DRILLING FLUID (VARIATIONS) Russian patent published in 2007 - IPC C09K8/18 

FIELD: well drilling engineering.

SUBSTANCE: invention relates to boring oil and gas wells, in particular to drilling fluids for drilling and completing wells. According to first variant, drilling fluid contains, wt %: clay 3-15, filtration reducing agent 0.1-0.6, phosphone complexone 0.01-0,05, alkali metal organosiliconate 0.05-0.8, mixture of polyalkylene glycols and polypropylene glycol monoalkyl ether (polyether concentrate) 0.5-2.0, bactericide 0.1-0.5, and water - the balance. According to second variant, drilling fluid contains, wt %: clay 3-15, filtration reducing agent 0.1-0.6, complex reagent KP-03 (aqueous solution of phosphone complexone/sodium aluminomethylsiliconate reaction product 0.3-1.0, above-defined polyether concentrate 0.5-2.0, bactericide 0.1-0.5, and water - the balance. Fluid may further contain 0.3-1.5 vol % of additive and weighting agent.

EFFECT: enabled creation of non-foaming drilling fluid with improved surfactant properties, resistant to microbiologic damages, and maximally preserving natural filtration characteristics or producing strata.

6 cl, 3 tbl, 4 ex