Well stimulation pump control and method

Patent metadata

Field	Value
Publication number	US-10247182-B2
Application number	US-201615015339-A
Country	US
Kind code	B2
Filing date	Feb 4, 2016
Priority date	Feb 4, 2016
Publication date	Apr 2, 2019
Grant date	Apr 2, 2019

Abstract

A pumping system for use in a well stimulation application includes a pump controlled by a controller, the controller operating to monitor operation of the pump and determine when cavitation is present or imminent in the pump. When cavitation is present, the controller automatically adjusts an operating condition of the pump reduce pump speed or increase a fluid pressure at the pump inlet.

First claim

We claim:

1. A pumping system for use in a well stimulation application, comprising:
a pump having an inlet and at least one pumping element, each pumping element including a piston reciprocally disposed in a bore, an inlet check valve in fluid communication with the inlet and an outlet check valve associated with a variable volume defined in a bore;
a pressure sensor disposed to measure a fluid pressure at a location between the inlet check valve and the inlet of the pump;
a drive mechanism for driving a reciprocal motion of the piston;
a speed sensor disposed to measure a speed of the pump at the drive mechanism; and
a controller associated with the pump and disposed to receive signals indicative of the fluid pressure and the speed of the pump;
wherein the controller is programmed to:
determine an operating point of the pump based on the fluid pressure and the speed of the pump;
compare the operating point of the pump with a cavitation map that is predefined;
determine whether cavitation is present in the at least one pumping element based on a result of the comparison between the operating point and the cavitation map; and
when cavitation is present, at times, adjust an operation of the drive mechanism to reduce a speed of the pump, and
provide an indication of a desired slurry composition.

2. The pumping system of claim 1 , wherein the cavitation map includes a two dimensional array of operating points with respect to the fluid pressure and the speed of the pump, and wherein a cavitation area is defined by a collection of operating points in the cavitation map at which cavitation occurs or is imminent.

3. The pumping system of claim 2 , wherein the controller is further programmed to interpolate the operating point of the pump onto the cavitation map, and to determine whether the operating point of the pump falls within the cavitation area.

4. The pumping system of claim 1 , wherein the drive mechanism includes a driver connected to an input drive shaft of the pump via a transmission device.

5. The pumping system of claim 4 , wherein the controller adjusts the operation of the drive mechanism by commanding a change in a gear ratio of the transmission.

6. The pumping system of claim 4 , wherein the driver includes an internal combustion engine connected to an electrical power generator, and an electric motor that is connected to the input drive shaft of the pump and wherein, during operation, the internal combustion engine operates the electrical power generator to produce electrical power, which electrical power is provided to operate the electric motor.

7. The pumping system of claim 6 , wherein the controller adjusts the operation of the drive mechanism by commanding a change in a rotational speed of the electric motor.

8. The pumping system of claim 1 , wherein the inlet of the pump is adapted to be connected to a source of stimulation fluid via a valve, the valve being responsive to commands from the controller for adjusting at least one of a flow rate and a pressure of stimulation fluid provided to the inlet of the pump.

9. The pumping system of claim 8 , wherein the controller is further programmed to, at times when cavitation is present, adjust a position of the valve to increase the pressure of stimulation fluid provided to the inlet of the pump.

10. The pumping system of claim 8 , wherein the source of stimulation fluid is a mixer device that is configured to provide a fluid in mixture with an aggregate as the slurry to the inlet of the pump, and wherein the mixer device is responsive to commands to adjust the composition of the slurry.

11. The pumping system of claim 1 , wherein the controller is programmed to store in a database a plurality of predefined cavitation maps, and to select an appropriate cavitation map based on system operating parameters, the system operating parameters including physical characteristics of the stimulation fluid provided to the inlet of the pump and flow characteristics of piping associated with the pump.

12. The pumping system of claim 1 , further including a second pump connected in parallel flow arrangement with the pump, wherein the controller is further programmed to adjust operation of the second pump when cavitation is present in the pump.

13. A method for operating a pump for use in a hydraulic fracturing system, comprising:
in a controller, selecting one appropriate cavitation map from a plurality of cavitation maps stored in the controller, the selecting being based on operating parameters of the hydraulic fracturing system;
using the controller, monitoring operation of the hydraulic fracturing system with regard to at least a pressure of stimulation fluid at an inlet of a pump, and a speed of the pump, to determine an operating condition of the pump;
in the controller, comparing the operating condition of the pump with the selected one appropriate cavitation map;
by use of the controller, determining whether cavitation is present or imminent in the pump based on a result of the comparison; and
when cavitation is present, using the controller to adjust the operating condition of the pump, in real time, and
using the controller to provide an indication of a desired slurry composition.

14. The method of claim 13 , wherein adjusting the operating condition of the pump includes increasing a pressure of the stimulation fluid at the inlet of the pump.

15. The method of claim 13 , wherein adjusting the operating condition of the pump includes reducing the speed of the pump.

16. The method of claim 13 , wherein reducing the speed of the pump includes at least one of changing a gear ratio in a transmission device disposed between a power unit used to operate the pump and an input shaft of the pump, reducing a speed of an internal combustion engine used to operate the pump, and reducing an amount of electrical power provided to a motor operating the pump.

17. The method of claim 13 , further comprising connecting the inlet of the pump to a source of stimulation fluid via a valve, the valve being responsive to commands from the controller for adjusting at least one of a flow rate and a pressure of stimulation fluid provided to the inlet of the pump, and adjusting a position of the valve to increase the pressure of stimulation fluid provided to the inlet of the pump.

18. The method of claim 17 , wherein the source of stimulation fluid is a mixer device that is configured to provide a fluid in mixture with an aggregate as the slurry to the inlet of the pump, wherein the mixer device is responsive to commands to adjust the composition of the slurry.

19. The method of claim 13 , wherein the system further includes a second pump connected in parallel flow arrangement with the pump, and wherein adjusting the operating condition of the pump is accomplished at least in part by adjust a corresponding operating condition of the second pump.

Assignees

• Caterpillar Inc

Inventors

• Zhang Yanchai
• Dong Zhaoxu
• Hu Xuefei

Classifications

• F04B49/065 Primary

  and making use of computers · CPC title

• F04B49/20

  by changing the driving speed · CPC title

• F04B17/03

  driven by electric motors · CPC title

• F04B51/00

  Testing machines, pumps, or pumping installations · CPC title

• F04B47/00

  Pumps or pumping installations specially adapted for raising fluids from great depths, e.g. well pumps (by using positive or negative pressurised fluid medium acting directly on the liquid to be pumped F04F1/00) · CPC title