Fluid mixing system

• US 6,491,421 B2
• Filed: 11/29/2000
• Issued: 12/10/2002
• Est. Priority Date: 11/29/2000
• Status: Expired due to Term

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Rondeau, Joel, Vigneaux, Pierre
• Primary Examiner(s): SOOHOO, TONY GLEN
• Application Number:
  US09/726,784
• Publication Number:
  US 20020093875A1
• Time in Patent Office: 741 Days
• Field of Search: 366/136, 366/137, 366/152.2, 366/152.1, 366/152.6, 366/141, 366/153.1, 366/18, 366/17, 366/8
• US Class Current: 366/8
• CPC Class Codes: B01F 2101/28 Mixing cement, mortar, clay, plaster or concrete ingredients
• CPC Class Codes: B01F 2101/49 Mixing drilled material or ingredients for well-drilling, earth-drilling or deep-drilling compositions with liquids to obtain slurries
• CPC Class Codes: B01F 2215/0409 Relationships between different variables defining features or parameters of the apparatus or process
• CPC Class Codes: B01F 23/59 Mixing systems, i.e. flow charts or diagrams
• CPC Class Codes: B01F 25/53 in which the mixture is discharged from and reintroduced into a receptacle through a recirculation tube, into which an additional component is introduced
• CPC Class Codes: B01F 35/20 Measuring; Control or regulation
• CPC Class Codes: B01F 35/21 Measuring
• CPC Class Codes: B01F 35/2111 Flow rate
• CPC Class Codes: B01F 35/21112 Volumetric flow rate
• CPC Class Codes: B01F 35/2112 Level of material in a container or the position or shape of the upper surface of the material
• CPC Class Codes: B01F 35/2117 Weight
• CPC Class Codes: B01F 35/213 of the properties of the mixtures, e.g. temperature, density or colour
• CPC Class Codes: B01F 35/2132 Concentration, pH, pOH, p(ION) or oxygen-demand B01F35/2133 takes precedence
• CPC Class Codes: B01F 35/2134 Density or solids or particle number
• CPC Class Codes: B01F 35/2211 Amount of delivered fluid during a period
• CPC Class Codes: B01F 35/881 by weighing, e.g. with automatic discharge
• CPC Class Codes: B28C 7/022 by measuring the consistency or composition of the mixture, e.g. with supply of a missing component
• CPC Class Codes: E21B 21/062 by mixing components
• CPC Class Codes: E21B 33/13 Methods or devices for cementing, for plugging holes, crevices or the like
• CPC Class Codes: G05D 11/132 by controlling the flow of the individual components G05D11/133 takes precedence
• CPC Class Codes: G05D 11/135 : by sensing at least one property of the mixture G05D11/139 takes precedence

Abstract

A method for continuously mixing a borehole fluid such as cement includes using a measurement of the solid fraction of a cement slurry as it is being mixed to determine the ratio of the solid and liquid components to be added to the slurry. A system for mixing the includes a liquid material (water) supply including a flow meter; a solid material (cement) supply; a mixer which receives the liquid and solid materials and includes an output for delivering materials from the mixer to a delivery system; a device for measuring the amount of material in the mixer; and a flow meter in the output; wherein measurements from the flow meters and the device for measuring the amount of material in the mixer are used to control the amount of solid and/or liquid material added to the mixer.

Claims

1. A system for mixing a cement slurry in a well cementing operation, comprising:

i) a liquid material supply including means for controlling the flow of liquid therefrom, and a first flow meter for determining the flow rate of liquid supplied therefrom;

ii) a solid cement supply including means for controlling the flow of solid cement supplied therefrom;

iii) a mixer which receives the liquid and solid cement from the liquid material supply and solid cement supply respectively and mixes them to form a slurry, and includes an output for delivering materials from the mixer, a second flow meter being located in the output for determining the flow rate of slurry from the mixer;

iv) a device for determining the variation over time of the amount of slurry in the mixer;

v) a delivery system connected to the output of the mixer for delivering the slurry to a well; and

vi) a monitoring system which determines the ratio of solid cement and liquid in the mixer from flow rates determined by the first and second flow meters and from the determined variation over time of the amount of slurry in the mixer;

wherein the means for controlling the flow of liquid and means for controlling the flow of solid cement are operated to control the relative amounts of solid and liquid material added to the mixer according to the determined ratio of solid cement and liquid in the mixer.

2. A system as claimed in claim 1, wherein the liquid material supply includes water and the solid material supply includes cement and other solid materials.

3. A system as claimed in claim 2, wherein the supply of solid cement comprises separate supplies of cement and dry additives, a third flow meter being provided to measure the rate of flow of the dry additives to the mixer.

4. A system as claimed in claim 3, wherein the supply of dry additives comprises multiple separate supplies of additives, each with its own flow meter.

5. A system as claimed in claim 1, wherein the monitoring system determines the solid fraction of the slurry in the mixer in order to determine the ratio of solid cement and liquid in the mixer, the means for controlling the flow of solid cement being operated according to the determined solid fraction to control the amount of solid cement added to the mixer.

6. A system as claimed in claim 1, wherein the flow meters are selected from mass flow meters and volumetric flow meters.

7. A system as claimed in claim 1, wherein the flow meters are selected from Coriolis meters and electromagnetic meters.

8. A system as claimed in claim 1, wherein the mixer comprises a mixing section, a mixing tub, a feeder which feeds slurry from the mixing section to the mixing tub, and recirculation system which recirculates a portion of the slurry from the tub to the mixing section.

9. A system as claimed in claim 8, wherein the device for measuring the variation over time of the amount of slurry in the mixer measures the variation over time of the amount of slurry in the tub.

10. A system as claimed in claim 9, wherein the device comprises a level sensor in the tub.

11. A system as claimed in claim 9, wherein the device comprises a load sensor which measures the weight of the tub over time so as to determine the variation over time of the amount of slurry therein.

12. A system as claimed in claim 8, wherein the recirculation system is located upstream of the second flow meter located in the output of the mixer.