# US 11,896,940 B2 · Volumetric control for proppant concentration in hydraulic fracturing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,896,940 B2 - Document ID: US11896940B2 - Status: Granted - Kind: B2 - Application number: 16/972,122 - Filed: 2018-07-31 - Published: 2021-07-29 - Granted: 2024-02-13 - Earliest claimed: 2018-07-31 - Assignees: Halliburton Energy Services, Inc. - Applicants: Halliburton Energy Services, Inc. - Inventors: Mehdi Mazrooee; Michael Linley Fripp - Web page: https://patentgrep.com/patent/US11896940B2 ## CPC - B01F 23/51: {Methods thereof} - B01F 23/59: {Mixing systems, i.e. flow charts or diagrams} - B01F 35/21112: {Volumetric flow rate} - B01F 35/2134: {Density or solids or particle number} - B01F 35/2203: {Controlling the mixing process by feed-forward, i.e. a parameter of the components to be mixed is measured and the feed values are calculated} - B01F 35/2217: {Volume of at least one component to be mixed} - E21B 43/2607: {Surface equipment specially adapted for fracturing operations} - B01F 2101/49: Mixing drilled material or ingredients for well-drilling, earth-drilling or deep-drilling compositions with liquids to obtain slurries - E21B 43/267: reinforcing fractures by propping - B01F: MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING (mixing paints B44D3/06) - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract Methods and systems for controlling proppant concentration in a hydraulic fracturing slurry include measuring volumetric flow rates of fracturing fluid input to a blender and hydraulic fracturing slurry output from the blender, using these measured values to calculate a volumetric flow rate of proppant input, a slurry density and/or a slurry volume fraction, adjusting first and second valves to control rates of fluid and proppant delivery to the blender and re-measuring the volumetric flow rates and recalculating until target values of volumetric flow rate of proppant input, slurry density and/or slurry volume fraction are achieved. ## Claims ### Claim 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. ### Claim 2 (depends on 1) The method of claim 1, further including: the transmitting of step (a) includes the target input value of a slurry volume fraction (Cs-target); the executing of computer readable instructions of step (f) includes calculating a slurry volume fraction according to the formula: Cs=({dot over (V)}sl−{dot over (V)}fl)/{dot over (V)}sl; step (g) includes determining difference (ΔCs) between the Cs-target and the Cs; and then as part of step (h), if the ΔCs is not less than an acceptable slurry density margin of error (ER-Cs), then 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 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 repeats steps (d)-(f), and as part of step (i), if the ΔCs is less than the ER-Cs, 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. ### Claim 3 (depends on 1) The method of claim 1, further including: after step (b) and prior to step (c), calibrating the first volume flow rate sensor and the second volume flow rate sensor including confirming that the volumetric flow rate value of the fracturing fluid input to the blender, as measured from the first volume flow rate sensor, is substantially equal to the volumetric flow rate value of the fracturing fluid output from the blender, as measured from the second volume flow rate sensor. ### Claim 4 (depends on 1) The method of claim 1, further including: as part of step (g), determining a volume fraction of proponent in the hydraulic fracturing slurry (C s) output from the blender according to the formula: Cs=({dot over (V)}sl−{dot over (V)}fl)/{dot over (V)}sl and then as part of step (h), if the value of C s is equal to or greater than a maximum accepted slurry volume fraction (MAX-Cs), send instructions to cause the command signal to incrementally change the {dot over (V)}fl or send instructions to cause the second command signal to incrementally change the {dot over (m)}pr and then repeat the steps (d)-(f). ### Claim 5 (depends on 4) The method of claim 4, wherein the MAX-Cs equals about 0.50. ### Claim 6 (depends on 1) The method of claim 1, further including: as part of step (h), determining if the {dot over (V)}sl measured using the second volume flow rate sensor is less than a minimum slurry volumetric flow rate (MIN-{dot over (V)}sl) and then as part of step (h), if the value of {dot over (V)}sl is less than MIN-{dot over (V)}sl send instructions to cause the command signal to incrementally change the {dot over (V)}sl or send instructions to cause the second command signal to incrementally change the {dot over (m)}pr and then repeat the steps (d)-(f). ### Claim 7 (depends on 6) The method of claim 6, wherein MIN-{dot over (V)}sl equals about 42 G/min. ### Claim 8 (depends on 1) The method of claim 1, wherein as part of step (h) both the {dot over (V)}fl and the {dot over (m)}pr are incrementally changed. ### Claim 9 (depends on 1) The method of claim 1, wherein the incremental change to the {dot over (V)}fl is not more than 10 percent. ### Claim 10 (depends on 1) The method of claim 1, wherein the incremental change to the {dot over (m)}pr is not more than 10 percent. ### Claim 11 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, a target slurry volumetric flow rate ({dot over (V)}sl-target), a target input value of a slurry volume fraction (Cs-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 volume fraction according to the formula: Cs=({dot over (V)}sl−{dot over (V)}fl)/{dot over (V)}sl; g) determining, in the central processing unit, a difference (Δ{dot over (V)}sl) between the {dot over (V)}sl-target and the {dot over (V)}sl, and, a difference (ΔCs) between the Cs-target and the Cs; and then h) if the Δ{dot over (V)}sl is not less than an acceptable slurry volumetric flow rate margin of error (ER-{dot over (V)}sl) or the ΔCs is not less than an acceptable slurry volume fraction margin of error (ER-Cs), then 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 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 repeats steps (d)-(h), and i) if the Δ{dot over (V)}sl is less than ER-{dot over (V)}sl and the ΔCs is less than the ER-Cs, 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. ### Claim 12 A blending system for controlling proppant concentration of a hydraulic fracturing slurry, comprising: blender control unit, the blender control unit including: an input device configured accept target input values of a slurry density (ρsl-target) a slurry volumetric flow rate ({dot over (V)}sl-target), or, a slurry volume fraction (Cs-target), and inputs of a known density of a fracturing fluid (ρfl) and known density of a proppant (ρpr); a command signal transmitter configured to send a command signal to actuate a first valve to deliver the fracturing fluid to a blender and send 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); a signal receiver configured to a receive a signal corresponding to a measured volumetric flow rate ({dot over (V)}fl) of the fracturing fluid input to the blender and receive a signal corresponding to a measured volumetric flow rate ({dot over (V)}sl) of the hydraulic fracturing slurry output from the blender; a non-transient computer readable memory configured to store the target values of ρsl-target, {dot over (V)}sl-target, or Cs-target and the inputs of the ρfl and the ρpr and to store computer readable instructions to calculate a volumetric flow rate of proppant input (V pr) to the blender according to the formula: {dot over (V)}pr=({dot over (V)}sl−{dot over (V)}fl), to calculate a slurry density (ρsl) according to the formula: ρsl=(({dot over (V)}fl·ρfl)+({dot over (V)}pr·ρpr))/{dot over (V)}sl, and to calculate a slurry volume fraction according to the formula: Cs=({dot over (V)}sl−{dot over (V)}fl)/{dot over (V)}sl; and a central processing unit configured to: read the computer readable instructions and to calculate: the {dot over (V)}pr and the ρsl, and to determine a difference (Δ{dot over (V)}sl) between the {dot over (V)}sl-target and the {dot over (V)}sl and a difference (Δρsl) between the ρsl-target and the ρsl, or, to calculate: the {dot over (V)}pr and the Cs and to determine a difference (Δ{dot over (V)}sl) between the {dot over (V)}sl-target and the {dot over (V)}sl and a difference (ΔCs) between the Cs-target and the Cs, and then: if the Δρsl is not less than an acceptable slurry density margin of error (ER-{dot over (V)}sl) 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), then send instructions to cause the command signal to further actuate the first valve to incrementally change the {dot over (V)}fl or to cause the second command signal to further actuate the second valve to incrementally change the {dot over (m)}pr and if the Δρsl is less than ER-ρsl and the Δ{dot over (V)}sl is less than ER-{dot over (V)}sl, then send an output signal to a display unit of the blender control unit to indicate that the target input values have been achieved, or, if the Δ{dot over (V)}sl is not less than an acceptable slurry volumetric flow rate margin of error (ER-{dot over (V)}sl) or the ΔCs is not less than an acceptable slurry density margin of error (ER-Cs), then send instructions to cause the command signal to further actuate the first valve to incrementally change the {dot over (V)}fl or to cause the second command signal to further actuate the second valve to incrementally change the {dot over (m)}pr and if the Δ{dot over (V)}sl is less than ER-{dot over (V)}sl and the ΔCs is less than the ER-Cs, 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. ### Claim 13 (depends on 12) The blending system of claim 12, further including the blender, the blender including: an fluid inlet port for fracturing fluid intake via a fluid input conduit coupled to the fluid inlet port, an proppant inlet port for proppant intake via a proppant input conduit coupled to the proppant inlet port, and an slurry outlet port for hydraulic fracturing slurry output via a slurry output conduit coupled to the slurry outlet port. ### Claim 14 (depends on 13) The blending system of claim 13, further including a first volume flow rate sensor coupled to the fluid input conduit and configured to measure the {dot over (V)}fl of the fracturing fluid input to the blender from the fluid input conduit and to transmit a signal corresponding to the measured {dot over (V)}fl to the signal receiver of the blender control unit. ### Claim 15 (depends on 14) The blending system of claim 14, wherein the first volume flow rate sensor is configured as a rotating sensor, a turbine flow sensor, a differential pressure sensor, an orifice flow sensor, or venture flow sensor. ### Claim 16 (depends on 13) The blending system of claim 13, further including a second volume flow rate sensor coupled to the slurry output conduit and configured to measure the {dot over (V)}sl of the hydraulic fracturing slurry output from the blender via the slurry output conduit and to transmit a signal corresponding to the measured {dot over (V)}sl to the signal receiver of the blender control unit. ### Claim 17 (depends on 16) The blending system of claim 16, wherein the second volume flow rate sensors is configured as a rotating sensor, a turbine flow sensor, a differential pressure sensor, an orifice flow sensor, or venture flow sensor. ### Claim 18 (depends on 13) The blending system of claim 13, further including a first valve coupled to the fluid input conduit and configured to actuate fluid flow such that the Vii can be incrementally adjusted. ### Claim 19 (depends on 13) The blending system of claim 13, further including a second valve coupled to the proppant input conduit and configured to actuate mass flow such that a mass flow rate of the proppant to the blender ({dot over (m)}pr) can be incrementally adjusted. ### Claim 20 (depends on 12) The blending system of claim 12, wherein the blender control unit is configured as PID controller, an adaptive controller, or a state-space controller.