COLMATAGE DRILLING FLUID AND METHOD OF COLMATAGE LAYER REMOVAL Russian patent published in 2009 - IPC C09K8/10 C09K8/52 E21B43/27 

FIELD: chemistry.

SUBSTANCE: invention concerns deep drilling technology and methods of bottom-hole formation zone. Colmatage drilling fluid includes, wt %: hydroxycellulose 1.0 - 1.2; potassium chloride 5-7; chrysotile asbestos 0.5 - 0.65; aluminium sulfate 0.5 - 0.65; lubricant additive FK-2000⁺ 1.0 - 1.2; carboxymethylcellulose or carboxymethyloxyethylcellulose, hydroxyisopropylcarboxymethyl-cellulose 0.5 - 0.7; trixane PENTA-465 0.01- 0.03; potassium hydroxide to maintain pH at 8-9; the rest is water. Method of removing colmatage layer formed by the claimed method involves bottom-hole formation zone processing by acid and salt composition containing, wt %: HCl 5-10; NH₄HF₂ 1.7-3.4; KCl 5-7, the rest is water, the composition placed in well hole in colmatage interval of productive formation and matured for 6 hours, with further well discharge by standard method.

EFFECT: prevention of drilling fluid foaming, enhanced colmatage and inhibition properties of drilling fluid.

2 cl, 4 ex, 3 tbl