METHOD OF TREATING PRODUCED OR FLOWBACK WATER WITH NUCLEOPHILIC AGENT TO DEACTIVATE BREAKER Russian patent published in 2019 - IPC C09K8/52 C09K8/86 E21B43/22 E21B43/26 

FIELD: drilling soil or rock.

SUBSTANCE: invention relates to the treatment of water obtained during well treatment operations. Method of treating produced or flowback water from an underground formation, including: mixing produced water or flowback water from an underground reservoir with a sulphur- or phosphorus-containing nucleophilic agent, wherein the produced water or flowback water comprises a viscosifying polymer or a remnant thereof, as well as a breaker comprising vitamin B1, a breaker comprising a ylide, or and a breaker comprising vitamin B1, and a breaker comprising a ylide, deactivating said breaker in the presence of a sulphur- or phosphorus-containing nucleophilic agent to produce recyclable water, and pumping the recyclable water into an underground reservoir. Method of treating a fluid with reduced viscosity after a fracturing operation on a subterranean formation, through which a well passes, using a fracturing fluid, where said fluid comprises a viscosifying polymer and a breaker comprising vitamin B1, a breaker comprising a ylide, or a breaker comprising vitamin B1, and a breaker comprising a ylide, and said method includes: reduction of viscosity of the fracturing fluid due to at least partial degradation of the viscosifying polymer in the presence of vitamin B1, ylide or vitamin B1 and ylide, to produce a fluid with reduced viscosity, deactivation of vitamin B1, ylide or vitamin B1 and ylide as part of a fluid with reduced viscosity when a sulphur- or phosphorus-containing nucleophilic agent is added to said fluid, where the fluid with reduced viscosity is produced or flowback water. Method of treating produced or flowback water comprising a viscosifying polymer remnant, including the addition of vitamin B1, ylide or vitamin B1 and ylide to the produced or flowback water and reduction of the viscosity of the produced or flowback water, and adding a sulphur- or phosphorus-containing nucleophilic agent to the produced or flowback water to deactivate vitamin B1, ylide or vitamin B1 and ylide. Method for intensifying a subterranean formation through which a well passes, including pumping into a well a well treatment fluid comprising a first viscosifying polymer and vitamin B1, ylide or vitamin B1 and ylide, under pressure sufficient to effect or initiate a fracture, reducing the viscosity of the well treatment fluid using vitamin B1, ylide or vitamin B1 and ylide, extracting produced or flowback water from the well, deactivation of vitamin B1, ylide or vitamin B1 and ylide in the produced or flowback water by adding a sulphur- or phosphorus-containing nucleophilic agent to the produced or flowback water, adding a second viscosifying polymer to the produced or flowback water to obtain a second treatment fluid and pumping the second treatment fluid into the well under pressure sufficient to effect or initiate fracturing. Invention is developed in dependent items of the formula.

EFFECT: higher efficiency of treatment of produced or flowback water.

19 cl, 1 ex