THERMO-GAS-GENERATING SYSTEMS AND METHODS FOR OIL AND GAS WELL STIMULATION
A method of treating a subterranean reservoir includes the steps of delivering a stabilized, non-explosive combustible oxidizing solution (COS) to a desired treatment area in the reservoir and activating the COS with an activator which reduces the pH of the COS. Upon activation, the COS reacts to produce sufficient heat and gas to stimulate the treatment area.
1 . A method of treating a subterranean reservoir, comprising the steps of:
(a) delivering a stabilized, non-explosive combustible oxidizing solution (COS) to a desired treatment area in the reservoir,
(b) activating the COS with an activator which reduces the pH of the COS, wherein upon activation, the COS reacts to produce sufficient heat and gas to stimulate the treatment area.
2 . The method of claim 1 wherein the activator is either consecutively injected after the COS, or is encapsulated in an emulsion with the COS.
3 . The method of claim 1 wherein the treatment zone is a near well-bore zone and/or a zone radially distal from the wellbore within the reservoir.
4 . The method of claim 1 wherein the COS comprises an aqueous solution comprising:
(a) a nitrate salt,
(b) a nitrite salt, and
(c) a stabilizer.
5 . The method of claim 4 wherein the nitrate salt comprises ammonium nitrate.
6 . The method of claim 4 wherein the nitrate salt comprises sodium nitrite.
7 . The method of claim 6 wherein the weight percent composition (w:w) of the COS comprises ammonium nitrate of 15.0-50.0%, sodium nitrite of 15.0-40.0%, and stabilizer of 0-2.0%.
8 . The method of claim 4 wherein the COS comprises an oil-in-water or water-in-oil emulsion, and further comprises and oil and an emulsifier.
9 . The method of claim 8 wherein the composition comprises oil in a weight percent of 10.0-25.0, and emulsifier in a weight percent of 0.1-2.0%.
10 . The method of claim 4 wherein the COS further comprises a viscosifier.
11 . The method of claim 10 wherein the viscosifier comprises guar or a polyacrylamide in a weight percent amount of 0.1-0.5%.
12 . The method of claim 6 wherein the COS comprises a BSS composition, and the activator comprises an aqueous inorganic acid solution.
13 . The method of claim 10 wherein the activator comprises hydrochloric acid.
14 . The method of claim 6 wherein the COS comprises a BSV composition, and the activator comprises an organic acid solution or emulsion.
15 . The method of claim 14 wherein the activator comprises acetic acid, formic acid, propionic acid or sulphamic acid.
16 . The method of claim 14 wherein the COS is nitrified or foamed prior to placement in the treatment area.
17 . The method of claim 8 wherein the activator is emulsified within the COS, in a water-in-oil emulsion.
18 . The method of claim 4 wherein the stabilizer comprises sodium carbonate, a hydroxide, or a pyridine, combinations thereof.
19 . The method of claim 1 wherein the COS is solids-free.
20 . The method of claim 1 wherein the activator is encapsulated.
21 . The method of claim 20 wherein the activator is encapsulated by a three-phase emulsion, comprising an inner phase comprising the activator, a middle phase comprising an oil, and an outer phase comprising the COS.
22 . The method of claim 10 wherein the COS comprises a fracturing proppant, and the COS is sufficiently viscous to transport the proppant into the treatment area.