Classifications

• • 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
  • C09K8/582—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids characterised by the use of bacteria
• • 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
  • C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
  • C09K8/504—Compositions based on water or polar solvents
  • C09K8/5045—Compositions based on water or polar solvents containing inorganic compounds
• • 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
  • E21B33/00—Sealing or packing boreholes or wells
  • E21B33/10—Sealing or packing boreholes or wells in the borehole
  • E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
  • E21B33/138—Plastering the borehole wall; Injecting into the formation
• • 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
• • 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
  • E21B43/32—Preventing gas- or water-coning phenomena, i.e. the formation of a conical column of gas or water around wells

Definitions

• the present invention relates to a method of extracting petroleum from oil reservoirs by injecting aqueous flooding media into a petroleum formation by injection drilling and withdrawal of petroleum through production wells, the method comprising several cycles of process steps alternately involving oil mobilizing microorganisms and flood water injected. It further relates to a process in which one additionally blocks highly permeable regions of the petroleum formation.
• cavities of porous reservoirs which are closed to the earth's surface by impermeable facings.
• a deposit will continue to contain more or less saline water.
• the cavities may be very fine cavities, capillaries, pores or the like, for example those having a diameter of only about 1 ⁇ ; however, the formation may also have areas of larger diameter pores and / or natural fractures.
• Microbial Enhanced Oil Recovery Another technique of tertiary mineral oil production is known to use microorganisms, in particular bacteria to increase the oil yield. This technique is known as "Microbial Enhanced Oil Recovery” (MEOR), which either injects suitable microorganisms, nutrients for the microorganisms and possibly oxygen into the petroleum formation, or promotes the growth of microorganisms already contained in the petroleum formation by injecting nutrients and possibly oxygen ,
• MEOR Microbial Enhanced Oil Recovery
• RU 2 060 371 C1 discloses a method of conveying petroleum using microorganisms from a reservoir of inhomogeneous permeability, which has at least one injection and at least one production well.
• the reservoir pressure is periodically increased and decreased.
• a nutrient solution is injected into the petroleum formation to activate microorganisms contained in the petroleum formation.
• the injection well is closed. By removing oil or water mixtures through the production bore, the pressure is reduced again.
• RU 2 194 849 C1 discloses a method for conveying petroleum using microorganisms from a reservoir with inhomogeneous permeability, which has at least one injection and at least one production well.
• the reservoir pressure is periodically increased and decreased.
• microorganisms and nutrient solution are respectively injected into the formation through the injection and production bores.
• phases of pressure reduction the injection well is closed and liquid is withdrawn through the production well of the formation.
• mesophilic bacteria are injected into the injection well and thermophilic bacteria are introduced into the production well.
• a disadvantage of this method is the low efficiency, since the production well does not produce continuous oil, but is switched off regularly.
• Ru 2 204 014 C1 discloses a method for pumping petroleum, in which a nutrient solution and carbon-oxidizing bacteria are injected into a petroleum formation and subsequently a biotechnologically produced polyacrylamide together with a crosslinker. When flooding but still more difficulties can occur. Ideally, a water front emanating from the injection well should press the oil evenly across the entire petroleum formation to the production well. In practice, however, a petroleum formation has regions with different high flow resistance. In addition to finely porous, oil-saturated reservoir rocks with a high flow resistance for water, there are also areas with low resistance to flow for water, such as natural or artificial fractures or very permeable areas in the reservoir rock. Such permeable areas may also be de-oiled areas.
• Consance Control can be achieved by using comparatively low-viscosity formulations of certain chemical substances which can easily be pressed into the formation and their viscosity only after Pressing into the formation under the conditions prevailing in the formation conditions significantly increases.
• Such formulations contain inorganic or organic or polymeric components which are suitable for increasing the viscosity.
• the viscosity increase of the pressed-in formulation can easily be delayed.
• formulations are also known in which the increase in viscosity is essentially triggered by the increase in temperature when the injected formulation in the deposit gradually heats up to the reservoir temperature.
• Formulations whose viscosity increases only under formation conditions are known, for example, as “thermogels” or “delayed gelling system”.
• SU 1 654 554 A1 discloses mixtures of aluminum chloride or aluminum nitrate, urea and water, which are injected into the petroleum formation. At elevated temperatures in the formation, the urea hydrolyzes to carbon dioxide and ammonia. The release of the base ammonia significantly increases the pH of the water and precipitates a high viscosity aluminum hydroxide gel which clogs the highly permeable zones.
• US 4,889,563 discloses the use of aqueous solutions of aluminum hydroxide chloride in combination with urea or hexamethylenetetramine (urotropin) to block subterranean petroleum formations. Again, the hydrolysis of urea or hexamethylenetetramine in the formation leads to an increase in the pH and the precipitation of aluminum hydroxide.
• US 4,844,168 discloses a method of blocking portions of high temperature petroleum formations comprising passing polyacrylamide and a polyvalent metal ion such as Fe (III), Al (III), Cr (III) or Zr (IV) into a petroleum formation having a reservoir temperature of at least 60 ° C pressed. Under the conditions in the formation, the amide groups -CONH2 partially hydrolyze to -COOH groups, the metal ions crosslinking the formed -COOH groups to form a gel with a certain time delay.
• a polyvalent metal ion such as Fe (III), Al (III), Cr (III) or Zr (IV)
• Petroleum formations often do not have a homogeneous temperature distribution, but have more or less severe temperature gradients. Such temperature gradients can be of natural origin, but they can be caused in particular by measures of secondary and / or tertiary mineral oil production.
• cold water is often injected into the formation for months or even years.
• the formation temperature in the area around the injection well generally decreases more or less strongly.
• Table 1 shows the temperature drop of the formation temperature for some deposits in northern Siberia after prolonged flooding:
• Table 1 Site temperatures of various Siberian deposits S1 to S6 after prolonged flooding.
• the object of the invention was to provide an improved method for MEOR.
• a process for extracting oil from subterranean oil reservoirs using microorganisms has been found, with at least one injection well and at least one production well drilled into the reservoir, reservoir temperatures (T ij ranging from 45 ° C to 120 ° C and from the reservoir oil promotes by injecting into the at least one injection well aqueous flood media and promotes oil through the at least one production well, and wherein the method comprises at least m cycles Zi to Z m , wherein
• Mobilizing petroleum in the formation by injecting at least one aqueous formulation of oil mobilizing microorganisms, nutrients, and optionally an oxygen source, the microorganisms having an optimal growth temperature Tw, and
• Tw of the injected microorganisms during the implementation of one of the cycles Zi is to Z m not changed and give the m microorganisms used a different optimum growth temperature T w having at each of the process cycles Zi to Z, in the execution of the first process cycle Zi microorganisms are injected with the highest Tw, and each time the process cycle Z is carried out, microorganisms are injected which have a lower optimal growth temperature T w than the microorganisms injected in the preceding process cycle Z.
• FIG. 1 Schematic representation of water flooding in the course of process step (II).
• FIG. 1 Schematic representation of the closure of the first flood zone
• Figure 3 Schematic representation of the formation of a new flood zone after closing the first flood zone.
• the process of the present invention is applied after the primary oil production has ceased due to the inherent pressure of the reservoir and the pressure in the reservoir is maintained by injecting aqueous flooding media. It is particularly suitable for those deposits in which water flooding does not lead to a satisfactory result, because the oil yield is too low. This may be the case, for example, for deposits which are low permeable and / or the oil is not very mobile, so that it can not or only badly be pushed out by the flood water. However, the method is not limited to use in such deposits. deposits
• the oil reservoirs may be deposits for all grades of oil, such as those for light or heavy oil, provided that the reservoir temperatures (T L ) are in the range of 45 ° C to 120 ° C, preferably 50 ° C to 100 ° C, more preferably 50 ° C to 80 ° C.
• reservoir temperature is meant the naturally prevailing temperature in the reservoir. It can be changed by the method steps described below.
• Drilled production well and at least one injection well As a rule, a deposit is provided with several injection wells and possibly multiple production wells.
• the injection wells allow aqueous flooding media to be injected into the oil reservoir, and production wells (also called production wells) are used to extract oil from the reservoir.
• production wells also called production wells
• the aqueous flooding media used in each of the individual process steps are described below. According to the invention are for Injecting the aqueous flooding media in the process steps described below always used the same injection wells; so it will not be drilled new injection wells.
• injection well or production well
• at least one injection well or “at least one production well” should be meant.
• phase-pure petroleum does not mean phase-pure petroleum, but rather the usual emulsions comprising oil and formation water, which are conveyed from crude oil reservoirs. The oil and water phases are separated from one another after conveying in a manner known in principle ,
• Process Cycles Z The process according to the invention comprises m process cycles Zi to Z m , where m> 2. In other words, the method comprises at least two process cycles Z.
• Each of the process cycles Zi to Z m comprises at least two process steps (I) and (II), which are each carried out alternately several times in succession.
• step (I) suitable microorganisms are injected in formation capable of mobilizing petroleum in the formation.
• process step (II) oil is pumped by water flooding.
• the steps (I) and (II) are carried out alternately several times in succession, ie at least twice.
• Each of the cycles Zi to Z m thus comprises at least the steps (I) - (II) - (I) - (II).
• step (I) the crude oil formation is treated with suitable microorganisms for the mobilization of crude oil by injecting suitable microorganisms into the deposit.
• suitable microorganisms are in particular bacteria.
• first geophysical and biochemical investigations of petroleum formation should be carried out.
• the temperature distribution of petroleum formation is determined, at least in the area between the injection well and the production well.
• Methods for determining the temperature distribution of a crude oil deposit are known in principle to the person skilled in the art. It is usually carried out from temperature measurements at specific points of the formation in combination with simulation calculations, which is taken into account in the simulation calculations, inter alia, in the formation of introduced amounts of heat and the amount of heat dissipated from the formation.
• biochemical A- The presence and amount of aerobic and anaerobic microorganisms in the borehole close to the injection well and the production well can be determined by means of analyzes.
• injected microorganisms can be both aerobic as well as anaerobic, preferably anaerobic microorganisms.
• nutrients and optionally an oxygen source are injected into the petroleum formation.
• the components are formulated in a suitable manner in an aqueous medium for this purpose.
• the three components, microorganisms, nutrient solution and, optionally, an oxygen-containing gas can be injected together, or also successively in individual portions, so that microorganisms, nutrient solution and, optionally, the oxygen source mix together only in the formation.
• An oxygen-containing gas may be injected as such or it may preferably be an oxygen-containing flood medium, in particular oxygen-containing water or sols injected.
• the concentration of dissolved oxygen in the aqueous flooding medium, in particular water may for example be 0.05 to 0.5 m 3 oxygen / m 3 flooding medium.
• the injection of an oxygen source, preferably an oxygen-containing gas takes place when using aerobic microorganisms and is omitted when using anaerobic microorganisms. Suitable microorganisms for mobilizing petroleum in a petroleum formation are the
• the mobilization of petroleum may be due to one or more of the following mechanisms: formation of surfactants, reduction of petroleum viscosity by degradation of high molecular weight hydrocarbons, formation of CO2 and / or methane, formation of organic acids capable of attacking the rock formation and thus new ones Creating flow paths or by the separation of the petroleum from the rock surface.
• suitable microorganisms include anaerobic members of various genera such as Clostridium sp., Bacillus sp., Desulfovibrio sp., Arthrobacter sp., Mycobacterium sp., Micrococcus sp., Brevibacillus sp., Actinomyces sp. or Pseudomonas sp.
• Suitable nutrient solutions for microorganisms are known in principle to the person skilled in the art. They contain, for example, phosphate or ammonium salts.
• They may contain as main components, for example NaN0 3 , KN0 3 , NH 4 N0 3 , Na 2 HPO 4 , NH 4 Cl, trace elements such as B, Zn, Cu, Co, Mg, Mn, Fe, Mo, W, Ni, Se, vitamins such as Folic acid, ascorbic acid, riboflavin, electron acceptors such as S0 4 2_ , N0 3 2 , Fe +3 , humic acids, mineral oxides, quinone compounds or combinations thereof.
• trace elements such as B, Zn, Cu, Co, Mg, Mn, Fe, Mo, W, Ni, Se
• vitamins such as Folic acid, ascorbic acid, riboflavin
• electron acceptors such as S0 4 2_ , N0 3 2 , Fe +3 , humic acids, mineral oxides, quinone compounds or combinations thereof.
• the maximum growth rate of microorganisms depends on the temperature.
• the temperature at which the growth of microorganisms is greatest will be referred to as Tw.
• Tw The temperature at which the growth of microorganisms is greatest.
• the person skilled in the art distinguishes between different classes of microorganisms, namely psychrophilic, mesophilic, thermophilic and hyperthermophilic bacteria, wherein the temperature ranges of maximum growth rate may be slightly differently defined depending on the literature citation. Table 3 below shows a common classification to be used for the present invention.
• Table 2 Minimum, maximum and optimal growth temperature for different classes of microorganisms.
• Table 3 shows some microorganisms, each having an optimum growth temperature:
• the flood water used may be any type of water, for example, fresh water, salt water or brine, and the water may optionally also contain other additives.
• the flood water used for injection has a temperature of less than 45 ° C, typically less than 25 ° C and, for example, less than 20 ° C. It may, for example, be seawater. The duration of the flood depends on the conditions in the formation; it can take months or even years.
• steps (I) and (II) are carried out n times successively per cycle, where n> 2 and the number n can assume different values for each cycle.
• n is a number from 2 to 5, preferably 2 or 3
• the sequence of the process steps may therefore preferably be (I) - (II) - (I) - (II) or (I) - (II) - (I) - (II) - (I) - (II).
• Each cycle thus includes at least two M EOR process steps, each followed by water floods.
• the optimum growth temperature Tw of the microorganisms used during a cycle in the process steps (I) is not changed within one cycle, i. The same microorganisms are used during each cycle.
• the floodwater pushes the mobilized petroleum in the direction of the production well, through which it can be removed.
• Water is injected into the injection well (1) from there in the direction of the production well (2) and presses oil from the pores in the direction of the production well.
• the flow direction is indicated by the arrows (3).
• oil is at least partially displaced by the water front.
• the direction of the water front (3) as well as the size and location of the zone (4) are determined by the conditions in the deposit, for example the spatial dynamics of the permeability index, the fracture or local geological disturbances.
• the zone (4) may have a complicated branched shape, especially if there are multiple injection wells for water and multiple production wells on that section.
• the flood water usually does not press the crude oil in front of it in a uniform manner. The reason for this is that even in the flow zone the permeability is generally not uniform. If more porous areas are present, for example fine gaps, fractures or cracks, the water preferably flows through these zones of lower flow resistance.
• the oil may be only partially removed from pores. For example, an oil droplet can remain in a pore, which is no longer carried along by the water flowing through this pore. With increasing duration of water flooding, More and more preferential flood paths for the water are forming.
• the method according to the invention comprises m process cycles Zi to Z m . At least two of the process cycles are carried out, ie m> 2 applies.
• m is a number from 2 to 5, preferably 2 or 3.
• the microorganisms injected in each process cycle Zi to Z m have a different optimal growth temperature Tw.
• Tw optimal growth temperature
• the optimum growth temperature Tw of the first injected portion of microorganisms is expediently dimensioned such that it corresponds approximately to the natural reservoir temperature TL, which lies between 45 ° C. and 120 ° C.
• Tw and TL are about the same, the microorganisms in the formation grow fastest and thus oil in the formation is also well mobilized.
• thermophilic and / or hyperthermophilic microorganisms can be used, depending on the TL.
• thermophilic bacteria such as a strain selected from the group of Streptococcus thermophilus, Geobacillus stearothermophilus, Thermus aquaticus, Streptomyces thermogriseus, Clostridium stercorarium, Thermovorax subterraneus or Geothermobacter ehrlichii.
• the flood water used for injection is comparatively cold and has a temperature of less than 45 ° C, as a rule, less than 25, as shown above ° C and, for example, less than 20 ° C.
• the temperature distribution in the crude oil formation changes with increasing duration of the flooding.
• the temperature of the deposit at the location of the injection well decreases from the originally prevailing reservoir temperature TL.
• the flood water in the direction of the production well ie the zone (4)
• other areas of the flow-through zone can cool down.
• the cooling effect at the injection well is strongest and decreases with increasing distance from the production well.
• the temperature of the flooded zone may well drop to 25 to 45 ° C over time.
• microorganisms having a lower optimum growth temperature Tw than in the first cycle are used in order to take account of this cooling of the petroleum formation in the flooded region.
• T w should therefore be chosen to be about TF.
• mesophilic microorganisms can be injected.
• a storage temperature TL in the range of 50 to 80 ° C as described above, one can select the method after lowering the temperature to 30 ° C to 40 ° C, for example, with mesophilic bacteria selected from the group of Escherichia coli, Streptomyces coelicolor, Bacillus subtilis, Corynebacterium glutamicum, Pseudomonas putida, Salmonella enterica or Micrococcus luteus.
• mesophilic bacteria selected from the group of Escherichia coli, Streptomyces coelicolor, Bacillus subtilis, Corynebacterium glutamicum, Pseudomonas putida, Salmonella enterica or Micrococcus luteus.
• a new cycle Z 3 can be started again, in which microorganisms are used with a further reduced Tw.
• microorganisms for example, psychrophilic microorganisms can be used.
• the method can be selected after the temperature has dropped below 25 ° C., for example using psychrophilic bacteria from the group of Flavobacterium antarcticum, Photobacterium profundum , Shewanella benthica, Chlamydomonas nivalis, Flavobacterium frigidarium, Leptothrix mobilis or Bacillus marinus.
• the cycles can, in principle, be executed repeatedly m times, reducing Tw every time compared to Twe's previous cycle.
• the process cycles Z are preferably carried out two or three times in succession, more preferably twice.
• the formation is treated in accordance with the decreasing temperature of the flood zone TF, respectively, with microorganisms adapted Tw and thus achieves a particularly good de-oiling.
• the method optionally comprises an additional process step (III).
• process step (III) highly permeable regions of the formation can be blocked.
• the highly permeable regions are essentially the zone through which flows through in the region between the at least one injection bore and the at least one production bore, that is to say the zone which has only formed by carrying out the process cycles Z.
• aqueous formulations are injected through the injection well into the formation, which can cause the highly permeable regions to become closed.
• the blocking of highly permeable regions of the formation is preferably carried out by injecting at least one aqueous, gel-forming formulation (F) through the injection well, the formulations forming highly viscous gels after being pressed into the deposit under the influence of the reservoir temperature. After being injected into the formation, the formulations (F) naturally flow essentially through the highly permeable regions and close them after the gel has formed. This is shown schematically in Figure 2.
• a gel plug (5) seals the high permeability areas between the injection and production wells.
• the aqueous gel-forming formulations (F) comprise, in addition to water, one or more different water-soluble or water-dispersible chemical components which are responsible for gelation. It is preferably at least two different components. These may be both inorganic components and organic components, and of course also combinations of inorganic and organic components.
• these may be formulations based on water-soluble polymers, as disclosed, for example, in US Pat. No. 4,844,168, US Pat. No. 6,838,417 B2 or US Pat. No. 2008/0035344 A1, or formulations based essentially on inorganic components, such as, for example, SU 1 654 554 A1, US Pat. No. 4,889,563, RU 2 066 743 C1, WO 2007/135617, US Pat. No. 7,273,101 B2 or RU 2 339 803 C2. Suitable formulations are also commercially available.
• the temperature starting from gelation (hereinafter referred to as TGei) and the time at which this happens (hereinafter called tGei) can be influenced, for example, by the nature and concentration of the components. They can be adjusted so that between 20 ° C and 120 ° C, preferably 30 to 120 ° C and more preferably 40 to 120 ° C gels are formed. The cited citations contain information. The formulations can thus be adjusted so that the formulations form gels at the desired location of the highly permeable areas and block the high-permeability areas.
• formulation (F) is an acidic aqueous formulation, preferably having a pH ⁇ 5, which comprises at least
• a water-soluble activator comprising, at a temperature T> TG, an increase in the pH of the aqueous solution.
• the formulation may optionally include other water-miscible organic solvents. Examples of such solvents include alcohols.
• the formulations (F) should comprise at least 80% by weight of water with respect to the sum of all solvents of the formulation, preferably at least 90% by weight and more preferably at least 95% by weight. Most preferably, only water should be present.
• the dissolved metal compound is preferably aluminum compounds, in particular dissolved aluminum (III) salts, such as, for example, aluminum (III) chloride, aluminum (III) nitrate, aluminum (III) sulfate, aluminum (III) acetate or aluminum (III ) acetylacetonate.
• dissolved aluminum (III) salts such as, for example, aluminum (III) chloride, aluminum (III) nitrate, aluminum (III) sulfate, aluminum (III) acetate or aluminum (III ) acetylacetonate.
• it may also be partially hydrolyzed aluminum (III) salts, such as, for example, aluminum (III) hydroxychloride.
• the pH of the formulation is generally ⁇ 5, preferably ⁇ 4.5.
• Suitable water-soluble activators are all compounds which, on heating to a temperature T> TGei, release bases in an aqueous medium or bind acids and thus ensure an increase in the pH of the solution.
• water-insoluble gels are formed, which comprise metal ions, hydroxide ions and optionally further components.
• an aluminum hydroxide or oxide hydrate gel can form, in which, of course, further components, such as for example the anions of the aluminum salt used, may comprise.
• urea substituted ureas such as ⁇ , ⁇ '-alkyl ureas, in particular ⁇ , ⁇ '-dimethylurea, Hexamethylentetra- min (urotropin) or cyanates
• urea substituted urea substances or hexamethylenetetramine urea, for example hydrolyzed in aqueous Medium to ammonia and CO2.
• mixtures of several different activators can be used. It is preferably urea and / or hexamethylenetetramine.
• the formulations may further comprise other components which can accelerate or retard gelation. Examples include other salts or naphthenic acids.
• concentrations of the metal compounds used are selected by the skilled person so that a gel forms with the desired viscosity. He will therefore use the activator in such a concentration that a sufficient amount of base can be formed to lower the pH so much that a gel can actually precipitate. Furthermore, it is also possible to determine the gel formation time tGei by way of the amounts or the proportions. The higher the concentration of the activator, the greater the rate of gelation at a given metal compound concentration. This connection can the
• Gel-forming formulations which are particularly suitable for low storage temperatures, can be obtained by replacing urea as an activator in whole or in part by urotropin (hexamethylenetetramine) as an activator. Urotropin also releases ammonia under reservoir conditions. Such gel-forming formulations also lead
• Typical aqueous formulations may comprise 4 to 16% by weight of urea, 2 to 8% by weight of urotropin and 2 to 4% by weight of aluminum chloride or nitrate (calculated as the anhydrous salt) and water or salt water.
• Such formulations are disclosed, for example, in RU 2 066 743 C1.
• Table 6 below presents some of the formulations disclosed in RU 2,066,743 C1, pages 5 to 7 and their gelation at different temperatures.
• the described preferred formulations based on dissolved metal compounds, in particular aluminum salts and activators have the advantage that inorganic gels are formed.
• the gels are stable up to temperatures of 300 ° C.
• the inorganic gels can also be removed from the formation very easily by injecting acid into the formation and dissolving the gels.
• process step (I II) After the optional execution of process step (I II), the oil production is continued, for example by flooding.
• the oil production is carried out by repeatedly executing process cycles Z. This is shown schematically in Figure 3. It forms a new Flutzone (6), from which oil is now extracted.
• the process cycles Z to Z m - are carried out, where m '> 2, preferably 2 to 5 and particularly preferably 2 or 3.
• the new flood zone (6) initially has the storage temperature or at least approximately the storage temperature and T w is set accordingly.

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Citations (19)

• 2012
  • 2012-02-06 EA EA201391044A patent/EA023613B1/ru not_active IP Right Cessation
  • 2012-02-06 EP EP12703086.4A patent/EP2673333A1/de not_active Withdrawn
  • 2012-02-06 CA CA2823750A patent/CA2823750A1/en not_active Abandoned
  • 2012-02-06 WO PCT/EP2012/051912 patent/WO2012107373A1/de active Application Filing

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