WO2022099939A1 - Procédé d'exploitation de pétrole à viscosité élevée - Google Patents

Procédé d'exploitation de pétrole à viscosité élevée Download PDF

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Publication number
WO2022099939A1
WO2022099939A1 PCT/CN2021/075005 CN2021075005W WO2022099939A1 WO 2022099939 A1 WO2022099939 A1 WO 2022099939A1 CN 2021075005 W CN2021075005 W CN 2021075005W WO 2022099939 A1 WO2022099939 A1 WO 2022099939A1
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oil
low
viscosity oil
temperature
viscosity
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PCT/CN2021/075005
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English (en)
Chinese (zh)
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钟立国
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中国石油大学(北京)
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Publication of WO2022099939A1 publication Critical patent/WO2022099939A1/fr

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    • 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
    • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G53/00—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes
    • C10G53/02—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes plural serial stages only
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G7/00—Distillation of hydrocarbon oils
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G7/00—Distillation of hydrocarbon oils
    • C10G7/06—Vacuum distillation
    • 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
    • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
    • E21B43/166—Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium
    • 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
    • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
    • E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
    • 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
    • E21B43/34—Arrangements for separating materials produced by the well
    • E21B43/40—Separation associated with re-injection of separated materials
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00—Investigating or analyzing materials by the use of thermal means
    • G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity
    • G01N25/22—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity on combustion or catalytic oxidation, e.g. of components of gas mixtures
    • G01N25/26—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity on combustion or catalytic oxidation, e.g. of components of gas mixtures using combustion with oxygen under pressure, e.g. in bomb calorimeter

Definitions

  • the invention relates to a method for exploiting high-viscosity oil, belonging to the technical field of petroleum exploitation.
  • Heavy oil and high pour point oil with high viscosity are generally recovered by thermal methods such as steam injection.
  • steam injection recovery methods include steam huff and puff, steam flooding and steam-assisted gravity drainage.
  • a boiler is also used to heat the purified water to generate high-temperature steam.
  • steam injection to recover heavy oil can achieve remarkable recovery effect, there are still many problems: (1) Steam injection recovery mainly heats the oil layer through high-temperature steam, which consumes a lot of energy, has high cost, and is harmful to the environment due to the production of a large amount of carbon dioxide and sewage.
  • the viscosity of heavy oil or high pour point oil can also be significantly reduced by mixing or dissolving crude oil with lower viscosity.
  • Viscosity reducers, etc. can improve the effect of wellbore viscosity reduction and wellbore lifting oil recovery or reduce the amount of thin oil blended (References 1-7).
  • thermal oil plugging removal method can relieve the organic damage of near-well formation and the effects of "splitting water and oil repelling" to improve oil well production (References 8-10).
  • the invention patent "A method and device for the integrated production and transportation of heavy oil catalytic upgrading and viscosity reduction” (Reference 12) provides an integrated method of heavy oil catalytic upgrading, viscosity reduction, production and transportation for the recovery of heavy oil reservoirs.
  • the light components are injected into the oil well by distillation to reduce the amount of dilute oil mixed with the wellbore when the wellbore is lifted.
  • the technical scheme is: according to the mass ratio of dilute oil to heavy oil 0.4-1.0, it is mixed into the wellbore to reduce the viscosity of the heavy oil; then the dilute heavy oil is extracted from the well, heated by a heat exchanger, and heated to 350 °C in a heating furnace, Enter the distillation tower, collect the distillate oil before 350°C, cool it down by the heat exchanger, and inject it into the wellbore to dilute the heavy oil for recycling; after 350°C, the heavy distillate oil is pumped to the heating furnace to heat up to 370°C-420°C, and then added by the pump
  • the upgrading catalyst is fed into the reaction tower together; in the reaction tower, under the action of the upgrading catalyst, the heavy distillate oil is catalytically upgraded to a low-viscosity heavy oil, and the upgraded heavy oil is directly exported after heat exchange.
  • the essence of this technical solution is to collect the pre-distillate oil at 350°C and cool it to 60°C and then inject it into the wellbore to reduce the viscosity of the heavy oil flowing from the formation through diluting.
  • the problem of increased oil viscosity and poor fluidity has not been proposed to inject light fractions into the formation to recover the high viscosity heavy oil in the formation.
  • the purpose of the present invention is to provide a high-viscosity oil recovery method, which is to reduce the viscosity of the high-viscosity oil by injecting the high-temperature low-viscosity oil into the formation of the high-viscosity oil reservoir, so as to realize low cost and low energy consumption. mining.
  • the present invention provides a method for producing high-viscosity oil, wherein the method is a method for injecting high-temperature low-viscosity oil or a combination of high-temperature low-viscosity oil and gas into a high-viscosity oil reservoir for huff and puff production; wherein , the high-temperature and low-viscosity oil or the combination of high-temperature and low-viscosity oil and gas reduces the viscosity of the high-viscosity oil in the formation by dissolving and heating, and increases the formation pressure; wherein, the high-temperature and low-viscosity oil includes the high-viscosity oil on-site One or more combinations of light fractions and middle distillates obtained by ground distillation; the light fractions are obtained by carrying out atmospheric distillation of the high-viscosity oil that has undergone dehydration and desalination; the middle fractions are obtained by dehydrating The heavy fraction obtained by atmospheric distillation of the desalted high
  • the method of the invention is to obtain high-temperature and low-viscosity oil by distilling the high-viscosity oil produced from the oil well, and then injecting the high-temperature and low-viscosity oil into the "stratum" of the oil reservoir, and then recovering the high-viscosity oil.
  • This method mainly utilizes the dilution and viscosity reduction of high-temperature and low-viscosity oil and the heating of oil layer to improve the fluidity of high-viscosity oil in the "formation" of the reservoir, and increase the formation pressure and oil displacement, thereby improving oil well production and reservoir recovery.
  • the low-viscosity oil produced from the low-viscosity oil reservoir in the oilfield can be recovered. (such as thin oil, etc.) or oil with a viscosity lower than the produced high-viscosity oil from other sources is mixed with the produced high-viscosity oil for distillation, that is, the mixture of the dehydrated and desalted high-viscosity oil and the low-viscosity oil is used for distillation. pressure distillation.
  • the gas includes one or a combination of two or more of natural gas, nitrogen, carbon dioxide and flue gas.
  • the injection of the combination of high-temperature and low-viscosity oil and gas into the formation of a high-viscosity oil reservoir is performed according to simultaneous injection of the two or The method of slug injection, wherein the simultaneous injection is performed by mixing high temperature and low viscosity oil and gas in the surface pipeline, wellhead mixing or bottom hole mixing, that is, the gas injection method can be surface pipeline mixing, wellhead mixing , bottom-hole mixing (respectively injected by the tubing and the annular space between the tubing and the casing, the mixing is at the bottom of the hole, the mixing refers to the mixing of gas and high-temperature and low-viscosity oil), and the slug injection is injected at high temperature and low viscosity.
  • the gas is injected in a slug type before the viscous oil, after the injection of the high temperature and low viscosity oil, or during
  • the temperature of the atmospheric distillation is 350°C-360°C.
  • the temperature of the vacuum distillation is 350°C-370°C.
  • the water content of the high-viscosity oil treated by dehydration and desalination is below 5%.
  • the atmospheric distillation and the vacuum distillation are carried out using high-viscosity oil produced from oilfield production wells after sedimentation treatment and dehydration and desalination treatment at the oil production site. carried out by means of local distillation.
  • the device for on-site distillation is composed of a settling tank with heat exchange function, a dehydration and desalination treatment tank, an atmospheric heating furnace, an atmospheric tower, a vacuum heating furnace, a vacuum tower ( Also known as vacuum distillation tower), buffer tank and pump, wherein the outlet of the sedimentation tank is connected to the inlet of the dehydration and desalination treatment tank through a pipeline, and the outlet of the dehydration and desalination treatment tank is connected to the atmospheric pressure heating furnace through a pipeline, and the atmospheric pressure heating furnace
  • the outlet is connected to the middle and lower part of the atmospheric tower through a pipeline, the bottom of the atmospheric tower is connected to the inlet of the decompression heating furnace through a pipeline, the outlet of the decompression heating furnace is connected to the lower part of the decompression tower through a pipeline, and the top of the atmospheric tower is connected to the lower part of the decompression tower through a pipeline.
  • the top of the decompression tower is connected with the inlet of the internal heat exchanger of the dehydration and desalination treatment tank and the inlet of the inner heat exchanger of the settling tank through the pipeline, the bottom of the decompression tower is connected with the vacuum residue output pipe, and the bottom of the dehydration and desalination treatment tank is connected.
  • the outlet of the heat exchanger is connected to the inlet of the low-viscosity oil buffer tank through a pipeline, the outlet of the low-viscosity oil buffer tank is connected to the wellhead of the high-viscosity oil production well, and the gas injection pipeline is also connected to the wellhead of the high-viscosity oil production well, so as to The fractions obtained by distillation are injected into production wells as high-temperature, low-viscosity oil.
  • in-situ distillation is implemented by placing the produced heavy oil or high-point oil and other high-viscosity oil at the oil production site, such as an oil production well site, a combined station, a transfer station, an oil refinery close to the oil field, etc. Distilled in situ.
  • the on-site in-situ distillation may include the following steps: injecting the high-viscosity oil produced from the production well into the settling tank through a pump for primary dehydration and desanding;
  • the desalination treatment tank is subjected to deep dehydration and desalination treatment, and the moisture content of the high-viscosity oil is preferably reduced to below 5%; 350°C-360°C) and then enter the atmospheric distillation tower for atmospheric distillation to obtain light fractions and heavy fractions, and then inject the heavy fractions into the vacuum heating furnace through a pump, and heat the high-viscosity oil (the vacuum distillation temperature is preferably 350 °C).
  • the production method injects high-temperature and low-viscosity oil into a high-viscosity oil reservoir formation through an oil pipe (preferably an insulated oil pipe).
  • an oil pipe preferably an insulated oil pipe.
  • the temperature of the high-temperature low-viscosity oil or the combination of high-temperature and low-viscosity oil and gas injected into the high-viscosity oil reservoir formation is controlled below the safe injection temperature; the low-viscosity oil safe injection temperature is controlled according to the The minimum ignition temperature of the high temperature and low viscosity oil or the combination of high temperature and low viscosity oil and gas is determined.
  • the safe injection temperature of high temperature and low viscosity oil should take into account the injection into the reservoir to achieve better oil recovery effect, safe injection without fire, and lower than the temperature limit of oil well tubing string and tools and equipment.
  • the maximum injection temperature for simply injecting high-temperature and low-viscosity oil is preferably 100°C-240°C.
  • gas such as nitrogen, carbon dioxide, and inert gas
  • the gas can play a certain protective role.
  • the injection temperature of viscous oil can be increased to 240°C-300°C.
  • the minimum ignition temperature is estimated according to the ignition temperature of the high temperature and low viscosity oil or the combination of the high temperature and low viscosity oil and gas, and is determined through ignition simulation experiments.
  • the ignition simulation experiment is performed using an ignition simulation experimental device
  • the ignition simulation experimental device at least includes: a first injection pump, a first intermediate container, a high temperature box, a heating coil, a back pressure valve, visual combustion kettle, collector, gas cylinder (including air cylinder, oxygen cylinder and nitrogen cylinder, etc.), pressure gauge; wherein, the first injection pump is connected to the bottom of the first intermediate container through a pipeline, The upper outlet of the first intermediate container is connected to the inlet of the heating coil in the high temperature box through a pipeline, the outlet of the heating coil is connected to a back pressure valve through a pipeline, and the back pressure valve is connected to the visible combustion kettle through a pipeline Connected, the upper part of the visual combustion kettle is connected to the air cylinder, the oxygen cylinder and the nitrogen cylinder respectively through pipelines, a pressure gauge is installed on the pipeline, and the lower part of the visual combustion kettle is connected to the collector through pipelines.
  • the ignition simulation experiment device further includes a second injection pump and a second intermediate container, the second injection pump is connected to the bottom of the second intermediate container through a pipeline, and the upper outlet of the second intermediate container is connected through a pipeline Connected to the inlet of the heating coil in the high temperature box.
  • Some components of the above-mentioned ignition simulation experimental device preferably meet the following conditions: the maximum injection pressure of the injection pump is 30MPa-70MPa, the maximum heating temperature of the high temperature box is above 500°C, the temperature control accuracy is ⁇ 0.5°C, and the return temperature is ⁇ 0.5°C.
  • the pressure control range of the pressure valve is 0-70MPa, the length of the heating coil is 10m-20m, the diameter is 3mm, and the pressure resistance is 30MPa-70MPa.
  • the experimental pressure range of the visual combustion kettle is 0-10MPa, and equipped with pressure resistance A viewing window and a heating and temperature control system; the pipeline between the heating coil and the visible combustion kettle is provided with thermal insulation components, such as insulating materials.
  • the ignition simulation experiment includes the following steps:
  • composition of high-temperature and low-viscosity oil select the corresponding fraction and/or low-viscosity oil to make the experimental sample, or directly use the high-temperature and low-viscosity oil as the experimental sample; add the experimental sample to the first intermediate container, and pressurize the low-viscosity oil through the first injection pump.
  • the viscous oil is injected into the heating coil in the high temperature box (when gas needs to be injected, the gas is added to the second intermediate container, and the gas is mixed with the experimental sample by the second injection pump and then enters the heating coil in the high temperature box), high temperature box
  • the set temperature is the experimental temperature
  • the experimental sample heated to the experimental temperature is controlled at the experimental pressure level through the back pressure valve, so that the experimental sample of high temperature and high pressure enters the visual combustion kettle under the set temperature, pressure and gas environment, and is observed through the window Whether the experimental sample flowing into the visual combustion kettle catches fire;
  • the experimental pressure controlled by the back pressure valve is set according to the injection pressure of the high-temperature and low-viscosity oil or the combination of high-temperature and low-viscosity oil and gas on site, and the visual combustion
  • the temperature, pressure and gas environment of the kettle simulate the environment where leakage may occur; the heating temperature of the high-temperature box is determined according to the temperature at which the injected experimental sample may ignite.
  • the minimum ignition temperature is estimated according to the composition of the experimental sample, and adjusted up and down Carry out the ignition simulation experiment at a certain temperature (preferably 5°C-10°C), and adjust the heating temperature of the ignition simulation experiment according to the results of the ignition simulation experiment, until the minimum ignition temperature of the experimental sample is determined; multiplying the minimum ignition temperature by the safety factor can The corresponding safe injection temperature of the high-temperature and low-viscosity oil is obtained; preferably, the estimated ignition temperature can be estimated by performing a volume-weighted average or a mass-weighted average based on the composition of the experimental sample and the ignition temperature of each component.
  • the high-temperature and low-viscosity oil is heat-exchanged with the high-viscosity oil subjected to sedimentation treatment and/or dehydration and desalination treatment to lower the temperature to safe injection temperature.
  • the following methods can be used: exchanging heat with the high-temperature and low-viscosity oil through the sedimentation tank for producing the high-viscosity oil and the dehydration and desalting treatment tank, and at the same time as the high-viscosity oil is produced in the heating tank, the high-temperature and low-viscosity oil is appropriately cooled down to Safe injection temperature.
  • the production method provided by the present invention is to obtain high-temperature and low-viscosity oil fractions by in-situ distillation of crude oil produced from oil wells at the oil production site, and to pass appropriate heat exchange through a dehydration desalination treatment tank and a settling tank. Cool down to a safe injection temperature, and use low-temperature and low-viscosity oil, gas or water and other displacement media to replace the high-viscosity oil production well tubing and tubing with the gas in the casing annulus, and then inject the high-temperature and low-viscosity oil fractions into the reservoir through the tubing of the oil well. At the same time, other media such as gas can be injected into the stratum, and oil production can be carried out after stopping the injection and soaking for a period of time.
  • the mining method provided by the present invention may comprise the following steps:
  • the displacement medium includes one or two of low-temperature and low-viscosity oil, gas and water more than one combination;
  • gas is injected through the oil pipe and/or the oil jacket annulus, so as to expand the stratum swept range of the injected high-temperature and low-viscosity oil; wherein, the injection
  • the volume ratio of the gas to the low-viscosity oil under atmospheric pressure is preferably determined according to the injection amount of the low-viscosity oil, the solubility of the gas in the low-viscosity oil, the gas swept range, the formation fluid saturation in the swept range, and the oil formation pressure to be achieved;
  • the current cycle of production is terminated, and the next cycle of injection of high-temperature and low-viscosity oil or a combination of high-temperature and low-viscosity oil and gas is performed for huff and puff.
  • repeating the above steps (1)-(4) is called one cycle.
  • the recovery method comprises the following specific steps:
  • the high-temperature and low-viscosity oil after heat exchange is injected into the formation of the high-viscosity oil reservoir through the tubing of the high-viscosity oil production well.
  • the oil well is opened for production.
  • the high-viscosity oil diluted and heated by the injected low-viscosity oil flows to the bottom of the well. And production, improve the production speed and recovery rate of formation high-viscosity oil.
  • the extracted high-viscosity oil is re-distilled, injected, simmered and recovered, so as to carry out circulating huff and puff extraction, and the high-viscosity oil is recovered by on-site distillation.
  • the low-viscosity oil fraction in the medium and the auxiliary gas continuously develop the high-viscosity oil in the reservoir formation, so that the low-viscosity oil obtained by the distillation of the high-viscosity oil itself can be reinjected into the “belt” of the high-viscosity oil in the reservoir.
  • the water quality treatment of conventional steam injection production and boiler production of steam greatly reduce the production water volume, so that the production cost of high viscosity oil can be reduced to less than 1/2 of the steam huff and puff, and it has the advantages of environmental friendliness, which can be used to replace the existing high energy consumption. , High-cost steam huff and puff mining method.
  • step (1) and step c can be carried out in the following manner: before injecting high-temperature and low-viscosity oil, inject low-temperature, low-viscosity oil into a high-viscosity oil production well, preferably through an annulus of tubing and tubing and casing.
  • Substitute medium such as viscous oil, gas or water to displace the air in the annular space between the tubing and the tubing and casing, ensuring the safety of subsequent injection of high-temperature and low-viscosity oil.
  • the injection gas can be nitrogen, carbon dioxide, or the like.
  • the displacement method can directly inject low-temperature and low-viscosity oil, gas or water and other displacement media into the formation under high pressure through the oil pipe, the oil pipe and the casing annulus, and can also inject the low-temperature low-viscosity oil, gas or water and other displacement media from the oil pipe.
  • the gas such as air in the circulating displacement well can be produced from the tubing and casing annulus
  • the displacement medium such as low-temperature and low-viscosity oil, gas or water can also be injected from the tubing and casing annulus, and the gas such as air in the circulating displacement well can be produced from the tubing. .
  • the injection amount of the high-temperature low-viscosity oil, the injection amount of the low-viscosity oil when the high-temperature low-viscosity oil is combined with the gas is based on the viscosity of the high-viscosity oil, the oil The degree of reservoir exploitation and the type of oil well are determined.
  • the degree of recovery of the oil reservoir is characterized by the swept radius of the oil reservoir, and the swept radius of the oil reservoir is the distance from the outer boundary of the produced oil reservoir to the production well; when it is newly put into production
  • the swept radius of the reservoir can be 3m-5m, that is, the swept radius of the reservoir can be 3m-5m when the low-viscosity oil is injected into huff and puff in the first cycle of newly put into production vertical wells or directional wells;
  • the swept radius of the reservoir can be 1m-3m, that is, when the first cycle of newly put into production horizontal wells, branch wells and fishbone wells adopts low-viscosity oil injection and huff and puff production
  • the swept radius of the reservoir can be 1m-3m.
  • the injection intensity of the high-temperature and low-viscosity oil during huff and puff production of high-viscosity oil is the amount of high-temperature and low-viscosity oil injected per meter of oil layer period, or the combination of high-temperature and low-viscosity oil and gas
  • the amount of high temperature and low viscosity oil can be calculated according to the following formula:
  • I o [a+b ln(R/h)] ⁇ [c ln ln( ⁇ )-d]
  • I o is the injection strength of low-viscosity oil, m 3 /m; a and b are parameters related to the degree of reservoir production, c and d are parameters related to the viscosity of high-viscosity oil, which can be passed according to the target reservoir conditions.
  • the injection strength of the high temperature and low viscosity oil is:
  • I ho [1+0.15ln(R/h)] ⁇ [120lnln( ⁇ )-150]
  • I ho is the injection strength of high temperature and low viscosity oil, m 3 /m; R is the swept radius of the reservoir, m; h is the thickness of the reservoir, m; ⁇ is the viscosity of high viscosity oil under formation conditions, mPa ⁇ s;
  • the injection strength of the high temperature and low viscosity oil is:
  • I ho [1+0.1ln(R/h)] ⁇ [12lnln( ⁇ )-15]
  • I ho is the injection strength of high temperature and low viscosity oil, m 3 /m; R is the swept radius of the reservoir, m; h is the thickness of the reservoir, m; ⁇ is the viscosity of high viscosity oil under formation conditions, mPa ⁇ s.
  • the gas that is, during the injection of the high-temperature and low-viscosity oil or after the high-temperature and low-viscosity oil is injected , the volume ratio of the gas injected through the oil pipe and/or the oil jacket annulus) to the high temperature and low viscosity oil under atmospheric pressure is based on the injection amount of the low viscosity oil, the solubility of the gas in the low viscosity oil, the gas sweep range, and the sweep range.
  • the gas swept range is calculated according to the swept radius of the reservoir, the thickness of the oil layer and the porosity of the oil layer, and the swept radius of the oil reservoir is outside the produced oil reservoir.
  • the distance from the boundary to the oil well; the volume ratio of the injected gas to the low-viscosity oil under atmospheric pressure is preferably calculated according to the following formula:
  • IGOR is the volume ratio of injected gas to low-viscosity oil at atmospheric pressure
  • I o is the injection strength of low-viscosity oil, m 3 /m
  • D g is the solubility of injected gas in low-viscosity oil injected into the reservoir
  • R is Reservoir swept radius, m
  • ⁇ is the average porosity of the reservoir
  • S o is the oil saturation within the swept range of the reservoir
  • Sw is the water saturation within the swept range of the reservoir
  • S g is the swept range of the reservoir Gas saturation
  • ⁇ P is the increase in reservoir pressure, MPa
  • P 0 is atmospheric pressure, MPa.
  • the production method provided by the present invention is a method for injecting high-temperature and low-viscosity oil or a combination of high-temperature and low-viscosity oil and gas into a high-viscosity oil reservoir for huff and puff production.
  • the conditions and the composition of the injected low-viscosity oil determine the safe injection temperature and injection intensity. Below the safe injection temperature, control the appropriate injection intensity to inject the high-temperature low-viscosity oil or the combination of high-temperature and low-viscosity oil and gas into the high-viscosity oil reservoir.
  • the high viscosity oil in the medium is dissolved and heated to reduce the viscosity, increase the formation pressure, and perform huff and puff production.
  • High-temperature low-viscosity oil is injected into a high-viscosity oil reservoir, which can improve the fluidity of the high-viscosity oil in the formation by dissolving, diluting and heating, and quickly recover it. Because the water quality treatment of boiler water is removed, the fuel consumption of heating and distilling crude oil is significantly lower than the fuel consumption of steam generated by the boiler, and the amount of produced water is greatly reduced. Therefore, the cost of producing high-viscosity oil by injecting low-viscosity oil into the formation with huff and puff will be obvious. It is lower than steam injection methods such as steam huff and puff.
  • the high-viscosity oil recovery method of the invention has the advantages of economy, high efficiency and energy saving, and the cost is obviously lower than that of steam injection recovery methods such as steam huff and puff, especially when high-viscosity oil is recovered by on-site distillation of low-viscosity oil fractions and huff and puff.
  • the high-viscosity oil recovery method of the present invention can be used for the recovery of high-viscosity oil reservoirs such as heavy oil and high-point-point oil, and is especially suitable for high-viscosity oil reservoirs with poor steam injection thermal recovery effect or high cost, and due to water sensitivity or water shortage, etc. The reason is high-viscosity oil reservoirs that cannot be injected with water or steam.
  • the high-viscosity oil production method of the present invention can produce high-viscosity oil production wells in vertical wells, directional inclined wells, horizontal wells, lateral wells, fishbone wells or other well types.
  • the scope of application of the high-viscosity oil recovery method of the present invention is not limited to the above-mentioned scope, and is applicable to all oil reservoirs that can be recovered by using the low-viscosity oil fractions provided by the present invention by on-site distillation.
  • the high-viscosity oil recovery method provided by the present invention utilizes the light components, intermediate components and heavy components obtained by extracting the high-viscosity oil distillation, and has low requirements on the cutting precision of the components, the distillation process is relatively simple, and the equipment and relatively low operating costs.
  • the high-viscosity oil recovery method provided by the present invention utilizes on-site distillation of low-viscosity oil fractions to huff and puff to exploit high-viscosity oil
  • the high-temperature and low-viscosity oil obtained by on-site distillation can be heat-exchanged by a settling tank and a dehydration desalination treatment tank , while heating the high-viscosity oil in the sedimentation tank and the dehydration and desalination treatment tank, the low-viscosity oil is cooled to a safe injection temperature, thereby simplifying the process and saving energy.
  • the high-temperature and low-viscosity oil obtained by the distillation of the high-viscosity oil is injected into the oil well or mixed with other media to produce high-viscosity oil by huff and puff.
  • Oil layer heating can improve the fluidity of high-viscosity oil in the formation, and can also improve formation pressure and oil displacement, thereby achieving the effect of improving oil well production and reservoir recovery.
  • the high-viscosity oil recovery method provided by the present invention is by injecting the high-temperature and low-viscosity oil obtained by extracting the high-viscosity oil distillation into the oil layer to carry out oil recovery, and comprehensively utilizes the dissolution, dilution and heating effects of the high-temperature and low-viscosity oil to improve the fluidity of crude oil, Compared with the high temperature steam injection method which mainly relies on heating, the energy consumption and cost are significantly reduced. At the same time, since the re-injection of high-temperature and low-viscosity oil utilizes the heat of distillation, the thermal efficiency is further improved and the cost is reduced.
  • the high-temperature and low-viscosity oil re-injected by the high-viscosity oil recovery method provided by the present invention can dissolve and dilute the formation high-viscosity oil, reduce the viscosity and weaken the temperature sensitivity, easy to lift and transport, and can eliminate or reduce the wellbore lift difficulty and cost.
  • the high-viscosity oil extraction method provided by the present invention can use the low-viscosity oil and/or residual oil obtained by high-temperature distillation as the fuel for technological processes such as distillation and power generation.
  • the high-viscosity oil recovery method provided by the present invention greatly reduces the amount of injected water and produced water, and reduces the difficulty and cost of surface water treatment.
  • the high-viscosity oil recovery method provided by the present invention can gradually dissolve and dilute the high-viscosity oil in the formation by injecting the high-temperature and low-viscosity oil obtained by distillation back into the oil layer, and can convert heavy oil reservoirs and high-point pour oil reservoirs into "thin oil". Oil” reservoirs greatly reduce the difficulty of exploitation, and further, they can be converted into conventional exploitation methods such as water injection and polymer injection for exploitation.
  • the high-viscosity oil recovery method provided by the present invention comprehensively utilizes the dissolution dilution and heating effects of re-injection of high-temperature and low-viscosity oil, and can be mixed with other media for oil recovery, and is suitable for a wide range of oil reservoirs. It is suitable for heavy oil reservoirs and high pour point oil reservoirs, especially for high viscosity oil reservoirs with poor thermal recovery effect or high cost of steam injection, and oil reservoirs where water or steam injection cannot be performed due to water sensitivity or water shortage.
  • Fig. 1 is a schematic diagram of the method for producing high-viscosity oil by huff and puff of distilled low-viscosity oil fraction according to Example 1.1, the specific meanings of the symbols in the figure are: 1: oil layer, 2: overlying rock layer, 3: oil well, 4: high-viscosity oil pipeline, 5: Pump, 6: Settling tank, 7: Dehydration and desalination treatment tank, 8: Brine pipeline, 9: High-viscosity oil pipeline after dehydration and desalination, 10: Atmospheric pressure heating furnace, 11: Atmospheric pressure tower; 12: Light fraction Pipeline, 13: heavy distillate pipeline, 14: vacuum heating furnace, 15: vacuum tower, 16: middle distillate pipeline, 17: vacuum residue pipeline, 18: high temperature and low viscosity oil pipeline, 19: low viscosity after cooling down Oil pipeline, 20: buffer tank, 21: high viscosity oil production well, 22: other medium pipeline, 23: gas action area, 24: low viscos
  • Fig. 2 is the flow chart of the ignition simulation experiment device in the method for producing high-viscosity oil by huff and puff of distilled low-viscosity oil fraction according to Example 1.1, the specific meanings of the symbols in the figure: 2011: the first injection pump, 2012: the second injection pump, 2021: First Intermediate Vessel, 2022: Second Intermediate Vessel, 2031: First Valve, 2032: Second Valve, 204: Collection Valve, 205: High Temperature Box, 206: Heating Coil, 207: Back Pressure Valve, 208: Visual combustion kettle, 209: flame combustion chamber, 210: window, 211: pressure gauge; 212: air cylinder, 213: oxygen cylinder, 214: nitrogen cylinder, 215: low-viscosity oil collection container;
  • Fig. 3 is a thick layer super-heavy oil reservoir model diagram of deploying horizontal wells by utilizing distilled low-viscosity oil fraction huff and puff production according to Example 2.1;
  • Fig. 4 is the viscosity distribution diagram of oil reservoir crude oil at the end of 10 cycles of injection using distillation low-viscosity oil fraction + carbon dioxide huff and puff according to Example 2.1;
  • Fig. 5 is the single well daily oil production and daily water production dynamic curve predicted by numerical simulation of the middle-deep thick layer ordinary heavy oil reservoir in which the horizontal well is exploited by utilizing distilled low-viscosity oil fraction and nitrogen huff and puff according to embodiment 2.2;
  • Fig. 6 is the single well day predicted by the numerical simulation of the medium-deep thick ordinary heavy oil reservoir in which the horizontal well is deployed in order to compare the steam huff and puff (injection and production period of 8 months) of the distilled low-viscosity oil fraction and nitrogen huff and puff (injection and production period of 8 months) of Example 2.2 Oil production and daily water production dynamic curves;
  • Fig. 7 is a model structure diagram of a thick-layer super-heavy oil reservoir deploying vertical wells by utilizing distilled low-viscosity oil fraction huff and puff production according to Example 3.2;
  • Fig. 8 is the model diagram of utilizing distillation low-viscosity oil fraction huff and puff to exploit thick layer edge bottom water common heavy oil reservoir according to embodiment 4.1;
  • Fig. 9 is the sectional view of utilizing distillation low-viscosity oil fraction huff and puff to exploit common heavy oil reservoir with thick edge and bottom water according to embodiment 4.1;
  • Fig. 10 is the model diagram of utilizing distillation low-viscosity oil fraction huff and puff to exploit thin-layer edge-bottom water common heavy oil reservoir according to Example 4.2;
  • Fig. 11 is a cross-sectional view of a common heavy oil reservoir with thin edge and bottom water produced by huff and puff of distilled low-viscosity oil fraction according to Example 4.2.
  • the low-viscosity oil is obtained by in-situ distillation and the safe injection temperature of the low-viscosity oil is determined by adopting the method of huffing and puffing low-viscosity oil fractions by on-site distillation.
  • oil well 3 passes through overlying rock layer 2 into oil layer 1, and the high-viscosity oil produced by oil well 3 is injected into sedimentation tank 6 through high-viscosity oil pipeline 4 through pump 5 for a dehydration and desanding treatment; And the high-viscosity oil after the desanding treatment is injected into the dehydration and desalination treatment tank 7 through a pump for deep dehydration and desalination treatment, the high-viscosity oil is dehydrated to less than 5%, and the brine produced by the dehydration and desalination treatment tank 7 is discharged through the brine pipeline 8; The high-viscosity oil after dehydration and desalination is injected into the atmospheric pressure heating furnace 10 after the high-viscosity oil is dehydrated and desalted by the pump, and the high-viscosity oil is heated to 350°C-360°C and then enters the atmospheric distillation tower 11 for atmospheric distillation.
  • Light distillate and heavy distillate wherein the light distillate enters the high temperature and low viscosity oil pipeline 18 through the light distillate line 12 and then enters the dehydration and desalting treatment tank 7 for heat exchange, and the heavy distillate passes through the heavy distillate 13.
  • Pressure heating furnace 14 heat the high viscosity oil to 350°C-370°C and then enter vacuum tower 15 for vacuum distillation to obtain middle distillate and vacuum residue, and finally obtain three kinds of light distillate, middle distillate and heavy residue Distillate, wherein, the middle distillate enters the high temperature and low viscosity oil pipeline 18 through the middle distillate pipeline 16 and then enters the dehydration and desalination treatment tank 7 for heat exchange, and the heavy residual oil passes through the vacuum residual oil pipeline 17 after heat exchange and is exported or used as on-site distillation.
  • Fuels such as heating, light distillate, middle distillate or a mixture of the two in a certain proportion can be used as a high-temperature and low-viscosity oil to inject into the oil well through the high-temperature and low-viscosity oil pipeline 18, and pass through the dehydration and desalination treatment tank 7 and the internal heat exchange of the settling tank 6. After cooling down, the low-viscosity oil pipeline 19 enters the buffer tank 20.
  • the low-viscosity oil in the buffer tank 20 can be injected into the high-viscosity oil production well 21 through a pump, and the high-temperature and low-viscosity oil forms a low-viscosity oil action area 24 injected into the formation.
  • gas such as nitrogen gas or other medium can be injected into the high-viscosity oil production well 21 through other medium pipelines 22 to form a gas action area 23 to assist the high-temperature and low-viscosity oil extraction underground high-viscosity oil.
  • the safe injection temperature of low-viscosity oil is a key parameter for the invention to utilize the distillation of low-viscosity oil fractions to huff and puff to exploit high-viscosity oil.
  • a high-viscosity oil from a certain oilfield is used to simulate 350°C atmospheric distillation and vacuum distillation experiments to obtain light fractions. and middle distillate, and according to the methods recorded in ASTMD-2892/92 and ASTMD-5236-92 in "Crude Oil Evaluation Method" (1994 edition), the light distillate and middle distillate were subjected to conventional distillation experiments respectively, and obtained different boiling point ranges. Distillate content, the results are shown in Table 1.
  • the ignition temperatures of the light fraction and middle fraction obtained by distillation under atmospheric pressure can be estimated to be 291°C and 201°C, respectively, and the light fraction and middle fraction are 1:1.
  • Ignition temperature at atmospheric pressure was estimated to be 246°C when proportionally mixed.
  • the ignition simulation experiment of this embodiment is carried out by using the ignition simulation experiment device shown in FIG. 2 .
  • the ignition simulation experiment device at least includes: a first injection pump 2011 , a first intermediate container 2021 , a first valve 2031 , a second injection pump 2012 , The second intermediate container 2022, the second valve 2032, the collection valve 204, the high temperature box 205, the heating coil 206, the back pressure valve 207, the visual combustion kettle 208 (with the flame combustion chamber 209, the window 210), the pressure gauge 211, Air cylinder 202, oxygen cylinder 213, nitrogen cylinder 214, and low-viscosity oil collection container 215; wherein, the first injection pump 2011 is connected to the bottom of the first intermediate container 2021 through a pipeline, and the upper outlet of the first intermediate container 2021 passes through The pipeline (with the first valve 2031) is connected to the inlet of the heating coil 206 in the high temperature box 205, the second injection pump 2021 is connected to the bottom of the second intermediate container 2022 through the pipeline, and
  • the above-mentioned ignition simulation experimental device is used to test the ignition temperature of light fraction, middle fraction, low-viscosity oil (a mixture of light fraction and middle fraction in a ratio of 1:1) and their mixture with nitrogen.
  • the pressure of the back pressure valve 207 is controlled at 10MPa, and the pressure in the combustion kettle 208 can be seen as atmospheric pressure, and the gas is air.
  • the light fraction ignition test temperature ie the temperature of the high temperature box
  • the ignition test temperature of middle distillate was set to 191 °C, 201 °C and 211 °C, respectively, and the ignition test temperature of low-viscosity oil was set to 236 °C, 246 °C and 256 °C, respectively.
  • the ignition condition of the high temperature and low viscosity oil at the outlet of the pipeline is observed through the window 210 of the visual combustion kettle 208 .
  • the lowest ignition temperature of the middle distillate was measured to be 194 °C, and the minimum ignition temperature of the mixture of light distillate and middle distillate in a ratio of 1:1 was 230 °C.
  • Table 2 The results of the ignition simulation experiment of light fractions obtained by simulated distillation of high-viscosity oil in an oilfield
  • the minimum ignition temperature of low-viscosity oil can be increased by injecting inert gas such as nitrogen while injecting low-viscosity oil.
  • inert gas such as nitrogen
  • the minimum ignition temperatures measured by the ignition simulation experiment method were 282°C, 337°C, 396°C and 471°C, respectively.
  • a thick super-heavy oil reservoir in which horizontal wells are deployed is exploited by huff and puff of in-situ distillation of low-viscosity oil fractions.
  • the in-situ distillation process similar to Example 1.1 is used to obtain injectable low-viscosity oil, and the light components and intermediate components obtained by distillation are mixed to obtain 50°C viscosity of 150 mPa ⁇ s, 75 mPa ⁇ s and 37.5 mPa ⁇ s, respectively. mPa ⁇ s low viscosity oil.
  • a 600m ⁇ 600m ⁇ 30m horizontal, homogeneous, thick-layered heavy oil reservoir with a top depth of 1000m and a thickness of 30m has three horizontal wells deployed in parallel. It is deployed at a position of 3.5m from the bottom of the oil layer.
  • the specific reservoir parameters are shown in Table 3.
  • a homogeneous oil reservoir geological model with 60 ⁇ 30 ⁇ 30 grids was established. The grid size in the X direction is 5m, the grid size in the Y direction is 20m, and the grid size in the Z direction is 1m.
  • the injection strength of the low-viscosity oil and the low-viscosity oil in the first cycle can be obtained.
  • the maximum injection strengths are 8.8m 3 /m and 13.6m 3 /m, respectively, and the volume ratio of injected nitrogen to low-viscosity oil (referred to as gas-oil ratio for short) is 101.
  • the calculation process is as follows:
  • the injection strength of low viscosity oil in the first cycle is:
  • the maximum low viscosity oil injection strength is:
  • the injection medium includes high temperature and low viscosity oil (the viscosity of high temperature and low viscosity oil at 50°C is 150mPa ⁇ s, 75mPa ⁇ s and 37.5mPa ⁇ s), high temperature and low viscosity oil + nitrogen, high temperature and low viscosity oil + carbon dioxide, and the injection medium temperature is 270 °C (In this example, when the volume ratio of injected gas and low-viscosity oil under atmospheric pressure is 50-100, the minimum ignition temperature is 350-400°C. In order to ensure the safety of injection, the actual maximum injection temperature of low-viscosity oil on site is 300°C.
  • the temperature of the low-viscosity oil at the bottom of the well is about 270°C after considering the heat loss of the wellbore), and the daily oil injection rate is 300m 3 /d.
  • the injection volume of low-viscosity oil in the first three cycles is 3500m 3 , 4000m 3 and 4500m 3 respectively, and the injection volume of low-viscosity oil in the last seven cycles is 5000m 3 . Two cases of reducing the implant by 20% and increasing it by 20% were considered.
  • the volume ratio of injected gas and low-viscosity oil at atmospheric pressure was determined to be 100.
  • the soaking time is 4 days, the maximum daily liquid production of the oil well is 100m 3 /d, and the minimum flow pressure is 2.5MPa.
  • the steam injection temperature is 344°C; the dryness of steam injection is 0.3; the steam injection speed of the first cycle is 200m 3 /d, and the steam injection speed after the second cycle is 300m 3 /d; the steam injection volume of the first three cycles is For 3000m 3 , 4500m 3 and 6000m 3 , the periodic steam injection volume of the last seven cycles is 7500m 3 .
  • the soaking time is 4 days, the maximum daily liquid production of the oil well is 100m 3 /d, and the minimum flow pressure is 2.5MPa.
  • the STARS thermal recovery simulator of CMG company was used to carry out the reservoir numerical simulation. It can be seen that the cumulative oil recovery (net oil recovery after low-viscosity oil injection is removed) for 10 cycles of huff and puff with low viscosity oil injected at 270°C and 150 mPa ⁇ s is 73.3% of that of steam huff and puff, but the produced water is only 6.2% of steam huff and puff. %.
  • the cumulative oil recovery of low-viscosity oil injected at 270°C and 150mPa ⁇ s + nitrogen (gas-oil ratio 100) or carbon dioxide huff and puff (gas-oil ratio 100) is close to that of steam huff and puff, reaching 93.1% and 99.5% of steam huff and puff, respectively.
  • the volume ratio of injected gas to low-viscosity oil was increased to 200, the cumulative oil recovery by injecting low-viscosity oil and carbon dioxide at 270 °C, 150 mPa ⁇ s and carbon dioxide increased significantly, reaching 1.17 times that of steam huff and puff.
  • the oil recovery effect can reach or exceed the conventional steam huff and puff, and no water injection or steam is required, and the cumulative water production in 10 cycles of production is only 10% of the steam huff and puff. 6.2%-14.1%, and the water treatment process of the ground boiler is eliminated, and the dehydration treatment capacity is greatly reduced.
  • the cost of injecting nitrogen or carbon dioxide and the amount of low-viscosity oil injected is only 71% of the steam injection amount of steam stimulation, it is estimated that the cost of producing super-heavy oil by utilizing on-site distillation of low-viscosity oil fractions in the present invention can be reduced to steam. Throughput about 1/2.
  • the cumulative oil recovery of 10 cycles of production has all The reason for the decrease is that the swept range will be reduced when the injection is low, while the recovery of low-viscosity oil will take too long when the injection is high, and the formation temperature will decrease, which will affect the periodic production effect. Therefore, a reasonable injection strength of low-viscosity oil needs to be adopted when adopting the on-site in-situ distillation high-temperature low-viscosity oil huff and puff production process of the present invention. At the same time, it shows that the low-viscosity oil injection strength design method provided by the present invention is reliable.
  • Figure 4 shows the oil viscosity distribution profile of the reservoir at the end of 10 cycles of low-viscosity oil injected at 270 °C and 150 mPa ⁇ s + CO2 huff and puff (gas-oil ratio 100). It can be seen that due to the action of injected high temperature and low viscosity oil and CO 2 , the viscosity of crude oil within 20m near the wellbore is reduced to 1500mPa ⁇ s, while the viscosity of crude oil within 10m near the wellbore can be as low as below 200mPa ⁇ s.
  • the viscosity of the produced oil gradually increases during the cycle of high temperature and low viscosity oil (150 mPa ⁇ s) + carbon dioxide huff and puff (gas-oil ratio 100), and the viscosity of the produced oil gradually decreases when the huff and puff cycle increases.
  • the viscosity of the produced oil was the highest, and the viscosity of the produced oil at the bottom hole was 3800 mPa ⁇ s.
  • the bottom-hole viscosity of the produced oil is only about 200 mPa ⁇ s.
  • the viscosity of the produced oil is greatly reduced when the low-viscosity oil or the combination of low-viscosity oil and gas is used for huff and puff production of super-heavy oil, and even wellbore dilution and heat tracing can be eliminated.
  • the viscosity of the low-viscosity oil obtained by distillation after the ultra-heavy oil is diluted by injection into the low-viscosity oil gradually decreases, and the production increase effect will gradually increase.
  • the high-temperature low-viscosity oil Or it can be combined with nitrogen/carbon dioxide injection into super heavy oil reservoirs for huff and puff production.
  • the viscosity of heavy oil within 20m near the well can be significantly reduced, and the production of oil wells can be significantly improved, which can reach or exceed conventional steam.
  • the effect of super-heavy oil recovery can be improved by increasing the gas-oil ratio of huff and puff injection gas and low-viscosity oil, increasing the temperature, optimizing the composition and injection strength of low-viscosity oil.
  • the injection temperature of low-viscosity oil is low, in order to ensure the recovery effect, the content of light components in the low-viscosity oil produced by distillation should be increased, and the viscosity of the injected low-viscosity oil should be reduced.
  • the bottom hole temperature and crude oil viscosity during different periods of injection of 150°C, 37.5mPa ⁇ s (50°C) high-temperature and low-viscosity oil + CO 2 huff and puff for ultra-heavy oil production are shown in Table 5.
  • the mining time increases gradually and gradually decreases with the increase of the throughput period.
  • the super-heavy oil with the formation viscosity of 52800mPa ⁇ s after hot oil+CO 2 huff and puff reduces the crude oil viscosity to 4821.7-107.4mPa ⁇ s at the end of the cycle (the viscosity level of ordinary heavy oil).
  • the viscosity of produced oil can be reduced to below 1000-2000 mPa ⁇ s, which can eliminate the dilution and heat tracing process during wellbore lifting and reduce the cost of oil production.
  • the viscosity of the injected low-viscosity oil can be 5mPa ⁇ s-500mPa ⁇ s when the low-viscosity oil fraction is recovered by huff and puff of the present invention. (50°C), the injection temperature can be 100°C-300°C. Since the viscosity of super heavy oil is sensitive to temperature, the injection temperature should be increased as much as possible in the first few cycles of huff and puff production. Lower the injection temperature.
  • the injection strength of low-viscosity oil can be 10m 3 /m oil layer-15m 3 /m oil layer, which can be determined by calculation with reference to the method provided by the present invention.
  • the injected gas can be natural gas, nitrogen, carbon dioxide, flue gas and other gases.
  • the volume ratio of the amount to the injection amount of low-viscosity oil is 50-100 at atmospheric pressure, and the injection method can be mixed injection or subsequent slug injection.
  • the injection period can be 3-12 months.
  • the soaking time after injection of low viscosity oil and gas can be 1-10 days.
  • the present embodiment utilizes in-situ in-situ distillation of low-viscosity oil fractions to huff and puff out a thick-layer common heavy oil reservoir where horizontal wells are deployed.
  • Example 1.1 the in-situ distillation process similar to Example 1.1 was used to obtain injectable low-viscosity oil, and three types of low-viscosity oils were obtained by mixing in different proportions. 75mPa ⁇ s and 100mPa ⁇ s.
  • the developed reservoir model is the same as that in Example 2.1, except that the heavy oil is ordinary heavy oil, and the viscosity of the heavy oil is 1500 mPa ⁇ s (the viscosity of degassed oil is 5260 mPa ⁇ s) under formation conditions.
  • the injection of high temperature and low viscosity oil + nitrogen huff and puff is used for 10 cycles, the injection and production cycle is 1 year, and the total production is 10 years.
  • the injection temperature of low-viscosity oil was 50°C, 150°C, 180°C, and 200°C, respectively, and the viscosity of injected low-viscosity oil at 50°C was 37.5 mPa ⁇ s and 75 mPa ⁇ s, respectively.
  • the reasonable periodic low-viscosity oil injection strength determined with reference to the design method provided by the present invention is 6.2-8.3 m 3 /m, and the volume ratio of injected gas to low-viscosity oil under atmospheric pressure is 68.7.
  • the injection volume of low-viscosity oil is 2000m 3 -3000m 3
  • the volume ratio of injected nitrogen to low-viscosity oil under atmospheric pressure is 66.7 (considering that the daily injection volume of ordinary nitrogen injection equipment on site is 20,000m 3 , the distillation unit meets the low
  • the daily injection volume of viscous oil is 300m 3 ), and the well is kept for 5 days, and the production flow pressure is 2.5MPa.
  • the steam injection temperature is 344°C; the dryness of steam injection is 0.3; the steam injection speed of the first cycle is 200m 3 /d, and the steam injection speed after the second cycle is 300m 3 /d; the steam injection volume of the first three cycles is For 3000m 3 , 4500m 3 and 6000m 3 , the steam injection volume of the last 7 cycles is 7500m 3 , the soaking time is 4 days, the maximum daily fluid production of the oil well is 100m 3 /d, and the minimum flow pressure is 2.5MPa.
  • CMG's STARS thermal recovery simulator was used for reservoir numerical simulation.
  • the calculation results of single-well injection and production parameters calculated by different methods of huff and puff production in thick layer ordinary heavy oil reservoirs for 10 years are shown in Table 6.
  • the injection of low viscosity oil and nitrogen huff and puff The dynamic curves of daily oil production and daily water production of a single well (injection and production period of 8 months) are shown in Figure 5, and the dynamic curves of daily oil production and daily water production of a single well with steam huff and puff (injection and production period of 8 months) are shown in Figure 6.
  • the cumulative oil production of 10 cycles of high temperature and low viscosity oil + nitrogen huff and puff production at 150°C and viscosity of 37.5mPa ⁇ s, 75mPa ⁇ s and 100mPa ⁇ s (50°C), respectively is 105479m 3 and 101783m 3 , respectively. and 98201m 3 , which are 1.24, 1.2 and 1.15 times of the steam huff and puff respectively, and have achieved a significant increase in production.
  • the water production is only less than 1/5 of the steam huff and puff. Therefore, when the low-viscosity oil fraction is distilled in-situ by the method of the present invention, the high-temperature and low-viscosity oil is injected with low energy consumption, low water production and low cost during huff and puff production.
  • the cumulative oil production of 10 cycles of huff and puff production by injecting low-viscosity oil with a viscosity of 37.5 mPa ⁇ s at 50°C and temperatures of 50°C, 150°C, 180°C and 200°C and nitrogen gas for 10 cycles is 99125m 3 , 105479m 3 , 106595m 3 and 107283m 3 , respectively 1.16, 1.24, 1.25 and 1.26 times the steam huff and puff. It can be seen that, for ordinary heavy oil with lower viscosity, the injection of low-viscosity oil with lower temperature and nitrogen can achieve obvious production increase effect.
  • the injection strength of the oil can be 5-10m 3 /m, and the periodic low-viscosity oil injection volume is 2000m 3 -4000m 3 .
  • the injected gas can be nitrogen, carbon dioxide, natural gas, flue gas, etc., and the volume ratio of the gas injection amount to the low-viscosity oil injection amount under atmospheric pressure can be 50-100.
  • This embodiment utilizes on-site in-situ distillation of low-viscosity oil fraction huff and puff to exploit thick super-heavy oil reservoirs in which horizontal wells are deployed in the middle and late stages of steam huff and puff.
  • Example 1.1 an in-situ distillation process similar to that of Example 1.1 was used to obtain an injectable low-viscosity oil, and the viscosity at 50° C. was 37.5 mPa ⁇ s.
  • the reservoir model and well deployment are the same as in Example 2.1. After 10 cycles and 20 cycles of steam huff and puff, respectively, 10 cycles of high temperature and low viscosity oil + nitrogen huff and puff were carried out.
  • the working system during oil production was the same as in Example 2.1.
  • the injection-production cycle of each cycle of steam huff and puff is 0.5 years, the steam injection temperature is 344°C, and the steam injection dryness is 0.3; the steam injection rate in the first cycle is 200m 3 /d, and the steam injection rate in the second and subsequent cycles is 300m. 3 /d; the steam injection volume of the first 3 cycles is 3000m 3 , 4500m 3 and 6000m 3 in turn, and the cycle steam injection volume of the last 7 cycles is 7500m 3 .
  • the soaking time is 4 days, the maximum daily liquid production of the oil well is 100m 3 /d, and the minimum flow pressure is 2.5MPa.
  • the low-viscosity oil fraction of the present invention is used for huff and puff production.
  • nitrogen is injected at the same time as the low-viscosity oil fraction is injected, and 10 cycles of huff and puff are carried out.
  • the injection-production cycle of each cycle is 0.5 years, a total of 5 years of mining.
  • the viscosity of the injected low-viscosity oil is 37.5 mPa ⁇ s (50°C), and the temperature of the injected low-viscosity oil is 150°C-300°C.
  • the reasonable injection strength of low-viscosity oil transfer injection can be obtained as 8.8m 3 /m-13.6m 3 /m, and the volume ratio of injected nitrogen to low-viscosity oil is 101 According to this, the oil injection volume of the first two cycles is 3000m 3 and 4000m 3 respectively, and the oil injection volume of the last eight cycles is 5000m 3 .
  • the volume ratio of injected nitrogen and low-viscosity oil at atmospheric pressure is 90 (considering that the daily injection volume of the ordinary nitrogen injection equipment on site is 20,000m 3 , and the daily injection volume of the low-viscosity oil for the distillation unit is 300m 3 , the injection is performed during the low-viscosity oil injection stage.
  • the volume ratio of nitrogen to low-viscosity oil is 66.7, but after stopping the injection of low-viscosity oil, nitrogen is continuously injected, and finally the volume ratio of nitrogen to low-viscosity oil is 90).
  • the daily oil injection rate is 300m 3 /d, and the soaking time is 5 days. During oil production, the maximum daily liquid production of the oil well is 100m 3 /d, and the minimum flow pressure is 2.5MPa.
  • the cumulative oil recovery of 10 cycles is 47858.3 m 3 , which is 93.1% of the cumulative oil recovery of the next 10 cycles of steam huff and puff.
  • the cumulative oil recovery of high temperature and low viscosity oil + N 2 huff and puff for 10 cycles is 53728.3m 3 , which is 1.05 times of the cumulative oil recovery of steam huff and puff in the next 10 cycles.
  • the cumulative oil recovery of 150°C high temperature and low viscosity oil + N2 huff and puff for 10 cycles is equivalent to that of 30 cycles of steam huff and puff.
  • the viscosity of the injected low-viscosity oil can be 5 mPa ⁇ s when the low-viscosity oil fraction is huff and puff produced by in-situ distillation of the present invention.
  • the injection temperature can be 100°C-300°C
  • the injection strength of low-viscosity oil can be 5m 3 /m oil layer to 15m 3 /m oil layer, which can be determined by calculation with reference to the method provided in the present invention
  • the injection gas can be natural gas, nitrogen, carbon dioxide, flue gas and other gases.
  • the volume ratio of gas injection to low-viscosity oil injection under atmospheric pressure is 50-100.
  • the injection method can be mixed injection or subsequent slug injection.
  • the injection period can be 8-16 months.
  • the soaking time after injection of low viscosity oil and gas can be 1-10 days.
  • the low-viscosity oil fraction huff and puff of the present invention can achieve the effect equivalent to that of steam huff and puff by on-site distillation, and can be further improved by reducing the viscosity of the injected low-viscosity oil, increasing the injection temperature of the low-viscosity oil, properly increasing the gas-oil ratio and optimizing the injection amount Yield increase effect.
  • steam huff and puff it has obvious advantages of low energy consumption, low produced water volume and low cost.
  • the super-heavy oil reservoir in which the vertical well is deployed in the later stage is exploited by utilizing the on-site in-situ distillation of low-viscosity oil fraction huff and puff to exploit the steam huff and puff of the present invention.
  • Example 1.1 an in-situ distillation process similar to that of Example 1.1 was used to obtain an injectable low-viscosity oil, and the viscosity at 50° C. was 35 mPa ⁇ s.
  • an ultra-heavy oil reservoir with a depth of 600m and an area of 200m ⁇ 200m has three oil layers, each of which is 5m thick, with a total thickness of 15m.
  • the thickness of the upper and lower layers is 4m and 3m respectively.
  • the top-to-bottom porosity of the three oil layers is 0.33, 0.315 and 0.34, and the permeability is 3000mD, 2000mD and 4000mD, respectively.
  • the viscosity of heavy oil is 121088mPa ⁇ s
  • the viscosity of degassed oil at 45°C is 212903mPa ⁇ s.
  • the original oil layer temperature is 45°C
  • the original oil layer pressure is 6MPa
  • the original oil saturation is 0.675.
  • the numerical simulation reservoir model has a total of 40 ⁇ 40 ⁇ 20 grids, the size of the grid in the X and Y directions is 5m, and the size of the grid in the Z direction is 1m-2m.
  • in-situ distillation of low-viscosity oil fraction huff and puff is used to exploit the super-heavy oil reservoir in which vertical wells are deployed in the later stage of steam huff and puff.
  • the steam huff and puff is exploited for 10 cycles, and the injection-production cycle of each cycle is 0.5 years, for a total of 5 years of exploitation.
  • the steam injection rate of the first cycle of a single well is 200m 3 /d
  • the steam injection rate of the subsequent cycles is 300m 3 /d.
  • the cyclical steam injection volume for 5 cycles of a single well is 1000m 3 , 1500m 3 , 1800m 3 , 2400m 3 and 3000m 3 respectively.
  • the steam injection temperature was 344°C
  • the steam injection dryness was 0.3
  • the well soaking time was 3 days.
  • the maximum daily liquid production of a single well was 50m 3 /d
  • the minimum flow pressure was 0.5MPa.
  • 10 cycles of low-viscosity oil injection and nitrogen huff and puff were carried out, and the injection and production cycle of each cycle was 0.5 years, for a total of 5 years of production.
  • the injected low-viscosity oil has a viscosity of 35 mPa ⁇ s at 50°C, an injection temperature of 150°C, and a daily oil injection rate of 200m 3 /d-300m 3 /d for a single well.
  • the reasonable injection strength of low-viscosity oil injection is 71m 3 /m-118m 3 /m, and the volume ratio of injected nitrogen gas to low-viscosity oil is 108.
  • the designed single-well cycle low-viscosity oil injection volume is 1000m 3 -1800m 3 .
  • the soaking time is 3 days.
  • the maximum daily liquid production of a single well is 50 m 3 /d and the minimum flow pressure is 0.5 MPa during oil production. In order to compare the effect, 20 cycles of steam huff and puff were also carried out.
  • the first 10 cycles were the same as the above steam huff and puff, and the last 10 cycles were all injection-production cycles of 0.5 years.
  • the well steam injection rate is 300m 3 /d
  • the single well cycle steam injection volume is 3000m 3
  • the well soaking time is 3 days
  • the maximum daily liquid production of the oil well is 50m 3 /d
  • the minimum flow pressure is 0.5MPa.
  • the cumulative oil recovery after 5 cycles of huff and puff after the injection of low-viscosity oil is 1.08 times that of the steam huff and puff, and the water produced by the latter 5 cycles of huff and puff is only 14% of that of the steam huff and puff.
  • the low-viscosity oil injected by the on-site in-situ distillation low-viscosity oil fraction huff and puff method of the present invention is much lower than the steam injection amount of the steam huff and puff, and the combustion consumption of heating the low-viscosity oil is much lower than that of the high-temperature steam. In the process of boiler water treatment, the amount of produced liquid dehydration is also greatly reduced.
  • the viscosity of the injected low-viscosity oil can be 5 mPa ⁇ s- 500mPa ⁇ s (50°C)
  • injection temperature can be 100°C-300°C
  • injection intensity can be 50m 3 /m oil layer-150m 3 /m oil layer
  • injection gas can be natural gas, nitrogen, carbon dioxide, flue gas and other gases
  • the volume ratio of gas injection and low-viscosity oil injection under atmospheric pressure is 30-120 (the amount of injected gas can be reduced when steam channeling between wells is obvious in the middle and late stages of steam huff and puff)
  • the injection method can be mixed injection, front slug Or for subsequent slugs
  • the injection-production cycle can be 3-12 months.
  • the soaking time after injection of low viscosity oil and gas can be 1-10 days.
  • This embodiment utilizes on-site in-situ distillation of low-viscosity oil fraction huff and puff to exploit the thick-layer edge-bottom water common heavy oil reservoir with horizontal wells.
  • Example 1.1 an in-situ distillation process similar to that of Example 1.1 was used to obtain an injectable low-viscosity oil, and the viscosity at 50° C. was 37.5 mPa ⁇ s.
  • the developed reservoir model is an anticline structural edge-bottom water reservoir, the structure of the reservoir model is shown in Figure 8, and the section of the reservoir model is shown in Figure 9.
  • the depth of the oil layer is 1550m
  • the heavy oil is ordinary heavy oil
  • the viscosity of the heavy oil is 4500mPa ⁇ s under formation conditions (the viscosity of the degassed oil is 6370mPa ⁇ s at 50°C);
  • the oil layer thickness is 30m, the oil layer porosity is 0.3, and the permeability is 1500mD;
  • the volume ratio of reservoir edge and bottom water to oil area volume is 50; a total of 3 horizontal wells are deployed in parallel, with a horizontal well length of 300m and a well spacing of 100m. Oil wells far from the edge and bottom water are deployed at a distance of 13.5m from the bottom.
  • the reasonable injection strength of low-viscosity oil transfer injection can be obtained as 8.7m 3 /m-12.4m 3 /m, and the volume ratio of injected nitrogen to low-viscosity oil is 76, According to this, the injection volume of low-viscosity oil in the design cycle is 3000m 3 , and the volume ratio of injected nitrogen gas to low-viscosity oil is 66.7 (considering that the daily injection volume of ordinary nitrogen injection equipment on site is 20,000m 3 , the daily injection volume of low-viscosity oil for the distillation unit is 300m 3 ), soaking the well for 5 days, and the production flow pressure is 2.5MPa.
  • the steam injection temperature of steam huff and puff is 344°C; the dryness of steam injection is 0.3; the steam injection speed of the first cycle is 200m 3 /d, and the steam injection speed after the second cycle is 300m 3 /d; the cycle steam injection volume of each cycle According to 3000m 3 , 4500m 3 , 6000m 3 and 7500m 3 , after increasing to 7500m 3 , it will not increase.
  • the soaking time is 4 days, the maximum daily liquid production of the oil well is 100m 3 /d, and the minimum flow pressure is 2.5MPa.
  • the STARS thermal recovery simulator of CMG company is used to simulate the reservoir numerically.
  • the calculation results of injection and production parameters of each well calculated by different methods of huff and puff production for 10 years in the thick-layer edge-bottom water ordinary heavy oil reservoir are shown in Table 9. It can be seen that under the same injection-production parameters, the first-line wells, the second-line wells and the third-line wells whose distances from the edge and bottom water become farther in turn have great differences in the production effect due to the influence of water intrusion.
  • the cumulative oil production of high temperature and low viscosity oil with a viscosity of 37.5 mPa ⁇ s (50 °C) at 150 °C and nitrogen huff and puff production is comparable to that of steam huff and puff.
  • the cumulative water production of wells and third-line wells is significantly lower than that of steam huff and puff due to no steam injection, and the heat consumption and cost are also significantly lower than those of steam huff and puff.
  • the first-line well is close to the water at the edge and bottom and is prone to water intrusion, it is suitable for low oil production rate. Since the Hesanxian well is not prone to water invasion, the oil production rate can be increased.
  • the production effect of injecting high temperature and low viscosity oil + nitrogen huff and puff for 1 year and 2 cycles is better than that of 1 year and 1 cycle.
  • the viscosity of the injected low-viscosity oil can be 5 mPa ⁇ s- 300mPa ⁇ s (50°C)
  • the injection temperature can be 100°C-300°C
  • the injection strength of low-viscosity oil can be 5m 3 /m oil layer-15m 3 /m oil layer, which can be determined by calculation with reference to the method provided in the present invention
  • the injected gas can be natural gas, nitrogen, carbon dioxide, flue gas, etc.
  • the volume ratio of gas injection to low-viscosity oil injection under atmospheric pressure is 50-100.
  • the injection method can be mixed injection or subsequent slug injection.
  • the injection period can be 8-16 months.
  • the soaking time after injection of low viscosity oil and gas can be 1-10 days.
  • Oil temperature reducing the viscosity of injected low-viscosity oil, optimizing injection-production parameters such as low-viscosity oil injection and nitrogen gas-oil ratio can achieve better production effect than steam huff and puff, and have the advantages of low energy consumption, low produced water volume and low cost .
  • the thin-layer edge-bottom water common heavy oil reservoir with horizontal wells is exploited by huff and puff of on-site distillation of low-viscosity oil fractions.
  • Example 1.1 the in-situ distillation process similar to Example 1.1 was used to obtain injectable low-viscosity oil, and two types of low-viscosity oils were obtained by mixing in different proportions.
  • the viscosity at 50°C was 37.5mPa ⁇ s and 100mPa, respectively. ⁇ s.
  • the structure of the reservoir model is shown in Figure 10, and the section of the reservoir model is shown in Figure 11.
  • the oil layer depth of the reservoir model is 1550m
  • the oil layer thickness is 10m
  • the porosity is 0.3
  • the permeability is 1500mD.
  • the water volume to oil zone volume ratio was 50.
  • a total of 3 parallel horizontal wells are deployed.
  • the length of the horizontal wells is 300m and the well spacing is 100m.
  • the oil wells close to the edge and bottom water are deployed at a distance of 7.5m from the bottom, and the middle oil wells are deployed at a distance of 5.5m from the bottom, away from the oil wells of the edge and bottom water. Deployed at 2.5m from the bottom.
  • the distance between the edge and bottom water is 200m from the nearest oil well.
  • the reasonable injection strength of low-viscosity oil transfer can be obtained as 9.4m 3 /m-10.6m 3 /m, and the volume ratio of injected nitrogen gas to low-viscosity oil is 72 , the injection volume of low-viscosity oil in the design cycle is 3000m 3 , and the volume ratio of injected nitrogen gas to injected low-viscosity oil is 66.7 (considering that the daily injection volume of ordinary nitrogen injection equipment on site is 20,000m 3 , the distillation unit meets the daily injection volume of low-viscosity oil.
  • the injection volume was 300m 3 ), the well was simmered for 5 days, and the production flow pressure was 2.5MPa.
  • the steam injection temperature of steam huff and puff is 344°C; the dryness of steam injection is 0.3; the steam injection speed of the first cycle is 200m 3 /d, and the steam injection speed after the second cycle is 300m 3 /d; the cycle steam injection volume of each cycle After increasing to 7500m 3 according to 3000m 3 , 4500m 3 , 6000m 3 and 7500m 3 , it will not increase.
  • the soaking time is 4 days, the maximum daily liquid production of the oil well is 100m 3 /d, and the minimum flow pressure is 2.5MPa.
  • Table 10 shows the calculation results of single-well injection-production parameters calculated by different methods of huff and puff production in ordinary heavy oil reservoirs with thin layer edge and bottom water for 10 years.
  • the cumulative oil production in 10 cycles of huff and puff is 93.5% of that of steam huff and puff, but the accumulated water volume is only 23.1% of that of steam huff and puff, and no water steam needs to be injected when low-viscosity oil + nitrogen huff and puff (in the case of steam huff and puff, it needs to be injected every cycle).
  • 3000m 3 -7500m 3 steam 3000m 3 -7500m 3 steam
  • the cost of nitrogen injection is significantly lower than that of steam injection. Therefore, in this example, 3000m 3 of 150°C, 100mPa s (50°C) low-viscosity oil + nitrogen huff and puff is injected per cycle. The effect is comparable to that of steam huff and puff and the cost is significantly lower than that of steam huff and puff.
  • the viscosity of the injected low-viscosity oil can be 5 mPa ⁇ s- 300mPa ⁇ s (50°C)
  • the injection temperature can be 100°C-300°C
  • the injection strength of low-viscosity oil can be 5m 3 /m oil layer-15m 3 /m oil layer, which can be determined by calculation with reference to the method provided in the present invention
  • the injected gas can be natural gas, nitrogen, carbon dioxide, flue gas, etc.
  • the volume ratio of gas injection to low-viscosity oil injection under atmospheric pressure is 50-100.
  • the injection method can be mixed injection or subsequent slug injection.
  • the injection period can be 8-16 months.
  • the soaking time after injection of low viscosity oil and gas can be 1-10 days.
  • the low-viscosity oil fraction huff-puff production and deployment of vertical wells are used in on-site in-situ distillation of low-viscosity oil fraction common heavy oil reservoirs.
  • the low-viscosity oil injected in this example is low-viscosity oil produced in the oil field, and has a viscosity of 70 mPa ⁇ s at 50°C. After being heated in a heating furnace, it is injected into an ordinary heavy oil reservoir with low oil saturation through a vertical well. Nitrogen is injected into the casing annulus for low-viscosity oil and nitrogen huff and puff.
  • the structure of the reservoir model is the same as in Example 3.2, as shown in Figure 7. The difference is that the reservoir depth is 1500m, the viscosity of heavy oil is 1065mPa ⁇ s under formation conditions, the viscosity of degassed oil is 8700mPa ⁇ s, the formation permeability is 2000mD, the original oil layer temperature is 60°C, the original oil layer pressure is 15MPa, and the original oil layer pressure is 15MPa. The oil saturation is 0.55 and the water saturation is 0.45.
  • Four vertical wells are deployed in the reservoir according to the square well pattern, the well spacing is 100m, and the oil layers are perforated.
  • the numerical simulation reservoir model has a total of 40 ⁇ 40 ⁇ 10 grids, the size of the grid in the X and Y directions is 5m, and the size of the grid in the Z direction is 1m.
  • low-viscosity oil and nitrogen huff and puff are injected for production and low-saturation ordinary heavy oil reservoirs with vertical wells are deployed.
  • the huff and puff cycle is 10 cycles, and the injection and production cycle of each cycle is 1 year. Mining for 10 years.
  • the injected low-viscosity oil had a viscosity of 70 mPa ⁇ s at 50°C, and an injection temperature of 150°C.
  • the reasonable injection strength of low-viscosity oil huff and puff can be obtained as 76.3m 3 /m-88.4m 3 /m, and the volume ratio of injected nitrogen to low-viscosity oil is 92.
  • the injection volume of low-viscosity oil in this design period is 1200m 3 , and the volume ratio of injected nitrogen gas to injected low-viscosity oil is 100 (considering that the daily injection volume of ordinary nitrogen injection equipment on site is 20,000m 3 , the daily injection volume of low-viscosity oil in the distillation unit is satisfied is 300m 3 , the volume ratio of nitrogen to low-viscosity oil is 66.7 in the low-viscosity oil injection stage, but after the injection of low-viscosity oil is stopped, nitrogen is continuously injected, and finally the volume ratio of nitrogen to low-viscosity oil is 100).
  • the daily oil injection rate of a single well is 300m 3 /d, and the soaking time is 3 days.
  • the maximum daily liquid production of a single well is 50m 3 /d, and the minimum flow pressure is 0.5MPa.
  • the steam injection rate of the first cycle of a single well is 200m 3 /d, and the steam injection rate of the subsequent cycles is 300m 3 /d.
  • the cyclical steam injection volumes of the first 4 cycles of a single well are 1000m 3 , 1500m 3 , 1800m 3 and 2400m 3 respectively, and the latter 6 cycles are all 3000m 3 .
  • the steam injection temperature was 344°C
  • the dryness of steam injection was 0.2
  • the soaking time was 3 days.
  • the maximum daily liquid production of a single well was 50m 3 /d, and the minimum flow pressure was 0.5MPa.
  • the simulation of low-viscosity oil and nitrogen huff and puff after 5 cycles of steam huff and puff was also carried out.
  • the injection and production parameters of steam huff and puff in the first 5 cycles were the same as those of steam huff and puff.
  • the temperature is 150°C
  • the daily oil injection rate of a single well is 300m 3 /d
  • the periodical injection rate of low-viscosity oil in a single well is 1200m 3
  • the soaking time is 3 days
  • the maximum daily liquid production of a single well is 50m 3 /d during oil production.
  • the minimum flow pressure is 0.5MPa.
  • the cyclical water recovery of steam huff and puff and low-viscosity oil and nitrogen huff and puff is high, but the cumulative water production of low-viscosity oil and nitrogen huff and puff is only 70%-80% of that of steam huff and puff. If the cumulative oil recovery of low-viscosity oil and nitrogen huff and puff after 5 cycles of steam huff and puff is 1.08 times that of steam huff and puff, it shows that switching to low-viscosity oil and nitrogen huff and puff in the middle and late stage of steam huff and puff will achieve better recovery effect.
  • the viscosity of injected low-viscosity oil can be 5mPa ⁇ s-300mPa ⁇ s (50°C)
  • the injection temperature can be 100°C-300°C
  • the injection strength of low-viscosity oil can be 50m 3 /m oil layer-100m 3 /m oil layer, which can be determined by calculation with reference to the method provided by the present invention.
  • the injected gas can be natural gas, nitrogen, carbon dioxide, flue gas and other gases, and the volume ratio of the gas injection amount to the low-viscosity oil injection amount under atmospheric pressure is 30 -120, the injection mode may be mixed injection or subsequent slug injection.
  • the injection period can be 6-12 months.
  • the soaking time after injection of low viscosity oil and gas can be 1-10 days.

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Abstract

Est divulgué un procédé d'exploitation de pétrole à viscosité élevée. Le procédé consiste à injecter du pétrole à basse viscosité à haute température ou une combinaison de pétrole à basse viscosité à haute température et de gaz dans un réservoir de pétrole à viscosité élevée permettant la stimulation cyclique par la vapeur. Le pétrole à basse viscosité à haute température ou la combinaison de pétrole à basse viscosité à haute température et de gaz réduit la viscosité du pétrole à viscosité élevée dans la strate par dissolution et chauffage, et augmente la pression de strate ; le pétrole à basse viscosité à haute température comprend au moins deux fractions légères et/ou des fractions intermédiaires obtenues par distillation sur site du pétrole à viscosité élevée.
PCT/CN2021/075005 2020-11-16 2021-02-03 Procédé d'exploitation de pétrole à viscosité élevée WO2022099939A1 (fr)

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