METHOD FOR PREPARATION OF BLOCKING FLUID FOR KILLING WELLS Russian patent published in 2022 - IPC E21B43/12 C09K8/02 

FIELD: gas industry.

SUBSTANCE: invention relates to the gas industry, in particular to water-based fluids for temporary blocking of a productive formation, and can be used in the overhaul of gas and gas condensate wells under conditions of abnormally low reservoir pressure (ALRP) at reservoir temperatures of 60-80°C. The method for preparing blocking liquid for killing wells consists in the following: to prepare 1000 g of blocking liquid, 839.8 g - 859.85 g of fresh water are measured and divided into two equal portions, one of which is heated to a temperature of 50°C and diluted in her starch, in the amount of 5-6 wt.% by weight of the blocking fluid. Then the resulting aqueous starch solution is left to stand for 12 hours, after which the liquid phase is separated from the resulting precipitate, and fresh water at a temperature of 20°C is added to the precipitate, in the volume of the separated liquid phase, and the solution is stirred until a homogeneous suspension is obtained. Sodium bicarbonate and sulfacell are sequentially introduced into the second portion of fresh water at a temperature of 20°C with continuous stirring, with sodium bicarbonate being introduced in an amount of 1 wt.% by weight of sulfacell, and sulfacell 1.5-2 wt.% by weight of the blocking liquid. The resulting portion of the solution is mixed with a portion of a homogeneous suspension and mixing is carried out, after which polycell is introduced into the resulting solution in an amount of 7.5-8 wt.% of the mass of the blocking liquid and mixed until a homogeneous solution is obtained.

EFFECT: obtaining a blocking fluid for killing wells based on available reagents, without the use of special equipment, which ensures the preservation of the reservoir properties of the bottomhole zone of the productive formation, which has improved structural and rheological characteristics that promote smooth structuring during the injection process and prevent deep penetration of the liquid phase into the formation, and also the possibility of release from the reservoir at low pressure drops, which has low adhesion to the tubing.

1 cl, 5 ex