WO2021168525A1 - Système et procédé de production de gaz offshore avec écoulement monophasé vers la terre - Google Patents

Système et procédé de production de gaz offshore avec écoulement monophasé vers la terre Download PDF

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Publication number
WO2021168525A1
WO2021168525A1 PCT/BR2021/050076 BR2021050076W WO2021168525A1 WO 2021168525 A1 WO2021168525 A1 WO 2021168525A1 BR 2021050076 W BR2021050076 W BR 2021050076W WO 2021168525 A1 WO2021168525 A1 WO 2021168525A1
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WO
WIPO (PCT)
Prior art keywords
gas
liquid
phase
pipeline
offshore
Prior art date
Application number
PCT/BR2021/050076
Other languages
English (en)
Portuguese (pt)
Inventor
Roberto Rodrigues
Guilherme MIRANDA PATERNOST
Original Assignee
Petróleo Brasileiro S.A. - Petrobras
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 Petróleo Brasileiro S.A. - Petrobras filed Critical Petróleo Brasileiro S.A. - Petrobras
Publication of WO2021168525A1 publication Critical patent/WO2021168525A1/fr

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP 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
    • E21B43/34—Arrangements for separating materials produced by the well
    • E21B43/36—Underwater separating arrangements
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP 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
    • E21B43/34—Arrangements for separating materials produced by the well

Definitions

  • the present invention is related to the production and guarantee of the flow of subsea gas wells in offshore fields far from the coast. More particularly, the present invention is related to a system and method for single-phase gas flow, which enables the use of a single larger diameter pipeline, reducing back pressure at the head of producing wells for the purpose of increasing production and the recovery factor of an offshore gas field.
  • liquid is also produced, being a mixture of condensed hydrocarbons and water.
  • the amount of condensed hydrocarbons is minimal.
  • the amount of water can be significant, reaching tens or hundreds of m 3 per day.
  • higher flow velocities are used, with smaller diameters. Both the higher velocity and higher average fluid density due to the liquid cause higher back pressure at the wellhead, reducing produced volumes and the field's recovery factor.
  • a problem inherent to gas production at great depths concerns the risk of obstruction of pipelines by formation of hydrates, resulting from the direct contact of gas and water under conditions of high pressure and low temperature.
  • hydrate inhibitors are usually used that require long-length piping to transport large volumes of inhibitor (MEG) to the injection points on the seabed.
  • MEG inhibitor
  • methanol and ethanol can also be used, but without regeneration.
  • the order of magnitude of volume of inhibitor required is in the ratio of 1 to 1, that is, for each liter of water, a liter of inhibitor is needed. This increases the liquid volume of the pipeline's multiphase flow, increasing the risks of liquid accumulation and slugs and consequently the frequency of pig passage.
  • the multiphase flow demands an ascending pipe, avoiding low points (valleys) in the route, which can accumulate large amounts of liquid, generating head losses, instability and slugs.
  • Document W02005088071 A1 refers to the recovery of helium or methane gas, which is mixed with water at the bottom of the sea or ocean and, in particular, to a procedure and apparatus for its extraction, where in a The first operation is the rise, from the seabed, of a mixture of methane gas and water to a process unit at sea level. Then, due to the pressure reducing action of the mixture, as well as the increase in temperature, the separation of gas from sea water is obtained. Subsequently, the suction of free gas from the upper side of the process unit takes place, and finally, the suction of water and its discharge back into the sea takes place.
  • the document also shows that the gas/liquid separation compartment can be at sea or on land.
  • the in-water separation site is only effective when there is a greater distance from the coast, as an intermediate compression station between the separation and the shore is required.
  • the mixture is collected and sent to a submerged separation platform, with subsequent delivery of the gas to the onshore production unit and discharge of water from the platform directly into the sea, unlike the invention that injects the water into a shallow aquifer.
  • the document also deals with a gas/water separation process pumping to the onshore unit, it uses an intermediate compression station between the separation site and the onshore unit, unlike the present invention, which uses a direct connection.
  • the document US20170037720A1 discloses a system and method of processing natural gas, produced from a subsea well.
  • the system includes subsea processing to receive natural gas, separate free and condensable liquids comprising water and optionally liquid hydrocarbons, and produce a single-phase dry gas. It has a subsea processing unit that receives natural gas from the well, separating free and condensable liquids, compressing water and optionally, liquid hydrocarbons and producing a single-phase gas.
  • the fluids are then transported by risers to a surface production facility with a processing system located therein to process the separated free and condensable liquids in the subsea system.
  • a pipeline then transports the single-phase gas to the onshore production unit.
  • the single-phase dry gas produced in the subsea processing system is transported to an onshore production facility via a subsea pipeline.
  • the subsea system operates at high pressure and the surface system operates at low pressure.
  • Hydrocarbon liquids processed in surface production facilities can be combined with single-phase dry gas to produce a dense dry phase for transport through the subsea pipeline.
  • the document also makes reference to a method of managing hydrates and corrosion in a subsea production system. Unlike the invention that uses the fluid pressure itself to reduce the risk of hydrate and slugs, the document reveals the use of high pressure in the subsea processing system in addition to not sending the gas directly to the onshore unit.
  • the document WO2015048186A1 discloses an automated system to extract gas from an underground aquifer and methods such as gas/liquid separation and reinjection of the liquid into an aquifer.
  • the system consists of compressors, filtration units, sensors to measure parameters and flow controllers that regulate the flow of gas and liquid and coordinate the operation of the system to produce gas and introduce the fluid or fluid vapor into an aquifer.
  • the process consists of producing gas, performing gas/liquid separation, conditioning the gas in a container for a period of time that allows the gas to separate from the liquid, gas compression, distribution, fluid treatment and injection of the fluid into an aquifer.
  • Maintaining the fluid in an anaerobic state is desirable to prevent the growth of bacteria in the fluid during processing to prevent the introduction of algae and bacteria into the aquifer when the fluid is reintroduced into the aquifer.
  • the document discloses a storage tank for gas/liquid separation, which differs from the invention that uses a subsea separator with a depressurization system.
  • the present invention deals with a subsea offshore gas production system, in deep waters, with separation and reinjection of produced water into a reservoir, for example a shallow aquifer, through a simplified injection well or with well exploitation dry exploration, without a production column and flow of dry gas through a single pipeline, directly interconnected with the onshore production unit (subsea to shore), without the need for an offshore production unit, in order to reduce CAPEX and OPEX, to increase the flow rate and the recovery factor of an offshore gas field, compared to a production system without liquid separation.
  • the dry gas preferentially flows with its own pressure, with less risk of hydrate and a smaller amount of inhibitor, without the need for higher flow velocities to reduce the risk of slugs, and it is possible to use larger diameters that reduce the back pressure at the head of the producing wells, increasing the volumes produced and the recovery factor.
  • the invention also provides a reduction in the risk of hydrate in the pipeline during shutdowns by operating in a single-phase regime with almost 100% gas.
  • the present invention aims to provide a gas flow system based on a single pipeline, with liquid phase separation using a single separation train and injection of the same preferably into a shallow aquifer through a disposal well.
  • the present invention aims to dispose of liquid in a shallow aquifer through a simple disposal well.
  • the present invention aims to prevent contaminants from being released to the bottom of the sea. [0024]
  • the present invention aims to flow the dry gas through a single pipeline, directly interconnected with the onshore production unit, without the need for an offshore production unit.
  • the present invention aims to reduce CAPEX and OPEX costs.
  • the present invention aims to increase the flow rates and the recovery factor of an offshore gas field, if compared to the production system without liquid separation.
  • the present invention aims to provide operational methods for producing gas by a single pipeline, safely, minimizing hydrate risks.
  • FIG. 1 schematically illustrating a gas production system according to a first embodiment of the present invention, comprising a set of gas producing wells coupled to a single injection line;
  • FIG. 5 schematically illustrates an embodiment where the separator is a vessel for gravitational separation and the injection pump is mounted on a skid.
  • one or more gas wells (Pg1) are interconnected through production lines (9, 10), to a liquid separator of gas (2), eg a VASPS type separator, Vertical Annular Separation and Pumping System, or another type of gravity separator.
  • a liquid separator of gas (2) eg a VASPS type separator, Vertical Annular Separation and Pumping System, or another type of gravity separator.
  • the separated liquid composed mainly of produced water, is admitted by the pump (3) through the piping (11) and injected into an injection well (Pi) through the discharge piping (14).
  • the dry gas taken from the top of the separator (2) is sent through the pipeline (1) to a production unit (5) located on land.
  • the elements are also illustrated: surface compressor (6) and land pipeline (7) and sea surface (19).
  • a scraper (pig), rigid or gel, can be used periodically to give greater assurance that any liquid is removed from the pipeline.
  • a cartridge-type pig underwater launcher (13) can be added to the system giving greater robustness and operational flexibility.
  • the water may, instead of being injected into the injector well (Pi), be drained to the seabed or to a reservoir or even to a shallow aquifer (15), however this procedure requires approval of competent environmental agency.
  • FIG. 2 illustrates an optional embodiment where a wet gas compressor (20) can be used for eventual depressurization of lines and subsea equipment to mitigate hydrates.
  • the compressor depressurizes the separator through the compressor suction line (21). All fluid removed is injected into the waste pit (Pi) through the compressor discharge line (22).
  • Several shut-off valves (24) allow you to select which piping will be depressurized.
  • FIG. 3 illustrates an embodiment where the separated liquid is pumped and drained to the onshore production unit (5) through a long pipe (10a) of smaller diameter, with likely parallel to the pipeline (1).
  • FIG 4 illustrates an embodiment where the separated liquid is stored in a monobuoy (16).
  • the elements are still indicated: mooring lines (17) of the monobuoy (16) and offloading and relief vessel (18).
  • the monobuoy (16) can also host renewable energy generation systems, such as wind turbine (26) and solar panels (27).
  • the monobuoy (16) can also host other utilities such as: gas power generation, remote control system, etc.
  • Figure 5 schematically illustrates an embodiment where the separator (2) is a vessel for gravitational separation and the injection pump (3) is mounted on a Skid (25).
  • a subsea compressor (28) at the separator outlet (2), in order to reduce the back pressure at the wellhead and also to send the gas to more distant places, tens and even hundreds of kilometers.
  • the present invention further provides a method for Offshore gas production with reduction of back pressure at the head of producer wells, comprising the steps of:
  • the method of the present invention comprises the additional step of periodically pigging to remove any liquid accumulated in the pipeline, measuring the volumes of liquid removed in pigging operations, optimizing the frequency of pig passage, injecting inhibitor of hydrate at the ends of the subsea pipeline, inject hydrate inhibitor into the production lines and Christmas trees of each well.
  • It provides a gas production system with a gas-liquid separation system with the additional function of dissolving the hydrate remotely in subsea pipelines, equipment and pipeline, without the need to mobilize a vessel or offshore probe; and d. It provides a gas production system directly to land with a single pipeline (1), without the need for an offshore production unit, significantly reducing the complexity of offshore installations resulting in a reduction in construction, installation, operation and maintenance costs (CAPEX and OPEX ); and is. It allows an operation with less risk to the environment, since the water produced is reinjected, reducing the consumption of hydrate inhibiting chemicals; and f. Mitigates hydrate risks in the pipeline (1) during stoppages as it operates in a single-phase regime, with almost 100% gas; and g. It does not present technological obstacles with regard to the equipment used, since the system according to the present invention comprises the integration of components and established technologies.

Abstract

La présente invention concerne un système sous-marin de production de gaz offshore, en eaux profondes, avec séparation et réinjection d'eau produite dans un aquifère peu profond, au moyen d'un puits d'injection simplifié, et écoulement du gaz sec à travers un gazoduc unique, relié directement à l'unité de production sur terre (« subsea-to-shore »), sans qu'il soit nécessaire d'utiliser une unité de production offshore, l'objectif étant de réduire les coûts CAPEX et OPEX, d'augmenter les débits et le facteur de récupération d'un champ offshore de gaz, par comparaison avec le système de production sans séparation de liquide. Le gaz sec s'écoule de préférence sous l'action de sa propre pression, d'où une diminution du risque de formation d'hydrates et une quantité d'inhibiteur utilisé réduite, sans qu'il soit nécessaire de recourir à des vitesses supérieures d'écoulement pour réduire le risque de formation de bouchon, avec possibilité d'utiliser des diamètres supérieurs qui réduisent la contre-pression au niveau de la tête des puits de production, augmentant ainsi les volumes produits et le facteur de récupération. L'invention permet également de réduire le risque de formation d'hydrates dans le gazoduc pendant les interruptions du fait d'un fonctionnement en régime monophasé avec presque 100 % de gaz.
PCT/BR2021/050076 2020-02-28 2021-02-19 Système et procédé de production de gaz offshore avec écoulement monophasé vers la terre WO2021168525A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BRBR1020200040278 2020-02-28
BR102020004027-8A BR102020004027A2 (pt) 2020-02-28 2020-02-28 Sistema e método de produção de gás offshore escoado monofasicamente para terra

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WO2021168525A1 true WO2021168525A1 (fr) 2021-09-02

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WO (1) WO2021168525A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024042351A1 (fr) * 2022-08-25 2024-02-29 Al Ajaji Abdulaziz Opérations sans torche à l'aide de tuyaux non métalliques

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101555797A (zh) * 2009-05-19 2009-10-14 四川大学 海底天然气水合物开采装置及其开采方法
US20090321366A1 (en) * 2006-07-07 2009-12-31 Edwin Poorte Method of processing and separating a multiphase well effluent mixture
CN103867165A (zh) * 2014-03-14 2014-06-18 大连理工大学 一种安全高效的海洋天然气水合物降压分解开采装置和方法
CN103883305A (zh) * 2014-01-20 2014-06-25 中国石油大学(华东) 一种深水海底油水分离及回注装置
WO2018009073A1 (fr) * 2016-07-06 2018-01-11 Aker Solutions As Ensemble de production de méthane sous-marin

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090321366A1 (en) * 2006-07-07 2009-12-31 Edwin Poorte Method of processing and separating a multiphase well effluent mixture
CN101555797A (zh) * 2009-05-19 2009-10-14 四川大学 海底天然气水合物开采装置及其开采方法
CN103883305A (zh) * 2014-01-20 2014-06-25 中国石油大学(华东) 一种深水海底油水分离及回注装置
CN103867165A (zh) * 2014-03-14 2014-06-18 大连理工大学 一种安全高效的海洋天然气水合物降压分解开采装置和方法
WO2018009073A1 (fr) * 2016-07-06 2018-01-11 Aker Solutions As Ensemble de production de méthane sous-marin

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024042351A1 (fr) * 2022-08-25 2024-02-29 Al Ajaji Abdulaziz Opérations sans torche à l'aide de tuyaux non métalliques

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