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Performance Report: Nizhnevartovsk Siberia, Russia - SILDRIL K System

Challenge: An effective drilling and drill-in fluid was required to drill the 8½” interval. The objective was to use the same fluid to drill the soft, reactive clays and shales in the top section and the low permeability sedimentary formation in the Jurassic reservoir.

Solution:

Silicate water base fluids are recognized in the fluid industry as an effective solution for chemical wellbore stability. Silicate fluids require the potassium ion in the form of an organic or inorganic salt for optimum performance. A potassium silicate additive, SILDRIL K, provides both the silicate chemistry and the potassium ion for shale stability.

Return permeability and pressure tests on a core sample showed favorable results with the SILDRIL K system.

Result:

The 8½” interval was drilled with the potassium silicate system from 820 meters to 2694 meters in eight days. The initial ROP for the interval was 26.5 meters per hour and the final ROP was 5.9 meters per hour (average ROP = 15 meters per hour).

Conventional systems used to drill this interval have resulted in few cuttings and rapid increases in the mud weight and viscosity. Dry hard cuttings (up to 10 cm) with excellent integrity were observed throughout the entire interval.

Fine mesh screens (>110 mesh) were used to effectively control the mud weight and the viscosity. The only maintenance volume required was for hole volume drilled.

No excessive torque and drag was observed and pump pressures was significantly lower than on previous wells. Bit runs were reduced (Bit life was improved by 35%) and 3 drilling days were saved on the interval.

The hole was in gauge with no shale sloughing, bit or BHA balling, or screen blinding typical of previous wells.

Well Information
Location Samotlor Field, Siberia
Spud / Completion September 30, 2001
Intervals Drilled 8½” from 820m to 2694m (1874 meters)
Formations Drilled Gumbo, clay, shale, sandstone
Maximum Density 1.12 SG / 9.34 ppg
Maximum Deviation 16.5°
Total days on interval 8 days
Problems none

The Details

SILDRIL K offers several technical advantages to a conventional SILDRIL formulation:

  • Low salinity for onshore disposal
  • Low salinity for log optimization
  • A truly simple, shale-stabilizing water base fluid formulation

Download: Nizhnevartovsk Siberia, Russia - SILDRIL K System (0.49 MB PDF)

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Summary Data

Mud VolumeROP Performance
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