Wellbore systems and methods for supplying treatment fluids via more than one path to a formation

1. An apparatus for use in a wellbore for treating a formation zone along a wellbore, comprising:

an assembly deployable in the wellbore, the assembly including:

an outer string;

an inner string including a tubular having a frac port, the tubular defining a first fluid flow path on an inside of the tubular for supplying a first fluid from a surface location to the frac port;

a second fluid flow path on an outside of the tubular between the inner string and outer string for supplying a second fluid from the surface location;

a flow control device that combines the first fluid and the second fluid, wherein second fluid is supplied into the first fluid via the flow control device and the combined fluid is supplied to the formation zone from within the inner string via the frac port; and

a first barrier that prevents the flow of the first fluid below a first selected location and a second barrier that prevents the flow of the second fluid from reaching the formation zone prior to the combining of the first fluid and the second fluid.

2. The apparatus of claim 1 , wherein the first flow path and the second flow path are independent of each other prior to the combining of the first fluid and the second fluid.

3. The apparatus of claim 1 , wherein the first fluid is slurry for treating the formation zone.

4. The apparatus of claim 1 further comprising a fluid supply system that supplies the first fluid and the second fluid in a manner that is one of: a first pump that supplies the first fluid into the first fluid flow path and a second pump that supplies the second fluid into the second fluid flow path; a pump that supplies a common fluid into the first fluid flow path and the second fluid flow path, wherein fluid flowing through the first fluid flow path defines the first fluid and the fluid flowing through the second fluid flow path defines the second fluid.

5. The apparatus of claim 1 further comprising a flow control device for controlling the flow of the combined fluid to the formation zone.

6. The apparatus of claim 1 , wherein the assembly is configured to be placed inside a casing in the wellbore that has been perforated at the formation zone.

7. The apparatus of claim 1 further comprising a screen that at least inhibits flow of solid particles above a selected size to flow from the wellbore into the tubular.

8. The apparatus of claim 1 , wherein:

the outer string includes an isolation packer that isolates the formation zone.

9. A method of supplying fluid to a formation zone along a wellbore, the method comprising:

providing an inner string and an outer string in the wellbore;

providing a first barrier that prevents the flow of a first fluid below a first selected location in the wellbore and a second barrier that prevents the flow of a second fluid from reaching the formation zone prior to the combining of the first fluid and the second fluid;

supplying the first fluid to the first location in the wellbore via a first fluid path within the inner string;

supplying the second fluid to the second location in the wellbore via a second fluid path between the inner string and outer string;

combining the second fluid into the first fluid in the wellbore by opening a mixing device in the inner string; and

supplying the combined fluid from within the inner string to the formation zone via a frac sleeve.

10. The method of claim 9 , wherein combining the first fluid and the second fluid further comprises:

combining the first fluid and the second fluid via a device to provide a combined fluid; and

supplying the combined fluid to the formation zone.

11. The method of claim 9 further comprising controlling the flow of the combined fluid into the formation zone by a flow control device in the wellbore.

12. The method of claim 9 further comprising using a system to supply the first fluid and the second fluid that is selected from a group consisting of: a first pump to supply the first fluid and a second pump to supply the second fluid; a unit that supplies the a common fluid as the first fluid and the second fluid.

13. The method of claim 9 further comprising:

supplying the first fluid from a surface location at first pressure and supplying the second fluid from the surface location at a second pressure.

14. The method of claim 9 , wherein at least one of the first fluid and the second fluid contains a proppant.