METHOD OF FORMATION ISOLATION Russian patent published in 2002 - IPC

FIELD: oil producing industry, particularly, method of formations isolation with help of viscoelastic materials; applicable in isolation of formations in well. SUBSTANCE: method includes running into well of casing string provided with device for isolation of producing formation; location of device in well against producing formation; communication of well annulus above and below interval of producing formation by means of bypass channel of said device; injection into annular space of grouting viscoelastic material; washing of well after its cementing; washing of annular space, prior to injection of viscoelastic grouting material, with drilling mud with colmatage additives and supply of crust-removing fluid which is held for 5-15 min. In this case, viscoelastic grouting material is used in form of precipitating and gelling substances. First, injected into water-bearing bed is precipitating substance at pressure less than formation hydraulic fracturing pressure, and then gelling substance under pressure less than injection pressure of precipitating substance. In this case, viscoelastic grouting material is held in annular space up to beginning of gelling. Colmatage additives are used in form of rubber crumb. Crust removing fluid is used in form of 5% solution of NaOH. Precipitating substance if used in form of aqueous solution of hydrolyzed acryl polymers and salts of polyvalent metals. Said polymers are used in form of polyacrylamide with hydrolysis degree of, at least, 30%. Said salt is used in form of CaCl₂. Gelling substance is used in form of aqueous solutions of partially hydrolyzed acryl polymers. Said polymers are used in form of polyacrylamide with hydrolysis degree of, at least 30%. EFFECT: increased isolation reliability.