U.S. patent application number 10/627986 was filed with the patent office on 2004-04-22 for method for providing a stream of pressurized substantially inert gas.
Invention is credited to Krill, Ross Michael.
Application Number | 20040074637 10/627986 |
Document ID | / |
Family ID | 25529969 |
Filed Date | 2004-04-22 |
United States Patent
Application |
20040074637 |
Kind Code |
A1 |
Krill, Ross Michael |
April 22, 2004 |
Method for providing a stream of pressurized substantially inert
gas
Abstract
Disclosed is a method of producing a pressurized stream of
substantially inert gas. The method comprises collecting at least a
portion of the exhaust gases from an internal combustion engine.
The collected exhaust gases are directed into the intake of a
compressor which compresses the exhaust gases such that the exhaust
gases exit the compressor at a pressure that is above atmospheric
pressure. A portion of the compressed exhaust gases are
re-circulated back into the intake of the compressor. The
re-circulated portion of the compressed exhaust gases are of a
sufficient volume to maintain the pressure within the compressor
intake above atmospheric pressure and to thereby prevent
atmospheric gases from being drawn into the intake of the
compressor and into the stream of substantially inert gas.
Inventors: |
Krill, Ross Michael; (Red
Deer, CA) |
Correspondence
Address: |
MEREK, BLACKMON & VOORHEES, LLC
673 South Washington Street
Alexandria
VA
22314
US
|
Family ID: |
25529969 |
Appl. No.: |
10/627986 |
Filed: |
July 28, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10627986 |
Jul 28, 2003 |
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09983461 |
Oct 24, 2001 |
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6662885 |
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Current U.S.
Class: |
166/90.1 ;
166/258; 166/305.1 |
Current CPC
Class: |
F02C 6/06 20130101; F02C
3/34 20130101; B01J 2219/00108 20130101; F02D 29/04 20130101; B01J
19/14 20130101; C09K 8/38 20130101 |
Class at
Publication: |
166/090.1 ;
166/305.1; 166/258 |
International
Class: |
E21B 019/00 |
Claims
I claim:
1. A method of producing a pressurized stream of substantially
inert gas, the method comprising: (i) collecting at least a portion
of the exhaust gases from an internal combustion engine; (ii)
directing said collected exhaust gases into the intake of a
compressor, said compressor compressing said exhaust gases such
that said exhaust gases exit said compressor at a pressure that is
above atmospheric pressure; and, (iii) re-circulating a portion of
said compressed exhaust gases back into said intake of said
compressor, said re-circulated portion of said compressed exhaust
gases being of a sufficient volume to maintain the pressure within
said compressor intake above atmospheric pressure to thereby
prevent atmospheric gases from being drawn into said intake of said
compressor and into said stream of substantially inert gas.
2. The method as claimed in claim 1 wherein said compressor is
driven by an electric or hydraulic motor and said exhaust gases are
collected from one or more remote internal combustion engines.
3. The method as claimed in claim 1 wherein said internal
combustion engine drives said compressor.
4. The method as claimed in claim 3 including the step of
controlling the volume of re-circulated compressed exhaust gases
delivered to said compressor intake to increase the volumetric
throughput of said compressor and to increase the load on said
internal combustion engine to thereby generate a volume of exhaust
gas from said engine that substantially matches the input
requirements of said compressor.
5. The method as claimed in claim 1 including the further step of
utilizing one or more valves situated within a re-circulation
conduit that delivers said re-circulated compressed exhaust gases
to said compressor intake to control the volume of said
re-circulated compressed exhaust gas delivered to said compressor
intake.
6. The method as claimed in claim 1 including monitoring the gas
pressure within said compressor intake and adjusting the volumetric
flow of said re-circulated compressed exhaust gases delivered to
said compressor intake in response to fluctuations in the pressure
within said compressor intake so as to maintain the pressure within
said compressor intake above atmospheric pressure and within
pre-determined levels.
7. The method as claimed in claim 1 including the further step of
collecting the exhaust gases from a plurality of internal
combustion engines and directing said exhaust gases into said
intake of said compressor.
8. A method of producing a pressurized stream of substantially
inert gas and to assist in maintaining the purity of said stream of
substantially inert gas, the method comprising: (i) directing a
stream of substantially inert gas into the intake of a compressor,
said compressor compressing said gas such that said gas exits said
compressor at a pressure that is above atmospheric pressure; and,
(iii) re-circulating a portion of said compressed gas exiting said
compressor back into said intake of said compressor to maintain the
pressure within said compressor intake above atmospheric pressure
and to thereby help maintain the purity of said substantially inert
gas by preventing atmospheric gases from being drawn into said
intake of said compressor and into said stream of substantially
inert gas.
9. The method as claimed in claim 8 wherein said stream of
substantially inert gas is the exhaust from one or more internal
combustion engines.
10. The method as claimed in claim 8 wherein said stream of
substantially inert gas is the exhaust from an internal combustion
engine that is used to drive said compressor.
11. The method as claimed in claim 8 including the further step of
utilizing one or more valves to control the volume of said
re-circulated compressed gas delivered to said compressor
intake.
12. The method as claimed in claim 8 including monitoring the gas
pressure within said compressor intake and adjusting the volumetric
flow of said re-circulated compressed gas delivered to said
compressor intake in response to fluctuations in the pressure
within said compressor intake so as to maintain the pressure within
said compressor intake above atmospheric pressure and within
predetermined levels.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of and claims priority
from U.S. patent application Ser. No. 09/983,461, filed Oct. 24,
2001.
FIELD OF THE INVENTION
[0002] This invention relates to a method for producing a stream of
pressurized substantially inert gas, and in one particular
embodiment to a method for producing a stream of pressurized
substantially inert gas for use in drilling wells through
hydrocarbon formations.
BACKGROUND OF THE INVENTION
[0003] A stream of readily available, inexpensive and substantially
inert gas is often required for a variety of different industrial
applications. In this context the term substantially inert is used
to generally describe gases with little or no appreciable free
oxygen content. Such gases may contain varying amounts of
hydrocarbons and other compounds and are for that reason not be
truly inert, however, for the intended applications described below
if a gas contains little or no appreciable free oxygen it will be
considered to be substantially inert.
[0004] One such industry that requires a source of substantially
inert gas is the petroleum industry. In oil drilling and
production, substantially inert gases are often required for
purposes of drilling, reservoir pressure maintenance, and for
purging systems. For example, when drilling an oil or gas well,
drilling fluids are often required to be circulated from the
surface down through the drill string to the drill bit and back up
to the surface again. The function of the drilling fluids is
largely to control subsurface pressures, to carry away cuttings and
other debris from the bottom of the well bore, and to eventually
flush the cuttings from the well. In some instances the drilling
fluids may also be used to "power" a downhole motor used to drive a
drill bit. In certain types of drilling, and most notably
underbalanced drilling, relatively low density drilling fluids that
have densities generally less than water are utilized. In many such
instances the low density fluids are comprised of gases. To
minimize potential fire, explosion, and corrosion problems, ideally
such gases are substantially inert.
[0005] Historically inert gases (for example nitrogen) that are
required for use in drilling operations have been transported to
drilling sites in sealed pressure vessels. However, due to the
transportation costs associated with bringing large volumes of
inert gas to a remote oil or gas drilling site, a practice has
developed wherein the exhaust gas stream from an internal
combustion engine is utilized as a source of substantially inert
gas. In such applications exhaust gases from the internal
combustion engine are typically collected, cooled, deacidified if
necessary, and then directed to a compressor where their pressure
is increased prior to being injected into a well. Provided that the
internal combustion engine operates at a high enough level of
efficiency there will be either no oxygen in the exhaust or only a
relatively minor amount of oxygen present.
[0006] While the exhaust stream from an internal combustion engine
provides a somewhat convenient and readily accessible supply of
substantially inert gas, an inherent problem that arises when
utilizing exhaust gas as a feed source for a compressor is that the
compressor will typically have a higher capable throughput than the
volume of exhaust gas that can be created by the engine. Where
there is insufficient exhaust to feed the compressor, a vacuum will
tend to form within the intake manifold. This vacuum in turn has a
tendency of drawing atmospheric air into the system. If atmospheric
air is allowed to enter the gas stream the percentage of oxygen in
the gas injected into the well increases, thereby increasing the
possibility of an explosion or fire, and increasing the likelihood
of corrosion.
[0007] To combat this problem others have tried to direct the
output from other unrelated internal combustion engines (for
example nearby generator sets, etc.) into the feed stream of the
compressor to balance the available exhaust gas stream with the
compressor's input. Unfortunately the amount of unrelated exhaust
gas readily available is rarely sufficient. Still others have
connected hydraulic or mechanical brakes, generators or other
devices to the internal combustion engine in an attempt to force it
to operate under an enhanced load situation so as to generate
excess exhaust. While such attempts have had limited success under
specific circumstances, they add mechanical complexity, expense,
and a further source for mechanical breakdown.
SUMMARY OF THE INVENTION
[0008] The invention therefore provides a method for producing a
stream of substantially inert gas from an internal combustion
engine that provides a means of effectively increasing the load on
the engine to enhance exhaust gas production, while simultaneously
providing sufficient intake gas to meet the needs of a compressor
or bank of compressors. The invention accomplishes this result
without the need to utilize the exhaust gases from unrelated
internal combustion engines, and without the addition of complex
and costly mechanical structures. The invention also provides for
the establishment and the maintenance of a positive gas pressure
within the compressor intake manifold to limit the ingress of
atmospheric air into the compressor system.
[0009] Accordingly, in one of its aspects the invention provides a
method of producing a pressurized stream of substantially inert
gas, the method comprising collecting at least a portion of the
exhaust gases from an internal combustion engine; directing said
collected exhaust gases into the intake of a compressor, said
compressor compressing said exhaust gases such that said exhaust
gases exit said compressor at a pressure that is above atmospheric
pressure; and, re-circulating a portion of said compressed exhaust
gases back into said intake of said compressor, said re-circulated
portion of said compressed exhaust gases being of a sufficient
volume to maintain the pressure within said compressor intake above
atmospheric pressure to thereby prevent atmospheric gases from
being drawn into said intake of said compressor and into said
stream of substantially inert gas.
[0010] In a further aspect the invention provides a method of
producing a pressurized stream of substantially inert gas and to
assist in maintaining the purity of said stream of substantially
inert gas, the method comprising directing a stream of
substantially inert gas into the intake of a compressor, said
compressor compressing said gas such that said gas exits said
compressor at a pressure that is above atmospheric pressure; and,
re-circulating a portion of said compressed gas exiting said
compressor back into said intake of said compressor to maintain the
pressure within said compressor intake above atmospheric pressure
and to thereby help maintain the purity of said substantially inert
gas by preventing atmospheric gases from being drawn into said
intake of said compressor and into said stream of substantially
inert gas.
[0011] Further advantages of the invention will become apparent
from the following description taken together with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] For a better understanding of the present invention, and to
show more clearly how it may be carried into effect, reference will
now be made, by way of example, to the accompanying drawings which
show the preferred embodiments of the present invention in
which:
[0013] FIG. 1 is a side pictorial view of an internal combustion
engine driving a compressor depicting the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] The present invention may be embodied in a number of
different forms. However, the specification and drawings that
follow describe and disclose only some of the specific forms of the
invention and are not intended to limit the scope of the invention
as defined in the claims that follow herein.
[0015] With reference to FIG. 1 there is shown pictorially an
apparatus constructed in accordance with one of the preferred
embodiments of the present invention. FIG. 1 shows a compressor 1
having an intake manifold 2 and an output manifold 3.
[0016] Compressor 1 may take the form of any one of a wide variety
of commonly available compressors or compressor systems and may be
driven by an equally wide variety of power sources. In the
embodiment shown in FIG. 1, compressor 1 is driven by means of the
rotating drive shaft 4 of an internal combustion engine 5.
[0017] Where, as in the case of the present invention, there is a
desire to produce a pressurized stream of substantially inert gas,
intake manifold 2 is preferably designed to receive the output
exhaust gas stream from one or more internal combustion engines. In
configurations such as that shown in FIG. 1 delivering an output
exhaust gas stream to intake manifold 3 can be accomplished through
connecting the exhaust manifold 6 of internal combustion engine 5
to intake manifold 2 by means of a duct or conduit 7. Depending
upon the proximity of compressor 1 to internal combustion engine 5,
in some instances it may be possible to directly connect compressor
intake manifold 2 to internal combustion engine exhaust manifold
6.
[0018] Whether or not the two manifolds are connected directly, or
indirectly through use of a duct or conduit 7, in the described
configuration the compressor feed will be comprised of the output
exhaust gas stream from internal combustion engine 5. It should be
noted that in some circumstances it may also be desirable to direct
the exhaust gas stream from additional internal combustion engines
operating in the general vicinity of compressor 1 into intake
manifold 2. Similarly, where compressor 1 is driven by an electric
motor or other power source, it will be understood that the exhaust
gas stream from one or more separate internal combustion engines
will need to be directed to the compressor's intake manifold.
[0019] When producing a stream of substantially inert gas for a
particular application (for example for down hole drilling through
hydrocarbon formations, reservoir pressure maintenance, purging,
etc.) it is often imperative that the gas stream be essentially
devoid of any oxygen content. Typically, during the operation of
compressor 1, a vacuum condition would be established within the
compressor's intake manifold as it draws air or gas through it.
Where, as in the present case, the feed for the compressor is the
exhaust gas stream from an internal combustion engine, to the
extent possible it is therefore preferable to balance the draw of
the compressor against the exhaust output of the engine so as to
limit the draw of atmospheric air into the system. Unfortunately,
from a practical perspective it is rarely possible to precisely
match the output of the engine with the requirements of the
compressor over all ranges of operating conditions. As a result a
vacuum condition within the compressor's intake manifold is often
established causing the compressor to draw into its intake manifold
atmospheric air and introducing oxygen into the compressed gas
stream.
[0020] To combat this scenario, the present invention utilizes a
compressed gas re-circulation passageway or conduit 8 that connects
compressor output manifold 3 to intake manifold 2 such that a
portion of the pressurized gas exiting compressor 1 is
re-circulated from the output manifold back to the intake manifold.
The provision of pressurized gas from the output to the intake
manifold in this manner assists in maintaining the gas pressure
within intake manifold 2 above atmospheric pressure. Provided that
the feed of compressor 1 is substantially inert, the compressed gas
that is re-circulated through conduit 8 will also be substantially
inert and its introduction into intake manifold 2 will not result
in the addition of oxygen or atmospheric gases into the compressor
system. Pressurizing intake manifold 2 with substantially inert gas
in this manner, such that the gas pressure within the intake
manifold is maintained above atmospheric pressure, will prevent any
draw of atmospheric gases (including oxygen) into the system.
[0021] It will be appreciated that the re-circulation of a portion
of the compressed exhaust gases will require that the compressor be
designed with an increased capacity above and beyond the capacity
of output gas required for the desired application. That is, since
a portion of the gas exiting the compressor through output manifold
3 will be recycled back to the intake manifold, the entire output
of the compressor will not be available for use in the desired
application. The compressor will therefore have to be oversized to
accommodate the re-circulation of a portion of its pressurized
output stream. Oversizing the compressor and effectively increasing
its volumetric throughput provides the added benefit of increasing
the load on internal combustion engine 5, which in turn increases
the production of exhaust gases that will be available for
compressor feed. The oversized compressor can thus be used to
maximize the horsepower output of the internal combustion engine
(and hence the production of exhaust gases) while at the same time
preventing the compressor from being "starved" of feed gas on
account of the re-circulation of pressurized gases from output
manifold 3 to intake manifold 2 by means of re-circulation conduit
8.
[0022] With reference again to FIG. 1, in a preferred embodiment of
the invention a valve 9 is situated within gas re-circulation
conduit 8 to allow for the control of the volume and flow of gas
therethrough. Depending on the desired degree of automation, valve
9 can be either manually controlled or automatically controlled
through pneumatic, hydraulic or electric actuators. Alternatively,
valve 9 could also be a regulator that maintains compressor inlet
pressure by way of a spring. Where valve 9 is manually controlled
typically there would be placed within intake manifold 2 a pressure
gauge indicating to an operator the internal gas pressure within
the manifold so that manual adjustments to valve 9 may be made as
necessary in order to maintain a desired manifold pressure.
[0023] In a further embodiment of the invention a pressure sensor
10 may be mounted within intake manifold 2 and connected to a
microprocessor control 11. In this embodiment valve 9 would
preferably be an automatic valve having an actuator also controlled
by microprocessor 11. Programming the microprocessor control will
then allow valve 9 to be automatically adjusted in response to
changes in gas pressure detected within intake manifold 2 by
pressure senor 10. Microprocessor control 11 will thus help to
ensure that the flow of compressed gas from output manifold 3 to
intake manifold 2 is controlled in response to fluctuations in the
gas pressure within the intake manifold so as to maintain the
pressure within the intake manifold between a pre-determined upper
and lower limit. In the event that the gas pressure within intake
manifold 2 should for some reason (whether it be through mechanical
breakdown, blockage of conduits, etc.) drop below atmospheric
levels, microprocessor 11 could be designed to activate an alarm to
notify an operator that there is a danger that atmospheric air may
be drawn into the system or, alternatively, the compressor system
may be caused to shut down pending an investigation of the
problem.
[0024] It will therefore be appreciated that the above described
device provides an apparatus and a method for producing a
pressurized stream of substantively inert gas that minimizes the
risk that atmospheric oxygen may be drawn into the gas stream. This
apparatus and method also allows for the utilization of a readily
available source of substantially inert gas in the form of the
exhaust gas stream from an internal combustion engine. The
described apparatus and method may also either reduce the necessity
of employing expensive catalytic convertors or other devices to
remove atmospheric oxygen that may otherwise be drawn into the
system, or reduce the amount of oxygen that such systems are
required to remove from the exhaust stream and thereby reduce the
operating costs of such secondary systems. The described device and
method may also be retrofitted onto existing compressor systems and
readily lends itself to automatic control. The compressed
substantially inert gas that is expelled through output manifold 3
of compressor 1 will be substantially devoid of oxygen and
generally suitable for a wide variety of different applications,
including injecting into a wellbore while drilling through
hydrocarbon formations.
[0025] It is to be understood that what has been described are the
preferred embodiments of the invention and that it may be possible
to make variations to these embodiments while staying within the
broad scope of the invention. Some of these variations have been
discussed while others will be readily apparent to those skilled in
the art.
* * * * *