METHOD OF PROCESSING PRIMARILY FLAT HORIZONTAL WELL HOLE FOR REMOVAL OF MUD BULK FROM BOTTOM-HOLE FORMATION ZONE Russian patent published in 2012 - IPC E21B43/27 E21B37/06 C09K8/52 

FIELD: oil-and-gas industry.

SUBSTANCE: invention relates to construction, completion and pull-out of holes. Proposed method comprises adding peroxide compound into mud used for tailing-in and flushing including polysaccharides and mudding agent to be replaced by acid process fluid including said peroxide compound, acid and water, curing in reaction with subsequent removal of reaction products from the bed. Said peroxide represents urea peroxyhydrate, or sodium peroxyborate, or sodium percarbonate. It includes also adding said compound in concentration of 0.5-1.0 wt % to mud solution during circulation in last lift of drilling tool from the well and lowering of tubing with curing said composition in reaction for art least four hours. Note here that acid process fluid comprises the following components in wt %: said peroxide compound 0.5-3.0, hydroxycarboxylic, citric or lactic acid 5.0-10.0, nonionic surfactant - oxanol or neonol "АФ"_9-12, or LML-4312, or "МЛ"-80 0.005-0.02, saline water making the rest. Note here that density of said acid process fluid equals that of mud solution used in tailing-in, or differs therefrom by not over 10%.

EFFECT: higher efficiency, ease of mudding compound removal.

5 cl, 3 ex, 4 tbl