U.S. patent application number 13/513513 was filed with the patent office on 2012-11-08 for flow measurements in an oil reservoir.
This patent application is currently assigned to S2Phase Limited. Invention is credited to Sam Simonian.
Application Number | 20120279292 13/513513 |
Document ID | / |
Family ID | 41641839 |
Filed Date | 2012-11-08 |
United States Patent
Application |
20120279292 |
Kind Code |
A1 |
Simonian; Sam |
November 8, 2012 |
FLOW MEASUREMENTS IN AN OIL RESERVOIR
Abstract
The present invention provides for a down-well fluid measuring
arrangement, and related methods, having at least one surface
defining part of a fluid path, the at least one surface having
first and second ports each arranged to deliver fluid to a single
pressure gauge (28), one of the ports being provided in the region
of an obstruction formation (30) provided in the fluid path, the
arrangement further including switch means (34) arranged to change
the port delivering fluid to the gauge so as to allow for
determination of a pressure difference of the fluid at the said
ports and a third port located either upstream or downstream of the
first port delivering fluid the gauge to allow of determination of
a pressure difference and hence volume fraction.
Inventors: |
Simonian; Sam; (Paris,
FR) |
Assignee: |
S2Phase Limited
Tortola
VG
|
Family ID: |
41641839 |
Appl. No.: |
13/513513 |
Filed: |
December 3, 2010 |
PCT Filed: |
December 3, 2010 |
PCT NO: |
PCT/GB2010/052019 |
371 Date: |
July 25, 2012 |
Current U.S.
Class: |
73/152.51 |
Current CPC
Class: |
G01F 1/44 20130101; E21B
47/10 20130101; G01F 1/42 20130101; G01F 1/363 20130101; G01F 1/74
20130101; G01F 15/061 20130101; E21B 47/06 20130101; G01F 1/56
20130101 |
Class at
Publication: |
73/152.51 |
International
Class: |
E21B 47/06 20120101
E21B047/06 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 3, 2009 |
GB |
0921145.9 |
Claims
1. A down-well fluid measuring arrangement having at least one
surface defining part of a fluid path, the at least one surface
having first and second ports each arranged to deliver fluid to a
single pressure gauge, one of the ports being provided in the
region of an obstruction formation provided in the fluid path, the
arrangement further including switch means arranged to change the
port delivering fluid to the gauge so as to allow for determination
of a pressure difference of the fluid at the said ports.
2. An arrangement as claimed in claim 1 and comprising an annular
arrangement.
3. An arrangement as claimed in claim 2 and comprising a
cylindrical arrangement having the parts provided on the inner or
outer surface of a cylindrical section.
4. An arrangement as claimed in claim 1 and comprising an element
of production tubing to be employed as one functional element of a
production tubing string.
5. An arrangement as claimed in claim 1, wherein the pressure gauge
comprises a combined pressure temperature gauge.
6. An arrangement as claimed in claim 1, wherein three ports are
provided each of which is arranged to be switched, in turn, to the
pressure gauge.
7. An arrangement as claimed in claim 1 wherein a separate switch
valve arrangement is provided with each port and which feed
respective conduits leading to a connector block or delivering
fluid to the gauge.
8. An arrangement as claimed in claim 1 and including conduits from
each of the ports leading to a multi-way valve switch arranged to
be controlled to determine which of the ports delivers fluid to the
gauge.
9. An arrangement as claimed in claim 7, wherein the switch(es)
is/are arranged to be controlled in a cyclical manner to allow for
repeated delivery of fluid from each of the ports in a repeated
cyclical manner.
10. An arrangement as claimed in claim 1, including three ports
wherein a first and second of the ports are located in a relatively
close manner, with the third port being remote therefrom.
11. An arrangement as claimed in claim 10, wherein one of the first
and second ports is provided at the throat of or just after the
obstruction formation, and the other at the inlet thereof.
12. An arrangement as claimed in claim 10, comprises an elongate
tubing section with the said third port being spaced in the order
of one to two metres from the obstruction formation.
13. An arrangement as claimed in claim 1 wherein the obstruction
formation is arranged to exhibit a degree of flexibility and
resilience.
14. An arrangement as claimed in claim 1 and further including
means for facilitating communication of data from the pressure
gauge in a wired, or wireless, manner.
15. An arrangement as claimed in claim 1 and including packer means
provided interspersed on an outer surface of the arrangement.
16. An arrangement as in claim 1, further comprising a down-well
tubing string.
17. An arrangement as defined in claim 1, wherein the obstruction
formation comprises a venturi or orifice formation.
18. (canceled)
19. A method of down-well fluid measurement, including introducing
fluid to first and second parts of a measuring arrangement
switching in a cylindrical manner the parts into, and out of, fluid
communication with a single pressure gauge to obtain pressure
readings at the parts by means of the said gauge.
20. A down-well two-phase fluid sensor device arranged to be
exposed to fluid in an open hole section of a producing well and
having a sensor element arranged to be exposed to the fluid and to
determine the volume fraction of the two phases in the fluid, the
sensor element also being located so as to sense fluid external of
the device and in the generally annular space between reservoir
rock and the outer device surface.
21. A device as claimed in claim 20 and including a flow rate
detector.
22. A device as claimed in claim 21 wherein the flow rate detector
comprises a pressure-drop detector employing an obstruction
formation.
23. A device as claimed in claim 22 wherein the obstruction
formation comprises a flexible and resilient member arranged to
allow passage of down-well tools.
24. A device as claimed in claim 20, wherein the sensor comprises
one of a capacitive sensor or resistive sensor.
25. A device as claimed in claim 20, and packer means provided
interspersed between sensor elements including means for
facilitating communication of output derived from the sensor can be
provided and such communication means can comprise wired or
wireless connection means.
26. (canceled)
27. A down-hole production tubing string comprising a fluid sensor
device as in claim 20.
Description
[0001] The present invention relates to the measurements to be
taken in a down-hole environment such as that of a producing oil
well.
[0002] Known arrangements are available for taking down-well
measurements and can comprise pressure and temperature gauges
located along the production tubing with a retrievable or fixed
venturi for measuring downhole flowrates and volume fractions. The
typical arrangement has been to use three separate pressure and
temperature gauges; two of which are provided to measure the
pressure drop across the venture, and third of which is located
typically 100 meters downstream the first two gauges for measuring
the volume fraction.
[0003] The differential pressure measurement has historically been
made by two individual pressure gauges measuring the inlet and
throat pressures across a venturi shaped restriction. By
subtracting the inlet and throat pressures, the differential
pressure is measured or calculated. The third of the gauges is, as
noted above, employed in relation to volume-fraction
measurement.
[0004] The present invention relates to down-well measurements and,
in particular, to the measurement of fluid flow particularly of
two-phase fluids such as for example those comprising oil and water
phases, or liquid and gas phases within a producing oil well where
liquid should be understood as either oil or water or a combination
of oil and water.
[0005] According to the first aspect of the present invention there
is provided a down-well fluid measuring arrangement having at least
one surface defining part of a fluid path, then at least one
surface having first and second ports each arranged to deliver
fluid to a common pressure gauge, one of the ports being provided
in the region of, or just after, an obstruction formation provided
in the fluid path, the arrangement further including switch means
arranged to change the port delivering fluid to the gauge so as to
allow for determination of a pressure difference of the fluid at
the set ports. A third port located some distance downstream or
upstream of the first port (this is the port just before the
obstruction in the flow path) is arranged such that the same switch
means can be employed to deliver fluid from the third port to the
gauge.
[0006] The invention can prove particularly advantageous insofar as
forming a basis for any required flow and/or volume fraction
measurements in a reliable, efficient and easily maintained manner
within the down well environment.
[0007] A particular advantage of the present invention over the
prior art employing two or more individual gauges is that
manufacturing differences (such as thermal drift, pressure
accuracy) between the two or more gauges are eliminated; hence
eliminating any drift or accuracy differences between the
gauges.
[0008] Advantageously, the arrangement can comprise an annular
arrangement and which can offer a substantially cylindrical
form.
[0009] The ports can be provided in an inner or outer surface of
such a cylindrical arrangement which, as a particular advantage, is
adapted to form part of a pipe section of a production string. The
gauge, switch valve and associated downhole electronics can be
either mounted onto a gauge-carrying mandrel which in turn can be
welded onto a standard production string, or by the mandrel can
comprise a "stand alone" carrier such that it can be threaded in a
correspondingly similar manner to the production string and can be
added as an "extra" section of the production string.
[0010] The arrangement can therefore advantageously take on the
form of production tubing to be employed as one functional element
of a production tubing string for achieving the appropriate
hydrocarbon recovery but whilst also providing the fluid
measurement functionality.
[0011] In particular, the pressure gauge can comprise a combined
pressure temperature gauge.
[0012] Of course, it should be appreciated that the arrangement can
comprise any appropriate number of ports as required to achieve the
requirement measurement scenarios.
[0013] In one particular functional arrangement, which can
nevertheless be provided in a relatively compact manner, three
ports are provided each of which can be switched, in turn, to the
pressure gauge.
[0014] Of course, any variety of switching arrangements can be
provided.
[0015] For example, a separate switch valve arrangement can be
provided at each port and which feed respective conduits leading to
a connector block or delivering fluid to the gauge.
[0016] The switches are controlled in turn such that only one port
can deliver fluid to the gauge at any one time; however the switch
controller can open a combination of ports to allow `bleeding` or
`stabilization` of the pressure contained within the system.
[0017] As will be appreciated, in order to achieve the appropriate
measurements, a series of measuring results are built up so as to
arrive at an average value. In this manner, the switches can be
controlled in a cyclical manner to allow for repeated delivery of
fluid from each of the ports in a repeated cyclical manner.
[0018] Alternatively, conduits from each of the ports can lead to a
multi-way valve switch which is controlled to determine which of
the ports delivers fluid to the pressure gauge.
[0019] Again, the multi-way switch valve can be controlled in a
cyclical manner so as to achieve the required repeated measurements
at each of the ports and thus the calculation of an average value
if required.
[0020] In one arrangement, for example with three ports, first and
second ports are located in a relatively close manner, with the
third port being remote therefrom.
[0021] Advantageously the obstruction formation can comprise an
inner annular member which can be arranged as a venturi or orifice
formation.
[0022] One of the first and second ports can be provided at the
throat of the obstruction formation, or just downstream therefrom,
and the other at the inlet thereof. One particular embodiment of
the present invention comprises an elongate tubing section with the
said third port being spaced in the order of one or two metres from
the obstruction formation; however, the tubing section could be as
long as the standard production tubing length which is typically 30
ft.
[0023] Advantageously, the overall longitude dimension of the
arrangement is slightly greater than the separation between the
third port and the obstruction formation. A particular further
advantage of the present invention is that the obstruction
formation exhibits a degree of flexibility and resilience.
[0024] In this manner, although the obstruction formation
effectively represents a reduction in internal diameter of the
tubing section, down well tools can nevertheless pass through
insofar as they can cause the obstruction formation to flex so as
to allow passage thereby.
[0025] The arrangement can further comprise means for facilitating
communication of data from the pressure gauge and which can
comprise wired communication means.
[0026] Alternatively, wireless connection means can be provided. It
should also be appreciated that the present invention can provide
for a down well sensor string comprising a plurality of
arrangements such as those discussed above.
[0027] If required, packer means can be provided interspersed on an
outer surface of the arrangement.
[0028] The invention can further provide for a method of
determining two-phase flow and including steps of the controlled
alternating activation of accessing of pressure gauge devices of a
sensor string as noted above.
[0029] Of course, the method can include the controlled
interrogation of the pressure gauges and, in particular, the
retrieval of reading there from in a cyclical manner.
[0030] Yet further, the invention can comprise oil well production
tubing including an arrangement as defined above
[0031] Thus, a down hole production tubing sting can be provided
comprising one or more of the said arrangements as required.
[0032] According to another aspect of the present invention there
is provided a down-well two-phase fluid sensor device arranged to
be exposed to fluid in an open hole section of a producing well,
and having a sensor element arranged to be exposed to the fluid and
to determine the volume fraction of the two or single phases in the
fluid, the sensor element also being located so as to sense fluid
external of the device and in the generally annular space between
reservoir rock and the outer device surface.
[0033] As will be appreciated, this aspect of the present invention
is particularly useful for measuring the volume fraction of the two
or single phases of the fluid flowing within the open hole section
but outside of the production tubing.
[0034] The device can also include a flow rate detector and can
further comprise, or include, a carrier member on which the
detector and element are mounted.
[0035] As should be appreciated, the flow rate detector can
comprise a pressure-drop detector and, in particular, a pressure
gauge employing an obstruction formation and a switch valve
mechanism to switch between the ports in a cyclic manner as
required similar to above.
[0036] Further, the detector can be associated with a flow diverter
or flow restrictor or indeed any obstruction formation serving to
affect the smooth flow of fluid in relation to the device.
[0037] Advantageously, the obstruction formation comprises a
flexible and resilient material arranged to allow passage of
down-well tools thereby or therethrough.
[0038] The sensor can comprise one of a capacitive sensor or
resistive sensor. Preferably, the carrier member can comprise a
substantially tubular member such that the device can effectively
form an integral part of a production tubing string.
[0039] Means for facilitating communication of output derived from
the sensor can be provided and such communication needs can
comprise wired or wireless connection means. The invention can
again comprise a down well sensor string comprising a plurality of
devices such as those defined above and mounted in series of long
string.
[0040] Advantageously, packer means can be provided interspersed
between the sensor devices.
[0041] The invention can also provide for method of determining
two-phase flow and including the steps of the controlled
alternating activation or accessing of sensor devices of the string
such as that defined above.
[0042] Advantageously, the method includes the controlled
interrogation of the sensor devices and, further, includes taking
readings from each of the sensors both for a predetermined period
in turn, and, in particular, in a cyclical manner.
[0043] Yet further, the invention can provide for a down hole
production tubing string comprising a plurality of devices as
defined above.
[0044] It will therefore be appreciated that a particular aspect of
the present invention is the provision of an apparatus for, and
related method of, measuring two-phase (oil and water or liquid and
gas) in a producing oil or gas well. The apparatus can be
permanently installed into a producing well without limiting
down-hole access for tools etc. As naturally occurring reservoir
fluids flow from the reservoir to the surface, the apparatus
firstly detects the amount of oil and water (in an oil/water well)
or gas and condensate (in a gas well) and secondly the flow rates
of the two-phase mixture. The apparatus is also capable of
measuring single phase low rates e.g. flow of injected water. The
apparatus is made up of a single downhole pressure and temperature
gauge which is used to measure the pressure at certain points along
the apparatus.
[0045] A device and arrangement embodying the present invention is
typically located above the production packer and can form part of
the production tubing which runs to the surface. A single
electrical cable from the surface can be deployed with the
apparatus which forms the communication and power controls from the
surface to the apparatus located downhole. In one specific example,
the arrangement can include a single downhole Quartz pressure and
temperature gauge along with a solenoid actuated valve along with a
flexible venturi or orifice section.
[0046] The invention is described further hereinafter, by way of
example only, with reference to the accompanying drawings in
which:
[0047] FIG. 1 is a schematic sectional view of a producing well
employing an embodiment of the present invention;
[0048] FIG. 1A is a schematic sectional view of a producing well
employing an embodiment of the present invention;
[0049] FIG. 2 is a schematic sectional view of a producing well
employing another embodiment of the present invention;
[0050] FIG. 3A is a schematic sectional view of a sensor
arrangement according to an embodiment of the present
invention;
[0051] FIG. 3B is a schematic sectional view of the gauge and
switch arrangement of FIG. 3A but in greater detail;
[0052] FIG. 4A is a schematic representation of a tubing member
embodying one aspect of the present invention;
[0053] FIG. 4B is a schematic representation similar to that of
FIG. 4A but illustrating a different example of an obstruction
formation of an embodiment of the present invention;
[0054] FIG. 5 is a schematic representation illustrating the
hydraulic arrangement of FIG. 4;
[0055] FIG. 6 is a schematic representation of an alternative
hydraulic arrangement to that of FIG. 5;
[0056] FIG. 7 is a schematic illustration of an electrical
connection arrangement exhibited by an embodiment of the present
invention;
[0057] FIG. 8A and FIG. 8B are perspective views of one example of
a flexible venturi member according to the further embodiment of
the present invention;
[0058] FIG. 9 is a perspective view of a single mandrel arranged to
embody an example of the present invention;
[0059] FIG. 10 is a perspective view of a pipe tubing section,
forming one part of a production string, and employing a mandrel
such as that of FIG. 9; and
[0060] FIG. 11 is a perspective view of an obstruction formation
according to another embodiment of the present invention.
[0061] Various different examples of different embodiments of the
present invention are discussed below with reference to the above
mentioned drawings and, in particular, in relation to a producing
well which is experiences two-phase fluid flow.
[0062] The embodiment illustrated with reference to the FIGS. 1.-3.
relates to a producing well extending through gas, and into oil,
varying rock structures and which comprise an initial vertical
section and then a long generally horizontally extending
section.
[0063] Turning now to the FIG. 1, it should be appreciated that the
apparatus can be permanently installed into a producing well 10
having an openhole section 12 and, production tubing string 14. As
natural occurring reservoir water or injected water moves towards
the producing well 10, the apparatus firstly detects the presence
of water and secondly the flow rates for the oil and water. The
apparatus is made up of resistance or capacitance sensors 16,
located on the outside of a production tubing string 14.
[0064] It is an important aspect of this initial embodiment of the
present invention that the sensors are positioned as noted insofar
as this allows volume fraction measurements within the generally
annular space between the production tubing string 14 and the inner
face of the openhole section 12.
[0065] The readings for the sensors, and indeed the powering and
control thereof, is achieved by way of a surface acquisition system
20.
[0066] The communications between the sensors 16 and the surface
acquisition system 20 can be by way of a wired connection or by way
of a wireless arrangement.
[0067] Referring now to FIG. 1A, there is illustrated a schematic
sectional view of a producing well having a generally horizontal
open hole section 11 from which fluid flows in the direction of
arrow 13 into the production tubing 15. A standard production
packer 17 is employed to instill that all of the fluid flow during
retrieval from the open hole section 11 is via the production
tubing 15 so as to impinge on a flow meter 19 such as that
described herein and which receives power and control data, and
delivers measurement data, from/to surface by way of cable 21--it
should be noted that the measurement of data and control to the
meter can be wireless.
[0068] Referring to FIG. 2 there is illustrated a similar schematic
sectional view of a producing well but including a wireless
communications pod 22 allowing for wireless communication with each
of the sensors and which can then communicate with the surface
acquisition system 20 using any wired, or wireless, manner as
appropriate.
[0069] Turning now to FIG. 3A, there is illustrated further detail
of a sensor arrangement according to a further embodiment of the
present invention. As with the earlier example, an openhole section
12 of the producing well has a production tubing string located
therein with the openhole packers 18 serving to securely locate the
production string within the openhole section 12 and to
compartmentalise a section of the reservoir.
[0070] A volume fraction sensor 26 is again located outside the
tubing string and the body of this section of the tubing string can
comprise a single element in which a pressure gauge 28, switch
valve 34 and related controller electronics are located. The
pressure gauge 28 is in fluid communication by way of two pressure
ports at different points along the inner surface of the production
tubing sting. The switch valve 34 can be activated such that fluid
from one port provides a pressure-reading at one particular time
and the switch valve 34 is arranged to behave in a cyclic manner as
also described further herein.
[0071] In the region of these ports, there is provided an
obstruction formation which, in this example, takes the form of a
relatively shallow annular ring member forming, again in this
example, a venturi obstruction 30.
[0072] With regard to FIG. 3B, further detail of the gauge 28 and
switch valve 34 arrangement is illustrated, and in particular the
manner of switching access to the pressure gauge 28 for each of the
two pressure ports associated with an inlet, and throat, of the
obstruction formation comprising in this example a venturi
arrangement. As clearly illustrated, the switch valve 34 can be
controlled in an alternating cyclic manner such that each of the
two ports in turn, and in a repeating the manner, communicates
fluid pressure through to the single pressure gauge 28.
[0073] As illustrated, one of the pressure ports opens into the
inlet of the venturi obstruction assuming fluid flow in the
direction of arrow A, and a second of the ports opens into a throat
of the venturi obstruction.
[0074] The venturi obstruction 30 causes a pressure difference
between the two ports which is indicative of the speed of movement
of the fluid along the production tubing.
[0075] As will be appreciated therefore, the speed of movement of
fluid can be readily determined and such information combined with
the volume fraction measurements.
[0076] Indeed within this illustrated example in FIGS. 3A and 3B, a
further volume fraction sensor 32 is provided on the inside of the
production tubing string.
[0077] However, in an oil/gas reservoir, the resistance sensors can
be replaced by capacitance sensors since the capacitance sensors
will be able to measure the volume fraction of the oil and gas. By
using a similar ring arrangement in the tube with a pressure gauge,
the total rate of oil and gas is measured. Knowing the volume
fractions from the capacitance sensor, the individual phase rates
are calculated. The sensors are connected to the surface data
acquisition unit 20 which can also power and receives data from the
downhole sensors.
[0078] In further detail, and in their simplest form, the
capacitance sensors operate by measuring current flow from the
sensor. Any change in fluid type between the plates of the
capacitor would affect the dielectric constant of the capacitor and
thus the capacitance thereof. A change in capacitance would result
in a change in the amount of current flow and would therefore
indicate a change in die-electric material between the plates and
so from the Bruggeman law:
m = oil ( 1 - .beta. ) 3 ##EQU00001##
.di-elect cons..sub.m=Relative Permittivity of mixture .di-elect
cons..sub.oil=Relative Permittivity of oil .beta.=Water
fraction
[0079] The water fraction can then be determined.
[0080] An example of the resistance sensor is made of two plates
that are mounted on the outside of the tubing between the annular
space (between tubing outer diameter and wellbore inner diameter)
and the reservoir (wellbore inner diameter). Now from application
of the Ramu Rao law:
.sigma. m = .sigma. w 2 .beta. 3 - .beta. ##EQU00002##
.sigma..sub.m=Conductivity of mixture .sigma..sub.w=Conductivity of
water .beta.=Water fraction
[0081] As noted, a particular feature of the method of this
invention is that a volume fraction value is measured in the
annular space between the reservoir rock face 12 and the outside of
the tube 24 although if required volume faction measurements inside
the tubing can be taken. By having sensors measuring the volume
fraction on the outside of the tubing, it proves possible to
provide the user with information on exactly where the water or gas
is entering the lower completion. It should be noted that the
arrangements of the present invention is particularly appropriate
for long horizontal wells and can be placed in openhole segments
divided by openhole packers 18. The structure is intended to be
`multi-dropped` on a single wire from surface to the last sensor
set. Another method could be to package the sensors with acoustic
or radio-frequency communications such that the sensors along the
horizontal well communicate with central receiving pod located in
the upper completion which in turn is connected to the surface via
a wire.
[0082] As will be appreciated, in this illustrated embodiment of
the invention, it is proposed to chill a producing well in a
conventional manner; either vertical or horizontal. The producing
well will be cased to a certain depth thereafter will comprise a
vertical openhole section and/or horizontal openhole section. The
sensors for detecting water or gas and the two-phase rates will be
placed on the tubing which can be deployed into the well. The
tubing diameter will be smaller than that of the casing and the
openhole section. The array of sensors will be deployed in the
openhole section and will be separated by openhole packers. These
openhole packers can be either swellable or mechanical packers as
an example. The purpose of the packers is to compartmentalise the
vertical or horizontal openhole section.
[0083] Each sensor is electrically connected in a `daisy chain`
fashion across the openhole section either by wire or a wireless
communication system e.g. acoustics or radio-frequency. The last
sensor is directly connected to the surface via an electrical cable
or communicating with a wireless pod located some distance
downstream of the sensor--such as illustrated at 22 in FIG. 2. This
wireless pod communicates with the sensors in the lower completion
and in turn sends the signals/data to surface via a wired
connection. At the surface wellhead, an electrical connection is
made between the electrical wire that runs downhole and connects
all sensors to the surface data acquisition system. This surface
system powers and sends signals to the downhole sensors to be
switched. Once a sensor is switched `on` a series of measurements
are taken and the data is sent to the surface acquisition box.
Thereafter that sensor is switched off and the next sensor is
switched on. This switching on & off and taking a measurement
from each sensor is a continuous process. Using software, a surface
display of whether water is present in a compartment is given to
the user.
[0084] The sensors can be mounted onto a sub which can be either
metallic or fibre-glass. The sensors and sub are screwed onto the
main tubing and deployed into the well. Once the downhole equipment
has reached the bottom of the well, the packers are set (if
mechanical) or swell with time to form the compartments. The
sensors are exposed to the wellbore fluid; hence if water was to
arrive at the wellbore, then sensors will detect the presence of
water. Also, the two-phase rate will be calculated for each of the
flowing components. This illustrated embodiment of a sensor
assembly relating to this invention comprises four main components.
First, the sensors (e.g. either capacitance or resistance, or
combination thereof, and a pressure gauge). Then a carrier such as
a sub on-which the sensors are mounted with centralisation system.
Next there is the downhole switching electronics and finally the
surface data acquisition system and display
[0085] The sensors are mounted circumferentially onto the sub.
Electrical connection between the sensors and the switching
electronics is made. The sensors are exposed to the wellbore fluid.
The sensors are made up of stainless steel plates formed around the
circumference of the sub. If the sub is metallic, then insulation
will be required between the sensor and the sub. Since this
technology is to be used in producing wells, cost effective tubular
material e.g. fibre-glass can be used as the sub. In this case
insulation will not be required.
[0086] The sub can comprise a carrier for the sensors and the
switching electronics. The sub can be metallic or non metallic. If
metallic then insulation is required between the sensors and the
sub body. If non-metallic then insulation is not required. The
sensors are mounted on to the sub and fixed in position. Electrical
connections are made between the sensor and the switching
electronics.
[0087] As noted, the downhole switching electronics are housed
inside the sub and connections are made (top and bottom) between
subsequent sensors and the cable to surface. The switching
electronics is also connected to the sensors which power and
measure from the sensors.
[0088] The surface data acquisition system 20 serves to power and
read data from the downhole sensors. Electrical signals are sent
from the surface box 20 downhole to the switching electronics. Each
switching electronic has its own distinct signature such that when
a signal is sent from the surface box to the switching electronics
that particular switch is activated and in turn the sensor. The
measured voltage/signal from the sensor is sent to the surface data
box which in turn interprets the data and graphically displays the
information for the user.
[0089] Turning now to FIG. 4A. there is provided a schematic cross
section of a fluid monitoring device according to another
embodiment of the present invention and which generally takes on
the configuration of a tubing section that, in addition to
providing the fluid monitoring/measurement required, also forms an
integral part of a production tubing string.
[0090] Thus, the arrangement is generally of a tubular section
configuration arranged to be located in line with production tubing
sections or similar tubing section arrangements offering the
monitoring functionality illustrated.
[0091] Within FIG. 4 therefore there is provided a tubular pipe
section 32 within the casing in which is provided a hydraulic and
electrical system 34 providing the required functionality as to be
discussed further below.
[0092] For further illustration, a production packer 36 is
illustrated around the outside of part of the tubing section 32 so
as to illustrate the manner of secure location of the arrangement
within a cased section of a producing well (see FIG. 1A).
[0093] When producing, the two-phase flow is arranged to travel in
the direction of arrow B and, as illustrated, this passes along the
inside of the tube 32 and via an obstruction arrangement 38 which
in the illustrated example comprises an annular venturi formation
38. This appears in cross-section in FIG. 4 and as will be
appreciated comprises an elongate annular configuration which
includes the throat arranged to offer an abrupt reduction in
diameter on the upstream side of the arrangement 38, and a more
graduated increase in diameter in the downstream direction. An
alternative arrangement of such an obstruction can be formed by
using an orifice type formation as discussed in further detail
below.
[0094] FIG. 4B is a view similar to that of the
flow-detector/sensor arrangement of FIG. 4A but wherein a flexible
orifice member 39 is employed in place of the venturi arrangement
38 of FIG. 4A. Further specific details of an example of a flexible
orifice member such as that 39 is described later with reference to
FIG. 11. As will be appreciated from the positioning of the
flexible orifice member 39 relative to the ports 40, 42, the
"throat pressure" is now actually measured just downstream of the
obstruction formation in the FIG. 4B embodiment.
[0095] It is a particular feature of the present invention that the
venturi, or orifice, structure can comprise a flexible member
offering an appropriate degree of rigidity but also resilient
deformability. In one example, the venturi can be formed from a
polyethylene/nitrile material. This has the particular advantage
that, while offering appropriate impedance to the fluid flow B
generally by way of a decrease in effective diameter of the pipe
section 32, the flexible venturi can nevertheless deform when
abutted by, for example, a downhole tool so as to allow the tool to
pass through the throat of the venturi structure 38 and further
along the pipe string as required. Quite commonly, a production
logging tool is required to measure the performance of a well and
will require access below the production packer, and thus the
likely location of the venturi section. Historically, the venturi
section will have to have been removed to allow for the passage of
the logging tool to its required downhole location. This aspect of
the present invention however allows for resilient deformation of
the venturi section and thus the ready access of, for example,
logging tools beyond the packer and to any required location
[0096] At present, it is necessary to pursue a disruptive and
costly process of removal of the venturi arrangement so as allow
such a downhole tool to pass deeper into the production string as
and when required.
[0097] In the present invention, there is no such need for any
"down time" and related expense and the flexible venturi structure
38 can simply remain in place as the tool is urged to be passed
through, and then back again, as required.
[0098] The illustrated embodiment of the present invention in FIG.
4 is arranged to provide for volume fraction, and flow rate
measurements of the two-phase fluid flowing in the direction of
arrow B. To this end, there are provided three ports within the
inner surface of the tube section 32 such as ports 40, 42 and
44.
[0099] As will be appreciated, port 40 is located at the inlet of
the venturi section 38, port 42 is located in the throat of the
venturi section 38 while port 44 spaced some distance further along
the tubing section 32.
[0100] As a general example of the dimensions of such a tubing
section, and the spacing of the various ports, ports 40, 42 are
located generally close to each other so as to allow for pressure
difference measurements and thereby determination of the rate of
flow of the two-phase fluid. Port 44 however is located in the
order of one to two metres away from the venturi section 38.
[0101] The overall longitude dimension of the venturi section is
therefore in the order of just over two metres (the venturi is
typically 4 inches in length, the distance between the inlet &
throat pressure ports is 2 inches and the orifice is 1 inch in
length).
[0102] As will be appreciated further, provision of the third port
44 allows for volume fraction measurements and so the appropriate
measurements for determining the rate of flow of each of two phases
within a two-phase fluid can be obtained by way of the relatively
compact structure of just over two metres in length.
[0103] As is already known, the flow rate within the tube is
determined by the pressure differences at the ports 40, 42, and the
further measurement away from the venturi system of the pressure at
port 44 allows for the volume fraction measurements.
[0104] To this end, conduits 46, 48, 50 lead respectively from each
of the ports 40, 42, 44 and lead into a downhole solenoid switch 42
which is controlled such that any one of the ports and related
conduits 46, 44, 50 at any one time is open to a single downhole
pressure and temperature gauge as discussed with particular
advantages further.
[0105] The downhole solenoid switch valve 52 is controlled by way
of electrical signalling delivered from control wire 54 leading
from a connect block 56 which likewise connected to a cable 58
leading to the surface and which carries a variety of control wires
or can be a single wire.
[0106] While, as noted, three inlets 46, 48, 50 are provided to the
downhole solenoid switch valve 52, a single outlet 60 is provided
and which delivers fluid from either of the ports 40, 42, 44 to the
single downhole pressure and temperature gauge 62. Readings are
taken from the gauge 62 by way of a cable 64 which leads into the
connector block 56 and previously mentioned and then into the
single cable 58 leading to the surface.
[0107] Turning now to FIG. 5 there is provided clear illustration
of the hydraulic arrangement of the present invention insofar as
only one wall of the tubing section 32 is shown along with the
position of the three ports 40, 42, 44 and the related input
conduits 46, 48, 50 to the downhole solenoid switch valve 5, a
single outlet conduit 60 leading to the single pressure and
temperature gauge 62.
[0108] FIG. 5 therefore illustrates a particularly advantageous
aspect of this invention in that, through use of the switch ports
40, 42, 44 and respective conduits 46, 48, 50 it becomes possible
to require only a single pressure and temperature gauge 62 in order
to achieve all of the appropriate pressure difference measurements
or flow rate and volume fraction measurements.
[0109] Appropriate electrical control of the solenoid switch valve
52 dictates that only one of the three ports can communicate with
the pressure temperature gauge 62 at any one time however the
switch controller can open a combination of ports to allow
`bleeding` or `stabilization` of the pressure contained within the
system.
[0110] The switch valve 52 is therefore arranged to switch, in a
cyclical manner, each of the conduits 46, 48, 50 in turn to provide
pressurized fluid to the pressure temperature gauge for an
appropriate length of time, and for appropriate number of separate
measurements, in order to build up a volume of results that can be
analysed as appropriate to determine an average figure or
otherwise.
[0111] Employing just a single pressure temperature gauge in this
manner proves particularly advantageous insofar as there is no need
for any recalibration between gauges, nor likely for any drift in
the readings nor any inaccuracies that will otherwise arise between
the use of three separate gauges, or a differential pressure
gauge.
[0112] There are of course also associated advantages over cost and
simplicity of use and maintenance.
[0113] The particular example of FIG. 5 is in no way limiting and
any variety of control arrangements can be provided in order to
switch, in turn, each of a plurality of ports to a single pressure
and temperate gauge.
[0114] Merely as a yet further example, reference is therefore made
to FIG. 6 which again illustrates just one sidewall section of a
tubing section of the present invention and in which similar
features to those appearing in the previous diagrams employ similar
reference numerals.
[0115] Thus, there is again provided a series of three ports 40,
42, 44 each leading to a respective conduit 46, 48, 50.
[0116] However, in the example of FIG. 6, rather than leading to a
single downhole solenoid switch valve, each of the ports leads to
its own separate two-way i.e. open/close switch 66, 68, 70 as
illustrated.
[0117] Further conduits then lead from the outlets of each of the
switches 66, 68 and 70.
[0118] It is these outlet conduits 72, 73, 74 for each of the three
switches 66, 68, 70 respectively that leads to a four-way connector
block 76.
[0119] As illustrated, the four-way connector block has three
inputs faired respectively by each of the conduits 72, 73, 74, and
a single output conduit 60 which leads to the single pressure
temperature gauge 62 of the present invention.
[0120] Thus, rather than achieving the switching controlled
functionality at the connector block 76, each port is associated
with its own control switch 66, 68, 70 to determine which of the
ports communicates via the connector block 76, with the conduit 60
and thus the single pressure and temperature gauge 62.
[0121] No switching is provided within the connector block 66 and
appropriate cyclical control of each of the switches 66, 68, 70 is
provided by electrical means such that only one of the ports 40,
42, 44 can communicate through to the single pressure and
temperature gauge at any one time however the switch controller can
open a combination of ports to allow `bleeding` or `stabilization`
of the pressure contained within the system. Such open and closing
occurs in a repeated cyclical manner so that, as before, a series
of measurements can be built up and an appropriate volume of data
established. In the illustrated example, switch 70 is open such
that port 44 is in communication with the pressure and temperature
gauge 62 by way of the conduits 50, 74, the connector block 76 and
the conduit 60.
[0122] The pressure being experienced at port 44 within the tube
section is therefore determined at the pressure and temperature
gauge 62.
[0123] As with the hydraulic arrangements, a variety of electrical
arrangements can be provided although only one example is found in
FIG. 7 but a clear illustration of the arrangement employed within
the embodiment of FIG. 4.
[0124] Firstly, there is illustrated the downhole solenoid switch
valve 52 connected to control cabling 54 through which appropriate
control signals are received so as to establish the switched timing
of the solenoid switch valve so as to achieve the required cyclical
series of pressure readings at each of the three ports: The signals
being fed via the connect wire 54 and connect block 56 to the cable
58 which runs further with the downhole pipe string to the cable
and the surface-located electronic management/measurement
system.
[0125] Likewise there is illustrated the single pressure and
temperature gauge 62 which comprises a transducer member
experiencing the pressure provided at each port in turn and
producing an electrical signal delivered by way of electrical
connector cable 64 to the connector block 56 and then into the
cable 58 rising to the surface.
[0126] Reference is now made to FIGS. 8A and 8B which comprise
perspective illustrations of an annular flexible venturi
arrangement 38 such as that illustrated in FIG. 4.
[0127] FIG. 8A is shown in the direction of fluid flow into the
annular venturi arrangement 78 and shows clearly the steeper
incline 80 presented on the inlet side of the arrangement.
[0128] FIG. 8B illustrates the annular venturi arrangement 78 from
the opposite side and the somewhat more gentle incline 82 presented
by the outlet side is clearly illustrated.
[0129] Also illustrated within FIGS. 8A and 8B, although not shown
in a schematic representation of FIG. 4, are longitudinal fin
sections 84 upstanding along the length of the venturi arrangement
and serving to stabilize the flow of fluid through the venturi and
to allow `stand-off` between a production logging tool passing
through the venturi--this will allow fluid flow between inlet and
outlet of the venturi section and hence create zero differential
pressure between inlet and outlet, as a production logging tool
passes through it.
[0130] Turning now to FIGS. 9 and 10, there are illustrated by way
of perspective views, a single mandrel, of lengths in the order of
8 ft, and which is arranged to have mounted their on a
switching/sensing arrangement such as that discussed herein. The
mandrel itself can be threaded such as to be screwed into a
production tubing string or the mandrel itself is mounted onto a
section of production tubing string comprising tubing section such
as that of FIG. 10 and having a length in the order of 30 ft.
[0131] Finally, reference is made to FIG. 11 which comprises
perspective illustrations of another embodiment of obstruction
formation 86--and comprising an example of the flexible orifice 39
illustrated in FIG. 4B. This example of an obstruction formation 86
embodying the present invention comprises an annular body 88 having
four inwardly extending thin segments 90-96 separated from each
other as illustrated so as to flex independently. It should be
appreciated however that any appropriate number, and configuration,
of inwardly directed flexible things can be provided. Generally,
the degree of flexibility and strength will determine the number of
fins employed. As with the venturi arrangements discussed above the
orifice formation 86 forms a partial obstruction to the flow of
fluid within the production tubing so as to produce a pressure
difference which can be determined by the pressure gauge. The gap
between the fins are there such that fluid can flow between inlet
and outlet, and hence create zero differential pressure between
inlet and outlet, of the orifice during the passage of a production
logging tool.
[0132] While a tubing section can be provided with such an orifice
arrangement, or indeed a venturi section, formed integrally
therewith such arrangements/sections can be retrofitted or at least
removable and replaceable as required. In this manner, and with
specific reference to the orifice formation 86, the outer diameter
thereof is arranged such that it can be securely received at
appropriate location within the tubing section. Indeed, the said
appropriate location of the inside of the tubing section may
include a formation for engaging with the perimeter of the
formation 86.
[0133] As mentioned previously, a particular feature of the present
invention is that the venturi structure can be provided from a
flexible and resiliently deformable material so as to allow for the
passage in, and out, of downhole tools. In the current art use of
known venturi formations upstream of the venturi arrangement would
otherwise require initial removal of the pipe section offering the
venturi structure which of course would prove a particularly time
consuming, expensive and complex operation.
[0134] Typically, the system will measure the pressure and
temperature at one port position for 6 hours and then switch to the
next position. After 24 hours of measuring, analysis of the data is
performed by the surface acquisition system where
P1-P2=differential pressure across the venturi which in turns gives
the total flow rate and P1-P3=gradiomanometer pressure which in
turn gives the volume fractions between the two-phase fluids. Of
course, if a single phase fluid is flowing eg 100% water, then no
need to calculate P1-P3.
* * * * *