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WO2009023589A1 - Accumulation et recyclage de gaz capturé dans la récupération de fluides souterrains - Google Patents

Accumulation et recyclage de gaz capturé dans la récupération de fluides souterrains Download PDF

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Publication number
WO2009023589A1
WO2009023589A1 PCT/US2008/072685 US2008072685W WO2009023589A1 WO 2009023589 A1 WO2009023589 A1 WO 2009023589A1 US 2008072685 W US2008072685 W US 2008072685W WO 2009023589 A1 WO2009023589 A1 WO 2009023589A1
Authority
WO
WIPO (PCT)
Prior art keywords
gas
wellbore
vessel
lift
directing
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.)
Ceased
Application number
PCT/US2008/072685
Other languages
English (en)
Inventor
William G. Elmer
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.)
EOG Resources Inc
Original Assignee
EOG Resources Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by EOG Resources Inc filed Critical EOG Resources Inc
Publication of WO2009023589A1 publication Critical patent/WO2009023589A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • E21B43/122—Gas lift
    • E21B43/123—Gas lift valves

Definitions

  • the invention relates generally to a gas lift method and apparatus and, more particularly, to a method and apparatus for accumulation and/or recycling of captured gas in the recovery of subterranean fluids.
  • Gas lift is an artificial lift method accomplished by injecting gas into production tubulars to decrease the density of the fluid in the tubular, thereby allowing the formation pressure to lift the fluid column out of the wellbore.
  • Gas lift can be used in a variety of wells, including, but not limited to, oil and gas wells that have recently been fractured and thus are producing primarily fracture fluid, wells producing little gas, wells with heavy oils, wells with low reservoir pressure, coal bed methane extraction wells, or any well with liquid loading problems due to inadequate formation gas production.
  • the industry needs a simple and cost effective method and apparatus to obtain lift gas from wells producing little gas and to recycle the gas.
  • the industry needs a system that reduces or eliminates the need to rely on outside sources of lift gas for wells producing little or no gas.
  • the invention allows the capture and accumulation of gas from wellbore fluids containing small amounts of gas.
  • the accumulated gas is injected into the wellbore until a sufficient amount is present to serve as lift gas in the well.
  • a system in one embodiment, includes a separator for separating gases from wellbore fluid and a vessel for accumulating the separated gas.
  • the system also includes a switch that directs fluid from the vessel to a wellbore upon attainment of a condition, such as a certain pressure in the vessel.
  • the system may also include a compressor for compressing gas for injecting gas into the wellbore.
  • the switch is a valve that operates based on a pressure reading relating to the pressure in the vessel.
  • captured gas is stored in the vessel until the vessel reaches a certain pressure at which time the gas is directed from the vessel to the wellbore.
  • the pressure may be about 200, 100 psi, 50 psi, or less.
  • the valve may be set to close once the pressure in the vessel decreases to a second pressure, which may be, for example, 100 psi, 50 psi, 30 psi, or less.
  • the system will work with any wellbore fluid that has a low gas concentration such that lift gas cannot be readily obtained from it by traditional methods.
  • the concentration of gas in the wellbore fluid may be about 50, 20, or 10 standard cubic feet of gas per barrel of wellbore fluid, or less.
  • Gas lift valves allow captured gas that has been injected into the wellbore to pass through into a production portion of the wellbore.
  • the system may also include a high pressure vessel for storing excess lift gas.
  • a method in one embodiment, includes separating gases from wellbore fluid and collecting the gas in a vessel. The method also includes directing fluid from the vessel to a
  • the gas may be directed from the vessel to a compressor for compressing gas before injecting the gas into the wellbore.
  • the gas may be directed from the vessel to the wellbore until the attainment of a second pressure condition.
  • the steps are repeated until enough captured gas in injected into the wellbore to serve as lift gas. If enough gas has been injected into the wellbore, the method includes directing the gas through a gas lift valve into a production portion of the wellbore.
  • the method may also include charging the wellbore with gas from a portable charge gas source, such as a container containing less than about 25,000 standard cubic feet of gas.
  • FIGURE 1 is a schematic diagram of a lift gas capture and recycling apparatus representing one embodiment of the present invention
  • FIGURE 2 is a flow chart showing an embodiment of a method of using the present invention.
  • one embodiment of the present invention comprises wellbore 10, which includes annulus 100 between casing 101 and production tubing string 102.
  • Subterranean fluids also called wellbore fluids, are fluids that may be found in a wellbore, and may comprise, for example, natural gases, treatment gases, lift gases, air, treatment fluids, fracturing mixtures, water, hydrocarbons, drilling fluids, cuttings, salt, earthen materials, and the like.
  • the composition of wellbore fluids usually changes throughout the lifecycle of a well. For instance, because many wells are treated with large amounts of fracturing fluids to fracture the well, wellbore fluids produced in the early stages of a well's life may be predominantly fracturing fluids.
  • flow back fluid When a well is producing mostly fracturing fluids, the fluid is referred to as flow back fluid. Newly fractured wells will initially produce flow back fluids until enough of the fluid is removed to allow larger quantities of other subterranean fluids, such as natural gas and/or oil, to be produced. It may take days or weeks to remove enough flow back fluid to allow a well to produce a desirable amount of gas or oil.
  • flow back fluid may at first be produced without the need for artificial lift, but in most cases, as the well pressure decreases it will eventually require artificial lift, such as gas lift.
  • Gas lift involves directing a lift gas into a defined space such as a production tubing string to decrease the density of the fluid in the string, which results in the fluid being lifted to the surface.
  • Lift gas may comprise any gas or combination of gasses, and often comprises nitrogen and/or natural gas.
  • flow back fluids often comprise only small amounts of gas, sometimes called “early time gas.” Prior art systems, believing the concentration of gas to be too small for other uses, either sent early time gas to flare or vented it to the atmosphere. In some cases, flow back fluids contain less that 50 standard cubic feet of gas per barrel of wellbore fluid produced (“SCF/bbl”), while in other cases it may contain less that 20, 10, or 5 SCF/bbl, or less.
  • SCF/bbl standard cubic feet of gas per barrel of wellbore fluid produced
  • the current invention captures the small amounts of early time gas in the flow back fluid, accumulates the gas, and uses the accumulated gas for gas lift.
  • Wellbore fluids can be produced through well head 104 into separator 11.
  • Separator 11 separates gas, which leaves separator 11 through gas line 106, from other materials, which leave separator 1 1 through line 107.
  • Gas line 106 may include a vent 109 capable of venting to the atmosphere or to flare, but which is normally closed. While the system is accumulating gas, gas line 106 enters compressor 12, which directs the gas through valve 15 into lines 1 11 and 108. Gas volumes not returning to the compressor via line 1 11 will flow through line 108 to low pressure vessel 13.
  • compressor 12 may direct gas to valve 15 or valve 14.
  • valve 14 is a check valve that operates at a higher pressure than valve 15, and thus when valve 15 is open, gas will flow through valve 15.
  • valve 14 is closed when valve 15 is open.
  • valve 15 is connected to a control mechanism 16 that can be triggered to close valve 15 upon the attainment of a condition, such as upon reaching a certain pressure. Control mechanism 16 may be connected to a variety of equipment, such as valve 15 or low pressure vessel 13.
  • compressor 12 does not inject the gas into a pipeline or into wellbore 10 as lift gas. Instead, lines 108 and 11 1 allow compressor 12 to run in bypass mode to circulate a certain volume of gas from valve 15 through line 11 1 back to compressor 12 and to
  • Low pressure vessel 13 accumulates gas until a first condition is reached, such as a certain high pressure reading relating to the pressure in the low pressure vessel 13.
  • valve 15 blocks flow, causing gas to flow from low pressure vessel 13, through compressor 12, through valve 14, and into wellbore 10.
  • Compressor 12 directs gas from low pressure vessel 13 to wellbore 10 until a second condition is reached, such as a certain low pressure reading.
  • the first condition may be a pressure of 70 psi
  • the second condition may be a pressure of 30 psi.
  • the first and second condition may be different pressures, either higher or lower than the examples given, provided the second condition is a lower pressure than the first condition.
  • the pressure conditions may be determined by factors such as the well pressure, the constraints regarding back pressure on the well, the pressure rating of the equipment in the system, and safety factors, among others.
  • the first and second condition may be conditions other than pressure conditions, such as a timed interval.
  • Gas is injected through lift gas injection point 105 into wellbore 10.
  • Lift gas injection point 105 may appear on well head 104 or it may enter into wellbore 10 or a portion thereof from another location.
  • the amount of gas injected into wellbore 10 during any one accumulation phase will usually not be sufficient to direct gas through a gas lift valve in the wellbore.
  • the accumulation cycle is repeated until wellbore 10 contains enough gas to send it through one or more gas lift valves, such as gas lift valve 103 attached to production tubing string 102.
  • the reason that the amount of gas injected into wellbore 10 during any one accumulation phase will usually not be sufficient to direct gas through a gas lift valve in the wellbore is that the gas must be of sufficient volume to displace wellbore fluid in annulus 100.
  • wellbore fluid occupies annulus 100 and the inside of production tubing string 102.
  • gas from the accumulation cycle is directed by compressor 12 from low pressure vessel 13 into annulus 100, the level of the wellbore fluid in annulus 100 decreases in an amount
  • wellbore 10 may be 1,000 feet deep, and gas lift valve 103 may be 800 feet deep.
  • the system must inject sufficient gas in order to displace about 800 feet of wellbore fluid from annulus 100 in order to reach gas lift valve 103, which may require two or more accumulation and injection cycles.
  • wellbore 10 may be deeper or shallower, and gas lift valve 103 may be located at different depths.
  • lift gas may be injected into annulus 100, while in other embodiments it may be injected into a lift gas tubular (not shown) running alongside production tubing string 102. In a lift gas tubular embodiment, lift gas would accumulate in the lift gas tubular until it reaches a pressure sufficient to pass through the gas lift valve. In some embodiments, gas may be injected into a central tubular such as production tubing string 102 and the wellbore fluids produced through annulus 100. Those skilled in the art will recognize the many places into which lift gas may be injected in a wellbore. Hence, this specification and claims may refer generically to injecting gas into a wellbore, which includes, but is not limited to, injecting the gas as described in this paragraph.
  • relatively small and inexpensive sources of lift gas are used to prime the system instead of, or in addition to, the accumulation of early time gas.
  • conventional nitrogen bottles can be drained directly into wellbore 10 and/or into low pressure vessel 13. Utilizing small, portable sources of charge gas avoids the need for expensive systems such as nitrogen trucks or nitrogen membrane generation systems.
  • low pressure vessel 13 acts as a buffer against fluid slugging and allows for a steady flow of gas to the compressor. This can be important in some situations, such as where the lift gas comes out of the well at an uneven rate.
  • the early time gas that was stored is reused, allowing a continuous or semi-continuous supply of lift gas and obviating or reducing the need for any additional outside lift gas. Further, during the recycling phase, early time gas and other gas may still be captured, thus increasing the total amount of lift gas available. Excess lift gas can be stored in a back up lift gas supply, such as high pressure vessel 17. High pressure vessel 17 can obtain excess gas from line 1 10 coming from compressor 12, or it can be filled with nitrogen or other gases.
  • a method provides a means for accumulating and recycling lift gas from a well, especially a well producing wellbore fluid with a small gas concentration.
  • Oval 20 demonstrates providing a well that can benefit from gas lift.
  • a variety of wells may benefit from the present invention, including oil and gas wells, gas wells, coal bed methane extraction wells, and the like.
  • a well system may optionally be charged with a portable gas source, such as nitrogen bottles. Charging the system expedites the process of obtaining enough gas to initiate gas lift in the system.
  • gas is separated from remaining wellbore fluids, and, per box 23, the separated gas is directed to a vessel.
  • Diamond 24 demonstrates that the system directs separated gas to the vessel until the attainment of a condition.
  • the condition is a certain pressure. If the condition has not been attained, the system continues to separate gas and direct it to the vessel. If the condition has been attained, referring to box 25, the system directs some of the gas from the vessel into the wellbore. The amount of gas sent to the
  • wellbore may be determined by a second condition, such as a second pressure achieved in the vessel.
  • a second condition such as a second pressure achieved in the vessel.
  • some of the gas from the vessel may be diverted to a storage vessel.
  • the cycle is repeated beginning at box 22. If enough gas has been injected, the injected gas is directed through one or more gas lift valves so that it can serve as lift gas, as shown in box 27. Referring to diamond 28, after injecting the lift gas, if desired, the process is repeated. By repeating the process, lift gas can be efficiently and effectively recycled with the vessel acting as a buffer vessel to create steady flows of lift gas. If the process is not repeated, for instance, where the well comes in and lift gas is not required, the process can end as shown in oval 29.
  • the invention will work in a variety of embodiments for a variety of environments.
  • the invention will work for any system that can benefit from lift gas, including systems that cannot or prefer not to utilize the lift gas from a traditional source.
  • the invention will work with a well at any stage in its life cycle, wells producing little gas, wells with heavy oils, wells with low reservoir pressure, coal bed methane extraction wells, and the like.
  • the invention offers an inexpensive and efficient way to accumulate and/or recycle lift gas. Such a system can prevent costs and other difficulties from obtaining lift gas from an alternate source. Further, the invention allows operators to delay the decision of whether to tie a pipeline to a newly-drilled well, because the invention allows cheap lift gas production without a pipeline tie-in.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

L'invention concerne un système et un procédé pour capturer un gaz de soulèvement dans des puits avec une petite production de gaz de formation. Le système comprend un séparateur pour séparer des gaz d'un fluide de sondage et une cuve pour accumuler le gaz séparé. Le système comprend également un commutateur qui dirige le fluide de la cuve vers un sondage lors de l'atteinte d'une condition, telle qu'une certaine pression dans la cuve. Le procédé comprend les étapes de séparation du gaz d'un fluide de sondage, de direction du gaz vers une cuve d'accumulation et de direction du gaz de la cuve vers un sondage lors de l'atteinte d'une condition, telle qu'une certaine pression dans la cuve.
PCT/US2008/072685 2007-08-10 2008-08-08 Accumulation et recyclage de gaz capturé dans la récupération de fluides souterrains Ceased WO2009023589A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US11/837,047 US20090038806A1 (en) 2007-08-10 2007-08-10 Accumulation and recycling of captured gas in recovery of subterranean fluids
US11/837,047 2007-08-10

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Publication Number Publication Date
WO2009023589A1 true WO2009023589A1 (fr) 2009-02-19

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PCT/US2008/072685 Ceased WO2009023589A1 (fr) 2007-08-10 2008-08-08 Accumulation et recyclage de gaz capturé dans la récupération de fluides souterrains

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US (1) US20090038806A1 (fr)
CA (1) CA2638115A1 (fr)
WO (1) WO2009023589A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20240191606A1 (en) * 2022-12-09 2024-06-13 Liftrock, Llc Devices, systems, and methods for gas lift gas

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* Cited by examiner, † Cited by third party
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US12228020B2 (en) * 2022-12-09 2025-02-18 Liftrock, Llc Devices, systems, and methods for gas lift gas

Also Published As

Publication number Publication date
CA2638115A1 (fr) 2009-02-10
US20090038806A1 (en) 2009-02-12

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