Abstract: A method for managing a sequestration fluid including sequestering a fluid in a subsurface formation downhole of a caprock and downhole of a seal in a borehole, targeting a sample of formation fluid in the borehole uphole of the caprock and uphole of the seal in the borehole. A sequestration system including a borehole in a formation, the borehole extending downhole of a caprock, a string disposed in the borehole, a seal between the string and a wall of the borehole uphole of the caprock, and a port in the string uphole of the seal and the caprock, the port having access to a portion of the formation uphole of the caprock.

Abstract: A coreflood experiment may be modeled by generating a three dimensional computer simulation model of a core plug and modeling within the three dimensional computer simulation model one or both of a fluid introduction element or a fluid extraction element of a core holder used in the coreflood experiment. Once generated, the model may be loaded and used when running a simulation to model a heterogeneous distribution of fluid flow proximate one or more faces of the core plug.

Abstract: A method of increasing the strength of a carbonate rock is described. The carbonate rock may be located within a subterranean carbonate formation or may be located on a building exterior. The method involves contacting the carbonate rock with a composition comprising a zinc salt or a silicon alkoxide. This may increase the hardness of the carbonate rock by 10% or more.

Abstract: The disclosure is directed to methods and compositions delaying the gelation of polymers in water flooding by sequentially or co-injecting a carboxylate-containing polymer solution, a gel-delaying polymer, and gelation agent into a hydrocarbon reservoir. Delays of weeks are observed.

Abstract: A method for recovering crude oil from a reservoir including at least one layer of reservoir rock having crude oil and a formation water within the pore space thereof includes injecting into the layer(s) of reservoir rock from an injection well, alternating slugs of an aqueous displacement fluid comprising a concentrated solution of a water-soluble additive in an aqueous solvent and of an aqueous spacer fluid. The number of injected slugs of aqueous displacement fluid, n, is in the range of 15 to 1000 per swept pore volume, PVR, of the layer(s) of reservoir rock. The injected pore volume of each individual slug, PVSlug-i, of aqueous displacement fluid is in the range of 10?12 to 10?2 of the swept pore volume, PVR, of the layer(s) of reservoir rock. The total injected pore volume of the slugs of aqueous displacement fluid is in the range of 10?8 to 10?1 of the swept pore volume, PVR, of the layer(s) of reservoir rock.

Abstract: Embodiments of the disclosure include swellable smart gel sealants. In certain embodiments, the smart gel sealants reversibly swell when exposed to a certain trigger, such as temperature or pH. In specific embodiments, the smart gel is disposed within voids in a well and triggered to swell in order to seal the voids. One application of the smart gel sealant is to seal the casing of a well against the leakage of gas, such as CO2.

Abstract: Methods and systems are provided to enhance recovery of hydrocarbons from a formation by altering wettability at a surface of the formation towards more water-wet. One method includes: providing a formation; providing an aqueous stream for injecting into the formation; adding a reducing agent to the aqueous stream; and injecting the aqueous stream with the reducing agent into the formation to alter a surface charge of the surface of the formation to become more water-wet to enhance recovery of hydrocarbons from the formation. The reducing agent is responsive to characteristics of the formation, characteristics of brine of the formation, and characteristics of hydrocarbons of the formation. Also provided is a method to select a brine composition to be injected into a formation to alter wettability at a surface of the formation towards more water-wet to enhance recovery of hydrocarbons from the formation.

Abstract: A hydrocarbon-in-water purification system includes an anion exchange stage having an anion exchange resin and an inlet and a water permeate outlet and a hydrocarbon outlet. The inlet is in fluid communication with a hydrocarbon-in-water emulsion source.

Abstract: Methods and compositions comprising an emulsion or a microemulsion and a polymer for use in an oil and/or gas well are provided. In some embodiments, the emulsion or the microemulsion comprises water, a solvent, and a surfactant, and optionally, one or more additives. In certain embodiments, the polymer comprises a copolymer comprising an acrylamide.

Abstract: An integrated process for making high molecular weight hydrocarbons from a synthesis gas feed to a Fischer-Tropsch unit. A carbon monoxide resistant gold-on-palladium membrane system (membrane system) is used to control the hydrogen-to-carbon monoxide molar ratio of a feed to the Fischer-Tropsch unit. The membrane system is operatively connected between a steam reformer and the Fischer-Tropsch unit. The membrane system receives a synthesis gas stream and provides for the removal of hydrogen from the synthesis gas stream to provide a retentate stream having a desired H2/CO molar ratio that is fed to the Fischer-Tropsch unit.

Abstract: Disclosed are compositions, methods, and systems of treating a well. A method may comprise providing a treatment fluid comprising a fluorous oil external phase, a salt-free non-chloride containing internal phase, and a fluorous-based surfactant; and introducing the treatment fluid into a wellbore. A treatment fluid composition may comprise a fluorous oil external phase, a salt-free non-chloride containing internal phase, and a fluorous-based surfactant.

Abstract: Controlling microbial growth and activity during Microbial Enhanced Oil Recovery processes is disclosed. Specific control of microbial growth and activity in this process results in prevention of nutrient loss in transit and allows better targeting of microbial activity to the desired subsurface location(s).

Abstract: A method includes irradiating a surface of a sample, which is made-up of multiple types of materials, with a beam of primary electrons. Emitted electrons emitted from the irradiated sample are detected using multiple detectors that are positioned at respective different positions relative to the sample, so as to produce respective detector outputs. Calibration factors are computed to compensate for variations in emitted electron yield among the types of the materials, by identifying, for each material type, one or more horizontal regions on the surface that are made-up of the material type, and computing a calibration factor for the material type based on at least one of the detector outputs at the identified horizontal regions. The calibration factors are applied to the detector outputs. A three-dimensional topographical model of the surface is calculated based on the detector outputs to which the calibration factors are applied.

Abstract: A process for hydrocarbon recovery performs a steam assisted gravity drainage (SAGD) operation by injecting steam in a steam injection well of a SAGD well pair and continuing to inject steam to establish fluid communication between the steam injection well and an oxidizing gas injection well that includes an oxidizing gas injection well segment that is spaced generally above the steam injection well segment, and producing hydrocarbons from a hydrocarbon production well of the SAGD well pair, the hydrocarbon production well including a generally horizontal production well segment disposed generally parallel to and vertically below a generally horizontal steam injection well segment of the steam injection well such that the steam injection well segment is disposed generally vertically between the production well segment and the oxidizing gas injection well segment.

Abstract: Mineral oil is produced from underground mineral oil deposits by injecting one or more flooding media into an injection well and withdrawing mineral oil from a production well. Highly permeable zones are blocked in the region between the injection well and the production well by separately injecting, in succession, two different aqueous formulations, one having water and urotropin and the other having water and urea, through the injection well into the deposit. The two different aqueous formulations mix in the formation after injection to form viscous gels. Either or both formulations have at least one further metal or semimetal compound that can form gels when admixed with bases. The injection well temperature is not more than 60° C.

Abstract: Complexing-acidizing treatment fluids can be used in various subterranean treatment operations. Some methods include: providing or preparing a complexing-acidizing treatment fluid having an acid concentration of about 0.6 Molar, the complexing-acidizing treatment fluid including: an aminopolycarboxylic acid chelating agent, an aqueous base fluid, and an acid, placing the complexing-acidizing treatment fluid in a subterranean formation matrix penetrated by a well bore; allowing the acid to generate metal cations by dissolution of the subterranean formation matrix; reacting the aminopolycarboxylic acid chelating agent with the metal cations so as to form at least a plurality of aggregate blocking agents; and allowing the aggregate blocking agents to divert the complexing-acidizing treatment fluid to a main channel in the subterranean formation matrix that is distinct from a wormhole in the subterranean formation matrix.

Abstract: A composition including HCl, urea, complex substituted keto-amine-hydrochloride, an alcohol, an ethoxylate, and a ketone is provided in a method for solubilizing calcium carbonate in an aqueous suspension or dispersion of calcium carbonate.

Abstract: Multi-stage methods for the enhanced recovery of high viscosity oil deposits from low temperature, shallow subterranean formations. The methods may include the steps of heating potentially extractable hydrocarbons, such as high viscosity oil, by injecting a sufficient amount of a heating fluid having a temperature and viscosity sufficiently high to minimize channeling and to permit penetration into regions of the reservoir containing the potentially extractable hydrocarbons. Thereafter, there is injected an extraction fluid that forms a mobile emulsion with the oil, without need for a co-solvent. The extraction fluid may include either a surfactant-polymer formulation or an alkaline-surfactant-polymer formulation. This is followed by injecting a polymer drive medium into the reservoir to displace and drive hydrocarbons and fluids comprising oil to a production well. An aqueous driving medium is then injected into the reservoir to also drive hydrocarbons and fluids comprising oil to a production well.

Abstract: A multistage process for producing mineral oil from mineral oil deposits by injecting aqueous flooding media into a mineral oil formation through injection boreholes and withdrawing the mineral oil through production boreholes, in which the mineral oil yield is increased by the use of microorganisms in combination with measures for blocking highly permeable zones of the mineral oil formation.

Abstract: Heavy oil recovery from oil sand reservoirs is enhanced through the creation of subsurface high permeability pathways distributed throughout the oil sand reservoirs. The high permeability pathways may be boreholes that extend through the oil sand reservoir. A portion of the high permeability pathway may be packed with high permeability particulate to provide structural support and allow for high permeability throughout the boreholes. After establishing the high permeability pathways throughout the oil sand reservoir, solvent may be introduced into the oil sand reservoir. The solvent has the beneficial effect of lowering the viscosity of the heavy oil, which aids in the extraction of the heavy oil. Thermal recovery processes and other enhancements may be combined with these methods to aid in reducing the viscosity of the heavy oil. Advantages of these methods include, accelerated hydrocarbon recovery, higher production efficiencies, lower costs, and lower extraction times.

Abstract: A method of recovering petroleum from dormant oil wells or increasing the production of oil wells. An alkali metal or alkaline earth metal carbonate is introduced into a water layer associated with a subterranean petroleum reservoir and/or an explosive composition is introduced into an oil layer associated with a subterranean petroleum reservoir. CO2 gas is produced by reacting the alkali metal or alkaline earth metal carbonate with an acid and/or by detonating the explosive composition.

Abstract: Method for recovery of hydrocarbon includes: a. injecting mixture of high salinity brine and low salinity brine into the formation, wherein the mixture is injected into the formation through a first pump, wherein the first pump is an automated control pump, at a flow rate based on physical characteristics of the formation, the flow rate of the mixture gradually and continuously decreases, b. injecting fresh water into the formation, wherein the mixture is injected into the formation through a second pump, wherein the second pump is an automated control pump, wherein the fresh water is injected into the formation at a flow rate based on the physical characteristics of the formation, wherein the flow rate gradually and continuously increases; and c. introducing surfactants or polymers into the formation, wherein the surfactant acts as a motive force to drive the hydrocarbons towards one or more production wells.

Abstract: A method for mobilizing viscous hydrocarbons in a reservoir includes (a) injecting an aqueous solution into the reservoir with the reservoir at the reservoir ambient temperature. The aqueous solution includes water and a water-soluble chemical agent that is substantially non-decomposable and substantially non-reactive in the reservoir at the reservoir ambient temperature. In addition, the method includes (b) adding thermal energy to the reservoir at any time after (a) to increase the temperature of at least a portion of the reservoir to an elevated temperature greater than the ambient temperature of the reservoir. Further, the method includes (c) in response to the elevated temperature in (b), mobilizing at least a portion of the hydrocarbons in the reservoir by reducing the viscosity of the hydrocarbons and allowing the chemical agent to enhance mobilization of the hydrocarbons.

Abstract: A method for recovering viscous hydrocarbons from a reservoir in a subterranean formation includes (a) injecting steam into the reservoir. In addition, the method includes (b) injecting a surfactant into the reservoir with the steam during (a). Further, the method includes (c) decreasing the viscosity of the hydrocarbons in the reservoir with thermal energy from the steam. Still further, the method includes (d) emulsifying the hydrocarbons with the surfactant during (b) and (c). Moreover, the method includes (e) mobilizing at least some of the hydrocarbons in the reservoir.

Abstract: A method for recovering viscous hydrocarbons from a reservoir in a subterranean formation includes (a) injecting steam into the reservoir. In addition, the method includes (b) injecting a thermally activated chemical species into the reservoir with the steam during (a). The thermally activated chemical species decomposes at a temperature between 40° and 200° C. Further, the method includes (c) decreasing the viscosity of the hydrocarbons in the reservoir during (a) and (b). Still further, the method includes (d) mobilizing at least some of the hydrocarbons in the reservoir.

Abstract: Embodiments of the invention relate to methods for increasing the recovery of hydrocarbons from a subterranean reservoir. In one embodiment, a method for recovering hydrocarbons from a subterranean reservoir is provided. The method includes positioning a first device into a first horizontal well, injecting a first fluid into the first horizontal well through the first device, producing hydrocarbons from a second horizontal well disposed below the first well, injecting a second fluid into a third well laterally offset from each of the first and second wells to drive fluids in the reservoir toward the second well while continuing to produce hydrocarbons from the second well, and selectively ceasing injection into the first well when the second well is in fluid communication with the third well.

Abstract: The invention is directed to polymers that self-crosslink at acidic pH or can be crosslinked by phenolic agents in brine. Such polymers have lower viscosity and can be pumped deep into reservoirs, where they will cross link in situ, thus increasing their viscosity and/or form a gel and blocking thief zones. Methods of making and using such polymers are also provided.

Abstract: A method includes introducing a treatment fluid including a first polymer gel into a subterranean formation to generate a production fluid having an aqueous portion and a hydrocarbon portion, treating the aqueous portion of the production fluid with chlorine dioxide to separate additional hydrocarbons from the aqueous portion, and adjusting the viscosity of the treated aqueous portion prior to introducing the treated aqueous portion back into the subterranean formation.

Abstract: A method for recovering hydrocarbons from a subterranean reservoir by operating a substantially gravity-controlled recovery process with two adjacent well pairs. Each well pair includes an injector well and a producer well. A mobilized zone forms around each well pair through the gravity-controlled recovery process, and a bypassed region forms between the adjacent well pairs when the respective mobilized zone of each well pair merge to form a common mobilized zone. A plurality of infill producer wells are provided in the bypassed region. The plurality of infill producer wells are operated to establish fluid communication between the plurality of infill producer wells and the common mobilized zone. Once fluid communication is established, the plurality of infill producer wells and the adjacent well pairs are operated under a substantially gravity-controlled recovery process, and hydrocarbons are recovered from the plurality of infill producer wells and from the producer wells.

Abstract: The present invention provides a method of liquefying a carbonaceous material in situ to produce liquid hydrocarbon comprising applying an aqueous solution to the carbonaceous material to facilitate a liquefaction reaction in a reaction zone in the carbonaceous material that liquefies the carbonaceous material to liquid hydrocarbon, wherein the aqueous solution comprises components selected from the group consisting of water, hydrogen peroxide at a (w/w) concentration range between 0.1% to 70%, methanol at a (w/w) concentration range between 0.1% to 30%, and a catalyst. The aqueous solution may be a superheated fluid, a supercritical fluid, a high-velocity superheated fluid or a high-velocity supercritical fluid. In an embodiment, the reaction zone is heated to a desired temperature by applying a first aqueous solution prior to applying a second aqueous solution that is a superheated fluid, a supercritical fluid, a high-velocity superheated fluid or a high-velocity supercritical fluid.

Abstract: Disclosed herein is introduction of different nutrient solution formulations to a subterranean target site to prevent biofilm formation and biomass aggregation at the sand face of an injection well bore during MEOR or bioremediation processes. A first nutrient solution formulation supports growth of introduced microorganisms and a second nutrient solution formulation is used to promote biofilm formation to allow plugging of pores and channels in the subterranean target site, for MEOR or bioremediation.

Abstract: Method of treating a hydrocarbon-bearing formation having brine and treated hydrocarbon-bearing formations. The method includes contacting a hydrocarbon-bearing formation with a composition comprising solvent and a polymer. The polymer comprises divalent units represented by formula: (formula I); and a plurality of alkyleneoxy groups. In some embodiments, the solvent at least one of solubilizes or displaces the brine in the formation. In some embodiments, the solvent includes at least one of a polyol or polyol ether independently having from 2 to 25 carbon atoms and at least one of water, a monohydroxy alcohol, an ether, or a ketone, wherein the monohydroxy alcohol, the ether, and the ketone each independently have up to 4 carbon atoms. Hydrocarbon-bearing formations and proppants treated with the polymer are also disclosed.

Abstract: A process for enhanced oil recovery includes the steps of providing an alkali metal borohydride; providing an alkali metal bisulfite; combining the alkali metal borohydride and the alkali metal bisulfite along with water to provide an oxygen-scavenger composition; combining the oxygen-scavenger composition and an aqueous composition to provide an oil recovery solution; and introducing the oil recovery solution into an earthen formation at a pressure to provide for enhanced oil recovery.

Abstract: The present disclosure relates to enhanced oil recovery methods for highly viscous oil reservoirs containing large amounts of mobile water. One method includes injecting a carbon disulfide formulation or fluid into the formation via a first well and displacing the mobile water from the formation with the carbon disulfide fluid. The highly viscous oil is then solubilized using the carbon disulfide fluid, thereby generating a mixture of mobilized oil. The mixture of mobilized oil is then forced towards a second well and subsequently produced from the second well.

Abstract: Methods for improving the quality of hydrocarbon fluids produced by in situ pyrolysis or mobilization of organic-rich rock, such as oil shale, coal, or heavy oil. The methods involve reducing the content of olefins, which can lead to precipitation and sludge formation in pipelines and during storage of produced oils. The olefin content is reduced by arranging wells and controlling well pressures such that hydrocarbon fluids generated in situ are caused to pass through and contact pyrolyzed zones in which coke has been left. This contacting chemically hydrogenates a portion of the olefins in the pyrolysis oil by reducing the hydrogen content of the coke.

Abstract: Viscoelastic surfactant (VES) gelled aqueous fluids containing water, a VES in an amount effective to increase the viscosity of the water, and an internal breaker may be useful in removing a residual polymer from a hydraulic fracture. Optionally, a pseudo-crosslinker may be present to further improve the properties related to treatment fluid placement and polymer clean-up. A plurality of aliquots of VES gelled fluid may be injected into a subterranean formation. A stop-start interval may exist between the injection of each aliquot. The VES gelled fluid may contact at least some of the residual polymer in the hydraulic fracture, and a broken fluid is formed once the viscosity of the VES gelled fluid is reduced with the internal breaker. At least a portion of the residual polymer and a majority of the broken fluid may be removed.

Abstract: The present invention relates to a process for the production of mineral oil from mineral oil deposits with large temperature gradients, in which, for increasing the mineral oil yield, highly permeable regions of the mineral oil formation are blocked by injecting formulations which, after being forced into the deposit, form highly viscous gels under the influence of the deposit temperature. A plurality of portions of the formulation which in each case can form gels at different temperatures and therefore result in very complete blocking of highly permeable regions of the formation are used.

Abstract: A process for mineral oil production especially Winsor type III microemulsion flooding, in which an aqueous surfactant formulation which comprises at least one nonionic surfactant having 11 to 40 ethoxy units and a hydrophobic radical having 8 to 32 carbon atoms and at least one further surfactant differing therefrom is forced through injection wells into a mineral oil deposit and crude oil is removed from the deposit through production wells.

Abstract: A process for mineral oil production, especially Winsor type III microemulsion flooding, in which an aqueous surfactant formulation which comprises at least one nonionic surfactant having 8 to 30 ethoxy units, which has a polydispersity of from 1.01 to 1.12, and at least one further surfactant is forced through injection wells into a mineral oil deposit and crude oil is removed from the deposit through production wells.

Abstract: A method for enhancing oil recovery is disclosed. The method includes providing a subsurface reservoir containing hydrocarbons therewithin and a wellbore in fluid communication with the subsurface reservoir. A solution for injection into the reservoir is formed by mixing a composition with at least one non-ionic chemical, at least one polymer, and at least one alkali. The non-ionic chemical can be alcohol alkoxylates such as alkylaryl alkoxy alcohols or alkyl alkoxy alcohols. The solution is solution is clear and aqueous stable when mixed. The solution is injected through the wellbore into the subsurface reservoir.

Abstract: A cyclic remediation process to restore oil recovery from a primary oil production well that has watered off from bottom water encroachment (cone or crest) whereby: (a) the primary oil production well has a produced water cut in excess of 95% (v/v); (b) the oil is heavy oil, with in-situ viscosity >1000 cp; wherein said process includes: (c) injecting a steam slug with a volume of 0.5 to 5.0 times the cumulative primary oil production, with steam volumes measured as water volumes; (d) shutting in the well for a soak period, after the steam injection is complete; and (e) producing the well until the water cut exceeds 95%.

Abstract: A method of recovering petroleum from dormant oil wells or increasing the production of oil wells. An alkali or alkali earth carbonate is introduced into a water layer associated with a subterranean petroleum reservoir and/or an explosive composition is introduced into an oil layer associated with a subterranean petroleum reservoir. CO2 gas is produced by reacting the alkali or alkali earth carbonate with an acid and/or by detonating the explosive composition.

Abstract: A method of recovering petroleum from dormant oil wells or increasing the production of oil wells. An alkali or alkali earth carbonate is introduced into a water layer associated with a subterranean petroleum reservoir and/or an explosive composition is introduced into an oil layer associated with a subterranean petroleum reservoir. CO2 gas is produced by reacting the alkali or alkali earth carbonate with an acid and/or by detonating the explosive composition. An explosive composition can be introduced and detonated to achieve sufficient CO2 gas production to increase pressure within the subterranean petroleum reservoir. Petroleum recovery can be further enhanced through the use of techniques to reduce petroleum viscosity including sonication.

Abstract: A method of recovering petroleum from dormant oil wells or increasing the production of oil wells. An alkali or alkaline earth carbonate is introduced into a water layer associated with a subterranean petroleum reservoir and/or an explosive composition is introduced into an oil layer associated with a subterranean petroleum reservoir. CO2 gas is produced by reacting the alkali or alkaline earth carbonate with an acid and/or by detonating the explosive composition. An explosive composition can be introduced and detonated to achieve sufficient CO2 gas production to increase pressure within the subterranean petroleum reservoir. Petroleum recovery can be further enhanced through the use of recycling.

Abstract: A system comprising a carbon disulfide formulation storage; a mechanism for releasing at least a portion of the carbon disulfide formulation into a formation; and a mechanism for creating a pulse in the carbon disulfide formulation in the formation.

Abstract: A method for controlling driving fluid breakthrough caused by zones of pressure communication, i.e., a matrix bypass event (“MBE”) or a wormhole, having a void space and possibly areas of enhanced permeability (a halo region) associated with the void space, within a subterranean formation arising from use of a driving fluid in reservoirs where heavy/viscous oil is being produced. In embodiments, the method includes injection of a slurry of a cementitious material into the zone, which upon setting, provides a cement plug in the void space that reduces the pressure communication and flow of driving fluid within the zone. Another step injects a gel precursor within the zone, which upon setting, produces a gel plug that also reduces pressure communication and driving fluid flow through the halo region of the zone.

Abstract: Systems and methods for lifting drilling fluid from a well bore in a subsea formation are disclosed. Some system embodiments include a drill string suspended within a drilling riser to form the well bore, and a drilling fluid source for supplying drilling fluid through the drill string during drilling. A diverter is coupled between the drilling riser and a return line, while a power riser coupled to the return line at an interface. A lift fluid source supplies lift fluid through the power riser into the return line. The lift fluid is intermittently injected from the power riser through the interface into the return line to form one or more slugs of lift fluid positioned between slugs of drilling fluid, such that the combined density of lift fluid and drilling fluid in the return line is less than the density of the drilling fluid alone.

Abstract: Hydrocarbons are recovered from subterranean formations by waterflooding. The method comprises passing an aqueous displacement fluid via an injection well through a porous and permeable sandstone formation to release oil and recovering said released oil from a production well spaced from said injection well, wherein (a) the sandstone formation comprises at least one mineral having a negative zeta potential under the formation conditions; (b) oil and connate water are present in the pores of the formation; and (c) the fraction of the divalent cation content of the said aqueous displacement fluid to the divalent cation content of said connate water is less than 1.

Abstract: A method for enhancing oil recovery from reservoirs is described. The method includes partially recharging zones of pore space in a reservoir that has been previously waterflooded to extract oil, in order to obtain increased ultimate oil recovery by re-waterflooding the recharged zones. The recharging may be achieved by either reinjection of oil or by change in injection scheme, such as changing an oil producing well to a water injection well. This procedure of recharging with oil followed by waterflooding may be repeated. Application of the present method to increase recovery from reservoirs producing dry (water-free) oil to mature reservoirs which produce at high water-to-oil ratios is anticipated.

Abstract: A process for producing mineral oil from underground mineral oil deposits. One or more flooding media is injected into an injection well and mineral oil is withdrawn from a production well. Highly permeable zones are blocked in the region between the injection well and the production well by injecting aqueous formulation F1 and aqueous formulation F2 each separately in succession through the injection well into the deposit. F1 and F2 mix with one another in the formation after injection to form viscous gels. F1 comprises water and urotropin and F2 comprises water and urea. F1 and/or F2 comprise(s) at least one further compound M selected from metal compounds and semimetal compounds, which further compound can form gels when admixed with bases, the injection well temperature before process step (2) being not more than 60° C.