EP0636228B1 - Compressing combustible gas flowing through a conduit - Google Patents

Compressing combustible gas flowing through a conduit Download PDF

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Publication number
EP0636228B1
EP0636228B1 EP93911487A EP93911487A EP0636228B1 EP 0636228 B1 EP0636228 B1 EP 0636228B1 EP 93911487 A EP93911487 A EP 93911487A EP 93911487 A EP93911487 A EP 93911487A EP 0636228 B1 EP0636228 B1 EP 0636228B1
Authority
EP
European Patent Office
Prior art keywords
tubular
conduit
inlet valve
return inlet
oxidant
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP93911487A
Other languages
German (de)
French (fr)
Other versions
EP0636228A1 (en
Inventor
Egbert Leonardus Cox
Robert Bruce Stewart
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shell Internationale Research Maatschappij BV
Original Assignee
Shell Internationale Research Maatschappij BV
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Publication date
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Publication of EP0636228A1 publication Critical patent/EP0636228A1/en
Application granted granted Critical
Publication of EP0636228B1 publication Critical patent/EP0636228B1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C15/00—Apparatus in which combustion takes place in pulses influenced by acoustic resonance in a gas mass
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/12—Methods or apparatus for controlling the flow of the obtained fluid to or in wells
    • E21B43/121—Lifting well fluids
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B36/00—Heating, cooling or insulating arrangements for boreholes or wells, e.g. for use in permafrost zones
    • E21B36/02—Heating, cooling or insulating arrangements for boreholes or wells, e.g. for use in permafrost zones using burners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
    • F04F1/00—Pumps using positively or negatively pressurised fluid medium acting directly on the liquid to be pumped
    • F04F1/06—Pumps using positively or negatively pressurised fluid medium acting directly on the liquid to be pumped the fluid medium acting on the surface of the liquid to be pumped
    • F04F1/16—Pumps using positively or negatively pressurised fluid medium acting directly on the liquid to be pumped the fluid medium acting on the surface of the liquid to be pumped characterised by the fluid medium being suddenly pressurised, e.g. by explosion

Definitions

  • the present invention relates to compressing combustible gas flowing through a conduit.
  • An example of such combustible gas is natural gas.
  • a suitable application of the present invention is downhole compression of natural gas, this is done to enhance the production from an underground natural gas reservoir.
  • Natural gas is produced from an underground reservoir containing natural gas through a tubing arranged in a well drilled to the reservoir. During production, the cumulative amount of natural gas produced increases and consequently the reservoir pressure will decrease. As a result of the decrease in reservoir pressure the production rate decreases and, in order to maintain the production rate at an economically acceptable level the gas has to be compressed and suitably gas is compressed downhole. This downhole gas compression will result in an increased economic cumulative production.
  • USA patent specification No. 2 899 287 discloses a method of compressing an oxidant-containing gas flowing through a conduit provided with a tubular arranged coaxially in the conduit which tubular has an inlet end and an outlet end and is provided with a non-return inlet valve at its inlet end.
  • the known method comprises the steps of
  • the pressure increase for the compression stage is very small, the pressure at the outlet end of the conduit is about 2 or 3% above the pressure at the inlet end.
  • a pressure increase for a compression stage is unacceptably small. Therefore it is an object of the present invention to provide a method of compressing a combustible gas which will yield a much larger pressure increase per compression stage.
  • the method according to the invention comprises the steps of
  • Applicant has found that to obtain a large pressure increase it is required to let the combustible gas flow intermittently through the conduit so that the high pressure wave front is fully utilized to push the gas out of the tubular allowing to entrain the combustible gas passing through the annular space.
  • the invention further relates to an apparatus for carrying out the method of compressing combustible gas.
  • the apparatus comprises a conduit, a non-return inlet valve arranged at the inlet end of the conduit, a tubular which is open at both ends and arranged coaxially in the conduit downstream of the non-return inlet valve such that an annular passage is defined between the tubular and the conduit, a localized ignition source arranged in the tubular, and an oxidant supply debouching into the tubular, wherein the conduit is locatable at a downhole location in a gas production well and the tubular is equipped with an oxidant supply through which such an amount of oxidant can be supplied that at least part of the natural gas is combusted in the tubular.
  • US patent specification No. 2860484 discloses an apparatus for causing intermittent combustion of a fuel where air flows through a conduit containing a tubular which is open at one end only and fuel is injected centrally into the tubular to produce useful energy.
  • the apparatus 1 for compressing combustible gas comprises a conduit 3 having an inlet end 5 and an outlet end 8, which conduit 3 is provided with a non-return inlet valve 10 arranged at the inlet end 5 of the conduit 3.
  • the open-ended tubular 13 is fixed in the conduit 3 by means of struts 15.
  • the cross-sectional area of the open-ended tubular 13 is smaller than the cross-sectional area of the conduit 3 so that an annular passage 17 is defined between the outer wall of the open-ended tubular 13 and the inner wall of the conduit 3.
  • the apparatus 1 furthermore comprises an oxidant supply 18 of which the outlet opening 19 debouches into the open-ended tubular 13, and a localized ignition source 20 arranged in the open-ended tubular 13 downstream of the outlet opening 19 of the oxidant supply 18.
  • the localized ignition source 20 is connected to a supply of electric power (not shown) for allowing the source 20 to glow.
  • the apparatus 1 is arranged in a pipe for transporting combustible gas, for example the apparatus 1 is arranged in a tubing (not shown) arranged in a well through which natural gas can rise from the bottom of the well to surface.
  • Electric power is supplied to the localized ignition source 20 and the mixture of combustible gas and oxidant is allowed to ignite in the open-ended tubular 13.
  • This ignition yields a high pressure wave front closing the non-return inlet valve 10 and pushing gas out of the open-ended tubular 13 and a low pressure wave front.
  • the gas flowing out of the open-ended tubular 13 entrains gas flowing through the annular space 17.
  • the amount of gas combusted in the open-ended tubular 13 is smaller than the total amount of combustible gas flowing through the conduit 3.
  • the non-return inlet valve 10 Upon arrival of the low pressure wave front at the non-return inlet valve 10, the non-return inlet valve 10 opens allowing natural gas to enter into the apparatus 1, and the above described sequence of steps starts again to compress the natural gas.
  • the localized ignition source 20 When the localized ignition source 20 is sufficiently heated, the localized ignition source acts as a hot spot so that supply of electric power can be interrupted.
  • the oxidant is a gas containing free oxygen, an example of suitable oxidant is air, a further example is air enriched with oxygen.
  • the oxidant can furthermore contain water, which upon vaporizing in the open-ended tubular 13 will furthermore increase the pressure.
  • the non-return inlet valve 10 can be provided with a control device (not shown) allowing opening of the non-return inlet valve 10 at a pre-determined pressure difference across the valve.
  • a control device is a spring, another example is a magnetic latch.
  • the conduit 3 has a constant inner diameter; in an alternative embodiment of the invention, the conduit comprises in the direction of flow a narrowing section, a section having a constant diameter (in which section the open-ended tubular is arranged) and a widening section.

Landscapes

  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Fluid Mechanics (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Feeding And Controlling Fuel (AREA)
  • Incineration Of Waste (AREA)
  • Reverberation, Karaoke And Other Acoustics (AREA)
  • Percussion Or Vibration Massage (AREA)
  • Pipeline Systems (AREA)

Abstract

Method of compressing combustible gas flowing through a conduit (3) provided with a non-return inlet valve (10) arranged at its inlet end (5) and with an open-ended tubular (13) arranged in the conduit (3) comprising (a) allowing combustible gas to enter into the conduit (3); (b) supplying oxidant to the combustible gas in the tubular (13), the amount of oxidant being equal to the amount of oxidant required to combust at least part of the combustible gas in the tubular (13); (c) allowing the mixture of combustible gas and oxidant to ignite in the tubular (13), which ignition yields a high pressure wave front closing the non-return inlet valve (10) and pushing gas out of the tubular (13) and entraining gas flowing through the annular space (17) and a low pressure wave front; and (d) allowing the non-return inlet valve (10) to open on arrival of the low pressure wave front, followed by steps (a) through (d).

Description

  • The present invention relates to compressing combustible gas flowing through a conduit. An example of such combustible gas is natural gas.
  • A suitable application of the present invention is downhole compression of natural gas, this is done to enhance the production from an underground natural gas reservoir. Natural gas is produced from an underground reservoir containing natural gas through a tubing arranged in a well drilled to the reservoir. During production, the cumulative amount of natural gas produced increases and consequently the reservoir pressure will decrease. As a result of the decrease in reservoir pressure the production rate decreases and, in order to maintain the production rate at an economically acceptable level the gas has to be compressed and suitably gas is compressed downhole. This downhole gas compression will result in an increased economic cumulative production.
  • USA patent specification No. 2 899 287 discloses a method of compressing an oxidant-containing gas flowing through a conduit provided with a tubular arranged coaxially in the conduit which tubular has an inlet end and an outlet end and is provided with a non-return inlet valve at its inlet end. The known method comprises the steps of
    • (a) supplying fuel into the tubular;
    • (b) allowing oxidant to enter into the tubular through the non-return inlet valve;
    • (c) allowing the mixture of fuel and oxidant to ignite, which ignition yields a high pressure wave front closing the non-return inlet valve and pushing gas out of the outlet end of the tubular and a low pressure wave front; and
    • (d) allowing the non-return inlet valve to open on arrival of the low pressure wave front, followed by steps (a) through (d).
  • In the known method the pressure increase for the compression stage is very small, the pressure at the outlet end of the conduit is about 2 or 3% above the pressure at the inlet end. For pumping natural gas such a pressure increase for a compression stage is unacceptably small. Therefore it is an object of the present invention to provide a method of compressing a combustible gas which will yield a much larger pressure increase per compression stage.
  • To this end in accordance with the invention there is provided a method of compressing combustible natural gas flowing at a downhole location in a natural gas production well through a conduit which contains a non-return inlet valve arranged at its inlet end and with a tubular which is open at both ends such that an annular passage is defined between the conduit and tubular. The method according to the invention comprises the steps of
    • (a) allowing gas to enter into the conduit through the non-return inlet valve;
    • (b) creating a combustible mixture in the tubular by supplying such an amount of oxidant that at least part of the combustible gas is combustible in the tubular;
    • (c) allowing the mixture of combustible gas and oxidant to ignite, which ignition yields a high pressure wave front closing the non-return inlet valve and pushing gas out of the tubular and a low pressure wave front; and
    • (d) allowing the non-return inlet valve to open on arrival of the low pressure wave front, followed by steps (a) through (d).
  • Applicant has found that to obtain a large pressure increase it is required to let the combustible gas flow intermittently through the conduit so that the high pressure wave front is fully utilized to push the gas out of the tubular allowing to entrain the combustible gas passing through the annular space.
  • The invention further relates to an apparatus for carrying out the method of compressing combustible gas. The apparatus according to the invention comprises a conduit, a non-return inlet valve arranged at the inlet end of the conduit, a tubular which is open at both ends and arranged coaxially in the conduit downstream of the non-return inlet valve such that an annular passage is defined between the tubular and the conduit, a localized ignition source arranged in the tubular, and an oxidant supply debouching into the tubular, wherein the conduit is locatable at a downhole location in a gas production well and the tubular is equipped with an oxidant supply through which such an amount of oxidant can be supplied that at least part of the natural gas is combusted in the tubular.
  • It is observed that US patent specification No. 2860484 discloses an apparatus for causing intermittent combustion of a fuel where air flows through a conduit containing a tubular which is open at one end only and fuel is injected centrally into the tubular to produce useful energy.
  • The invention will now be described by way of example in more detail with reference to the accompanying drawing showing schematically a cross-sectional view of the apparatus for carrying out the method of compressing combustible gas according to the invention.
  • The apparatus 1 for compressing combustible gas comprises a conduit 3 having an inlet end 5 and an outlet end 8, which conduit 3 is provided with a non-return inlet valve 10 arranged at the inlet end 5 of the conduit 3.
  • In the conduit 3 is arranged coaxially an open-ended tubular 13 downstream of the non-return inlet valve 10. The open-ended tubular 13 is fixed in the conduit 3 by means of struts 15. The cross-sectional area of the open-ended tubular 13 is smaller than the cross-sectional area of the conduit 3 so that an annular passage 17 is defined between the outer wall of the open-ended tubular 13 and the inner wall of the conduit 3.
  • The apparatus 1 furthermore comprises an oxidant supply 18 of which the outlet opening 19 debouches into the open-ended tubular 13, and a localized ignition source 20 arranged in the open-ended tubular 13 downstream of the outlet opening 19 of the oxidant supply 18. The localized ignition source 20 is connected to a supply of electric power (not shown) for allowing the source 20 to glow.
  • The apparatus 1 is arranged in a pipe for transporting combustible gas, for example the apparatus 1 is arranged in a tubing (not shown) arranged in a well through which natural gas can rise from the bottom of the well to surface.
  • During normal operation natural gas flows through the tubing and enters the apparatus 1 through the non-return inlet valve 10 arranged at the inlet end 5 of the conduit 3. The gas flows through the annular space 17 and through the open-ended tubular 13. Oxidant is supplied to the combustible gas in the open-ended tubular 13, wherein the amount of oxidant is sufficient to combust at least part of the combustible gas in the open-ended tubular 13. Suitably the amount of oxidant equals the amount of oxidant required to combust the combustible gas in the open-ended tubular 13.
  • Electric power is supplied to the localized ignition source 20 and the mixture of combustible gas and oxidant is allowed to ignite in the open-ended tubular 13. This ignition yields a high pressure wave front closing the non-return inlet valve 10 and pushing gas out of the open-ended tubular 13 and a low pressure wave front. The gas flowing out of the open-ended tubular 13 entrains gas flowing through the annular space 17.
  • The amount of gas combusted in the open-ended tubular 13 is smaller than the total amount of combustible gas flowing through the conduit 3.
  • Upon arrival of the low pressure wave front at the non-return inlet valve 10, the non-return inlet valve 10 opens allowing natural gas to enter into the apparatus 1, and the above described sequence of steps starts again to compress the natural gas.
  • When the localized ignition source 20 is sufficiently heated, the localized ignition source acts as a hot spot so that supply of electric power can be interrupted.
  • The oxidant is a gas containing free oxygen, an example of suitable oxidant is air, a further example is air enriched with oxygen. The oxidant can furthermore contain water, which upon vaporizing in the open-ended tubular 13 will furthermore increase the pressure.
  • The non-return inlet valve 10 can be provided with a control device (not shown) allowing opening of the non-return inlet valve 10 at a pre-determined pressure difference across the valve. An example of the control device is a spring, another example is a magnetic latch.
  • It will be appreciated that more than one apparatus according to the present invention can be arranged in series, each following apparatus compressing the gas compressed by the previous one. If required, the compressed gas can be cooled between two successive compression stages.
  • The conduit 3 has a constant inner diameter; in an alternative embodiment of the invention, the conduit comprises in the direction of flow a narrowing section, a section having a constant diameter (in which section the open-ended tubular is arranged) and a widening section.

Claims (4)

  1. A method of compressing a combustible natural gas flowing at a downhole location in a natural gas production well through a conduit (3) which contains a non-return inlet valve (10) arranged at its inlet end and a tubular (13) which is open at both ends such that an annular passage (17) is defined between the conduit (3) and tubular (13), which method comprises the steps of
    (a) allowing gas to enter into the conduit (3) through the non-return inlet valve (10);
    (b) creating a combustible mixture in the tubular (13) by supplying such an amount of oxidant that at least part of the combustible natural gas is combustible in the tubular (13);
    (c) allowing the mixture to ignite in the tubular, which ignition yields a high pressure wave front closing the non-return inlet valve and pushing gas out of the tubular and a low pressure wave front; and
    (d) allowing the non-return inlet valve to open on arrival of the low pressure wave front, followed by steps (a) through (d).
  2. An apparatus for carrying out the method of compressing gas according to claim 1, comprising a conduit (3), a non-return inlet valve (10) arranged at the inlet end of the conduit, a tubular (13) arranged coaxially in the conduit (3) downstream of the non-return inlet valve (10) such that an annular passage is defined between the tubular (13) and the conduit (3), a localized ignition source (20) arranged in the tubular (13), characterized in that the conduit (3) is locatable at a downhole location in a natural gas production well, that the tubular (13) is open at both ends and equipped with an oxidant supply (18) through which such an amount of oxidant can be supplied that at least part of the natural gas is combusted in the tubular (13).
  3. The apparatus according to claim 2, wherein the non-return inlet valve (10) is provided with a control device allowing opening the inlet valve at a pre-determined pressure difference.
  4. The apparatus according to claim 2, wherein the localized ignition source (20) is formed by a glow plug.
EP93911487A 1992-04-22 1993-04-19 Compressing combustible gas flowing through a conduit Expired - Lifetime EP0636228B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP92201140 1992-04-22
EP92201140 1992-04-22
PCT/EP1993/000961 WO1993021477A1 (en) 1992-04-22 1993-04-19 Compressing combustible gas flowing through a conduit

Publications (2)

Publication Number Publication Date
EP0636228A1 EP0636228A1 (en) 1995-02-01
EP0636228B1 true EP0636228B1 (en) 1997-12-17

Family

ID=8210571

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93911487A Expired - Lifetime EP0636228B1 (en) 1992-04-22 1993-04-19 Compressing combustible gas flowing through a conduit

Country Status (9)

Country Link
EP (1) EP0636228B1 (en)
AU (1) AU671992B2 (en)
CA (1) CA2133989C (en)
DE (1) DE69315829T2 (en)
DK (1) DK0636228T3 (en)
MY (1) MY109218A (en)
NO (1) NO304324B1 (en)
NZ (1) NZ251978A (en)
WO (1) WO1993021477A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5391057A (en) * 1992-04-22 1995-02-21 Shell Oil Company Compressing gas flowing through a conduit
AR023360A1 (en) * 1998-12-30 2002-09-04 Shell Int Research PULSE COMBUSTION APPARATUS, A METHOD FOR IMPROVING THE FLUID FLOW IN A NATURAL GAS PRODUCTION WELL AND A METHOD FOR HEATING A SUB-GROUND FORMATION WITH SUCH DEVICE

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2899287A (en) * 1959-08-11 Gas producer with
US2636445A (en) * 1946-12-27 1953-04-28 Fred S Tutton Production method and apparatus
FR1011313A (en) * 1949-01-15 1952-06-23 Brev Tamassy Soc D Expl Des Device for causing water to move
US2860484A (en) * 1956-06-04 1958-11-18 Schmidt Paul Apparatus for causing intermittent combustion of a fuel in a chamber as a means of producing useful energy
US5391057A (en) * 1992-04-22 1995-02-21 Shell Oil Company Compressing gas flowing through a conduit

Also Published As

Publication number Publication date
DE69315829D1 (en) 1998-01-29
WO1993021477A1 (en) 1993-10-28
NZ251978A (en) 1996-06-25
CA2133989A1 (en) 1993-10-28
DE69315829T2 (en) 1998-04-09
DK0636228T3 (en) 1998-03-16
AU4040693A (en) 1993-11-18
NO943982L (en) 1994-10-20
EP0636228A1 (en) 1995-02-01
NO943982D0 (en) 1994-10-20
MY109218A (en) 1996-12-31
CA2133989C (en) 2004-08-10
AU671992B2 (en) 1996-09-19
NO304324B1 (en) 1998-11-30

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