Development and service of drilling fluid

Column closed interval 5388-4009 m, including Visean productive horizons.

When drilling interval used clayless biopolymer mud BIOCAR-MT.


  • Funnel viscosity – 100-115 s;
  • Density– 1,27-1,28 g/cm3;
  • Gel– 57/65 dPa;
  • Plastic viscosity – 25-30 mPa*с,
  • YP– 220-240 dPa,
  • Filtration loss– 3-3,5 cm3/30 min.;
  • Mud Cake Friction Coefficient – 0,11-0,12;
  • Salinity – 16,5-17,5%;
  • Concentration of KCl - 7-9%;
  • рН – 8,0-9,0.

The objective of further drilling to a depth of 5941 m is a showdown Tournaisian deposits with abnormally high reservoir pressures. Expected mud density 1540-1560 kg/m3.

High reservoir temperature at a depth of design (150°C) excludes the use of weighted mud clay-free polysaccharide based. In this regard, at the opening Tournaisian deposits will be used polymer clay washing system - similar to that employed previously, in liquidation of showings of gas and drilling with AHFP at Poltava.

The transition to a new type of drilling mud will be held at the end of the WOC casing.