Schlumberger

Performance Report: RHELIANT PLUS Achieves Flat Rheology Across Wide Temperature Range and Excellent Hole Cleaning in First Field Trial

Challenge:

  • The operator sought consistently flat rheology across a wide temperature range and excellent hole cleaning in the 17.5-inch and 12.25-inch sections.
  • Robust rheological properties in highly deviated, large ID holes can complicate hole cleaning from high mud-on-cuttings and associated surface losses.
  • Extensive back-reaming had historically been required after drilling 12.25-inch sections.

Solution: Used VERSACLEAN whole mud was added to the RHELIANT PLUS system while drilling in a 65:35 ratio.

Result:

  • VERSACLEAN behaved like RHELIANT PLUS.
  • Flat rheology was maintained across a wide temperature range.
  • Surface losses (mud-on-cuttings) were 50 percent of historical averages.
  • Achieved objectives included a reduction in back-reaming, higher flow rates and lower stand pipe pressure, lower PV values, improved solids tolerance, cost reduction goals and a reduction in disposed IBC/Drums.
  • Lower OWR resulted in a projected $1.2 million reduction in annual base oil costs.

Hole cleaning challenge

In the first field trial of RHELIANT PLUS offshore Sakhalin, Russia, the 17.5-inch and 12.25-inch sections were evaluated. Wells in the Piltun field typically have 17.5-inch sections of 2,000 to 3,400 meters with 50 to 80 degree inclinations that require a fluid system with robust rheological properties that can unintendedly result in high mudon- cuttings and surface losses. Drilling previously had been complicated as well by extensive back-reaming after drilling 12.25-inch sections.

Within three full circulations after displacement, the newly-built drilling fluid consisting of used VERSACLEAN whole mud added to the RHELIANT PLUS system in a 65:35 ratio reached targeted viscosity. Throughout drilling of both sections, flat rheology was maintained from 40°F to 176°F. Flow rate vs. SPP rose 15 percent in the 17.5- inch section using RHELIANT PLUS. Typical flow rates in the 17.5-inch section with VERSACLEAN were around 1,180 gpm. With RHELIANT PLUS, the average flow rate was approximately 1,350 gpm.


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