Continuous carbon dioxide injection during zipper hydraulic fracturing operations

1 . A method for hydraulically fracturing a plurality of wells from a pad, the method comprising:

for each of the plurality of wells, alternating, in sequence, between perforation, injection of CO 2 , and injection of proppant-carrying fracturing fluid, while simultaneously maintaining continuous CO 2 injection in at least one well of the plurality of wells when perforating or injecting proppant-carrying fracturing fluid in one or more wells in the plurality of wells.

2 . The method of claim 1 , wherein the plurality of wells comprise a first well and a second well, and wherein alternating, in sequence, between perforation, injection of CO 2 , and injection of proppant-carrying fracturing fluid comprises:

performing steps (a) to (l) in the listed order:

(a) perforating a first stage of the first well via a wireline;

(b) perforating a first stage of the second well via the wireline;

(c) injecting the CO 2 into the first stage of the first well;

(d) injecting the proppant-carrying fracturing fluid into the first stage of the first well, while simultaneously injecting the CO 2 into the first stage of the second well;

(e) perforating a second stage of the first well via the wireline, while the CO 2 is still being injected into the first stage of the second well;

(f) injecting the CO 2 into the second stage of the first well, while simultaneously injecting the proppant-carrying fracturing fluid into the first stage of the second well;

(g) perforating a second stage of the second well via the wireline, while the CO 2 is still being injected into the second stage of the first well;

(h) injecting the proppant-carrying fracturing fluid into the second stage of the first well, while simultaneously injecting the CO 2 into the second stage of the second well;

(i) perforating a third stage of the first well via the wireline, while the CO 2 is still being injected into the second stage of the second well;

(j) injecting the CO 2 into the third stage of the first well, while simultaneously injecting the proppant-carrying fracturing fluid into the second stage of the second well;

(k) perforating a third stage of the second well via the wireline, while the CO 2 is still being injected into the third stage of the first well; and

(l) injecting the proppant-carrying fracturing fluid into the third stage of the first well, while simultaneously injecting the CO 2 into the third stage of the second well; and

repeating steps (i) to (l) for subsequent stages of the first well and the second well.

3 . The method of claim 1 , wherein the injection of the CO 2 is performed during a pad phase for each stage, and wherein the injection of the proppant-carrying fracturing fluid is performed for a remainder of the zipper hydraulic fracturing of each stage.

4 . The method of claim 1 , wherein the CO 2 is injected as supercritical CO 2 .

5 . The method of claim 1 , wherein the proppant-carrying fluid comprises a carrier fluid and proppant particles.

6 . The method of claim 5 , wherein at least a portion of the proppant particles comprise coke proppant particles.

7 . The method of claim 6 , wherein at least a portion of the coke proppant particles comprise microproppant coke particles.

8 . The method of claim 1 , wherein the CO 2 is injected at a pump rate in a range from 1 barrels per minute (bbl/min) to 150 bbl/min.

9 . The method of claim 1 , wherein the CO 2 is injected at a pressure in a range from 5,000 pounds per square inch (psi) to 12,000 psi.

10 . The method of claim 1 , wherein the CO 2 is injected at a temperature in a range from −60 degrees Fahrenheit (° F.) at surface to 70° F. at surface.

11 . The method of claim 1 , wherein an amount of CO 2 injected for each stage is in a range from 10 barrels (bbl) to 10,000 bbl.

12 . The method of claim 1 , wherein the proppant-carrying fracturing fluid is injected at a pump rate in a range from 10 barrels per minute (bbl/min) to 150 bbl/min.

13 . The method of claim 1 , wherein the two or more wells comprise a total of two to ten wells in the pad.

14 . The method of claim 1 , wherein the two or more wells comprise unconventional wells.

15 . The method of claim 1 , wherein at least a portion of the CO 2 is sourced from industrial sites.

16 . A method for hydraulically fracturing a plurality of wells from a pad wherein the plurality of wells comprises a first well and a second well, the method comprising:

(i) perforating the first well;

(ii) injecting CO 2 in the first well while simultaneously perforating the second well;

(iii) injecting CO 2 in the first well while simultaneously injecting proppant-carrying fracturing fluid in the second well;

(iv) injecting CO 2 in the second well while simultaneously injecting proppant-carrying fracturing fluid in the first well.

17 . The method of claim 16 further comprising continuously injecting CO 2 into the second well while simultaneously perforating a second stage of the first well.

18 . The method of claim 16 further comprising maintaining continuous CO 2 injection in one or more wells of the plurality of wells while simultaneously perforating or injecting proppant-carrying fracturing fluid in a subsequent stage of a well of the plurality of wells.