METHOD OF KILLING WELLS WITH ABNORMAL LOW FORMATION PRESSURE Russian patent published in 2008 - IPC E21B43/12 C09K8/42 

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil and gas industry, particularly to methods of killing and conservation of wells, to methods of preparation and using of liquids for a hydraulic formation breakdown, and it can also be used for restraint of water production in oil and gas wells The method of killing wells with abnormal low formation pressure consists in at first preparing a foaming solution, containing a thickener, a foaming agent and water, then in pumping of the solution into a well together with nitrogen, supplied from a nitrogen supply assembly at a volume ratio under normal conditions of the foaming solution: nitrogen as 1:1-10, correspondingly; at that the foaming solution and nitrogen are supplied through the first T-bend, while the produced foam is supplied through the second T-bend wherein a linking solution is also supplied at a volume ratio of the foaming solution: linking solution as 4-6:1, correspondingly; at that as thickener a guar gum or hydroxypropyl guar is used, as a foaming agent either a nonionic substance, a surface active agent -SAA- Neonol AF_9-12 or anionic SAA Neftenol ML, or a mixture of nonionic and anionic SAA - complex SAA Neftenol VVD is used, and as water - a sweet or mineralised water is used which predominantly contains univalent cations at a following ratio of ingredients, kg/m³ of sweet or mineralised water: the said thickener 4.0-8.0, the said foaming agent 1.0-10.0, and the linking solution contains a sweet or mineralized water, which predominantly contains univalent cations, borate linking BL-1 or BL-1.3 and diethanolamine at a following ratio of components, kg/m³ of sweet or mineralised water: the said linking agent 10.0-40.0, diethanolamine 0.0-100.0.

EFFECT: exclusion of lost circulation in wells with abnormal low formation pressure and facilitation of a well completion after repair works.

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