Setting tools and assemblies for setting a downhole isolation device such as a frac plug

1. A downhole setting tool for setting a downhole isolation device, the downhole setting tool comprising:

a mandrel having an upper end and a lower end, the mandrel comprising a chamber for housing expandable gas and two co-linear gas conduits in fluid communication with the chamber, the lower end of the mandrel being couplable to an upper end of a downhole isolation device mandrel, wherein the upper end of the mandrel is configured for coupling to a firing head that enables igniting a power charge to generate pressurized gas within the chamber;

a barrel piston having a central bore configured for housing the mandrel, a lower end of the barrel piston being couplable to a sleeve for setting the downhole isolation device;

an expansion region defined between the mandrel and the barrel piston and being in fluid communication with the co-linear gas conduits so as to receive the pressurized gas, the expansion region being further defined by seals provided in between the mandrel and the barrel piston, thereby enabling the pressurized gas to exert force on the mandrel and the barrel piston to cause a stroke of the barrel piston over the mandrel as the expansion region expands axially;

wherein the co-linear gas conduits extend perpendicularly with respect to a longitudinal axis of the setting tool from opposed sides of the mandrel; and

wherein the chamber has a main cylindrical portion and a downhole conical portion that extends directly from the main cylindrical portion and tapers inwardly downhole, and wherein the co-linear gas conduits extend directly into the downhole conical portion.

2. The downhole setting tool of claim 1 , wherein the chamber and the co-linear gas conduits are defined in a one-piece structure of the mandrel.

3. The downhole setting tool of claim 1 , wherein the co-linear gas conduits are cylindrical.

4. The downhole setting tool of claim 1 , wherein the co-linear gas conduits each extend partly into the downhole conical portion and partly into the main cylindrical portion, and the downhole conical portion includes a tip that is spaced away from the co-linear gas conduits.

5. The downhole setting tool of claim 1 , wherein the co-linear gas conduits are in fluid communication with a first configuration of the expansion chamber prior to gas pressurization, the first configuration being an annular space extending around a lower part of the mandrel and beyond both sides of each co-linear gas conduit.

6. The downhole setting tool of claim 1 , wherein the downhole isolation device is a frac plug.

7. The downhole setting tool of claim 1 , wherein the co-linear gas conduits are the only gas conduits in fluid communication between the chamber of the mandrel and the expansion region.

8. The downhole setting tool of claim 1 , wherein the co-linear gas conduits are drilled conduits provided through a wall of the mandrel.

9. The downhole setting tool of claim 1 , wherein the co-linear gas conduits extend into the chamber such that a side wall of each co-linear gas conduit forms a corner with a corresponding side wall of the main cylindrical portion of the mandrel chamber.

10. A downhole setting tool for setting a downhole isolation device, the downhole setting tool comprising:

a mandrel having an upper end and a lower end, the mandrel comprising a chamber for housing expandable gas and two co-linear gas conduits in fluid communication with the chamber, the lower end of the mandrel being couplable to an upper end of a downhole isolation device mandrel, wherein the upper end of the mandrel is configured for coupling to a firing head that enables igniting a power charge to generate pressurized gas within the chamber;

a barrel piston having a central bore configured for housing the mandrel, a lower end of the barrel piston being couplable to a sleeve for setting the downhole isolation device;

an expansion region defined between the mandrel and the barrel piston and being in fluid communication with the co-linear gas conduits so as to receive the pressurized gas, the expansion region being further defined by seals provided in between the mandrel and the barrel piston, thereby enabling the pressurized gas to exert force on the mandrel and the barrel piston to cause a stroke of the barrel piston over the mandrel as the expansion region expands axially;

a stroke indication system provided on the mandrel to indicate to an operator whether the barrel piston stroked a predetermined distance with respect to the mandrel such that a bleed port defined in the barrel piston is positioned in fluid communication with the expansion region;

wherein the co-linear gas conduits extend perpendicularly with respect to a longitudinal axis of the setting tool, and from opposed sides of the mandrel; and

wherein the chamber has a main cylindrical portion and a downhole conical portion that extends directly from the main cylindrical portion and tapers inwardly downhole, and wherein the co-linear gas conduits extend directly into the downhole conical portion.

11. The downhole setting tool of claim 10 , wherein the stroke indication system comprises a scribe line on the mandrel.

12. The downhole setting tool of claim 11 , wherein the scribe line extends circumferentially around the mandrel.

13. The downhole setting tool of claim 11 , wherein the scribe line is etched into the mandrel.

14. The downhole setting tool of any one of claim 10 , wherein the stroke indication system has a single scribe line.

15. The downhole setting tool of claim 10 , wherein the stroke indication system comprises one or more indicia provided on the mandrel.

16. The downhole setting tool of claim 15 , wherein the indicia are recessed with respect to an outer surface of the mandrel.

17. The downhole setting tool of claim 10 , wherein the stroke indication system comprises a continuous circumferential indicator disposed circumferentially about the mandrel.

18. The downhole setting tool of claim 10 , wherein the downhole isolation device is a frac plug.

19. A method for multistage fracturing of a reservoir comprising setting a downhole isolation device in a well using the downhole setting tool as defined in claim 1 to form an isolated well segment, subjecting the isolated well segment to a fracturing operation, and then repeating the isolation and fracturing for multiple segments along the well.

20. A method for multistage fracturing of a reservoir comprising setting a downhole isolation device in a well using the downhole setting tool as defined in claim 10 to form an isolated well segment, subjecting the isolated well segment to a fracturing operation, and then repeating the isolation and fracturing for multiple segments along the well.

21. A downhole setting tool for setting a downhole isolation device, the downhole setting tool comprising:

a mandrel having an upper end and a lower end, the mandrel comprising a chamber for housing expandable gas and a gas port in fluid communication with the chamber, the lower end of the mandrel being couplable to an upper end of a downhole isolation device mandrel, wherein the upper end of the mandrel is configured for coupling to a firing head that enables igniting a power charge to generate pressurized gas within the chamber;

a barrel piston having a central bore configured for housing the mandrel, a lower end of the barrel piston being couplable to a sleeve for setting the downhole isolation device;

an expansion region defined between the mandrel and the barrel piston and being in fluid communication with the gas port so as to receive the pressurized gas, the expansion region being further defined by seals provided in between the mandrel and the barrel piston, thereby enabling the pressurized gas to exert force on the mandrel and the barrel piston to cause a stroke of the barrel piston over the mandrel as the expansion region expands axially;

wherein the gas port extends perpendicularly with respect to a longitudinal axis of the setting tool; and

wherein the chamber has a main cylindrical portion and a downhole conical portion that extends directly from the main cylindrical portion and tapers inwardly downhole, and wherein the gas port extends directly into the downhole conical portion.