Mobil Oil Corporation

Electric Power Research Institute Incorporated

Mobile Oil Corporation

Thomas O Mitchell

Darrell D Whitehurst

Dennis H Hoskin

Paul Shu

Malvina Farcasiu

Harold S Chung

A S Chu

Costandi A Audeh

E Thomas Strom

Craig H Phelps

Joseph J Dickert, Jr

Francis J Derbyshire

An aqueous polymeric gel-forming composition capable of selectively plugging highly permeable zones in subterranean oil-bearing formations. The composition comprises an aqueous solution of an anionic acrylamide copolymer of high molecular weight, comprising about 5 to 95 weight percent of 2-acrylamido-2-methylpropanesulfonic acid, about 2 to 95 weight percent of N-vinyl-N-methyl acetamide and about 5 to 93 weight percent of acrylamide, and a crosslinking agent selected from the group consisting of transition metal ions, phenolic resins and amino resins. The compositions of this invention will form stable gels in brines of wide-ranging salinity and are effective at the pH levels encountered in carbon dioxide and water flooding operations. Also provided is a process for selectively plugging regions of higher permeability within an oil-bearing formation to improve sweep efficiency during a fluid flood oil recovery operation.

Enhanced oil recovery profile control with crosslinked anionic

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 as 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.

Oil reservoir permeability control

A composition capable of selectively plugging highly permeable zones in a subterranean formation. The composition forms a gel subsequent to its injection into the formation via an injection wall. The composition comprises an aqueous solution of a welan gum heteropolysaccharide biopolymer produced by the fermentation of a microorganism of the genus Alcaligenes, a phenolic compound, an aldehyde and water. The compositions of this invention will form stable gels even in low salinity brines. Also provided is a process for selectively plugging regions of higher permeability within an oil-bearing subterranean formation to improve sweep efficiency during a fluid flood oil recovery process using the gel-forming compositions of this invention.

Oil reservoir permeability profile control with crosslinked welan gum

A composition capable of selectively plugging highly permeable zones in a subterranean formation. The composition forms a gel subsequent to its injection into the formation via an injection well. The composition comprises an aqueous solution of a welan gum heteropolysaccharide biopolymer produced by the fermentation of a microorganism of the genus Alcaligenes, a phenolic compound, an aldehyde and water. The compositions of this invention will form stable gels even in low salinity brines. Also provided is a process for selectively plugging regions of higher permeability within an oil-bearing subterranean formation to improve sweep efficiency during a fluid flood oil recovery process using the gel-forming compositions of this invention.

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.

Method for imparting selectivity to otherwise nonselective polymer

A process for recovering hydrocarbonaceous fluids from a formation having a substantially low pH where a rehealable gel prepared ex-situ is used to close off a zone of greater permeability. Said gel is obtained by mixing into an aqueous medium sufficient biopolymer amounts of a Xanthan or Alcaligene polysaccharide. This mixture is maintained at a pH of about 5.5 while an aminoplast resin in excess of 4,000 ppm is added thereto which causes said gel to form in about 0.5 to 6 hours. The resultant gel is suitable for use in a carbon-dioxide flood process. Said gels are very stable at a pH of less than about 5.5.

Organic crosslinking of polymers for CO2 flooding profile control

An improved process for forming improved gels where biopolymers and synthetic polymers are cross-linked with melamine/formaldehyde and other amino resins at an optimal range of ratios of amine to aldehyde in the amino resins. This optimal range of ratios can vary from about 1:6 to about 1:30 amine to aldehyde. Resins utilized in said optimal range are most effective for producing improved firm, stable gels. The resultant gels are useful in waterflooding and carbon dioxide flooding operations during the recovery of hydrocarboneaceous fluids.

Melamine/formaldehyde cross-linking of polymers for profile control

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.

Gels for profile control in enhanced oil recovery under harsh conditions

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.

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. The second amount constitutes the remaining portion of the total amount required to improve the profile of the formation. Complete profile control is attained while not requiring any greater quantities of permeability control agent than those typically required in a single step profile control treatment.

Method of enhanced oil recovery from subterranean formations

The present invention relates to a novel method for improving the recovery of hydrocarbon fluids from oil shale. The method comprises treating a mixture of oil shale and hydrocarbon fluid at a temperature below the retorting temperature of the shale and for a period of time sufficient to recover product hydrocarbon fluids in amount equivalent to at least 100 percent Fischer Assay.

Enhanced recovery of hydrocarbonaceous fluids oil shale

A method and composition for improved enhanced oil recovery of oil from a subterranean hydrocarbon-bearing reservoir by effecting simultaneous mobility and profile control in gas flooding which includes pre-injecting into the reservoir an aqueous solution of a water-soluble polymer in combination with a stable surfactant, followed by injecting a gas into the reservoir under pressure sufficient to effect oil production while recovering oil at a producing well of said reservoir.

Method and composition for oil recovery by gas flooding

A combination process for the treatment of oil shale to recover hydrocarbonaceous material therefrom comprising the steps of solvent treating said oil shale, sequentially solvent extracting said treated oil shale, hydrotreating the extracts and processing any carbon remaining on said oil shale to recover heat or gas values therefrom.

Process for the efficient utilization of solvent modified oil shales

Organic compound conversion in the presence of a new class of heterogeneous catalyst is provided. Said new class of heterogeneous catalyst comprises a substrate having a minimum surface area of about 10 m.sup.2 /g and having pores with a minimum pore diameter of about 5 Angstrom Units, said substrate being modified by at least one amine functional member coordinated to a metal function, said amine functional member acting as a bridging member between said substrate and said metal function.

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Trenton, NJ, United States of America

Thomas O Mitchell