THERMOSALINE-RESISTANT DRILLING FLUID Russian patent published in 2021 - IPC C09K8/24 

FIELD: drilling of wells.

SUBSTANCE: invention relates to water-based drilling muds and can be used in drilling oil and gas wells, mainly during drilling salt and unstable clay rocks under conditions of high temperatures of up to 240 °C. Thermosaline-resistant drilling mud contains, wt %: clay powder 3–5; cationic copolymer Silfok 2540C 5–7; cationic copolymer Silfok 2540V 7–10; sodium chloride 3–30; organophilic bentonite 0.2–0.6; water—balance.

EFFECT: technical result is high salt resistance with preservation of thermal stability of solution before and after exposure to high temperatures of up to 240 °C by providing minimum values of filtration index before and after exposure to high temperatures in both normal and bottom-hole conditions.

1 cl, 1 dwg, 1 tbl