Abstract: The present invention provides methods and compressible foamed sealing compositions for sealing expandable pipe in well bores. The compressible sealant compositions for sealing expandable pipe are basically comprised of a hydraulic cement, a rubber latex, a rubber latex stabilizer, a gas and a mixture of foaming and foam stabilizing surfactants.

Abstract: Disclosed is a method for coding video in which a predetermined algorithm is used to predict portions of the image based on information that will already be available to the decoder at the time of decoding the image. By using known corresponding algorithms in both coder and decoder, and only information that will be available to the decoder, the need to transmit detailed information regarding choices made in coding, e.g. motion vectors is avoided. However, a vector relationship can still be derived for use in the prediction. Prediction can be made based on an assumption that the content of the portion to be coded is similar to the content of an associated image portion, and by determining a vector relating the associated image portion to a reference image (both of which will be available to the decoder), the current image portion can be predicted from a further part of the reference image. The invention can be used in a form of modified pyramid coding.

Abstract: A method for consolidating sand around a well, involving injecting hot water or steam through well casing perforations in to create a cement-like area around the perforation of sufficient rigidity to prevent sand from flowing into and obstructing the well. The cement area has several wormholes that provide fluid passageways between the well and the formation, while still inhibiting sand inflow.

Abstract: Methods and apparatus for forming metal or metal alloy casings in well bores are provided. A method of the invention comprises the steps of providing and pumping a fluid suspension of a particulate metal or metal alloy into a pipe string within a well bore having a casing forming tool connected thereto. The casing forming tool includes an internal passageway sealingly communicated with the pipe string and with a plurality of radial openings in the tool positioned around the periphery thereof. An internal heater for heating the fluid suspension and melting the particulate metal or metal alloy and an internal rotating impeller for imparting centrifugal force to the fluid suspension are provided in the casing forming tool. Centrifugal force is imparted to the fluid suspension by the rotating impeller whereby the melted particulate metal or metal alloy forms a casing which solidifies on the walls of the well bore.

Abstract: A molten metal plug which expands upon solidification can be used to form a pressure resistant seal in a tubular such as is used in oil and gas exploration and production.

Abstract: An apparatus and method for wellbore and formation heating. In the method, after perforation of the well, fracturing material is pumped into the perforations to fracture the formation. This fracturing material comprises a mixture of sand and thermosetting plastic. Heat is subsequently applied to the formation and thereby to the plastic to cause the plastic to set so that flow-back of the plastic and sand is prevented while still allowing fluid flow from the formation through the sand into the well casing. The heating apparatus comprises a dual tubing string with a burner chamber attached to the lower end thereof The outer tubing of the dual tubing string is adapted for connection to an oxygen source, and the inner tubing string is adapted for connection to a fuel source. The apparatus also comprises an ignition source for providing a spark to ignite the fuel and oxygen mixture.

Abstract: Method for sealing an annulus between two solid tubulars or between a solid tubular and a borehole which comprises the use of a thermoset or thermoplastic material in forming the seal between at least part of the outer surface of a tubular and at least part of the inner surface of the other tubular or the wellbore in which the seal is formed by expanding the inner tubular.

Abstract: An apparatus for connecting a main casing section to a lateral casing section using thermoset plastic molding. The apparatus is used to set a flexible sock made of a hardenable material at a location adjacent to an intersection between the main and lateral casing sections. The sock is inflated so that it conforms to the inner surfaces of the main and lateral casing sections. Heat is applied to the hardenable material so that the sock is cured in the inflated, operating position. Heat may be applied by releasing chemicals which provide an exothermic reaction and/or by using a heater positioned within the sock.

Abstract: An apparatus and method for wellbore and formation heating. In the method, after perforation of the well, fracturing material is pumped into the perforations to fracture the formation. This fracturing material comprises a mixture of sand and thermosetting plastic. Heat is subsequently applied to the formation and thereby to the plastic to cause the plastic to set so that flow-back of the plastic and sand is prevented while still allowing fluid flow from the formation through the sand into the well casing. The heating apparatus comprises a dual tubing string with a burner chamber attached to the lower end thereof. The outer tubing of the dual tubing string is adapted for connection to an oxygen source, and the inner tubing string is adapted for connection to a fuel source. The apparatus also comprises an ignition source for providing a spark to ignite the fuel and oxygen mixture.

Abstract: A method for treating a subterranean sand formation adjacent to a bore hole forms a permeable solid barrier which restrains the movement of sand particles while maintaining the permeability of the formation. The method includes the step of forming a consolidation fluid containing an asphaltene and a hydrocarbon solvent such as naphtha or reformate with a concentration of between about 40-80 grams of asphaltene per 100 ml of solvent. The consolidation fluid is injected into the sand formation to saturate the sand in a zone around the bore hole for a distance of 1 to 2 feet. This is followed by injecting an oxygen-containing gas at a temperature of between about 100° C. to about 150° C. for a period of time of between about 24 to about 72 hours. In one embodiment of the invention, the oxygen concentration of the effluent gas is monitored and the injection of oxygen-containing gas is continued until he oxygen concentration of the effluent gas is equal to the oxygen concentration of the injected gas.

Abstract: A tubular casing section for a subterranean well has side wall apertures therein which are temporally sealed with plug structures. The plugged casing section is positioned within a wellbore at a selected subterranean formation and cemented in place within the wellbore. The plugs are removed, such as by melting, fracturing, shearing or corrosion, and a stimulation tool is lowered into the casing and operated to pierce through the cement lining at the unplugged casing side wall apertures and into the surrounding subterranean formation to establish communication between the formation and the interior of the casing.

Abstract: A hydrocarbon producing well is treated by first igniting a gas generating charge in the well to clean out perforations communicating between the casing and the formation without creating high permeability channels adjacent the perforations or fracturing the formation in a macroscopic sense. Then, a treatment liquid is injected into the wells by a gas generating propellant charge placed in the production string and then ignited. The propellant charge is designed to produce a minimum horsepower sufficient to push the liquid more-or-less equally through all of the open perforations. The propellant charge is designed to produce a maximum horsepower which is less than what is necessary to fracture the formation. Basically, the combustion rate of the propellant charge is reduced by one of a multiplicity of techniques to produce a long, relatively slow combustion rate.

Abstract: An apparatus and method for sealing an inner wall of a portion of a casing positioned in a well employs an inflatable sleeve having an outer surface and a conformable composite sleeve of curable composition extending around the outer surface of the inflatable sleeve. The inflatable sleeve is inflated to compress the composite sleeve against the surface of the inner casing wall. A local, activatable energy source, positioned downhole to deliver heat to the composite sleeve, is activated to cure the composite sleeve to form a hardened sleeve. The hardened sleeve presses against the inner wall of the casing portion to create a fluid seal. The embodiments shown have a number of preferred features. The local energy source includes an exothermic heat energy source for generating heat energy to cure the composite sleeve. The composite sleeve includes a mixture of resin and a curing agent, and the exothermic heat source includes thermite. The thermite includes a composition having a metal oxide and a reductant.

Abstract: An apparatus and method for sealing an inner wall of a portion of a casing positioned in a well employs an inflatable sleeve having an outer surface and a conformable composite sleeve of curable composition extending around the outer surface of the inflatable sleeve. The inflatable sleeve is inflated to compress the composite sleeve against the surface of the inner casing wall. A local, activatable energy source, positioned downhole to deliver heat to the composite sleeve, is activated to cure the composite sleeve to form a hardened sleeve. The hardened sleeve presses against the inner wall of the casing portion to create a fluid seal. The embodiments shown have a number of preferred features. The local energy source includes an exothermic heat energy source for generating heat energy to cure the composite sleeve. The composite sleeve includes a mixture of resin and a curing agent, and the exothermic heat source includes thermite. The thermite includes a composition having a metal oxide and a reductant.

Abstract: A casing is cemented within a well bore (P) or pipe by means of a radially expandable tubular preform (1). For this purpose, a) folded preform (1) is inserted into the well (P) or pipe down to the required level; b) the well is sealed off at the bottom of the preform (10 by means of an inflatable hydraulic retainer (4); c) a curable fluid cement is injected onto the retainer so that it surrounds the lower portion of the preform; d) the preform is gradually unfolded from the top towards the bottom to press the cement against the wall of the well or pipe along the full length of the preform; e) the preform is cured to form a casing while the cement is allowed to set; and f) the retainer (4) is deflated and withdrawn from the well or pipe.

Abstract: A thixotropic thermal insulating fluid includes a heavy hydrocarbon, water and oleophilic clay, wherein said heavy hydrocarbon is present in an amount of between about 75% to about 92% by volume of the fluid, said water is present in an amount of between about 5% to about 15% by volume of the fluid, and said oleophilic clay is present in an amount of between about 3% to about 10% by volume of the fluid. The fluid may be prepared by mixing water in an amount of between about 5% to about 15% by total volume of the fluid with oleophilic clay in an amount of between about 3% to about 10% by total volume of the fluid so as to provide a substantially homogeneous first gel product; and mixing said first gel product with a heavy hydrocarbon in an amount of between about 75% to about 92% by total volume of the fluid under agitation for a time sufficient to provide a second thixotropic gel product.

Abstract: According to the present invention, the production of petroleum from a petroleum-bearing subterranean formation penetrated by a wellbore is accomplished by (a) fracturing the subterranean formation and injecting a conductive proppant into the fracture, the conductive proppant comprising particles which are at least partially coated with a heat hardenable, conductive resin to create a fluidly and electrically conductive fracture in the formation; (b) passing an electrical current into the formation through the wellbore to heat the formation and harden the conductive resin thereby at least partially aggregating the particles and retaining the particles in the fracture and heating the fracture and the subterranean formation in the vicinity of the fracture.

Abstract: An apparatus and method for selectively restricting fluid flow in a well or well conduit. A dissolvable core material is positioned in the well and is isolated from the well fluids with an inpermeable sheath. The sheath is punctured with a control mechanism or other device so that the sheath is breached. The fluid dissolves the core material and permits fluid flow through the well or well conduit. The sheath can be punctured by pressurizing the well fluid, or by controlling the fluid pressure to activate a pressure sensitive control mechanism.

Abstract: The addition of an adhesive coated material in intimate mixture with particulates for fracturing, gravel packing or other formation treatments decreases or substantially eliminates the flowback of particulates whether proppants or formation fines while stabilizing the particulate within the formation. Preferred adhesive coated materials include glass or ceramic fibers, polyolefins, polyamides, polyvinyls and cellulose derivatives in the form of particles, ribbons, fibers or flakes.

Abstract: A method of consolidating an incompetent particulate in a subterranean formation penetrated by a wellbore accomplished by introducing fluids to be injected into a wellbore into coiled tubing while the tubing is outside the wellbore and thereafter pumping the fluids from the coiled tubing into the wellbore after circulating ports open in a firing head in response to initiation of the variable delay firing head for ignition of a gas generator.

Abstract: A process and composition are provided for permeability reduction in a hydrocarbon-bearing formation to improve hydrocarbon recovery therefrom. The process includes placement of a crosslinked polymer gel in the treatment region preceded by surface preparation of a gelation solution from which the gel is formed. The gelation solution contains a crosslinkable polymer, a transition metal/poly-carboxylate precursor complex and an aqueous solvent. The gel is placed in the treatment region by injecting the gelation solution into a well bore in fluid communication with the formation, activating the gelation solution in situ, displacing the gelation solution into the desired treatment region and gelling the solution to completion forming the permeability-reducing gel in situ. The gelation rate is retarded in a controlled manner by adjusting the molar ratio of the polycarboxylate to transition metal in the precursor complex of the gelation solution.

Abstract: An improved method for hydraulically fracturing a formation or reservoir where a thermo-setting gellable mixture is utilized. This thermo-setting mixture is foamed either at the surface or in situ under fracturing pressures and conditions. The mixture and carrier fluid is of a composition such that the foamed mixture has a viscosity of sufficient magnitude to cause a created fracture to grow while the foamed mixture is kept under fracturing pressure and conditions. Once a fracture of a desired size and length has been generated, the resin is ignited and thermally set thus forming a porous hardened solid within the fracture thereby holding the fracture open. Once combustion is finished, no spent fracturing fluids or load fluids remain to be recovered. This porous solid props the fracture open thereby increasing the conductivity of the formation or reservoir and fluid flow therefrom.

Abstract: An oxygenated foam is injected into a loosely consolidated, clay-containing sandstone formation surrounding a well penetrating a hydrocarbon-bearing reservoir. Combustion is initiated between the oxygenated foam and hydrocarbons within the reservoir to burn the formation and form said consolidated zone around the well that acts as a barrier to the passage of sand into the well along with produced hydrocarbons.

Abstract: A method for treating a subterranean formation having zones of varying permeablities to alter the flow profile of the formation wherein a specific gelant (i.e. an aqueous solution of ungelled gelatin) is injected into the more permeable zones and is allowed to gel to form a flow-blocking gel therein.

Abstract: Disclosed are processes for treating a subterranean formation to improve the permeability distribution by reducing the permeability in high permeability zones, so fluids injected for oil recovery purposes will sweep more uniformly through the formation. The processes involve injecting a polymerizable compound, preferably a monomer or oligomer of furfuryl alcohol, together with a diluent, preferably an ester such as butyl acetate, and a suitable acid catalyst for the formation conditions, generally toluenesulfonic acid. The fluid may be injected in a liquid phase or mixed with steam or non-condensable gas to form an aerosol, which is injected then into the formation prior to the injection of the oil recovery fluid, which may be water, surfactant fluid, polymer fluid, or steam.

Abstract: Methods are provided for chemically consolidating subterranean formations around wells using resins. Resins are forced into the formations by high pressures instantaneously applied when perforations are formed in casing in wells or when pressures are released from tubing in wells. Perforating, explosives or gas generators may be used in addition to the high pressures for driving resins into formations. The resins are polymerized to form permeable consolidated zones around wells.

Abstract: In a well treatment method, a fluid is positioned in a wellbore have formation perforations in alignment with the portion thereof to be treated. A gas generator is positioned in proximity with the fluid and is actuated to disperse the fluid within the wellbore in accordance with a pressure/time relationship. In the preferred embodiment of the invention, the fluid is a fluid resin material which is polymerized following operation of the gas generator to form a consolidated, porous, permeable matrix which retains sand and other fine materials while permitting the flow of production fluid into the well.

Abstract: Oil recovery method using polymer solutions in which highly permeable strata are made significantly less permeable while less permeable strata are not made significantly less permeable. This is accomplished by heating more permeable strata by injection of hot fluids, and then injection of a crosslinkable vinyl aromatic-conjugated diolefin polymer and a temperature activated crosslinking agent. A crosslinked gel is formed in the initially more permeable strata, permitting recovery of oil from the initially less permeable strata.

Abstract: In a well treatment method, a fluid is positioned in a wellbore have formation perforations in alignment with the portion thereof to be treated. A gas generator is positioned in proximity with the fluid and is actuated to disperse the fluid within the wellbore in accordance with a pressure/time relationship. In the preferred embodiment of the invention, the fluid is a fluid resin material which is polymerized following operation of the gas generator to form a consolidated, porous, permeable matrix which retains sand and other fine materials while permitting the flow of production fluid into the well.

Abstract: A method for minimizing well recompletions in a multiple zone hydrocarbonaceous fluid containing formation. A steam flooding enhanced oil recovery (EOR) is conducted in the upper zone of said formation via fluidly communicating injector and producer wells which penetrate the upper and lower zones. The wells are unperforated and do not communicate with each other in the lower zone. Thereafter, a temperature activated gellable composition is injected into the upper zone where it forms a solid gel. Afterwards, both wells are perforated so as to fluidly communicate with each other in the lower productive interval. Subsequently, a steam-flooding EOR operation is conducted in the lower level and hydrocarbonaceous fluids are removed therefrom. Polymers utilized in the gellable composition include polyvinyl alcohol and polyacrylamide cross-linked with phenol and an aldehyde producing compound sufficient to form a phenolic resin in situ.

Abstract: A method for recovering viscous oil from a formation having a bottom water zone below an oil containing zone. Steam is directed into the bottom water zone thereby heating this zone and an oil containing zone thereabove. Afterwards, steam injection is ceased and a gellable composition is directed into the bottom water zone where it forms a solid gel. Once the solid gel has formed, steam is injected into the bottom water zone where the solid gel causes it to flow upwardly into the oil containing zone. Oil, water, and steam are removed via a recompleted producer well.

Abstract: Methods are provided for selectively consolidating naturally occurring mineral grains such as sand grains within a subterranean formation to form a fluid permeable barrier, which restrains the movement of sand particles when oil passes through the barrier. A sand consolidation fluid usually containing a monomer or oligomer of furfuryl alcohol is injected, either mixed with steam to form a multiphase treating fluid or injected as a liquid phase into the formation. The fluid contains an acid catalyst and an ester and an effective amount of a swelling polymer to reduce shrinkage of the furfuryl alcohol when it polymerizes in the formation. A preferred swelling polymer is a copolymer of starch and an acrylamides or acrylates.

Abstract: A process is described to direct heat towards a productive interval of a reservoir during a thermal enhanced oil recovery (EOR) operation. A chemical composition suitable for producing a rigid polymer foam is injected above or below the productive interval. Once in place the temperature of the composition is increased and it reacts to produce a foamed polymer thermal barrier. The temperature can be increased by steam injection or in-situ combustion. After a rigid foam is formed, thermal efficiency is increased by reducing heat losses to non-producing zones during a thermal stimulation.

Abstract: A process for selectively plugging zones of high permeability within an oil-bearing subterranean formation. The process of the present invention comprises the steps of injecting into the formation a high temperature selective gel-forming composition comprising an aqueous solution of a high molecular weight polyacrylamide having 30 percent or less hydrolysis, and an effective amount of a crosslinking agent which is a mixture of a phenolic component and an aldehyde, and gelling the solution in-situ by thermally reacting said gel-forming composition at a temperature effective to promote gelation. The resultant gel is exceptionally thermally stable and, therefore, can be used as an effective profile control agent in all thermal enhanced oil recovery operations, including steam flooding. Also provided is a process for recovering oil from a subterranean oil-bearing formation.

Abstract: A process for preventing steam entry into a bottom water zone of a formation. Performations are made in a well which perforations communicate with the lowest level of said bottom water zone. Air is injected into the lowest level of said zone via said well which initiates low temperature oxidation thereby increasing the viscosity of said oil and making a heavy oil. When a desired viscosity is obtained, air injection is ceased. Said well is recompleted and perforations are placed in said well which causes it to communicate with a higher level oil saturated zone. Steam is injected into said higher level since the lowest level of the bottom water zone is closed because of the high viscosity oxidized oil. Thus, steam injection causes oil to be removed from the higher level of said formation.

Abstract: A process for minimizing well recompletions in a hydrocarbonaceous fluid containing formation having an upper productive interval temperature in excess of 300.degree. F. In this process, a temperature activated gellable composition is injected into a producer well in the productive interval after cooling said well to a temperature of about 300.degree. F. to about 450.degree. F. Once in the productive interval, the formation heats the gellable composition to a temperature sufficient to cause the composition to form a solid gel thus closing pores in the upper productive interval. Thereafter, ungelled composition is either diluted or removed from cooler areas of the formation so as to prevent forming a solid gel therein. Afterwards, a steam-flooding or a steam stimulation oil recovery operation is conducted to remove hydrocarbonaceous fluids from a lower productive interval without recompleting said lower interval.

Abstract: A process for closing pores in a heated steam swept zone of a formation having zones of varying permeabilities where a temperature activated aqueous gellable mixture is utilized following a steam flooding or steam stimulation enhanced oil recovery method. After being placed into the steam swept zone having varying permeabilities, a temperature above 300.degree. F. activates components in the gellable mixture which causes a solid gel to form which closes pores in the steam swept zone. A spacer volume of cold water is pumped into the formation to remove any ungelled mixture. Steam is directed into an unswept zone and hydrocarbonaceous fluids recovered therefrom. Polymers utilized include polyvinyl alcohol and polyacrylamide cross-linked with phenol and an aldehyde producing compound sufficient to form a phenolic resin in situ.

Abstract: Methods are provided for selectively consolidating naturally occurring mineral grains such as sand grains within a subterranean formation to form a fluid permeable barrier, which restrains the movement of said particles when oil passes through the barrier. When applied to formations in which at least a portion of the sand grains are coated with a viscous oily residue of crude oil, or where the pore spaces between the sand grains contain excessive quantities of water, either of which interfere with the polymerization of the polymerizable monomer employed for said consolidation, a preflush is utilized which functions both to remove the oily residue from the said grains and to remove water from the pore spaces of the formation adjacent to the wellbore. the preflush is preferably an ester such as ethyl acetate or butyl acetate in an amount sufficient to occupy substantially all of the pore space of the formation into which the polymerizable component employed for sand consolidation are subsequently injected.

Abstract: The present invention provides a method of consolidating an incompetent subterrnean formation. An acid curable resin consolidating fluid is positioned within casing in a wellbore in the vicinity of perforations through the casing. A gas generating charge positioned within the casing then is ignited to generate gas pressure which rapidly forces the consolidating fluid through the perforations and into the subterranean formation while substantially simultaneously catalyzing the resin composition. The consolidating fluid is caused to rapidly harden to consolidate the formation in the vicinity of the perforation without any significant permeability loss.

Abstract: A method and composition for altering the permeability of a high temperature subterranean formation are provided. The composition of the invention is comprised of water, at least one water dispersible acrylamide containing polymer, and a water dispersible crosslinker for bringing about the delayed crosslinking of the polymer comprised of the combination of an aldehyde and a salicylic acid derivative.

Abstract: A composition for use in enhanced oil recovery procedures comprises steam having a vapor phase and a liquid phase and a fluorocarbon surfactant partitioned between the liquid and vapor phases. The partitioning of the fluorocarbon surfactant between the two phases is accomplished by maintaining the composition's pH at less than about 11, and preferbly within the range of 7 to about 11. By varying the fluorocarbon surfactant concentration, the composition can be used as a surface tension depressant well stimulation additive and/or as a foam former for selectively blocking more permeable portions of a formation.

Abstract: A process for closing pores in a bottom water zone where steam is directed so as to by-pass a zone of the formation containing hydrocarbonaceous fluids. Once a portion of the bottom water zone has reached a temperature in excess of about 300.degree. F., steam entry is ceased. Afterwards, a temperature activated gellable composition is placed into the bottom water zone. When the composition reaches that portion of the bottom water zone where a temperature in excess of about 300.degree. F. has been reached, the composition activates and forms a rigid gel. Thereafter, a steam flooding method is commenced. Steam is diverted from the bottom water zone and into an upper zone containing hydrocarbonaceous fluids.

Abstract: A process for profile control in a high permeability zone of a formation. A water flooding or carbon dioxide stimulation enhanced oil recovery (EOR) process is conducted in an an oil-containing formation having a high permeability zone. After breakthrough occurs, the EOR process is ceased. The high permeability zone is heated to a temperature of 300.degree. F. or higher by steam injection. Subsequently, steam injection is ceased and a temperature activated mixture is injected into the high permeability zone where it forms a solid gel. Thereafter, an EOR process can be used to remove hydrocarbons from a low permeability zone.

Abstract: Methods are provided for selectively consolidating naturally occurring mineral grains such as sand within a subterranean formation to form a fluid permeable barrier which restrains the movement of sand particles when oil passes through the barrier. A fluid comprising a polymerizable monomer such as furfural alcohol and as a diluent, a polar organic solvent such as methanol and a strong, non-volatile acid catalyst such as sulfuric acid is provided, mixed with steam to form a multiphase or aerosol treating fluid, and injected into the formation to be consolidated. An ester such as butyl acetate is incorporated in the fluid when the steam quality is less than 80 percent. The well is shut in for sufficient period of time for polymerization to convert the injected fluids into a permeable barrier around the wellbore.

Abstract: Shale oil is produced from a subterranean interval of oil shale, where the interval is initially substantially impermeable and contains a specified grade and thickness of oil shale. Said interval is conductively heated from borehole interiors which are kept hotter than about 600.degree. C. and are heated at a rate such that kerogen pyrolysis products formed within the oil shale create and flow through horizontal fractures which subsequently extend into fluid-producing wells that are positioned in specified locations.

Abstract: An improvement is presented in a process for increasing the yield of production wells in crude oil reservoirs having inhomogenous strata, wherein an aqueous solution of a salt is injected through an injection well into the reservoir, without causing fracturing thereof, and then salt crystals are formed at stratum temperature by removing water from the solution. If desired, the salt crystals can be redissolved and reformed at other parts of the reservoir.

Abstract: A method for selectively placing and removing a plugging agent in a formation adjacent a wellbore comprising preheating the wellbore, heating and injecting the plugging agent at a temperature higher than its melting point, shutting in the well to allow the plugging agent in the formation to cool and solidify, reheating the formation adjacent the wellbore, and swabbing back the liquidified plugging agent from the low permeability zones adjacent the wellbore. The expected benefit is reduction of permeability in the high permeability zones without a corresponding loss of permeability in the low permeability zones. The method provides better vertical sweep and improved recovery.

Abstract: Permeability of a highly permeable zone in a subterranean formation is reduced by injecting an oil external emulsion of an aqueous solution of alkali metal silicate. Emulsion adjacent the well bore is broken by the application of microwave. Released alkali metal silicate then forms a plug of gel at this point, through contact with formation brines, which holds the rest of the emulsion in place until it breaks down and gels. In one aspect a second internal phase containing a gelation agent is provided to accelerate gelling.

Abstract: A method is disclosed for selectively sealing thief zones in a formation. First, a saline pre-flush water is injected into the formation. Then, at least one slug of a saline soution of heat-sensitive sealing fluid is injected into the formation, followed by injection of a saline push water. Electrical resistance heating of the formation is induced sufficient to cause the sealing fluid to undergo in-situ transformation to seal the thief zones.

Abstract: High permeable thermally fluid swept zones in an oil containing formation are selectively plugged by a high temperature selective gel-forming solution without plugging the less permeable unswept portion of the formation. Ungelled solution in the less permeable unswept portion of the formation in the vicinity of the injection well is removed and a thermal fluid is injected into the formation that sweeps oil from the less permeable, unswept portion of the formation, thereby resulting in more complete displacement of oil from the formation.