Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
  • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
  • E21B43/164—Injecting CO2 or carbonated water
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/58—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids
  • C09K8/594—Compositions used in combination with injected gas, e.g. CO2 orcarbonated gas
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
  • Y02P90/70—Combining sequestration of CO2 and exploitation of hydrocarbons by injecting CO2 or carbonated water in oil wells

Definitions

• This invention relates generally to the recovery of oil from subterranean reservoirs. More specifically, this invention is directed to a method of recovering oil by a miscible phase displacement technique wherein the flood efficiency is improved by the use of carbon dioxide.
• the oil present in the reservoir is normally removed through the well by primary recovery methods. These methods include utilizing native reservoir energy in the form of water or gas existing under sufiicient pressure to drive the oil from the reservoir through the well to the earths surface. This native reservoir energy most often is depleted long before all of the oil present in the reservoir has been removed from it. Additional oil removal has been effected by secondary recovery methods of adding energy from outside sources to the reservoir either before or subsequent to the depletion of the native reservoir energy.
• Miscible phase displacement techniques comprise a form of enhanced recovery in which there is introduced into the reservoir through an injection well a fluid or fluids which are miscible with the reservoir oil and serve to displace the oil from the pores of the reservoir and drive it to a production well.
• the miscible fluid is introduced into the injection Well at a sufficiently high pressure that the body of fluid may be driven through the reservoir where it collects and drives the reservoir oil to the production well.
• the present invention is particularly concerned with a miscible slug type of miscible phase displacement.
• a liquefied hydrocarbon slug is developed within the reservoir by introducing through the injection well a condensable hydrocarbon, such as liquefied petroleum gas, propane, or butane, at such a pressure that the hydrocarbon will be reduced to the liquid phase or will remain in the liquid phase.
• a normally liquid hydrocarbon such as light naphtha
• the liquefied hydrocarbon slug is miscible with the reservoir oil and is driven through the formation to recover the oil.
• Other miscible materials may be employed, such as a diluted hydrocarbon slug comprising the above-identified condensable hydrocarbons diluted with natural gas.
• the diluted slug may be a liquid or it may be diluted to the extent that it is an enriched gas which will be miscible with the reservoir oil.
• a driving gas is normally injected into the formation behind the hydrocarbon fluid slug in order to drive the slug through the reservoir formation to the production well.
• the miscible slug technique is carried out at pressures of about 1000 pounds per square inch gauge and higher.
• the horizontal pattern of a flood that is, the configuration of the flood pattern in a horizontal plane extending through the formation perpendicular to the injection and production wells, is generally referred to as the areal sweep.
• the flood pattern along a perpendicular plane extending through the formation between the injection and production wells is referred to as the vertical sweep.
• the horizontal and vertical sweep efliciencies of a flood pattern are influenced by several factors including the mobility ratio of the displacing to the displaced fluid, which in essence is a measurement of the relative ease with which the fluids move through the formation.
• reservoir oil is recovered from a formation through a production well by injecting into the formation through an injection Well a quantityof carbon dioxide which is displaced by a liquid hydrocarbon slug driven by a fluid displacing material.
• the first step in the method of the invention is the introduction of carbon dioxide through an injection well into the formation from which oil is to be recovered.
• the carbon dioxide preferably is introduced into the injection well in the liquefied state because less energy is required than when handling it in the gaseous state.
• the injection pressure for the carbon dioxide is not particularly critical, it is preferred that it be at a value which will cause the specific volume of the carbon dioxide to range from 0.8 to 10.0 cubic feet per pound mol at reservoir temperature.
• the injected carbon dioxide is driven through the formation into contact with the oil which is to be displaced.
• the carbon dioxide is highly soluble in reservoir fluids and is generally much more soluble in oil than in water. Due to its solubility in oil, when the carbon dioxide contacts the reservoir oil a portion of it goes into solution with the reservoir oil, resulting in a viscosity reduction of the oil.
• the carbon dioxide In addition to the viscosity reduction, there is a preferential extraction from the oil by the carbon dioxide of light intermediate hydrocarbons containing from 2 to 5 carbon atoms, thereby developing an intermediate-rich carbon dioxide bank in the vicinity of the line of contact between the reservoir oil and the carbon dioxide.
• the intermediate-rich carbon dioxide bank may be completely miscible with the reservoir oil.
• the carbon dioxide should be injected in an amount which provides a transition zone of flowing fluid from the reservior oil to the displacing liquid hydrocarbon slug.
• Such a transition zone includes a portion next to the reservoir oil which is a carbon dioxide-reservoir oil mixture.
• Next is flowing carbon dioxide in phase equilibrium with any nonflowing oil in which carbon dioxide is dissolved, followed by a carbon dioxide-liquid hydrocarbon mixture adjacent to the pure liquid hydrocarbon slug.
• the region of flow of primarily carbon dioxide phase need be no more than a trace since the basic objective is to provide a smooth viscosity transition from the reservoir oil to the liquid hydrocarbon displacing material.
• the approximate quantity of carbon dioxide required may be determined by known procedures in laboratory-conducted floods under simulated reservoir conditions. The amount will, of course, be affected by reservoir conditions of temperature and pressure, together with the reservoir fluids characteristics.
• the second step of the invention involves introducing a liquefied hydrocarbon material into the formation through the injection well behind the carbon dioxide of step 1.
• liquefied hydrocarbons as used herein is intended to include such condensable hydrocarbons as liquefied petroleum gas, propane, butane, and light naphthas which under normal conditions of temperature and pressure exist as a liquid.
• the condensable hydrocarbons are introduced and maintained at a pressure which will retain them in the liquefied state.
• the liquefied hydrocarbons are driven into contact with the carbon dioxide with which they have a high mutual solubility.
• the solution of carbon dioxide and liquefied hydrocarbons thus formed provides a transition from the carbon dioxide to the liquefied hydrocarbons as discussed above.
• the driving fluid preferably is a dry hydrocarbon gas, such as a separator gas, consisting in major part of methane with minor amounts of ethane and trace amounts of higherboiling hydrocarbons.
• the driving fluid may, however, be a flue gas or air. In some cases it may be desirable to drive the injected liquefied hydrocarbons with an amphipathic liquid followed by water.
• An amphipathic liquid is a material having a mutual solubility with water and a hydrocarbon fluid, such as an alcohol of three or four carbon atoms and an aldehyde or a ketone. Injection of the driving fluid is continued to eflect displacement of the reservoir oil through the production well until either all of the oil has been displaced from the formation or until the economical limit of the ratio of the driving fluid to reservoir oil has been reached.
• a hydrocarbon fluid such as an alcohol of three or four carbon atoms and an aldehyde or a ketone
• first transition zone including a portion next to said oil which is a mixture of said carbon dioxide and said oil, and a carbon dioxide phase following said mixture of said carbon dioxide and said oil;
• step (c) is a dry hydrocarbon gas consisting in major part of methane.
• step (c) is an amphipathic liquid followed by water.

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• Geochemistry & Mineralogy (AREA)
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• Chemical Kinetics & Catalysis (AREA)
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• Physics & Mathematics (AREA)
• Oil, Petroleum & Natural Gas (AREA)
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• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
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Cited By (11)

Citations (5)

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• 1963
  • 1963-06-24 US US290167A patent/US3262498A/en not_active Expired - Lifetime
• 1964
  • 1964-06-24 DE DES91678A patent/DE1286475B/de active Pending

Patent Citations (5)

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