Method and apparatus for controlling the manufacture of well treatment fluid

1. A method for controlling the production of well treatment fluid comprising:

determining an output rate from a sand system;

sensing an output rate from a water system;

sensing an output rate from a pumping system;

sensing the height within a blender tub of a mixture of sand from the sand system and water from the water system;

providing a virtual rate control system; and

producing a drive signal to the pumping system using the virtual rate control system using a desired rate of well treatment fluid to be delivered to a well, the output rate of the sand system, the output rate of the water system, and the output rate of the pumping system.

2. The method of claim 1 comprising producing a drive signal to the pumping system by:

producing a first difference by subtracting the output rate of the pumping system by the desired rate;

producing a product by multiplying the first difference by a proportionality constant associated with the virtual rate control;

producing a second difference by subtracting from the product a torque feedback, the torque feedback being generated from the output rate of the sand system, the output rate of the water system, and the output rate of the pumping system;

producing a second product by multiplying said second difference by a virtual inertia constant; and

integrating said second product with respect to time.

3. The method of claim 1 further comprising:

producing a drive signal to the sand system using a blender volume control system based on a predetermined relationship between the drive signal to the pumping system and the height of contents of the blender tub; and

producing a drive signal to the water system using the blender volume control system based on a predetermined relationship between the drive signal to the pumping system and the height of contents in the blender tub.

4. The method of claim 3 further comprising producing a gel control signal using a height of contents in a gel tub and the drive signal to the water system.

5. The method of claim 4 further comprising:

producing a drive signal to a gel water system using a gel control system based on a predetermined relationship between the gel control signal and the drive signal to the gel water system; and

producing a drive signal to a gel system using a gel control system based on a predetermined relationship between the gel control signal and the drive signal to the gel system.

6. The method of claim 3 further comprising producing a resin control signal using a height of contents in a resin tub and the drive signal to the sand system.

7. The method of claim 6 further comprising:

producing a drive signal to a resin sand system using a resin control based on a predetermined relationship between the resin control signal and the drive signal to the resin sand system; and

producing a drive signal to a resin system using a resin control based on a predetermined relationship between the resin control signal and the drive signal to the resin system.

8. An apparatus for controlling the production of well treatment fluid at a predetermined rate comprising:

a sand system with a means for determining an output rate of the sand system;

a water system with an output rate sensor;

a pumping system with an output rate sensor;

a blender tub with a height sensor, wherein the blender tub is connected to the sand system and water system and receives sand from the sand system and water from the water system; and

a virtual rate control system, wherein the virtual rate control system is operable to:

produce a drive signal to the pumping system using a desired rate of well treatment fluid to be delivered to a well, the output rate of the sand system, the output rate of the water system, and the output rate of the pumping system.

9. The apparatus of claim 8 wherein the virtual rate control system produces the drive signal to the pumping system by:

producing a first difference by subtracting the output rate of the pumping system by the desired rate;

producing a product by multiplying the first difference by a proportionality constant associated with the virtual rate control;

producing a second difference by subtracting from the product a torque feedback, the torque feedback being generated from the output rate of the sand system, the output rate of the water system, and the output rate of the pumping system;

producing a second product by multiplying said second difference by a virtual inertia constant; and

integrating said second product with respect to time.

10. The apparatus of claim 8 further comprising a blender volume control system, wherein the blender volume control system is operable to:

produce a drive signal to the sand system based on a predetermined relationship between a desired rate of well treatment fluid to be delivered to a well, the height of contents in the blender tub, the output rate of the sand system, the output rate of the water system, and the output rate of the pumping system; and

produce a drive signal to the water system based on a predetermined relationship between a desired rate of well treatment fluid to be delivered to a well, the height of contents in the blender tub, the output rate of the sand system, the output rate of the water system, and the output rate of the pumping system.

11. The apparatus of claim 10 further comprising a gel control system and a gel system comprising a gel tub, a gel tub height sensor, a gel water valve, a gel water rate sensor, a gel delivery system, and a gel level sensor.

12. The apparatus of claim 11 wherein the gel control system is operable to:

transmit a gel rate and a gel water rate to the virtual rate control;

produce a drive signal to a gel water system based on a predetermined relationship between the gel control signal and the drive signal to the gel water system; and

produce a drive signal to a gel delivery system based on a predetermined relationship between the gel control signal and the drive signal to the gel delivery system.

13. The apparatus of claim 11 further comprising a resin control system and a resin system comprising a resin tub, a resin tub height sensor, a resin valve, a resin rate sensor, a resin sand system, and a resin sand rate sensor.

14. The apparatus of claim 13 wherein the resin control system is operable to:

transmit a resin sand rate and a resin water rate to the virtual rate control;

produce a drive signal to the resin sand system based on a predetermined relationship between the resin control signal and the drive signal to the resin sand system; and

produce a drive signal to the resin system based on a predetermined relationship between the resin control signal and the drive signal to the resin system.