Method of controlling static pressure in the reservoir of a liquefied gas and proppant blender

Patent metadata

Field	Value
Publication number	US-10472935-B2
Application number	US-201514921636-A
Country	US
Kind code	B2
Filing date	Oct 23, 2015
Priority date	Oct 23, 2015
Publication date	Nov 12, 2019
Grant date	Nov 12, 2019

Abstract

The present invention concerns a feedback control method for adjusting the proppant concentration in a fracturing fluid that is utilized in stimulation of an underground formation.

First claim

What is claimed is:

1. A method for dynamically adjusting a feedback control for proportional-integral-derivative (PID) control loops tuning gains in a fracturing fluid that is utilized in stimulation of an underground formation, wherein the loop output regulates the head pressure in a proppant reservoir comprising:
supplying proppant or proppant slurry from a sealed, pressurized proppant reservoir to a fracturing fluid stream;
supplying a fluid flow of liquefied gas and measuring the flow rate of said fluid by a flow meter, and providing a feedback signal to a computer;
combining the proppant or proppant slurry with the liquefied gas stream forming a fracturing fluid containing proppant and measuring a concentration of the proppant in said fracturing fluid downstream by a concentration meter, and providing a feedback signal to the computer; and
adjusting a PID controller for adjusting proportional, integral, and derivative gains of the PID control loops based on the feedback signals of flow and concentration to the computer, wherein the PID controller is given the following formula:

u
⁡

(
t
)

=

K
P

*

e
⁡

(
t
)

+

K
I

*

∫
0
t

⁢

e
⁡

(
τ
)

⁢
d
⁢

⁢
τ

+

K
D

*

de
dt

Equation
⁢

⁢
1

where u is the control signal and e is the control error and is the reference of the set point, and where the tuning parameters are based on the following:
K p =f (GFR,PC)= C 1 *GFR+ C 2 *PC+ C 3   Equation 2

K I =f (GFR,PC)= C 4 *GFR+ C 5 *PC+ C 6   Equation 3

K D =f (GFR,PC)= C 7 *GFR+ C 8 *PC+ C 9   Equation 4

where GFR is the liquefied gas flow rate, PC is the proppant concentration, and C 1_9 denotes predetermined constants.

2. The feedback control method of claim 1 , further comprising a method of measuring the rate of flow of proppant or proppant slurry from the proppant reservoir and programming an algorithm in said computer for adjusting gains of the PID control loops based on the flow rate from the proppant reservoir.

3. The feedback control method of claim 1 , wherein the PID controller is a dynamic PID controller having an algorithm integrated therein.

Assignees

• Scharmach William J
• Panuccio Gregory
• Praxair Technology Inc

Inventors

• Scharmach William J
• Panuccio Gregory

Classifications

• E21B21/062 Primary

  by mixing components · CPC title

• G05B2219/37371

  Flow · CPC title

• E21B43/267 Primary

  reinforcing fractures by propping · CPC title

• G05B19/416

  characterised by control of velocity, acceleration or deceleration (G05B19/19 takes precedence) · CPC title

• E21B43/26

  by forming crevices or fractures · CPC title