Downhole tool for determining flow velocity using measurements from a transducer and a plurality of electrodes

Patent metadata

Field	Value
Publication number	US-9915143-B2
Application number	US-201214350455-A
Country	US
Kind code	B2
Filing date	Oct 30, 2012
Priority date	Oct 31, 2011
Publication date	Mar 13, 2018
Grant date	Mar 13, 2018

Abstract

A downhole tool may include a tool housing extending along a longitudinal axis and having a circumference which is perpendicular to the longitudinal axis, the tool housing being adapted to be lowered into the inside of the borehole or borehole casing. The downhole tool may include a longitudinal transducer for transmitting a probing signal longitudinally from an end part of the tool housing into a fluid flowing in said borehole or borehole casing and for receiving a reflected signal reflected from reflective entrained surfaces in the fluid flowing along a longitudinal direction towards the end part of the tool housing. The downhole tool may include a plurality of electrodes arranged spaced apart around the longitudinal axis in the periphery of the downhole tool so that the fluid flows between the electrodes and a borehole wall or borehole casing wall.

First claim

The invention claimed is:

1. A downhole tool for determining a flow velocity of a fluid inside of a borehole or borehole casing, comprising:
a tool housing having a circumferential surface extending along and around a longitudinal axis of the downhole tool, said tool housing being adapted to be lowered into the inside of the borehole or borehole casing;
a longitudinal transducer configured to transmit a probing signal longitudinally from an end part of the tool housing into a fluid flowing in said borehole or borehole casing so that the transmitted probing signal is exposed to reflective entrained surfaces in the flowing fluid, and to receive a reflected signal reflected from reflective entrained surfaces in the fluid flowing along a longitudinal direction towards the end part of the tool housing;
a plurality of electrodes arranged spaced apart around the longitudinal axis in the periphery of the circumferential surface of the tool housing so that the fluid flows between the electrodes and a borehole wall or borehole casing wall, wherein the downhole tool has a space between every two electrodes filled up with a non-conductive material; and
a processing system configured to:
determine the flow velocity of the fluid from consecutively received reflected signals, and
determine, using the capacitance between two electrodes in all combinations giving n*(n−1)/2 capacitance measurements for n electrodes, properties of the fluid indicating a type of fluid flowing,
wherein the determined flow velocity is used for adjusting the determination of the type of fluid flowing or the determined type of fluid flowing is used for adjusting the flow velocity; and
adjust one or both of a frequency of the transducer and a transmitting angle of the transducer based on the capacitance measurements.

2. A downhole tool according to claim 1 , wherein the velocity of the fluid is determined from consecutively received reflected signals by application of the Doppler principle.

3. A downhole tool according to claim 1 , wherein the velocity of the fluid is determined from consecutively received reflected signals by application of ultrasonic speckle velocimetry.

4. A downhole tool according to claim 1 , wherein the downhole tool comprises a plurality of transducers arranged at the end part of the tool housing spaced apart around the longitudinal axis, each of the plurality of transducers is configured to transmit and receive in a predefined direction respectively.

5. A downhole tool according to claim 1 , wherein a frequency of the transmitted probing signal is a sonic signal in the range between 40 KHz and 5 MHz.

6. A downhole tool according to claim 1 , wherein a transmitting and receiving angle of the longitudinal transducer is in the range of 0-10 degrees from the longitudinal axis.

7. A downhole tool according to claim 1 , wherein the downhole tool further comprises a centraliser tool or a multifinger caliper for determining the diameter of the borehole or borehole casing.

8. A downhole tool according to claim 1 , wherein the processing system comprises a computation and data storing unit disposed inside of the tool housing for processing flow and capacitance measurements measured by the longitudinal transducer and the electrodes.

9. A downhole tool according to claim 1 , further comprising at least a first radial transducer transmitting a radial probing signal away from a central part of the tool housing towards the casing wall and at least a second radial transducer arranged on the central part spaced away from the first radial transducer, said second radial transducer receiving a reflected signal being the radial probing signal reflected by the casing wall.

10. A downhole tool according to claim 1 , further comprising a constant temperature anemometer or an impeller flow meter.

11. A downhole system comprising:
a wireline;
a tool string;
a driving unit; and
a downhole tool for determining the flow velocity of a fluid in a borehole or borehole casing according to claim 1 .

12. A downhole system according to claim 11 , furthermore comprising a logging tool, a key tool, a milling tool or a drilling tool.

13. A method of determining a flow velocity of a fluid surrounding a tool in a borehole, the tool comprising a tool housing having a circumferential surface extending along and around a longitudinal axis of the tool, a longitudinal transducer, and a plurality of electrodes arranged spaced apart around the longitudinal axis in the periphery of the tool, the method comprising:
transmitting, by the longitudinal transducer, a probing signal along a longitudinal axis of the tool from an end part of the tool housing into a fluid flowing in the borehole;
receiving, by the longitudinal transducer, a reflected signal from reflective entrained surfaces in the fluid in the borehole along a longitudinal direction;
measuring a capacitance in a capacitance measurement between at least two electrodes of the plurality of electrodes arranged spaced apart around the longitudinal axis in the periphery of the circumferential surface of the tool housing, thereby determining properties of the fluid surrounding the tool effecting the capacitance between said at least two electrodes;
determining flow velocity of the flowing fluid from the transmitted probing signals and received reflected signals;
determining properties of the fluid surrounding the tool from the capacitance measurement indicating a type of fluid flowing;
sending a set of the determined flow velocity and the determined properties of the fluid to a computation and data storing unit;
adjusting the type of fluid flowing based on the determined flow velocity of the fluid or adjusting the flow velocity of the fluid based on the determined type of fluid flowing; and
adjusting one or both of a frequency of the transducer and a transmitting angle of the transducer based on the measured capacitance.

14. A method according to claim 13 , further comprising:
measuring a set of calibration flow and capacitance measurements in a vertical part of the borehole above a heel of the borehole.

15. A method according to claim 13 , further comprising:
sending at least part of the flow and capacitance measurements to an uphole data processor for being received by a user.

16. A method according to claim 13 , further comprising:
selectively choosing a time interval during which a plurality of Doppler shifts are measured so that a scattering velocity profile is determined based on capacitance measurements made during the time interval.

17. A method according to claim 13 , further comprising:
sending data obtained by the capacitance measurements to the user uphole only if the calculated flow velocity falls outside a predefined range.

18. A downhole tool according to claim 1 , wherein the probing signals of the longitudinal transducer cover angles around the entire circumference of the downhole tool.

19. A downhole tool according to claim 1 , wherein the processing system is configured to adjust a frequency of the probing signal based on the capacitance between at least two electrodes.

20. A downhole system for making measurement of a fluid inside of a borehole or borehole casing, the downhole system comprising:
a downhole tool including a tool housing having a circumferential surface extending along and around a longitudinal axis of the downhole tool and having a circumference which is perpendicular to the longitudinal axis, a transducer configured to transmit a probing signal longitudinally from an

Assignees

• Welltec As

Inventors

• Hallundbæk Jørgen
• Kjærsgaard-Rasmussen Jimmy

Classifications

• E21B47/107 Primary

  using acoustic means · CPC title

• G01N27/221

  by investigating the dielectric properties (using microwaves G01N22/00; measuring loss factors or dielectric constants per se G01R27/26) · CPC title

• G01F1/668

  Compensating or correcting for variations in velocity of sound · CPC title

• G01F1/667

  Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters · CPC title

• G01F1/663

  by measuring Doppler frequency shift · CPC title