LIGHTWEIGHT DRILLING FLUID (OPTIONS) Russian patent published in 2019 - IPC C09K8/08 

FIELD: oil and gas industry.

SUBSTANCE: group of inventions relates to the oil and gas industry. Lightweight drilling fluid in the first embodiment includes, wt. %: technical chalk 3; modified starch 4; ZS-7 hydrogen sulfide neutralizer 2; xanthan biopolymer 0.1; technical sodium hydroxide 0.1; hollow glass microspheres of sodium borosilicate glass 5–10; technical fresh water 80.8–85.8. Lightweight drilling fluid according to the second variant includes, wt. %: technical chalk 3; modified starch 4; ZS-7 hydrogen sulfide neutralizer 2; xanthan biopolymer 0.1; technical sodium hydroxide 0.1; hollow glass microspheres of sodium borosilicate glass 5–10; brine 80.8–85.8. Lightweight drilling fluid in the third embodiment includes, wt. %: modified starch 4; ZS-7 hydrogen sulfide neutralizer 2; xanthan biopolymer 0.1; technical sodium hydroxide 0.1; hollow glass microspheres of sodium borosilicate glass 5–10; technical fresh water 83.8–88.8.

EFFECT: technical result – optimal structural and rheological properties of drilling fluid for use on hydrogen sulfide-containing oil, gas and gas condensate fields with low and abnormally low reservoir pressure, prevention of absorption of drilling fluid during the conduct of downhole operations, frost resistance, neutralization of hydrogen sulfide, minimization of negative environmental pressures on the environment.

3 cl, 2 tbl