Patent ID: 9738824
Date: 2017-08-22
CPC Classifications: C09K,E21B

Claim:
1. A method for stimulating production of gas in a tight-gas formation, the method comprising the steps of: injecting into the tight-gas formation an aqueous solution comprising an ammonium containing compound and a nitrite containing compound, wherein at least one of the ammonium containing compound and the nitrite containing compound are encapsulated with a coating operable to delay an exothermic reaction therebetween, wherein the aqueous solution is injected at a sufficient rate and pressure to cause fractures in the tight-gas formation, wherein the fractures extend into the tight-gas formation, wherein the fractures have a fracture surface; injecting an acidic activator into the tight-gas formation, the acidic activator comprising a weak acid being capable of initiating the exothermic reaction between the ammonium containing compound and the nitrite containing compound such that the reaction generates heat and nitrogen gas, wherein the exothermic reaction consumes all of the acidic activator; and allowing the generation of nitrogen gas and heat within the tight-gas formation, after all of the acidic activator is consumed, to effect stimulation of the fracture surface, wherein the stimulation of the fracture surface produces microfractures at the fracture surface without damaging the tight-gas formation, wherein the generation of nitrogen gas and heat increases cumulative pore volume and core permeability of the tight-gas formation, wherein the hydrostatic pressure within the reservoir is reduced to less than the reservoir fluid pressure, such that the rate of production of hydrocarbons from the tight-gas formation is increased, and wherein the coating is operable to delay the reaction according to: heat within the tight-gas formation being between about 60° C. and about 200° C.; concentration of the acidic activator being between about 2% and about 10% by volume; and concentration of the aqueous solution, wherein the aqueous solution comprises the ammonium containing compound and the nitrite containing compound in a molar ratio range of about 1.1:1 to about 1:1.1 ammonium containing compound to nitrite containing compound, such that the at least one encapsulated compound is released to react to create a pressure of at least about 400 psi to cause the fractures in the tight-gas formation.