Method of treating the near-wellbore zone of the reservoir
The invention describes a method for treating near-wellbore zones involving the steps of injecting a magnesium metal with a catalyst into the desired area of the formation to be treated. Subsequently, combustive-oxidizing solution (COS) is injected into the zone of the formation to be treated. The COS initially reacts with the magnesium, which in turn initiates a vigorous oxidation reaction of the COS. The reaction gases and heat produced by the COS oxidation reaction are harnessed to enhance the productivity of the well by creating fractures in the treatment zone and by melting of paraffin and resin deposits in the treatment zone. As a final step, acid is injected into the formation to react with the formation thereby further enhancing the porosity of the fractures. In one embodiment, the COS uses ammonium nitrate as the oxidizer, and in another, urea or ethylene glycol may be added as a reaction fuel.
1. A method of treating a near-wellbore formation zone of a geological reservoir comprising the following steps:
a. delivering a mixture of granular magnesium and catalyst to a desired treatment area within the near-wellbore formation zone;
b. delivering a combustive-oxidizing solution (COS) to the desired treatment area, the COS capable of reacting with the magnesium;
c. permitting the COS to react with the magnesium and the catalyst in the treatment area to increase the temperature and initiate an exothermic oxidation reaction of the COS, whereby the COS is decomposed without an explosion due to the catalyst and the catalyst reduces the temperature required to initiate the exothermic oxidation reaction of the COS to produce COS oxidation reaction gases and heat;
d. creating a localized zone of high pressure and high temperature in the treatment area from the COS oxidation reaction gases and heat; and
e. creating newly-formed fractures in the treatment area of the near-wellbore formation with the pressure resulting from the COS oxidation reaction gases.
2. The method of claim 1 further comprising the steps of:
f. after completion of the COS oxidation reaction, injecting an acidizing solution into the newly-formed fractures in the treatment area of the formation; and
g. producing from the reservoir to remove post-reaction products.
3. The method of claim 2 wherein the acidizing solution comprises a water-based solution of hydrogen chloride.
4. The method of claim 3 wherein the acidizing solution further comprises a surfactant.
5. The method of claim 1 wherein the granular magnesium and the catalyst are delivered along with a proppant during a fracturing operation.
6. The method of claim 1 wherein the magnesium and catalyst are delivered in an oil- or water-based fracturing fluid.
7. The method of claim 1 wherein the COS comprises an aqueous mixture of an oxidizer, a fuel, and a surfactant.
8. The method of claim 7 wherein the oxidizer is ammonium nitrate.
9. The method of claim 7 wherein the fuel is selected from the group consisting of urea and ethylene glycol.
10. The method of claim 7 wherein the oxidizer is ammonium nitrate in a percent composition range between about 50% to about 65%; wherein the fuel is urea in a percent composition range of about 10% to about 30%; wherein the surfactant is in a percent composition range of about 2% to about 3%; wherein the catalyst is in a percent composition range of about 3% to about 6%; and wherein the remaining percent composition comprises fresh water.
11. The method of claim 7 wherein the COS further comprises an acid in a percent composition range between about 1% to about 3%; wherein the oxidizer is ammonium nitrate in a percent composition range between about 52% to about 62%; wherein the fuel is ethylene glycol in a percent composition range of about 8% to about 15%; wherein the surfactant is in a percent composition range of about 2% to about 3%; wherein the catalyst is in a percent composition range of about 3% to about 6%; and wherein the remaining percent composition comprises fresh water.
12. A method for fracturing a near-wellbore formation zone of a geological reservoir comprising the following steps:
a. injecting into a desired near-wellbore treatment zone of the reservoir a hydraulic fracturing fluid containing a mixture comprising granular magnesium and a catalyst;
b. injecting into the near-wellbore treatment zone a combustive-oxidizing solution (COS);
c. contacting the magnesium and the catalyst in the near-wellbore treatment zone with the COS;
d. initiating an exothermic decomposition of the COS in the near-wellbore treatment zone to generate COS decomposition reaction gases without an explosion due to the catalyst and the catalyst reduces the temperature required to initiate the exothermic decomposition of the COS, to produce COS oxidation reaction gases and heat to cause a localized buildup of high pressure and high temperature, wherein the high pressure is sufficient to cause additional fracturing of the near-wellbore formation zone in the near-wellbore treatment zone;
e. after the COS decomposition reaction is substantially complete, injecting an acidizing solution, into an area of additional fracturing; and
f. producing from the reservoir to remove post-reaction products.
13. The method of claim 12 wherein the fracturing fluid further comprises proppant.
14. The method of claim 12 wherein the COS comprises an aqueous mixture of an oxidizer, a fuel, and a surfactant.
15. The method of claim 12 wherein the acidizing solution further comprises a surfactant.
16. A method of treating a near-wellbore formation zone of a geological reservoir comprising the following steps:
a. delivering a dry form of a nitrate salt with proppant to a desired treatment area within the near-wellbore zone;
b. delivering a granular magnesium to the treatment area with proppant;
c. delivering a catalyst to the treatment area;
d. delivering a combustive-oxidizing solution (COS) to the treatment area, the COS capable of reacting with the magnesium;
e. permitting the COS to react with the nitrate salt and the granular magnesium in the treatment area to increase the temperature and initiate an exothermic oxidation reaction of the COS, wherein the COS decomposes without an explosion due to the catalyst and the catalyst reduces the temperature required to initiate the exothermic decomposition of the COS to produce COS oxidation reaction gases and heat;
f. creating a localized zone of high pressure and high temperature in the treatment area from the COS oxidation reaction gases and heat; and
g. creating newly-formed fractures in the treatment area of the near-wellbore formation with the pressure resulting from the COS oxidation reaction gases.
17. The method of claim 16 wherein the nitrate salt is ammonium nitrate or sodium nitrate.
18. The method of claim 16 wherein the COS comprises a mixture of acid and ethylene glycol.
19. The method of claim 16 wherein the catalyst is a copper salt.
20. The method of claim 16 wherein steps (a) and (b) are performed together so that the nitrate salt and granular magnesium are delivered together to the treatment area with proppant prior to step (d).
21. The method of claim 16 wherein steps (a), (b) and (c) are performed together so that the nitrate salt, granular magnesium and catalyst are delivered together to the treatment area with proppant prior to step (d).
22. The method of claim 16 wherein step (b) is performed before step (a).
23. The method of claim 16 wherein steps (a), (b) and (c) are performed in any order before step (d).
24. The method of claim 16 wherein the catalyst is added to the COS and steps (c) and (d) are therefore combined and performed together after steps (a) and (b).