US3903967A - Method for recovering viscous petroleum - Google Patents

Method for recovering viscous petroleum Download PDF

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Publication number
US3903967A
US3903967A US508029A US50802974A US3903967A US 3903967 A US3903967 A US 3903967A US 508029 A US508029 A US 508029A US 50802974 A US50802974 A US 50802974A US 3903967 A US3903967 A US 3903967A
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Prior art keywords
zone
permeability
petroleum
formation
injection
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US508029A
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Charles D Woodward
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Texaco Inc
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Texaco Inc
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Priority to US508029A priority Critical patent/US3903967A/en
Priority to CA229,676A priority patent/CA1027039A/en
Priority to BR7505251*A priority patent/BR7505251A/pt
Priority to YU02221/75A priority patent/YU222175A/xx
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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
    • 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
    • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
    • E21B43/162—Injecting fluid from longitudinally spaced locations in injection well

Definitions

  • Woodward 1 Sept. 9, 1975 METHOD FOR RECOVERING VISCOUS steam flooding are applied to viscous oil containing PETROLEUM formations such as tar sand deposits, poor vertical [75] inventor: Charles D. Woodward, Houston, c9nformaqts freque'ltly results pamcularly whep the Tex oil formation contains one or more zones having a permeability substantially less than other zones in the [73] Assignee: Texaco lnc., New York, NY. formation. Recovery efficiency is improved if the injection well is completed so as to establish separate [22] Flled' Sept 1974 communication means between the surface and each [21] Appl. No.: 508,029 of the zones of different permeability.
  • This invention concerns a method for recovering viscous petroleum from a subterranean. viscous petroleum-containing formation such as a tar sand deposit, particularly from a formation having at least two zones differing substantially from one another in permeability.
  • steam flooding In which steam is injected into one or more injection wells to pass through the formation and heat the petroleum contained therein so as to decrease its viscosity.
  • the viscosity of the bituminous petroleum contained in tar sand deposits is known to be in the order to millions of centipoise at formation temperatures, the viscositytemperature relationship of petroleum is exceedingly shapr and is about 2 centipoise at ZOO-300F.
  • steam flooding is accomplished by injecting steam into one well, which steam passes through the formation to a remotely located production well and steam or steam condensate is recovered from the production well. The thermal energy contained in the steam raises the temperature of the viscous petroleum to a point that it will flow, and ultimately petroleum production is obtained from the production well as a result of the heating effect of steam injection.
  • a formation is comprised of two adjacent layers, one of which having a permeability substantially greater than the other, and steam is injected into the full thickness of the formation, steam flow will be confined to the more permeable layer and essentially no steam will pass into the less permeable layer.
  • SUMMARY OF THE INVENTION 1 have discovered that it is possible to treat a subterranean viscous petroleum-containing formation which is comprised of two or more intervals or zones having significantly difl'erent permeabilities to fluid flow in such manner that a thermal fluid such as steam introduced into the formation will move through both the more permeable and the less permeable streaks uniformly, thereby recovering petroleum from both zones.
  • the method requires the establishing of separate injection means between the surface and each of the petroleum saturated intervals. For example, a single well bore may be used for this purpose in a formation containing two petroleum saturated intervals.
  • the production tubing may be in fluid communication with the lower zone with a packer set between the zones and the annular space between the tubing and the well casing utilized as a second fluid communication means between the surface and the upper petroleum saturated zone.
  • the oil recovery fluid to be utilized is steam
  • steam injection is established into the more permeable zone first, in order to establish a pressure gradient in that zone which will preclude the movement of fluids from the less permeable zone into the more permeable zone
  • Afier steam injection has been established into the more permeable zone
  • a hydrocarbon solvent such as propane, natural gasoline, or other aliphatic hydrocarbons is introduced by the separate communication means into the less permeable zone. From about 0.05 to 0.5 pore volumes of hydrocarbon solvent is introduced into the less permeable zone after which it is displaced with any convenient gaseous drive fluid such as natural gas.
  • Steam is then injected into the pretreated low permeability zone in order to displace the hydrocarbon solvent away from the injection well.
  • the steam injection pressure into the low permeability zone is maintained at a value less than the steam injection pressure in the high permeability zone.
  • the steam injection pressure in the low permeability zone may be increased until the injection pressure in both zones is essentially equalized.
  • the drawing illustrates in cross sectional view, a subterranean petroleum formation containing two zones of significantly different permeability, into which formation an injection well is completed with separate communication means established between each zone and the surface of the earth for treatment according to the process of my invention.
  • Packer 8 is positioned between the two intervals in the unperforated portion of the casing 9.
  • Production tubing extends inside tubing 9 to a point adjacent perforation 7, so that tubing 10 is in fluid communication with the lower, low permeability oil sand zone 2 and the surface of the earth.
  • the annular space 11 between tubing 10 and easing 9 defines a separate flow path between the surface of the earth and the upper, high permeability interval 1.
  • steam generator 12 is in fluid communication with annular space 11, and also is connected through valve 13 to the production tubing 10.
  • Tank 14 contains the hydrocarbon solvent to be introduced into the lower, low permeability oil sand interval.
  • Pump 15 serves to inject the hydrocarbon solvent material into the lower, low permeability interval at a controlled rate.
  • Storage tank 16 contains a supply of an inert gas such as nitrogen, with appropriate lines connecting to both the tubing 10 and the annular space 11, through valves 17 and 18.
  • the first phase involves introduction of steam into the upper, high permeability strata 1 through annular space 11.
  • steam may be introduced directly into the formation without any pretreatment.
  • a preliminary sweep with an inert gas is highly desirable in order to establish gas saturation in the formation prior to the introduction of steam into the formation.
  • the inert gas such as nitrogen from supply tank 16 is introduced through opened valve 17 into the annular space 11, where it passes through perforations 6 into the upper, high permeability formation 1.
  • the inert gas is introduced until an indication of gas production is obtained at a remotely located production well. This will establish gas saturation in upper petroleum saturated sand interval 1, which will facilitate the subsequent introduction of steam thereinto.
  • valve 17 is closed and steam from generator 12 is introduced into the an nular space 11, from which it passes through perforations 6 into the upper, high permeability strata 1. This is continued until the pressure in upper strate has increased, and may be continued until there is an indication at a remotely located production well of the passage of steam thereinto, such as by the increase in that well s temperature.
  • the next step involves the introduction of a hydrocarbon material into lower, low permeability interval 2. This is accomplished by closing valves 13 and 18, opening valve 19 and activating pump 15 so as to pump the hydrocarbon substance from storage tank 14 into production tubing 10 where it passes through perforation 7 into the lower, low permeability petroleum-saturated interval 2.
  • a quantity of inert gas it is sometimes preferable in very low permeability formations to precede the hydrocarbon injection with a quantity of inert gas, and this may be accomplished as above by passing nitrogen or other inert gas into the production tubing for a period of several days prior to the initiation of hydrocarbon injection. If the permeability of the formation is sufficient to permit pumping hydrocarbon into the formation directly, the inert gas sweep step may be eliminated.
  • Any low molecular weight aliphatic hydrocarbon having from 1 to 10 carbon atoms may be utilized as the hydrocarbon solvent material in accordance with the process of my invention.
  • Gaseous hydrocarbons e. g. methane, ethane, propane and butane may be used.
  • Unsaturated hydrocarbons may also be utilized, although ordinarily economics would preclude the use of such olefinic hydrocarbons.
  • Carbon dioxide may also be used.
  • Normally liquid hydrocarbons, e.g. butane, pentane, heptane, hexane, octane, nonane or decane may be used effectively.
  • Aromatic hydrocarbons such as benzene, toluene, or xylene are also effective for this purpose. Mixtures of two or more of these hydrocarbon materials or a mixture of hydrocarbon and carbon dioxide may also be used effectively.
  • Commercially available mixtures such as naptha, natural gasoline, kerosene, and mixed aromatic-paraffinic hydrocarbon materials such as are sometimes available as waste streams of refinery operations are also very suitable materials for use in the process of my invention.
  • One preferred embodiment of the process of my invention involves the injection of a gaseous hydrocarbon solvent into the lower, low permeability zone 2 followed by the introduction of a liquid hydrocarbon solvent material.
  • the gaseous material is more readily displaced into the zone, and opens up the permeability of the zone so that the subsequently injected liquid hydrocarbon material may be pumped into the petroleum saturated zone.
  • a naturally gaseous material such as propane may be pumped into the low permeability zone, after which a normally liquid solvent such as natural gasoline is injected to displace the propane and further open up the permeability of the originally low permeability zone.
  • the amount of solvent to be introduced into the formation should be in a range from about 0.05 to about 0.5 pore volumes based on the area to be swept by the injected fluid in the particular pattern being employed.
  • zones of widely differing permeabilities it is meant that the permeability of one earth formation layer is at least 0.25 percent greater than the permeability of another adjacent earth formation layer.
  • steam injection may then be initiated into the low permeability interval while maintaining steam injection into the high permeability interval.
  • the steam injection pressure into the low permeability interval is maintained at a lower value than the steam injection pressure for the high permeability interval.
  • the reason for maintaining the steam injection pressure into the low permeability interval is to ensure that the steam injected into the low permeability interval does not channel through vertical communication points into the upper communication interval.
  • Steam pressure into the low permeability interval may be slowly increased until the injection pressure of steam being introduced into the high permeability interval is essentially the same as the steam pressure being introduced into the low permeability interval.
  • the above described process has been described in terms of a steam flooding operation, although the same pretreatment process may be used in application of in situ combustion or hot water flooding to subterranean formations where there are encountered two or more zones of widely differing permeabilities.
  • the process may be applied to subterranean formations containing relatively low viscosity crudes which are to be subjected to water flooding operations or to other supplemental recovery operations, or to other supplemental recovery operations involving the injection of an unheated aqueous fluid into the formation for the purpose of displacing petroleum toward the production well.
  • adjacent oil saturated intervals of widely varying permeabilities which are to be subjected to surfactant flooding may also be pretreated according ot the process of this invention, by the introduction of a solvent material into the low permeability strata while maintaining the positive pressure in the high permeability strata in order to confine the hydrocarbon treating material to the low permeability strata.
  • inventions include heating the inert gas and/or the solvent prior to introduction thereof into the low permeability zone of the formation.
  • the gas and/or solvent may be heated to a temperature of from about l00F to about 350F.
  • F lELD EXAMPLE A tar sand deposit located under an overburden thickness of 240 feet was penetrated by a dually completed injection well.
  • a production well was located 25 feet from the injection well. Although this was intended as a monitor well, it was completed for oil production, and the well was complete open hole throughout the full thickness of the tar sand deposit.
  • the tar sand interval was comprised of two separate zones, the upper zone being approximately 30 feet in thickness and the lower zone approximately 40 feet in thickness. A shale stringer separated the two zones although it was known that there was vertical communication between the two zones. The upper zone was the more permeable zone.
  • the well was completed essentially as shown in the attached drawing, with the tubing being in fluid communication with the lower, low permeability zone and the annular space establishing fluid communication between the surface and the upper, more permeable zone.
  • the permeability of the upper zone was about 250 millidarcies and the permeability of the lower zone was about millidarcies.
  • the oil recovery process being employed in this particular field was a controlled, low temperature combustion process accomplished by the introduction of a mixture of steam and air into the formation.
  • the ratio of steam to air was approximately 0.4 barrels of steam (as water) per million standard cubic feet of air.
  • Nitrogen was injected slowly into the upper formation first, to establish a gas saturation between the injection well and the monitor well located 25 feet away. Steam and air were then injected into the formation, and injection was continued until the temperature in the monitor well showed an increase, indicating that heated fluid had saturated the upper, more permeable zone.
  • recovery fluid is a mixture of air and steam.
  • a solvent for the formation petroleum selected from the group consisting of aliphatic or aromatic hydrocarbons having from 1 to 10 carbon atoms, carbon dioxide and mixtures thereof, into the zone of lower permeability,
  • a method as recited in claim 10 comprising the additional step of increasing the drive fluid injection pressure in the low permeability zone until the drive fluid is being injected at substantially equal pressures into the low permeability zone and the high permeability zone.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
US508029A 1974-09-23 1974-09-23 Method for recovering viscous petroleum Expired - Lifetime US3903967A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US508029A US3903967A (en) 1974-09-23 1974-09-23 Method for recovering viscous petroleum
CA229,676A CA1027039A (en) 1974-09-23 1975-06-19 Method for recovering viscous petroleum
BR7505251*A BR7505251A (pt) 1974-09-23 1975-08-15 Processo para recuperacao de petroleo de formacoes subterraneas contendo petroleo
YU02221/75A YU222175A (en) 1974-09-23 1975-09-02 Process for the exploitation of naphtha

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4099568A (en) * 1974-02-15 1978-07-11 Texaco Inc. Method for recovering viscous petroleum
US4715444A (en) * 1986-10-27 1987-12-29 Atlantic Richfield Company Method for recovery of hydrocarbons
EP2228514A1 (en) * 2009-03-10 2010-09-15 Shell Internationale Research Maatschappij B.V. Improving crude oil production from a layered oil reservoir
WO2017083954A1 (en) * 2015-11-16 2017-05-26 Nexen Energy Ulc Method for recovering hydrocarbons from low permeability formations

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3221810A (en) * 1964-03-11 1965-12-07 Phillips Petroleum Co Sweep efficiency in miscible fluid floods
US3358759A (en) * 1965-07-19 1967-12-19 Phillips Petroleum Co Steam drive in an oil-bearing stratum adjacent a gas zone
US3421583A (en) * 1967-08-30 1969-01-14 Mobil Oil Corp Recovering oil by cyclic steam injection combined with hot water drive

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3221810A (en) * 1964-03-11 1965-12-07 Phillips Petroleum Co Sweep efficiency in miscible fluid floods
US3358759A (en) * 1965-07-19 1967-12-19 Phillips Petroleum Co Steam drive in an oil-bearing stratum adjacent a gas zone
US3421583A (en) * 1967-08-30 1969-01-14 Mobil Oil Corp Recovering oil by cyclic steam injection combined with hot water drive

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4099568A (en) * 1974-02-15 1978-07-11 Texaco Inc. Method for recovering viscous petroleum
US4715444A (en) * 1986-10-27 1987-12-29 Atlantic Richfield Company Method for recovery of hydrocarbons
EP2228514A1 (en) * 2009-03-10 2010-09-15 Shell Internationale Research Maatschappij B.V. Improving crude oil production from a layered oil reservoir
WO2017083954A1 (en) * 2015-11-16 2017-05-26 Nexen Energy Ulc Method for recovering hydrocarbons from low permeability formations
US10760391B2 (en) 2015-11-16 2020-09-01 Cnooc Petroleum North America Ulc Method for recovering hydrocarbons from low permeability formations

Also Published As

Publication number Publication date
YU222175A (en) 1982-02-28
CA1027039A (en) 1978-02-28
BR7505251A (pt) 1976-08-03

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