U.S. patent application number 13/519745 was filed with the patent office on 2012-11-15 for thermography logging tool.
This patent application is currently assigned to Dkwelltec A/S. Invention is credited to Jorgen Hallundb.ae butted.k, Jimmy Kj.ae butted.rsgaard-Rasmussen.
Application Number | 20120285234 13/519745 |
Document ID | / |
Family ID | 42194754 |
Filed Date | 2012-11-15 |
United States Patent
Application |
20120285234 |
Kind Code |
A1 |
Hallundb.ae butted.k; Jorgen ;
et al. |
November 15, 2012 |
THERMOGRAPHY LOGGING TOOL
Abstract
The invention relates to a logging tool for determining the
properties of a fluid surrounding the tool arranged downhole in a
casing comprising a wall and having a longitudinal extension. The
logging tool has a substantially longitudinal cylindrical shape
with a longitudinal axis, and the logging tool comprises a sensor
unit comprising an anemometer having a resistance probe
electrically connected with three other resistors, a voltmeter and
an amplifier for forming a bridge circuit, such as a Wheatstone
bridge, having bridge current and bridge voltage. The invention
further relates to a method for determining the properties of a
fluid by means of the logging tool.
Inventors: |
Hallundb.ae butted.k; Jorgen;
(Graested, DK) ; Kj.ae butted.rsgaard-Rasmussen;
Jimmy; (Birkerod, DK) |
Assignee: |
Dkwelltec A/S
Allerod
DK
|
Family ID: |
42194754 |
Appl. No.: |
13/519745 |
Filed: |
December 29, 2010 |
PCT Filed: |
December 29, 2010 |
PCT NO: |
PCT/EP10/70832 |
371 Date: |
June 28, 2012 |
Current U.S.
Class: |
73/152.33 |
Current CPC
Class: |
G01F 1/69 20130101; E21B
47/07 20200501; G01F 1/6986 20130101; G01V 3/18 20130101; E21B
47/113 20200501 |
Class at
Publication: |
73/152.33 |
International
Class: |
E21B 47/00 20120101
E21B047/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 29, 2009 |
EP |
09180921.0 |
Claims
1. A logging tool (1) for determining the properties of a fluid (2)
surrounding the tool arranged downhole in a casing (3) comprising a
wall (4) and having a longitudinal extension and a longitudinal
axis (t), wherein the logging tool comprises: a sensor unit (5)
comprising an anemometer (6) having a resistance probe (7, R.sub.1)
electrically connected with three other resistors (R.sub.2,
R.sub.3, R.sub.4), a voltmeter (V) and an amplifier (25) for
forming a bridge circuit, such as a Wheatstone bridge, having a
first and a second bridge voltage, wherein the sensor unit
comprises switches (8) for disconnecting or connecting the
amplifier and connecting or disconnecting a voltage supply.
2. A logging tool according to claim 1, wherein the anemometer is a
hot wire anemometer or a hot film anemometer.
3. A logging tool according to claim 1, wherein the probe is
arranged on an outer face (20) of the tool.
4. A logging tool according to claim 1, wherein the sensor unit
comprises a plurality of anemometers all having a resistance
probe.
5. A logging tool according to claim 1, wherein the probes are
arranged on the outer face of the tool.
6. A logging tool according to claim 1, wherein the tool comprises
at least one thermocouple (18) arranged partly on the outer face of
the tool.
7. A logging tool according to claim 1, wherein the tool comprises
a plurality of electrodes (16) arranged spaced apart around the
longitudinal axis in the periphery of the tool, enabling the fluid
to flow between the electrodes and the casing wall.
8. A logging tool according to claim 1, further comprising a
positioning device (22) for determining a position of the logging
tool along the longitudinal extension of the casing.
9. A logging tool according to claim 1, wherein a temperature of
the probe resistance is maintained constant by varying the current
by means of the amplifier so that a first bride voltage is
substantially zero when a first measurement of a second bridge
voltage is performed by the voltmeter, and the second bridge
voltage is an alternating voltage when a second measurement of the
first bridge voltage is performed.
10. A logging tool according to claim 9, wherein the second bridge
voltage is maintained constant at a value different from zero by
the voltage supply when a third measurement of the first bridge
voltage is performed.
11. A logging tool according to claim 9, wherein a third
measurement is performed using the thermocouples.
12. A logging tool according to claim 9, wherein the alternating
voltage or alternating current have sine, square, rectangular,
triangle, ramp, spiked or sawtooth waveforms.
13. A method for determining the properties of a fluid (2) by means
of the logging tool according to claim 1, comprising the steps of:
submerging the logging tool into a casing, maintaining a constant
temperature in the resistance probe by varying the current,
increasing the bridge current by means of the amplifier if the
temperature in the resistance probe decreases until a first bridge
voltage is substantially zero, measuring a second bridge voltage by
means of the voltmeter, disconnecting the amplifier and the voltage
supply and connecting a second voltmeter by means of the switches,
providing the second bridge voltage as an alternating voltage, and
measuring the first bridge voltage by means of the second
voltmeter.
14. Use of the logging tool according to claim 1 for determining
the fluid properties of a fluid in a well downhole.
15. A detection system comprising a logging tool according to claim
1 and a calculation unit for processing capacitance measurements
performed by the electrodes and/or a driving unit for moving the
tool forward in the casing.
Description
TECHNICAL FIELD
[0001] The present invention relates to a logging tool for
determining the properties of a fluid surrounding the tool arranged
downhole in a casing comprising a wall and having a longitudinal
extension. The logging tool has a substantially longitudinal
cylindrical shape with a longitudinal axis, and the logging tool
comprises a sensor unit comprising an anemometer having a
resistance probe electrically connected with three other resistors,
a voltmeter and an amplifier for forming a bridge circuit, such as
a Wheatstone bridge, having bridge current and bridge voltage. The
invention further relates to a method for determining the
properties of a fluid by means of the logging tool.
BACKGROUND
[0002] During oil production, it may be useful to be able to
determine the fluid properties of a fluid in order to optimise the
production process. Samples may be taken during production, or a
tool able to conduct certain measurements may be loaded into the
well.
[0003] One of such tools is disclosed in U.S. Pat. No. 5,551,287.
In this tool, a constant temperature anemometer is used to
determine the velocity of a fluid. However, in order to measure the
velocity, the instrument must be calibrated to ensure that a change
in the resistance and thus in the temperature of the sensor depends
only on the velocity.
[0004] When measuring the velocity several places in a well, e.g.
in the side tracks, the fluid property changes from one position in
the well to another, and the tool needs calibration from position
to position in the well, or the measurements are inaccurate.
DESCRIPTION OF THE INVENTION
[0005] It is an object of the present invention to wholly or partly
overcome the above disadvantages and drawbacks of the prior art and
provide an improved logging tool providing more accurate
measurements of the fluid properties.
[0006] The above objects, together with numerous other objects,
advantages, and features, which will become evident from the below
description, are accomplished by a solution in accordance with the
present invention by a logging tool for determining the properties
of a fluid surrounding the tool arranged downhole in a casing
comprising a wall and having a longitudinal extension, the logging
tool having a substantially longitudinal cylindrical shape with a
longitudinal axis, wherein the logging tool comprises: [0007] a
sensor unit comprising an anemometer having a resistance probe
electrically connected with three other resistors, a voltmeter and
an amplifier for forming a bridge circuit, such as a Wheatstone
bridge, having bridge current and bridge voltage, wherein the
sensor unit comprises switches for disconnecting or connecting the
amplifier and connecting or disconnecting a voltage supply.
[0008] The anemometer may be a hot wire anemometer or a hot film
anemometer.
[0009] Furthermore, the probe may be arranged on an outer face of
the tool.
[0010] Moreover, the sensor unit may comprise a plurality of
anemometers all having a resistance probe.
[0011] Additionally, the probes may be arranged on the outer face
of the tool.
[0012] In one embodiment, the tool may comprise at least one
thermocouple arranged partly on the outer face of the tool.
[0013] In another embodiment, the tool may comprise a plurality of
electrodes arranged spaced apart around the longitudinal axis in
the periphery of the tool, enabling the fluid to flow between the
electrodes and the casing wall.
[0014] The logging tool may further comprise a positioning device
for determining a position of the logging tool along the
longitudinal extension of the casing.
[0015] Furthermore, the logging tool may have a space between every
two electrodes, which space is substantially filled with a
non-conductive means.
[0016] Furthermore, the logging tool may comprise a driving unit
for moving the tool in the casing.
[0017] In one embodiment, the invention relates to the logging tool
as described above, wherein [0018] a temperature of the probe
resistance is maintained constant by varying the current by means
of the amplifier so that a first bride voltage is substantially
zero when a first measurement of a second bridge voltage is
performed by the voltmeter, and [0019] the second bridge voltage is
an alternating voltage when a second measurement of the first
bridge voltage is performed.
[0020] In another embodiment, the second bridge voltage may be
maintained constant, at a value different from zero, by the voltage
supply when a third measurement of the first bridge voltage is
performed.
[0021] In yet another embodiment, a third measurement may performed
by using the thermocouples.
[0022] The alternating voltage or alternating current may have
sine, square, rectangular, triangle, ramp, spiked or sawtooth
waveforms.
[0023] In an embodiment, the logging tool may further comprise an
electrical motor powered by a wireline.
[0024] The invention also relates to a method for determining the
properties of a fluid by means of the logging tool according to any
of the preceding claims, comprising the steps of: [0025] submerging
the logging tool into a casing, [0026] maintaining a constant
temperature in the resistance probe by varying the current, [0027]
increasing the bridge current by means of the amplifier if the
temperature in the resistance probe decreases until a first bridge
voltage is substantially zero, [0028] measuring a second bridge
voltage by means of the voltmeter, [0029] disconnecting the
amplifier and the voltage supply and connecting a second voltmeter
by means of the switches, [0030] providing the second bridge
voltage as an alternating voltage, and [0031] measuring the first
bridge voltage by means of the second voltmeter.
[0032] The method may further comprise the steps of: [0033]
disconnecting the amplifier and connecting the voltage supply by
means of the switches, [0034] maintaining the first bridge voltage
constant with a value different from zero, and [0035] measuring the
second bridge voltage by means of the voltmeter.
[0036] In addition, the method may comprise the step of measuring
the fluid temperature by means of the thermocouples.
[0037] Furthermore, the invention relates to the use of the logging
tool described above for determining the fluid properties of a
fluid in a well downhole.
[0038] Finally, the invention relates to a detection system
comprising a logging tool and a calculation unit for processing
capacitance measurements performed by the electrodes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] The invention and its many advantages will be described in
more detail below with reference to the accompanying schematic
drawings, which for the purpose of illustration show some
non-limiting embodiments and in which
[0040] FIG. 1 shows a logging tool lowered into a casing of a
well,
[0041] FIG. 2A shows an anemometer measuring a circuit,
[0042] FIG. 2B shows another embodiment of the anemometer measuring
a circuit,
[0043] FIG. 3 shows another embodiment of the logging tool, and
[0044] FIG. 4 shows yet another embodiment of the logging tool.
[0045] All the figures are highly schematic and not necessarily to
scale, and they show only those parts which are necessary in order
to elucidate the invention, other parts being omitted or merely
suggested.
DETAILED DESCRIPTION OF THE INVENTION
[0046] The present invention relates to a logging tool 1 in which
temperature and velocity measurements of the fluid 2 surrounding
the tool downhole are conducted. In FIG. 1, the logging tool 1 is
shown in a casing 3. The tool 1 is lowered into the well and is
connected with a wireline 23 holding the tool in a vertical well.
The logging tool 1 comprises a sensor unit 5 having at least one
anemometer 6 with almost the same design as a constant temperature
anemometer. In FIG. 1, the tool 1 has eight anemometers 6 spaced
apart along the circumference of the tool.
[0047] The tool 1 comprises an electrical motor which is powered
through the wireline 23 to supply the sensor unit 5. The logging
tool 1 may also be supplied directly through the wireline 23
without having a motor for converting the electricity.
[0048] Each anemometer 6 has a resistance probe 7, R.sub.1 which is
connected with the fluid 2 in the casing 3, and the heat loss in
the resistance probe 7 depends on the temperature of the fluid, the
specific heat .mu. of the fluid, and the velocity v of the fluid.
In order to determine one of the properties of the fluid 2, at
least three measurements must be performed at almost the same time
to determine the equations and thus one of the fluid properties
being the specific heat .mu., velocity v and/or the temperature T.
Measurements of fluid velocity and temperature are often used when
having long side tracks since some of these may deliver more water
than oil or other undesired elements.
[0049] The resistance probe 7, R.sub.1 is electrically connected
with three other resistors R.sub.2, R.sub.3, R.sub.4, a voltmeter
V.sub.1, and an amplifier 25 to form a bridge circuit, in this case
a Wheatstone bridge, as shown in FIGS. 2A and 2B. The sensor unit 5
comprises switches 8 for disconnecting or connecting the amplifier
25 when performing some of the measurements. The amplifier 25 is
connected to two midpoints P, N on its input side and to a midpoint
M on its output side. The voltmeter V.sub.1 is connected to the
midpoints O, M, and switches are arranged on the input side of the
amplifier to enable disconnection or connection of the amplifier A.
The switches are furthermore arranged so that they connect or
disconnect a second voltmeter V.sub.2. In addition, a first power
supply S.sub.1, such as a signal generator, is connected to the
midpoints O and M in the bridge.
[0050] In the following, the three measurements will be explained,
and even though the measurements are referred to as a first, second
and third, they may be performed in any random order.
[0051] A first measurement is performed as a normal Constant
Temperature Anemometry (CTA) where the resistance probe 7 is heated
by electrical current. An amplifier, such as an operation amplifier
or a servo amplifier, keeps the bridge in balance so that a first
bridge voltage between the midpoints P and N is kept at
substantially zero by controlling the current flowing to the
resistance probe 7 so that the resistance and hence the temperature
are kept constant. A second bridge voltage V.sub.2 is measured
between the midpoints O and M, and the result represents how much
effect is needed to keep the bridge in balance. A representation of
the heat transfer of the fluid is illustrated in the equations
below.
[0052] The heat transferred from the probe to the fluid must be
equal to the energy conveyed to the probe by the current running
through it:
W = Q . ##EQU00001## U 2 R ( T p ) = vk f A .DELTA. T
##EQU00001.2##
[0053] The resistance of the probe R=R(T.sub.p) is a function of
the probe temperature , the heat transfer coefficient of the wire
with surface area A is v, and the thermal conductivity of the fluid
is k.sub.f. The potential across the probe is and the temperature
difference between the probe and the fluid is
.DELTA.T=T.sub.fluid-T.sub.p.
[0054] The heat transfer coefficient is a function of velocity,
meaning that the heat loss is velocity dependent. A commonly known
consequence of this is the `wind-chill` factor. The velocity
dependency is typically found to follow King's law:
U 2 R ( T p ) = .DELTA. T ( A + B V n ) ##EQU00002##
where A and B are calibration factors, V is the velocity and n<1
is another parameter.
[0055] A second measurement is performed when the amplifier 25 is
disconnected and the second voltmeter V.sub.2 is connected. The
second bridge voltage is provided by the signal generator S.sub.1
as an alternating voltage, and the second measurement is conducted
by measuring the second bridge voltage V.sub.2 representing the
alternating voltage after passing the probe resistance. A sequence
of second measurements may subsequently undergo a Fourier
transformation to make it possible to determine the specific heat
.mu. of the fluid 2 by comparing it with known measurements of
known fluids.
[0056] The alternating voltage may have a waveform, such as a sine,
a square, a rectangular, a triangle, a ramp, a spiked or a saw
tooth waveform.
[0057] A third measurement is performed by disconnecting the
amplifier 25 and the second voltmeter V.sub.2 and connecting a
second power supply S.sub.2 while maintaining the first bridge
voltage constant at a value different from zero by the second power
supply S.sub.2. The second measurement is performed by measuring
the second bridge voltage by means of the voltmeter V.sub.1.
[0058] The switches 8 enable the sensor unit 6 to perform three
different measurements at almost the same time, making it possible
to determine the fluid properties, i.e. the temperature T, the
specific heat .mu. and the velocity v, and it is thus unnecessary
to set up any presumptions or conduct calibrations before
performing a measurement in a new position in the well.
[0059] In this way, the logging tool 1 is submerged and three
measurements are performed.
[0060] As shown in FIG. 3, the logging tool 1 may comprise a
driving unit 9, such as a downhole tractor, for moving the tool
forward in the well. This is particularly advantageous when
performing measurements in a horizontal part of the well.
[0061] The tool 1 has a substantially cylindrical shape with a
longitudinal axis t, and when seen in cross-section, probes 7 are
arranged in the periphery of the tool, allowing the fluid 2 to flow
between the probes and the casing wall 4. The probes 7 are arranged
spaced apart and with an even distance between two adjacent probes,
creating a space between every two probes.
[0062] In FIG. 2, the tool 1 is shown comprising electrodes 16 for
measuring the capacitance of the fluid 2. Measuring the capacitance
enables determination of the specific heat .mu., and thus, one of
the second measurements may be dispensed from. Furthermore, the
probes 7 are wires extending radially outwards towards the casing
wall 4.
[0063] The electrodes 16 for measuring capacitance are positioned
in the periphery of the logging tool 1. Opposite the electrodes 16,
a dielectric material is arranged, forming a sleeve between the
well fluid 2 and the electrodes. The tool 1 comprises a printing
circuit (not shown). To improve the conductivity, the electrodes 16
are directly electrically connected to the printing circuit by
means of screws instead of a cord.
[0064] The tool 1 may also have thermocouples 18 arranged around
the circumference 19 and the outer face 20 of the tool so that the
tips of the electrodes 16 of the thermocouples 18 project radially
from the circumference of the tool, as shown in FIG. 4. Instead of
the third measurement, the fluid temperature may be measured
directly by means of the thermocouples.
[0065] As shown in FIG. 1, the probe 7 may also be a kind of film
probe with a thin-film sensor. The probe 7 may be a tungsten wire
sensor, 1 mm long and 5 .mu.m in diameter, mounted on two
needle-shaped prongs. The probes 7 are available with 1, 2 and 3
wires.
[0066] The voltmeter may be an analog to digital converter, also
called an ADC.
[0067] By fluid or well fluid 2 is meant any kind of fluid which
may be present in oil or gas wells downhole, such as natural gas,
oil, oil mud, crude oil, water, etc. By gas is meant any kind of
gas composition present in a well, completion, or open hole, and by
oil is meant any kind of oil composition, such as crude oil, an
oil-containing fluid, etc. Gas, oil, and water fluids may thus all
comprise other elements or substances than gas, oil, and/or water,
respectively.
[0068] By a casing 3 is meant all kinds of pipes, tubings,
tubulars, liners, strings, etc. used downhole in relation to oil or
natural gas production.
[0069] In the event that the tools are not submergible all the way
into the casing 3, a downhole tractor can be used to push the tools
all the way into position in the well. A downhole tractor is any
kind of driving tool capable of pushing or pulling tools in a well
downhole, such as a Well Tractor.RTM..
[0070] The logging tool may also be lowered into the casing by
means of coiled tubing. Although the invention has been described
in the above in connection with preferred embodiments of the
invention, it will be evident for a person skilled in the art that
several modifications are conceivable without departing from the
invention as defined by the following claims.
* * * * *