PowerPak HR Motor with Powerlast Elastomer Drills Reservoir Section in a Single Run, Kvitebjørn Field | Schlumberger
Case Study
Location
Norway, Europe, Offshore
Details

Challenge: Reduce NPT due to motor failures while drilling a 53/4-in reservoir section through an abrasive HPHT environment using thru-tubing drilling, managed pressure drilling (MPD) techniques, and a positive displacement motor (PDM).

Solution:Use the PowerPak HR* hard rubber motor with the Powerlast* life-extending motor elastomer to drill the entire section in a single run.

Results: 

  • Drilled the reservoir section in a single run
  • Eliminated 75 h of NPT caused by motor stalls and failures
  • Set field records by improving on the record section length by 60%, establishing the longest below-rotary hours and beating the pumping hours by 67%
Products Used

PowerPak HR Motor with Powerlast Elastomer Drills Reservoir Section in a Single Run, Kvitebjørn Field

Motor-elastomer combination eliminates 75 h of NPT and beats previous records for field section length by 60% and pumping hours by 67%, North Sea

Reduce NPT caused by motor failures

The wells in the Kvitebjørn Field in the North Sea are HPHT wells where operators commonly use highly abrasive muds to drill the reservoir sections. In 2006, after pressure depletion and a major well control incident, unconventional drilling techniques—including MPD, thru-tubing rotary drilling, and using wellbore strengthening materials and rig-assisted snubbing units—were employed to carry on production. In 2011, Statoil planned to drill the reservoir section with a 53/4-in bit, making drilling with a PDM necessary to minimize surface string rotation.

Due to the HPHT environment, the mud used, and the multiple motor stalls experienced, the motor and elastomer were typically left exposed to damage from abrasion and temperature. In the past, no operator in the field was able to drill the reservoir section in a single run due to these common motor failures. These failures caused about 75 hours of NPT per well, on average.

Use motor modelling techniques and durable elastomer to drill section in a single run

Statoil needed to reduce the NPT it experienced while drilling the section, which meant seeking out a new motor and elastomer combination.

Motor optimization modeling and a simulation strategy were used during the prejob planning phase. Statoil’s goal: to drill the 53/4-in section in a single run.

Nearly every simulation resulted in motor and elastomer failures, but Statoil found that the combination of the PowerPak HR motor with the Powerlast elastomer would be far more durable than any other option.

PowerPak HR Motor with Powerlast Elastomer Drills Reservoir Section in a Single Run, Kvitebjørn Field
Using the Powerlast elastomer enabled the PowerPak HR motor to run throughout the section without motor failures.

Eliminated motor NPT and set field records while completing section in a single run

The PowerPak HR motor and the Powerlast elastomer selected by the motor optimization modeling enabled drilling the entire 53/4-in reservoir section in a single run with no stalls even through thick cemented sandstone stringers—for the first time since MPD was introduced more than 6 years before. The motor also set field records for the longest run length of 1,152 ft [351 m], the longest below rotary hours of 444 h, and the field maximum pumping hours of 302 h. These are considered the highest statistics for Schlumberger for the 4 3/4-in motor size worldwide.

Overall, the PowerPak HR motor with the Powerlast elastomer was able to increase section lengths by 60% and pumping hours by 67% as compared with the previous field records. The technologies also completely eliminated the 75-h NPT associated with motors on previous drilling campaigns in the area. Unlike the previous elastomers, the Powerlast elastomer was not damaged from increased temperatures when pumps were inactive.

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Using the Powerlast elastomer, the operator was able to avoid motor failures entirely on two consecutive wells. In the offset wells drilled beforehand, motor failures were fairly regular.
Products Used

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