/09/2015
An operator was drilling three wells in a hard, abrasive formation with high compressive strength and downhole temperatures ranging from 150 degC to 160 degC. High downhole temperatures can limit the use of drilling tools and result in slow ROP. The operator wanted to reduce the number of runs needed, increase ROP for more efficient drilling, and maintain good hole quality. Schlumberger recommended running Neyrfor turbodrilling systems in all three well sections and Kinetic diamondimpregnated drill bits from Smith Bits, a Schlumberger company.
Neyrfor turbodrilling systems were chosen because the drive system efficiently converts hydraulic energy from the mud column into mechanical energy at the bit. This enables Neyrfor turbodrilling systems to deliver more downhole mechanical drilling power than other drive systems under equal hydraulic conditions. By rotating the drive shaft at a higher rpm while remaining dynamically stable, Neyrfor turbodrilling systems produce higher ROP without the negative effects of excess torque.
Kinetic drill bits, designed for abrasive formations, were selected for their durability. With PDC cutters,diamond-impregnated matrix materials, and grit hot-pressured inserts, the bits deliver optimal ROP. In addition, a WELL COMMANDER circulating tool was used because it reduces the risk of full flow at bottom that can induce lost circulation.
On the first well, the Neyrfor system enabled drilling more than 144 m at ROP of 2.06 m/h in 72 hours, saving almost 13 days of rig time. Only one bit run was required. On the second well, the Neyrfor system and Kinetic drill bit drilled a total of 704 m in two runs at twice the ROP of conventional systems. Total drilling and circulating time was 460.25 hours. The third well was drilled from 7,059.54 m to TD and avoided lost circulation while maintaining good hole quality.
ROP nearly double on all three wells, saving the operator valuable rig time. The actual Neyrfor turbodrilling operation took 12.98 days to complete; offset wells drilled using conventional motors and PDC bits took longer than 40 days.
Challenge: Drill 13 1/8-in, 8 1/2-in, and 6 5/8-in sections in three wells in a hard, abrasive basin with high probability of circulation loss.
Solution: Run Neyrfor turbodrilling systems with Kinetic diamond-impregnated bits for hard, abrasive formations.
Results: Drilled all three sections to TD at approximately twice the ROP of offset wells, saving approximately 29 rig days compared with offset wells.
