Method to measure acid diversion efficiency in matrix acidizing through nmr

2:

• The method of claim 1, wherein an NMR logging tool remains placed in the wormhole at two pressure regimes.

3:

• The method of claim 1, wherein if the diversion index is above 0.7, an operator can begin hydrofracking on a bore hole a subterranean rock formation.

4:

• The method of claim 1, wherein the HCl system is at least one selected from the group consisting of a solution comprising hydrochloric acid, a solution comprising HCl and a viscoelastic surfactant (VES), and a solution comprising HCl and a polymer.

5:

• The method of claim 1, wherein the method further comprises flooding the rock sample with at least one acid selected from the group consisting of acetic acid, citric acid, formic acid, a polymer-based acid, a VES acid, an emulsified acid, a foam acid, and a chelating agent-containing stimulation fluid.

6:

• The method of claim 4, wherein the HCl system comprises HCl and the VES as a mixture containing from 10 weight % (wt. %) to 20 wt. % hydrochloric acid per weight of the solution and of from 1 wt. % to 5 wt. % VES per weight of the solution.

7:

• The method of claim 4, wherein the HCl system comprises the HCl and the polymer as a mixture containing from 10 wt. % to 20 wt. % hydrochloric acid per weight of the solution and of from 0.02 wt. % to 0.1 wt. % of a polyacrylamide (PAM) per weight of the solution.

8:

• The method of claim 1, wherein the measuring the first porosity of the rock sample includes treating the rock sample with potassium chloride (KCl).

9:

• The method of claim 1, wherein the measuring the permeability of the rock sample includes treating the rock sample with KCl.

10:

• The method of claim 1, wherein the rock sample is a carbonate formation rock with a permeability of 1 to 50 millidarcy.

11:

• The method of claim 1, wherein the rock sample has a porosity of 5-50%.

12:

• The method of claim 1, wherein the flooding is carried out at a temperature of 80-120° C.

13:

• The method of claim 4, wherein the HCl system has a pH of 1-6.

14:

• The method of claim 4, wherein the HCl system comprises HCl and the VES and has a pH of 1-6.

15:

• The method of claim 4, wherein the HCl system comprises HCl and the PAM and has a pH of 1-6.

16:

• The method of claim 1, further comprising:
• verifying the acid diversion efficiency to computed tomography (CT) scans of the wormholes in the rock samples.

17:

• The method of claim 1, further comprising:
• measuring, with NMR, the diffusion tortuosity in a third z-direction.

18:

• The method of claim 1, wherein if the diversion index is below 0.7, a different HCl system is deployed with HCl at a concentration of 25 wt. % to 40 wt. % per weight of the HCl system.

19:

• The method of claim 1, wherein if the diversion index is below 0.7, a different HCl system comprising HCl and VES is deployed with HCl at a concentration of 25 wt. % to 40 wt. % per weight of the HCl system and 5 wt. % to 15 wt. % per weight of VES of the system.