Case Study: Verticality Maintained in Ultradeep, High Temperature Well

Chinese exploration well placed using PowerV vertical drilling system, increased ROP 25%

Challenge: Drill ultradeep, high-temperature sidetrack vertically in fragmentary layer with high dip.

Solution: Kick off sidetrack with high-temperature PowerPak steerable motor and steer wellbore using PowerV vertical drilling system and SlimPulse third-generation slim MWD service.

Result: Increased average ROP 25%, compared with traditional BHA; controlled inclination in fragmentary layer to less than 2° for 547 m; and achieved 0.25° inclination at TD.

Maintaining verticality a challenge

An operator began drilling the 8 1/2-in vertical section of its exploration well in China’s Xinjiang province using a traditional BHA. At 7,025.81 m MD in a high-dip fragmentary layer, inclination had increased to 15.98° and could not be corrected, so the hole was cemented back about 100 m to a depth at which inclination was less than 3°. The operator planned to sidetrack the well at that point and drill vertically to a TD of 7,600 m. The fragmentary layer and a bottomhole static temperature expected to exceed 150 degC made that a challenge.

Vertical drilling BHA needed for entire sidetrack

The sidetrack was kicked off using a high-temperature PowerPak steerable motor. Then a PowerV vertical drilling system, run with SlimPulse MWD service, automatically steered the wellbore back to vertical. When inclination had been reduced to 0.25°, the operator resumed drilling with a traditional BHA, but it proved unable to maintain verticality and was pulled out of the hole. Once again, the PowerV system steered the wellbore back to vertical and drilled it to TD at 7,510 m MD—the deepest a PowerV system had ever been run.

Maximized ROP in ultradeep well

Inclination at TD was just 0.25°. The PowerV system drilled a total of 547 m in the high-temperature, high-dip fragmentary layer and achieved an average ROP of 1.25 m/h—a 25% increase over the 1 m/h averaged with a traditional BHA.

Download: Verticality Maintained in Ultradeep, High Temperature Well (1.05 MB PDF)

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Verticality Maintained in Ultradeep, High Temperature Well
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