Method of Estimating Multi-Phase Fluid Properties in a Wellbore

• US 20160326866A1
• Filed: 05/06/2015
• Published: 11/10/2016
• Est. Priority Date: 05/06/2015
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Swett, Dwight W.
• Granted Patent: US 10,316,648 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B06B 1/0614 for generating several frequencies
• CPC Class Codes: E21B 47/107 using acoustic means
• CPC Class Codes: E21B 49/08 Obtaining fluid samples or testing fluids, in boreholes or wells
• CPC Class Codes: G01N 2291/014 Resonance or resonant frequency
• CPC Class Codes: G01N 2291/02433 Gases in liquids, e.g. bubbles, foams
• CPC Class Codes: G01N 2291/02809 Concentration of a compound, e.g. measured by a surface mass change
• CPC Class Codes: G01N 2291/02818 Density, viscosity
• CPC Class Codes: G01N 2291/101 one transducer
• CPC Class Codes: G01N 29/036 by measuring frequency or resonance of acoustic waves

Abstract

A system and method of estimating properties of a wellbore fluid that directs the fluid through a cavity, and generates acoustic waves in the fluid while in the cavity. The acoustic waves are generated by oscillating an electroactive material over a range of frequencies. An electrical admittance spectra of the electroactive material is measured over the range of frequencies; where the electrical admittance spectra includes the magnitude, real, and imaginary components. Differences between the maximum values for each component and a vacuum electrical spectra are calculated, the differences are substituted into estimator equations to estimate the fluid properties. Electrical admittance spectra of the electroactive material was simulated for a series of known fluids flowing through the cavity, and a multi-regression statistical analysis was then used to derive the estimator equations.

Claims

1. A method of analyzing a fluid within a wellbore comprising:

providing a sensor that comprises, a housing, a resonant cavity in the housing, a diaphragm, and an electroactive material coupled with the diaphragm;

disposing the sensor in the wellbore;

flowing fluid in the wellbore through the cavity;

generating acoustic waves in the cavity by oscillating the diaphragm over a range of frequencies;

measuring electrical voltage and current across the electroactive material for the range of frequencies to obtain an electrical admittance spectra corresponding to the fluid flow;

obtaining shifts in resonant frequencies of electrical admittance spectra by comparing the admittance spectra of the fluid flow with a reference admittance spectra obtained without the fluid in the cavity; and

estimating a property of the fluid by substituting the value of the resonant frequencies'"'"' shifts in electrical admittance spectra into an estimator equation developed chemometrically using fluids having known properties.

2. The method of claim 1, wherein the electrical admittance spectra associated with the resonant cavity comprises magnitude values, real values, and imaginary values.

3. The method of claim 1, wherein the electroactive material comprises one or more of an electroactive polymer and a piezoelectric stack.

4. The method of claim 1, further comprising providing electricity to the electroactive material, and wherein the step of measuring electrical admittance comprises measuring a change in voltage and current across the electroactive material.

5. The method of claim 1, wherein the estimator equation was derived by simulating flowing a series fluids with known properties through the cavity, simulating oscillating the diaphragm over a range of frequencies, obtaining a known electrical admittance spectra for each of the series of fluids by obtaining simulated values of electrical admittance through the electroactive material for each of the fluids with known properties and at selective values within the range of frequencies, estimating differences between maximum values in each of the electrical admittance spectra for each known fluid with maximum values in the reference electrical admittance spectra, conducting a multi-regression statistical analysis to identify estimator functions and algebraic relations.

6. The method of claim 1, wherein the fluid properties comprise parameters selected from the group consisting of composite fluid sound speed, composite fluid density, composite fluid bulk modulus, live oil sound speed, live oil bulk modulus, live oil mass density, live oil API density, gas oil ratio, and oil-water holdup.

7. The method of claim 1, wherein the fluid property comprises sound speed, the method further comprising estimating fluid density, and wherein the fluid sound speed and fluid density were obtained from a measurement of the same sample of fluid at the same time and within the cavity.

8. A method of analyzing a fluid within a wellbore comprising:

a) flowing a portion of the fluid into a cavity;

b) creating standing waves in fluid in the cavity with a diaphragm that is oscillated by a piezoelectric stack;

c) oscillating the piezoelectric stack over a range of frequencies;

d) monitoring an admittance across the piezoelectric stack over the range of frequencies to define a fluid admittance spectra;

e) comparing the fluid admittance spectra with a reference admittance spectra that was generated by oscillating the piezoelectric stack over a range of frequencies with the cavity being empty;

f) obtaining differences of maximum values of magnitude, real values, and imaginary values between the fluid admittance spectra and the reference admittance spectra; and

g) estimating properties of the fluid by substituting the differences obtained in step (f) into a estimator equation developed chemometrically using fluids having known properties.

9. The method of claim 8, further comprising providing electricity to the piezoelectric stack, and wherein the step of monitoring a change in voltage across the piezoelectric stack.

10. The method of claim 8, wherein the cavity is provided in a downhole tool, the method further comprising disposing the downhole tool within the wellbore.

11. The method of claim 8, wherein the diaphragm comprises a disk portion mounted on a stem, and wherein the disk portion projects into the cavity during the step of oscillating.

12. The method of claim 8, wherein the fluid flowing to the cavity is directed through an inlet channel, and wherein fluid exits the cavity through an exit channel having substantially the same dimensions as the inlet channel.

13. A fluid measurement system for analyzing fluid within a wellbore comprising:

a sensor assembly comprising,

a main body,

a cavity in the main body in communication with fluid ambient to the sensor assembly,

a piezoelectric stack in the main body that is selectively oscillated over a range of frequencies when energized, and

a diaphragm coupled to an end of the piezoelectric stack and disposed in the cavity, so that the diaphragm oscillates in the cavity when the piezoelectric stack is oscillated; and

a processor in communication with the sensor assembly that,

selectively receives data representing an electrical admittance spectra associated with the fluid that is defined by monitoring an electrical admittance across the piezoelectric stack over the range of frequencies when a fluid being monitored is in the cavity,

selectively receives data representing a reference electrical admittance spectra that is defined by monitoring an electrical admittance across the piezoelectric stack over the range of frequencies when the cavity is empty,

selectively obtains differences of maximum values of magnitude, real values, and imaginary values between the electrical admittance spectra of the fluid and the reference electrical admittance spectra, and

selectively estimates properties of the fluid by substituting the differences into an estimator equation developed chemometrically using fluids having known properties.

14. The fluid measurement device of claim 13, wherein the chamber has a generally cylindrical cross section and with a diameter that transitions radially inward away from the diaphragm.

15. The fluid measurement device of claim 13, wherein the diaphragm comprises a disk like member with upper and lower surfaces that project axially away from the piezoelectric stack with distance radially outward from a center of the diaphragm.

16. The fluid measurement device of claim 13, wherein the piezoelectric stack projects generally transverse to an axis of the main body and the cavity is radially offset from the axis.

17. The fluid measurement device of claim 13 further comprising channels formed through the body at ends of the cavity, wherein the channels have substantially the same dimensions.

18. The fluid measurement device of claim 17, wherein the channels are formed along a path that intersects the diaphragm.