METHOD OF ISOLATION OF LOST CIRCULATION ZONES IN WELL Russian patent published in 1999 - IPC

FIELD: drilling of oil and gas wells, particularly, isolation of lost circulation zones. SUBSTANCE: method includes injection of grouting mix into well in form of aqueous solution of water-swelling polymer. The latter is injected to formation to be isolated in form of first portion of powdery water-swelling polymer AK-639 in water with concentration equalling 10-20%, then it is held in well for 0.5-4 h, and second portion of said polymer in water is injected, whose concentration is less than that in the first portion and portions of injected grouting mix are forced into formation to be isolated. EFFECT: higher efficiency of isolation jobs due to filling of finely fissured and moderately fissured rocks, and reduced consumption of water-swelling polymers.