U.S. patent application number 13/393737 was filed with the patent office on 2013-02-14 for in-borehole gas monitor apparatus and method comprising a voc concentration analyser and a voc collector.
This patent application is currently assigned to INTELISYS LIMITED. The applicant listed for this patent is Steve Boult. Invention is credited to Steve Boult.
Application Number | 20130036811 13/393737 |
Document ID | / |
Family ID | 41202933 |
Filed Date | 2013-02-14 |
United States Patent
Application |
20130036811 |
Kind Code |
A1 |
Boult; Steve |
February 14, 2013 |
IN-BOREHOLE GAS MONITOR APPARATUS AND METHOD COMPRISING A VOC
CONCENTRATION ANALYSER AND A VOC COLLECTOR
Abstract
In-Borehole Gas Monitor Apparatus and Method An in-borehole gas
monitor (IGM) apparatus comprising a VOC concentration analyser and
a VOC collector.
Inventors: |
Boult; Steve; (Manchester,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Boult; Steve |
Manchester |
|
GB |
|
|
Assignee: |
INTELISYS LIMITED
Manchester
GB
|
Family ID: |
41202933 |
Appl. No.: |
13/393737 |
Filed: |
August 3, 2010 |
PCT Filed: |
August 3, 2010 |
PCT NO: |
PCT/GB10/51282 |
371 Date: |
April 6, 2012 |
Current U.S.
Class: |
73/152.27 |
Current CPC
Class: |
E21B 49/08 20130101;
G01N 33/004 20130101; G01N 33/0047 20130101; Y02A 50/20 20180101;
Y02A 50/249 20180101; G01N 1/26 20130101; G01N 1/2205 20130101 |
Class at
Publication: |
73/152.27 |
International
Class: |
E21B 49/08 20060101
E21B049/08 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 1, 2009 |
GB |
0915150.7 |
Claims
1. An in-borehole gas monitor (IGM) apparatus comprising a VOC
concentration analyser and a VOC collector.
2. The in-borehole gas monitor (IGM) apparatus of claim 1, wherein
the VOC concentration analyser is configured to provide a
non-specific real-time concentration of VOCs.
3. The in-borehole gas monitor (IGM) apparatus of claim 1, wherein
the VOC concentration analyser comprises a photo-ionisation
detector.
4. The in-borehole gas monitor (IGM) apparatus of claim 1, wherein
the VOC collector is configured to provide a specific concentration
by volume.
5. The in-borehole gas monitor (IGM) apparatus of claim 1, wherein
the VOC collector comprises a sorbent material.
6. The in-borehole gas monitor (IGM) apparatus of claim 1, wherein
the apparatus further comprises a pressure sensor configured to
measure atmospheric pressure.
7. The in-borehole gas monitor (IGM) apparatus of claim 1, wherein
the apparatus further comprises a clock.
8. The in-borehole gas monitor (IGM) apparatus of claim 1, wherein
the apparatus comprises a pump for pumping gas past the VOC
concentration analyser and the VOC collector in a downstream
direction and the apparatus is configured whereby the VOC
concentration analyser determines a VOC concentration at a
predetermined time by the pump pumping borehole gas past the VOC
concentration analyser and the VOC collector for a pumping
period.
9. The in-borehole gas monitor (IGM) apparatus of claim 8 wherein,
the apparatus is configured whereby the pumping period, a time of
measurement and an atmospheric pressure at the time of measurement
are recorded.
10. The in-borehole gas monitor (IGM) apparatus of claim 1, wherein
the apparatus comprises a pump for pumping gas past the VOC
concentration analyser and the VOC collector in a downstream
direction and a filter for removing any of particulates or moisture
from a gas input, wherein the VOC concentration analyser and the
VOC collector are upstream of the filter.
11. The in-borehole gas monitor (IGM) apparatus of claim 1, wherein
the apparatus comprises a pump for pumping gas past the VOC
concentration analyser and the VOC collector in a downstream
direction and there is a gas flow path comprising a gas input, a
first valve upstream of the pump and a pressure sensor, wherein the
apparatus is configured whereby with the first valve closed the
pump is activated for a predetermined period and if within the
predetermined period a predetermined pressure is not exceeded, as
measured by the pressure sensor, a pump fail signal is
generated.
12. The in-borehole gas monitor (IGM) apparatus of claim 11,
wherein the predetermined period is between 8 and 12 seconds and
the predetermined pressure is 100 mb.
13. The in-borehole gas monitor (IGM) apparatus of claim 1, wherein
the apparatus comprises a pump for pumping gas past the VOC
concentration analyser and the VOC collector in a downstream
direction and there is a gas flow path comprising a gas input, a
first valve upstream of the pump, a pressure sensor and a filter,
wherein the apparatus is configured whereby with the first valve
open a first pressure sensor reading is taken, the pump is
activated for a predetermined period after which a second pressure
sensor reading is taken, and if the magnitude of the difference
between the first pressure sensor reading and the second pressure
sensor reading is greater than a predetermined value, a filter fail
signal is generated.
14. The in-borehole gas monitor (IGM) apparatus of claim 13,
wherein the predetermined period is between 2 seconds and 6
seconds.
15. The in-borehole gas monitor (IGM) apparatus of claim 13,
wherein the predetermined value is 250 mb.
16. The in-borehole gas monitor (IGM) apparatus of claim 8, wherein
the time of sensing and the length of time for which the pump
operates are recorded.
17. The in-borehole gas monitor (IGM) apparatus of claim 11
wherein, the apparatus comprises a second valve downstream of the
first valve and a gas outlet.
18. The in-borehole gas monitor (IGM) apparatus of claim 1, wherein
the apparatus is configured to have a borehole side and an
atmospheric side, wherein there is a gas outlet to the borehole
side of the device and to the atmospheric side of the device.
19. The in-borehole gas monitor (IGM) apparatus of claim 1, wherein
the VOC concentration analyser and the VOC collector are in series
in a gas flow path with a gas analyser.
20. The in-borehole gas monitor (IGM) apparatus of claim 19,
wherein the gas analyser analyses one or more of hydrocarbons,
carbon dioxide, oxygen and hydrogen sulphide.
21. A method of operation of an in-borehole gas monitor apparatus,
which method comprises the use of an in-borehole gas monitor
apparatus according to claim 1.
22. The method of operation of an in-borehole gas monitor apparatus
of claim 21, wherein the VOCs collected by the VOC collector are
quantified.
23. The method of operation of an in-borehole gas monitor apparatus
of claim 21, wherein the apparatus comprises a pump for pumping gas
from the borehole past the VOC collector and the VOC analyser,
wherein the time of sensing and the length of time for which the
pump operates are recorded to determine the volume of gas passing
through the apparatus. This enables the VOC concentration to be
determined.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to in-borehole gas monitor
(IGM) apparatus and methods.
BACKGROUND TO THE INVENTION
[0002] The monitoring of gas concentrations, and in particular
methane and carbon dioxide, generated by landfill and associated
sites is becoming a more common legislative requirement due to the
potential problems these gases pose, such as the risk of explosion
and impacts as greenhouse gases. At present, the majority of
landfill gas analysis is achieved either through spot sampling or
through the use of large expensive fixed position monitoring
stations. More recently it has been recognised that gas production
and migration responds to environmental factors such as barometric
pressure and groundwater movement, with the accompanying
realisation that spot sampling will often miss such changes.
[0003] It is known from WO 2007/141512 to provide a self-contained
IGM apparatus comprising a detector for measuring a gas variable,
and a controller configured to automatically periodically use the
detector to measure a gas variable.
[0004] However, the apparatus and method disclosed in WO
2007/141512 do not deal with volatile organic compounds (VOCs).
[0005] It is an aim of preferred embodiments of the present
invention to address, overcome or obviate a disadvantage of the
prior art, whether such prior art or disadvantage is referred to
herein or otherwise.
SUMMARY OF THE INVENTION
[0006] According to the present invention in a first aspect, there
is provided an in-borehole gas monitor (IGM) apparatus comprising a
VOC concentration analyser and a VOC collector.
[0007] Suitably, the VOC concentration analyser is configured to
provide a non-specific real-time concentration of VOCs. Suitably,
the VOC concentration analyser comprises a photo-ionisation
detector.
[0008] Suitably, the VOC collector is configured to provide a
specific concentration by volume. Suitably, the VOC collector
comprises a sorbent material.
[0009] Suitably, the apparatus further comprises a pressure sensor
configured to measure atmospheric pressure.
[0010] Suitably, the apparatus further comprises a clock.
[0011] Suitably, the apparatus comprises a pump for pumping gas
past the VOC concentration analyser and the VOC collector in a
downstream direction and the apparatus is configured whereby the
VOC concentration analyser determines a VOC concentration at a
predetermined time by the pump pumping borehole gas past the VOC
concentration analyser and the VOC collector for a pumping period.
Suitably, the apparatus is configured whereby the pumping period, a
time of measurement and an atmospheric pressure at the time of
measurement are recorded.
[0012] Suitably, the apparatus comprises a pump for pumping gas
past the VOC concentration analyser and the VOC collector in a
downstream direction and a filter for removing any of particulates
or moisture from a gas input, wherein the VOC concentration
analyser and the VOC collector are upstream of the filter.
[0013] Suitably, the apparatus comprises a pump for pumping gas
past the VOC concentration analyser and the VOC collector in a
downstream direction and there is a gas flow path comprising a gas
input, a first valve upstream of the pump and a pressure sensor,
wherein the apparatus is configured whereby with the first valve
closed the pump is activated for a predetermined period and if
within the predetermined period a predetermined pressure is not
exceeded, as measured by the pressure sensor, a pump fail signal is
generated. Suitably, the predetermined period is between 8 and 12
seconds and the predetermined pressure is 100 mb.
[0014] Suitably, the apparatus comprises a pump for pumping gas
past the VOC concentration analyser and the VOC collector in a
downstream direction and there is a gas flow path comprising a gas
input, a first valve upstream of the pump, a pressure sensor and a
filter, wherein the apparatus is configured whereby with the first
valve open a first pressure sensor reading is taken, the pump is
activated for a predetermined period after which a second pressure
sensor reading is taken, and if the magnitude of the difference
between the first pressure sensor reading and the second pressure
sensor reading is greater than a predetermined value, a filter fail
signal is generated. Suitably, the predetermined period is between
2 seconds and 6 seconds. Suitably, the predetermined value is 250
mb.
[0015] Suitably, the time of sensing and the length of time for
which the pump operates are recorded
[0016] Suitably the apparatus comprises a second valve downstream
of the first valve and a gas outlet.
[0017] Suitably, the apparatus is configured to have a borehole
side and an atmospheric side, wherein there is a gas outlet to the
borehole side of the device and to the atmospheric side of the
device.
[0018] Suitably, the VOC concentration analyser and the VOC
collector are in series in a gas flow path with a gas analyser.
Suitably, the gas analyser analyses one or more of hydrocarbons,
carbon dioxide, oxygen and hydrogen sulphide.
[0019] According to the present invention is a second aspect, there
is provided a method of operation of an in-borehole gas monitor
apparatus, which method comprises the use of an in-borehole gas
monitor apparatus according to the first aspect of the invention in
a borehole.
[0020] Suitably, the VOCs collected by the VOC collector are
quantified.
[0021] Suitably, the apparatus comprises a pump for pumping gas
from the borehole past the VOC collector and the VOC analyser,
wherein the time of sensing and the length of time for which the
pump operates are recorded to determine the volume of gas passing
through the apparatus. This enable the VOC concentration to be
determined.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The present invention will now be described, by way of
example only, with reference to the drawings that follow; in
which:
[0023] FIG. 1 is a schematic illustration of a borehole site with
an in-borehole gas monitor according to the present invention.
[0024] FIG. 2 is a schematic cross-sectional elevation of an
in-borehole gas monitor apparatus according to the present
invention.
[0025] FIG. 3 is a schematic flow diagram illustrating a method of
operation of an in-borehole gas monitor apparatus according to the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] Referring to FIG. 1 of the accompanying drawings, there is
shown a borehole 2 in ground consisting of a landfill site. The
borehole 2 is supported by a liner 4 in which a plurality of
side-holes 6 are located to allow for sampling.
[0027] Referring to FIG. 2 of the accompanying drawings, there is
shown an in-borehole gas monitor (IGM) apparatus 8 including a cap
10. The cap 10 comprises an inner bore 12 for receiving the IGM
apparatus 8. The cap 10 includes an exterior screw thread 14 for
engaging with a corresponding interior screw thread (not shown) on
liner 4. Alternatively, the cap can be made as part of the housing.
A seal 16 is provided for fitting the IGM apparatus 8 in a borehole
when a suitable screw thread is not available for the cap 10 to be
used.
[0028] The IGM apparatus 8 consists of a body portion 17 which is a
self-contained unit meeting environmental rating IP-68, i.e.
essentially waterproof. The IGM apparatus 8 comprises a top 30 and
an external tube 32. The external diameter of tube 32 in this
embodiment is approximately 40 mm allowing for it to be inserted
into a typical borehole liner. In this embodiment of the invention,
the length of tube 32 is 800 mm, but may be less.
[0029] The IGM apparatus 8 further comprises a gas inlet 36
connected to a first entry valve 38, which gas inlet leads to a
volatile organic compounds ("VOC") detector 40 connected to a VOC
collector 42, connected to a water and particulate filter 44 for
removing any excess moisture and/or particles from the ingressed
gases. The filter 44 is connected to a first pressure sensor 46,
connected to a pump 48 connected to a gas detector 50 comprising a
plurality of gas analysers, in this case and H.sub.2S and CO sensor
52, a CO.sub.2 sensor 54, a CH.sub.4 sensor 56 and an O.sub.2
sensor 58. The detector is connected to a second valve 60 which is
connected to a return line (a first outlet) 62 back to the borehole
and a branched connection to a third valve 64 which is connected to
a second pressure sensor 66 from which extends a second outlet 68,
this time to atmosphere.
[0030] A suitable filter 44 is an in-line particulate and moisture
filter such as that available from Geotechnical Instruments of
Sovereign House, Queensway, Leamington Spa, United Kingdom.
[0031] The VOC detector 40 detects the presence and concentration
of a range of VOCs but does not distinguish between the various
VOCs. A suitable VOC sampler 40 is a photo-ionisation detector. The
VOC collector 42 is a sorbent and sorbs (that is, adsorbs or
absorbs) VOCs passing therethrough. A suitable VOC sampler 40 would
be a GORESorb (trade mark) tube with a multiplicity of small
sorbent balls therein.
[0032] Any suitable gas variable can be measured in the detector
50, the analysers typically being used to monitor hydrocarbons
(especially methane), carbon dioxide, oxygen carbon monoxide and
hydrogen sulphide concentrations.
[0033] The IGM apparatus 8 further comprises a combined controller
and memory 70 for controlling operation of the apparatus 8 and a
power cell (battery) 72 making the operation of the apparatus 8
self-contained, i.e. not reliant on data communication with or
power from an external source. The controller 70 includes a
clock.
[0034] A vent pipe 74 is provided running through the apparatus 8
from the bore-hole end to an outlet 76 through the top 30 to
atmosphere (the atmospheric end of the apparatus). A vent pipe
valve 78 is provided for the vent pipe 64 to control whether it is
open to atmosphere.
[0035] Also shown is a water detector 80, which detects the
presence or proximity of liquid water in the apparatus and upon
such detection transmits a signal to the controller 70. A
conductance sensor is used to determine a liquid water
presence.
[0036] Further, a water level detector (not shown) can be connected
to the bottom of the IGM apparatus and suspended therebelow in use
into the borehole. As wired pressure transducer can be used.
[0037] The top 30 includes a connector 82 allowing data
communication with a remote device and unit activation.
Additionally, a pressure sensor can be attached here for monitoring
borehole water level.
[0038] The IGM apparatus 8 is mounted in a borehole 2, within a
borehole liner with the cap 10 providing a gas-tight seal.
[0039] Over time, gases will build up in the borehole 2. The IGM
apparatus 8 is configured, specifically by programming of the
controller 70, to automatically and periodically test a gas sample
from the borehole. The process by which this is undertaken will now
be described.
[0040] First (step 100) a pump test is carried out. With first
valve 38 shut, the pump 48 is started and first pressure sensor 46
must read 100 mb within 10 seconds otherwise a FAIL warning is
produced by controller 70 as the pump 48 may have failed.
[0041] Next (step 102) a filter test is carried out. With first
valve 38 open after 4 seconds first pressure sensor 46 takes a
pressure reading BH. The pump 48 then runs for a predetermined
period and first pressure sensor 46 takes another pressure reading
BHP. If BHP-BH>250 mb a FAIL warning is produced by controller
70 as the filter 44 is likely to have become blocked.
[0042] Any FAIL warnings appear prominently as part of a data
download from the apparatus.
[0043] First and second valves 38 and 60 are opened (step 104) and
pump 48 is activated (step 106) to pump gas from the borehole
through the gas flow path described above to ensure the sensors
have an up to date gas sample from the borehole. The VOC detector
40 and VOC collector 42 precede the filter 44 which would otherwise
remove the VOCs from the gas flow. VOC's collected by the VOC
collector can be quantified by removing the VOC collector and
eluting the VOC's into an instrument such as a gas chromatograph.
Measurements (step 108) of VOC concentrations are made by the VOC
detector 40. Moisture and particulates are removed by the filter
44.
[0044] Borehole gas then passes through the detector 50 where it is
analysed by (step 110) by gas analysers 57, 54, 56 and 58.
[0045] A concurrent gas pressure measurement (step 112) is made by
first gas pressure sensor 38 and a reference measurement of
atmospheric pressure is made by second pressure sensor 66. The time
of the sensing and length of time for which the pump is operated
and recorded (step 114). Based on an empirical measurement or by
calculation, the volume of gas passing through the apparatus 8 per
unit time when the pump 48 is running can be determined.
Accordingly, it can be determined what volume of gas has passed
through the apparatus in any given testing period. This data is
stored in the controller/memory 70. The amount of VOC's collected
by the VOC collector can then be divided by the volume of gas
passed over the collector giving a measure of VOC
concentration.
[0046] First and second valves 38 and 60 are then closed (step
116). The gas from the borehole is circulated back to the borehole
through the borehole end of the apparatus.
[0047] Gas variable measurements are carried out by the gas
analysers 52, 54, 56 and 58. Any appropriate variable can be
monitored including one or more of the presence or absence of a
particular gas, a gas concentration level, a gas pressure, moisture
content in a gas, etc. The data from the gas variable measurements
is stored in the controller/memory 70.
[0048] A timer in the controller 70 is re-set (step 116) so that a
subsequent periodic measurement can be made.
[0049] The data stored in controller/memory 70 can be downloaded
over a hard-wired connection via the connector 82 or by wireless
transmission. This connection can also be used to program the
controller 70 to operate the apparatus 8 as desired. For instance,
variables such as the frequency of sampling, whether sampling is
regular or irregular, whether there should be a periodic venting to
atmosphere, etc can be set.
[0050] On an ongoing basis if the water detector 80 detects the
presence of water in the apparatus, a water detection signal is
sent to the controller 70 which can take an appropriate step, such
as deactivating the apparatus 8, transmitting an alert signal,
illuminating a warning light etc. This can both protect the
apparatus 8 from damage and avoid contaminated readings being
made.
[0051] As gases build up in the borehole over time, it can be
useful to open the borehole to atmosphere to reduce the pressure
therein, but also to provide the opportunity to, in effect,
re-start the sampling operation by allowing the borehole to
equilibrate to atmosphere. Thus, the base line for any monitoring
can be re-set and an analysis of the variation of gas variables
over time can be undertaken. The apparatus 8 can be configured to
vent the borehole to atmosphere periodically or on instruction.
[0052] Thus, there is provided a portable, self-contained IGM
apparatus that can be conveniently deployed in a borehole to take
periodic data readings of gas variables in the borehole.
[0053] In particular, preferred embodiments of the present
invention enable VOCs to be monitored. The combination of the VOC
detector together with the VOC collector and the determination of
the volume of gas passing through the apparatus enables a
calculation to be made of the absolute concentrations of specific
VOCs in the borehole and also how they vary over time. By
time-stamping the results, the variation of VOCs over time can be
monitored enabling, for instance, comparisons with other
time-variable phenomena, such as atmospheric pressure or weather
conditions.
[0054] Attention is directed to all papers and documents which are
filed concurrently with or previous to this specification in
connection with this application and which are open to public
inspection with this specification, and the contents of all such
papers and documents are incorporated herein by reference.
[0055] All of the features disclosed in this specification
(including any accompanying claims, abstract and drawings), and/or
all of the steps of any method or process so disclosed, may be
combined in any combination, except combinations where at least
some of such features and/or steps are mutually exclusive.
[0056] Each feature disclosed in this specification (including any
accompanying claims, abstract and drawings) may be replaced by
alternative features serving the same, equivalent or similar
purpose, unless expressly stated otherwise. Thus, unless expressly
stated otherwise, each feature disclosed is one example only of a
generic series of equivalent or similar features.
[0057] The invention is not restricted to the details of the
foregoing embodiment(s). The invention extends to any novel one, or
any novel combination, of the features disclosed in this
specification (including any accompanying claims, abstract and
drawings), or to any novel one, or any novel combination, of the
steps of any method or process so disclosed.
* * * * *