Challenge:
Developing wells on the Siberian Platform presents extreme geological and technical challenges. The formations are highly fractured, cavernous, and prone to catastrophic drilling fluid losses when bottomhole pressure exceeds fracture gradients. Conventional drilling often leads to circulation losses, stuck pipe, and increased well construction costs. Even the use of inert bridging materials and nitrogen-assisted MPD has provided only partial improvement, while creating new issues like unstable telemetry signals and increased torque and friction.
Solution:
Ultradeep Energy, in collaboration with academic and industry partners, introduced Double Gradient Drilling Technology (DGDT) as an evolution of Managed Pressure Drilling. The system creates two distinct pressure gradients using nitrogen or a light drilling fluid injected through a dedicated tailpipe at the dilution point. A decanter centrifuge separates returning fluids into light and heavy fractions, which are continuously reintroduced into the well. This configuration allows precise control of the pressure profile, maintaining wellbore stability while avoiding fracture or influx zones.
Results:
Simulation and design analysis showed that DGDT enables the same Eastern Siberia well to be drilled with four casing strings instead of six, increasing the final hole diameter from 4 ½” to 7”. Construction time is reduced by 20–30%, and the well design simplified. The dual gradient pressure profile remains within the pore pressure and fracture gradient limits, allowing longer intervals to be drilled safely without intermediate casing.
Impact:
DGDT demonstrates major advantages for complex wells:
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Enables drilling through narrow pressure windows safely.
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Improves cementing quality and zonal isolation.
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Reduces materials, rig time, and environmental footprint.
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Expands applicability to geothermal wells requiring larger bore diameters.
This case study was published in Springer Nature (2025) in the chapter “Dual Gradient Drilling Technology: An Effective Solution for Developing Challenging Wells in Eastern Siberia”, confirming DGDT as a next-generation method for efficient and safe well construction.
Read Publication: https://link.springer.com/chapter/10.1007/978-3-031-82210-0_15
