Patent ID: 11896940
Assignee: HALLIBURTON ENERGY SERVICES, INC.
Field: Chemical engineering (Chemistry)
Classification: CPC B  E | IPC B  E

Claim 0:
1. A method of controlling proppant concentration in a hydraulic fracturing slurry, comprising:
a) transmitting to a non-transient computer readable memory of a blender control unit, target input values of a slurry density (ρsl-target), a slurry volumetric flow rate ({dot over (V)}sl-target), and inputs of a known density of a fracturing fluid (ρfl) and known density of a proppant (ρpr);
b) sending from a transmitter of the blender control unit, a command signal to actuate a first valve to deliver the fracturing fluid to a blender;
c) sending from the transmitter of the blender control unit, a second command signal to actuate a second valve to deliver the proppant to the blender at a non-zero proppant mass flow rate ({dot over (m)}pr);
d) measuring, using a first volume flow rate sensor, a volumetric flow rate ({dot over (V)}fl) of the fracturing fluid input to the blender and transmitting a signal corresponding to the measured {dot over (V)}fl to a signal receiver of the blender control unit;
e) measuring, using a second volume flow rate sensor, a volumetric flow rate ({dot over (V)}sl) of the hydraulic fracturing slurry output from the blender and transmitting a signal corresponding to the measured {dot over (V)}sl to the signal receiver of the blender control unit;
f) executing computer readable instructions, stored in the memory of the blender control unit to calculate, in a central processing unit of the blender control unit:
a volumetric flow rate of proppant input ({dot over (V)}pr) to the blender according to the formula: {dot over (V)}pr=({dot over (V)}sl−{dot over (V)}fl), and,
a slurry density (ρsl) according to the formula: ρsl=(({dot over (V)}fl·ρfl)+({dot over (V)}pr·ρpr))/{dot over (V)}sl;

g) determining, in the central processing unit, a difference (Δρsl) between the ρsl-target and the ρsl, and, a difference (Δ{dot over (V)}sl) between the {dot over (V)}sl-target and the {dot over (V)}sl; and then
h) if the Δρsl is not less than an acceptable slurry density margin of error (ER-ρsl) or the Δ{dot over (V)}sl is not less than an acceptable slurry volumetric flow rate margin of error (ER-{dot over (V)}sl), the central processing unit sends instructions to cause the command signal to further actuate the first valve to incrementally change the {dot over (V)}fl or sends instructions to cause the second command signal to further actuate the second valve to incrementally change the {dot over (m)}pr, and then the central processing unit send instructions to cause steps (d)-(h) to be repeated, and
i) if the Δρsl is less than ER-ρsl and the Δ{dot over (V)}sl is less than ER-{dot over (V)}sl, then the central processing unit sends an output signal to a display unit of the blender control unit to indicate that the target input values have been achieved.