Schlumberger

Case Study: Integrated Drilling System Saves Gazprom Dobycha Astrakhan 7 Days in Russian Gas Condensate Field

Combination of RSS, PDC drill bit, and MWD service provides full directional control, increases ROP 230% in challenging vertical section

Challenge: Drill a vertical section through salt and clastic layers and acquire real-time information to log the borehole.

Solution: Combine the PowerV vertical drilling system with an MDSi616 SHARC high-abrasion-resistant PDC drill bit and TeleScope high-speed telemetry-while-drilling service to maintain trajectory inclination, reduce shock and vibration, and increase ROP.

Result: Reached TD after two runs, 7 days ahead of target. Increased ROP approximately 230% with an inclination of less than 0.1°.

Drill vertical section through salt and clastic layers

Gazprom Dobycha Astrakhan has traditionally drilled vertical wells without the use of MLWD technology. In a well in the Astrakhanskoe gas condensate field in southern Russia, checkshot surveys revealed that the wellbore had been built to an inclination of 22.5°. To bring the well back to vertical, the company had to plug back and sidetrack. However, the sidetrack showed an inclination of 24.8°, and it had to be plugged. To reduce NPT associated with redrilling, the company requested an integrated drilling system capable of delivering the directional control needed to maintain full verticality in an 115/8-in interval while also logging the wellbore in less time.

Stay in zone while drilling challenging section

An integrated BHA was designed to provide the optimal drilling parameters needed to reduce the trajectory inclination and shock and vibration. With full verticality in mind, the PowerV system was incorporated into the drilling system to automatically keep the well path within the target zone. A SHARC high-abrasion-resistant MDSi616 PDC drill bit with ONYX  premium PDC cutters from Smith Bits, a Schlumberger company, was selected to aggressively drill through the challenging rock layers because of its successful performance in an offset analysis. TheTeleScope MWD service enabled transmission of high-quality data that were used to improve BHA performance while logging the vertical borehole.

Save 7 days of rig time and increase ROP 230%

The integrated system drilled the 11 5/8-in vertical section to TD with an inclination of less than 0.1° in only two runs and without incident due to reduced shock and vibration. Drilling was completed in 10 days—7 days ahead of target—saving valuable rig time. The combination of the PowerV RSS and PDC drill bit allowed the drilling parameters to maintain the vertical trajectory path while increasing ROP 230%—two times faster than previous runs in similar intervals nearby. The TeleScope service provided high-quality downhole information usedto ensure the RSS achieved full verticality.

Gazprom Dobycha Astrakhan plans to use Schlumberger MLWD technology to drill more vertical and subhorizontal wells with greater accuracy and efficiency.


Download: Integrated Drilling System Saves Gazprom Dobycha Astrakhan 7 Days in Russian Gas Condensate Field (0.81 MB PDF)

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Engineered System Maintains Vertical Trajectory Path and Increases ROP 230%

Chart showing planned and actual hours drilled.
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