Abstract: A method for controlling the permeability profile of a subterranean oil-bearing formation utilizing polymeric gel-forming compositions which gel in-situ. The method comprises the steps of determining an amount of polymeric gel required for profile control; introducing a first aqueous gel-forming composition in a non-gelatinous state into the formation in an amount which is a portion of the total gel requirement; and, introducing into the formation in a non-gelatinous state at least a second aqueous composition capable of forming a gel at a rate in excess of the first gel-forming composition wherein the gelation of all compositions proceeds in timed relation such that each solution gels at approximately the same time. The method so described reduces reservoir shut-in time and is especially useful in the treatment of large reservoirs.

Abstract: A method for selectively closing pores in a formation's zone of greater permeability. A rehealable Xanthan or Alcaligenes biopolymer in an aqueous medium is combined with an organic or transition metal cross-linker which forms a first stage selective ex-situ gel. Second stage non-selective gel precursors are also included. The second stage gel comprises a polymer cross-linked with organic cross-linkers so as to form an in-situ gel more able to withstand formation conditions. The combination is injected into a formation after the first stage gel forms where it selectively enters a zone of greater permeability carrying therewith said non-selective gel. Once in the formation's zone of greater permeability, the gel reheals and forms a rigid gel having the desirable characteristics of the non-selective gel.

Abstract: A novel cross-linked polymer is obtained by cross-linking polyvinyl alcohol with a cross-linking agent which is a mixture of a phenolic component and an aldehyde or a mixture of a naphtholic component and an aldehyde. The resulting polymer is exceptionally thermally stable and, therefore, can be used as an effective permeability control agent in all enhanced oil recovery operations, including steam flooding.

Abstract: A novel cross-linked polymer is obtained by cross-linking polyvinyl alcohol with a cross-linking agent which is a mixture of a phenolic component and an aldehyde or a mixture of a naphtholic component and an aldehyde. The resulting polymer is exceptionally thermally stable and, therefore, can be used as an effective permeability control agent in all enhanced oil recovery operations, including steam flooding.

Abstract: The permeability of subterranean oil-bearing formations is controlled by injection of an organic polysilicate ester. The ester may be derived from simple, monohydroxylic alcohols such as methanol, ethanol, propanol or butanol, from diols such as ethylene glycol, from polyols such as glycerol and alkylene oxide polymerization products and from other organic compounds containing functional hydroxy groups, for example, partial ethers and esters of glycols and polyols. The polysilicates are injected into a formation through injection wells, suitably in an amount from 10 to 100% of the pore volume of the zone to be treated. In the formation, the polysilicate esters form gels which selectively decrease the permeability of the high permeability regions of the formation, to divert the flow of flooding liquid used in flooding operations to the less permeable regions of the formation.

Abstract: A composition of matter where a polymer is partially hydrolyzed to form a polymer intermediate which can be gelled. Said polymer intermediate consists of 2-acrylamido-2-methylpropane-3 sulfonate, N-vinyl-N-methyl acetamide, acrylamide, and an alkali metal hydroxide. When cross-linked with a transitional metal ion said polymer intermediate forms a gel suitable for profile control use under harsh conditions. Said gel is exceptionally stable under the hot temperature and saline conditions encountered in profile control usage during a water flood or carbon dioxide oil recovery operation.

Abstract: The permeability of a subterranean oil-bearing formation is controlled by the injection of an aqueous solution of a cross-linked block copolymer containing polar and non-polar segments, with the polar segments generally making up at least 50 percent, usually 60 to 99 percent, of the copolymer. The polar segments are derived from an alkylene oxide and the non-polar segments from styrene or an alkyl styrene either by itself or with a diene. The copolymers are cross-linked with an amino resin or a combination of a phenolic and a water-dispersible aldehyde component. The resulting copolymer gels are stable at low pH conditions, such as those of CO.sub.2 flood conditions.

Abstract: A method of enhancing the amount of oil recovered from a subterranean oil-bearing formation by controlling the profile of the formation by introducing a predetermined first amount of a permeability control agent in a non-gelatinous state into the formation so that it contacts at least a portion of the formation. A portion of the pores of the formation are plugged by allowing contact to be maintained for a sufficient period of time allowing the first portion to gel. The first amount constitutes a portion of the total amount required to improve the profile of the formation. A predetermined second amount of permeability control agent is thereafter introduced, in a non-gelatinous state, into the formation which contacts the first amount and the portion of the formation not contacted by the first amount for a time period sufficient to gelatinize the second amount so as to plug the remaining unproductive pores of the formation.

Abstract: The permeability of subterranean oil-bearing formations is controlled by injection of an organic polysilicate ester. The ester may be derived from simple, monohydroxylic alcohols such as methanol, ethanol, propanol or butanol, from diols such as ethylene glycol, from polyols such as glycerol and alkylene oxide polymerization products and from other organic compounds containing function hydroxy groups, for example, partial ethers and esters of glycols and polyols. The polysilicates are injected into a formation through injection wells, suitably in an amount from 10 to 100% of the pore volume of the zone to be treated. In the formation, the polysilicate esters form gels which selectively plug the high permeability regions of the formation, to divert the flow of flooding liquid used in flooding operations to the less permeable regions of the formation.

Abstract: An aqueous brine fluid is disclosed which contains a high salt concentration and a water-soluble copolymer of acrylamidomethylpropanesulfonic acid salts which serves to increase the viscosity thereof, particularly at elevated temperatures of above about 300.degree. F. These fluids are particularly useful as fluids for drilling operations.

Abstract: Novel sulfonate and sulfate surfactants which have low interfacial tension at high salinity, and their use in enhanced oil recovery are disclosed. These surfactants may be made from relatively inexpensive intermediates, such as monohydric alcohols and epichlorohydrin. These surfactants have 1,3-dihydrocarboxy-2-propyl hydrophobic tails linked by ethoxy linkages to sulfate or alkyl sulfonate moieties.

Abstract: The accumulation of inorganic mineral scale such as barium sulfate in oil field formations and/or production equipment is inhibited by adding to formation fluid or produced fluid a scale formation inhibitory amount of a polyalkoxy sulfonate of the general formula(RO[R'O].sub.x (CH.sub.2).sub.y SO.sub.3).sub.z Mwherein R is a hydrophobe, R'O is a C.sub.2 H.sub.4 O or a C.sub.3 H.sub.6 O group or some combination thereof, M is a monovalent or divalet cation, x is 2 to 10, y is 0 to about 4 and z is 1 or 2.

Abstract: Novel sulfonate and sulfate surfactants which have low interfacial tension at high salinity, and their use in enhanced oil recovery are disclosed. These surfactants may be made from relatively inexpensive intermediates, such as monohydric alcohols and epichlorohydrin. These surfactants have 1,3-dihydrocarboxy-2-propyl hydrophobic tails linked by ethoxy linkages to sulfate or alkyl sulfonate moieties.

Abstract: Novel sulfonate and sulfate surfactants which have low interfacial tension at high salinity, and their use in enhanced oil recovery are disclosed. These surfactants may be made from relatively inexpensive intermediates, such as monohydric alcohols and epichlorohydrin. These surfactants have 1,3-dihydrocarboxy-2-propyl hydrophobic tails linked by ethoxy linkages to sulfate or alkyl sulfonate moieties.