Attenuated acid formulations for acid stimulation
A method for acid treating a carbonate reservoir with an attenuated acid formulation is provided. The method includes mixing an acidic compound with a hygroscopic chemical to form the attenuated acid formulation, and injecting the attenuated acid formulation into a carbonate formation.
1. A method for treating a carbonate reservoir with an attenuated acid formulation, comprising:
mixing an acidic compound with a hygroscopic chemical to form the attenuated acid formulation, wherein the acidic compound comprises a hydrochloric acid solution and the hydroscopic chemical comprises diethylene glycol, wherein the DEG comprises between 5 and 40 vol. % of the attenuated acid formulation; and
injecting the attenuated acid formulation into a carbonate formation, wherein the pore volume for breakthrough (PV BT ) is less than 0.23 for an attenuated acid formulation comprising either a 28 wt. % or a 36 wt. % solution of HCl.
2. The method of claim 1 , wherein the acidic composition further comprises methane sulfonic acid.
3. The method of claim 1 , wherein the acidic compound comprises a compound that forms an acid in an aqueous solution.
4. The method of claim 1 , wherein the acidic compound comprises an alkylsulfonic acid.
5. The method of claim 4 , wherein the alkylsulfonic acid is methanesulfonic acid (MSA).
6. The method of claim 1 , comprising mixing the acidic compound with the hygroscopic chemical to form the attenuated acid formulation on-the-fly as materials are injected into the formation.
7. The method of claim 1 , wherein the DEG comprises between 20 and 25 vol. % of the attenuated acid formulation.
8. The method of claim 1 , wherein the attenuated acid formulation comprises a surfactant.
9. The method of claim 8 , wherein the surfactant comprises a fluorinated surfactant.
10. The method of claim 1 , wherein the attenuated acid formulation is an emulsion.
11. The method of claim 1 , wherein the attenuated acid formulation is a foam.
12. The method of claim 1 , comprising viscosifying the attenuated acid formulation by a gelling agent.
13. The method of claim 1 , wherein the attenuated acid formulation comprises a viscoelastic surfactant.
14. The method of claim 1 , wherein the attenuated acid formulation comprises a crosslinkable gelling agent.
15. The method of claim 1 , comprising:
acidizing a carbonate matrix with the attenuated acid formulation;
acid fracturing with the attenuated acid formulation;
acidizing an open hole with the attenuated acid formulation;
cleaning a wellbore with the attenuated acid formulation;
cleaning scale with the attenuated acid formulation;
increasing the permeability of injection wells with the attenuated acid formulation;
cleaning up filter cake; or
cleaning up drilling mud.