UNIDRIL is a oil-based drilling fluid. The oil-based drilling fluids have the following advantages versus any other water-based systems:

  • outstanding inhibitive properties;
  • low friction coefficient;
  • low filtration level and full absence of water in filtrate;
  • high stability of mud parameters;
  • high tolerance to the cuttings content;
  • high tolerance to contamination factors (cement, formation water, etc.);
  • recycling capability.

It allows to avoid the majority of problems, which may arise with the use of the water-based drilling fluids, especially when drilling high angle/ large displacement boreholes, even in the unexpected open-hole conditions, independent on the effects of the interval rocks.


The UNIDRIL system is optimal:

  • to penetrate in the easily sloughing intervals, when drilling boreholes with complex trajectories;
  • to drill horizontal wells in gas and gas condensate fields;
  • to maximize the quality of drilling operations, when drilling through the productive zone;
  • to drill wells with large displacement.


The UNIDRIL composition was designed with respect to the specific oil-base drilling fluid requirements applied in the Russian oil and gas fields, in particular, Yamal gas/ gas condensate fields. Multiple use of oil-base drilling fluids results in accumulation of fine colloidal solids. The size of solids does not allow to clean mud using conventional solids control equipment. The increase of the concentration of fine cuttings and solids in the mud results in the increase of the mud plastic viscosity followed by the increase of pump pressures and equivalent circulating densities (ECDs).

AKROS was proposed to use special range of surfactants and emulsifiers when designing the UNIDRIL system to reduce negative effect of cuttings. These special combination of surfactants interacts with fine drilled rock particles, thus preventing any significant increase of rheological properties.

This advantage allows to reduce the consumption of mineral oil, and to maintain proper plastic viscosity values.

The following additives may be used to treat UNIDRIL systems: a special lubricant for oil-based mud (to reduce torque and hook loads when drilling high deviated wells), and micro-barite. Micro-barite is mostly used to drill small size sidetracks. Drilling fluids with micro-barite additive have a relatively high density with minimal rheological properties (parameters), thus reaching minimal pressure values and equivalent circulating densities (ECDs) while drilling.

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