COMPOSITION OF DRILLING FLUID AND DRILLING METHOD, SUITABLE FOR REDUCING BITUMEN DEPOSITS ON DRILL COMPONENTS Russian patent published in 2019 - IPC C09K8/35 C09K8/04 C09K8/524 E21B37/06 

FIELD: chemistry.

SUBSTANCE: group of inventions related to oil production. Water-based drilling fluid contains an anti-sludge additive and, optionally, an agent for increasing viscosity. Anti-scale additive contains: i) from 5 to 50 parts by weight of a propoxylated alcohol of formula RO-(PO)_x-H(I), where R is a linear or branched alkyl having from 8 to 16 carbons, and x is from 1 to 10, and ii) from 50 to 95 parts by weight of a propoxylated and ethoxylated alcohol of formula R¹O-(PO)_y-(EO)_z-H (II), where R¹ is a linear or branched alkyl having from 8 to 16 carbons, y is from 2 to 10 and z is from 3 to 20, where parts by weight are based on the total weight of the propoxylated alcohol i and the propoxylated and ethoxylated alcohol ii, and EO and PO denote ethylene oxide and propylene oxide units, respectively.

EFFECT: technical result is reduction of sticking of bitumen and/or heavy oil materials on metal surfaces, such as drill heads, drill string, casing string and the like, good biodegradability and low toxicity for aquatic organisms against formation.

7 cl, 5 dwg, 2 tbl, 4 ex