HIGHLY INHIBITION DRILLING FLUID Russian patent published in 2022 - IPC C09K8/08 

FIELD: oil and gas wells construction.

SUBSTANCE: invention relates to the construction of oil and gas wells, namely to water-based drilling fluids used in the construction, completion and workover of wells in conditions of unstable clay deposits. The drilling fluid has a density of 1.08-1.16 g/cm³ with the possibility of weighting up to 1.30 g/cm³ and is thermally stable up to 110°C. The drilling fluid contains, wt.%: to control the structural-rheological and filtration properties of the solution - xanthan biopolymer 0.2-0.3 and lignosulfonate 0.8-1.0; to inhibit the process of clay hydration - potassium chloride 5.5-17.2; creating an impermeable filter cake on the walls of the well and achieving the required density of the solution - ground marble 4.3-21.6; to inhibit the process of hydration of clays, hydrophobization of the walls of the well and improve the tribological properties - saponified potassium tall oil 0.8-17.7; technical water treated with caustic soda and defoamer, the rest.

EFFECT: high inhibitory ability in relation to the process of hydration of clays, minimal impact on the reservoir properties of the bottomhole formation zone, optimal structural-rheological and frictional properties.

1 cl, 1 dwg, 4 tbl, 1 ex