Abstract: This specification discloses a process for the production of petroleum from a petroleum-containing subterranean reservoir employing an aqueous driving fluid containing, as a thickening agent, a biopolymer. The biopolymer is an extracellular heteropolysaccharide synthesized by an alga. A particular bipolymer is one synthesized by the alga Porphyridium aerugineum. The biopolymer may be employed in the aqueous driving fluid as an in-vivo solution or in a reconstituted form. There is also disclosed a process for the growth of, and synthesis of, biopolymer by an alga such as Porphyridium aerugineum.

Abstract: This specification discloses a method and apparatus for the synthesis of alga biopolymer. The method is comprised of two stages and involves subjecting an aqueous culture containing alga cells and nutrients required for the growth of the alga cells to a first stage of artificial illumination for a period of time such that growth of the alga and synthesis of biopolymer begins followed by a second stage of natural illumination provided by successive cycles of diurnal solar radiation and darkness. During the cycles of diurnal solar radiation and darkness in the second stage, the aqueous culture is continuously contacted with a mixture of carbon dioxide and air. Furthermore, during these cycles of diurnal solar radiation and darkness, the temperature of the aqueous culture is maintained at a level conducive to the growth of the alga cells. The apparatus is employed in the second stage and contains a lower chamber adapted to contain an aqueous thickening culture from a stage-one reactor.

Abstract: This specification discloses a process and a culture composition for growth of an alga and synthesis of biopolymer by the alga. The process involves growth of the alga and concomitant synthesis of the biopolymer in an aqueous culture containing as a source of phosphate for said alga dibasic sodium or dibasic potassium phosphate. The nitrogen source can be sodium nitrate or urea. Control of the pH of the culture is effected by injecting a mixture of carbon dioxide and air into the culture during growth of the alga and synthesis of the biopolymer. The carbon dioxide also serves as a source of carbon for growth of the alga and synthesis of the biopolymer and provides agitation/mixing within the culture chamber. Preferably, the mixture of carbon dioxide and air is injected continuously into the culture during the entire growth period of the alga.

Abstract: This specification discloses a technique of hydraulically fracturing a subterranean formation wherein there is used a fracturing fluid comprised of an aqueous solution of an interaction product of a polysaccharide and a galactomannan.

Abstract: Waterflooding process for the recovery of oil in which at least a portion of the injected water is thickened by the addition of a sulfonate surfactant and a C.sub.4 -C.sub.6 aliphatic alcohol having a hydrocarbon chain link of at least 3 carbon atoms. The action of the surfactant-alcohol system in increasing the viscosity of the water varies with the monovalent salt salinity of the water and the ratio of the amount of the sulfonate surfactant to the sum of the amounts of the sulfonate surfactant and alcohol in the water. A relatively viscous aqueous mobility control slug containing a sulfonate-alcohol system as previously described may be preceded by an aqueous surfactant slug. The aqueous solution of sulfonate surfactant and alcohol may be formulated and then aged for a time to allow the development of viscosity prior to injection into the oil reservoir. This viscosity development may be accelerated by heating.

Abstract: A process for the recovery of oil from subterranean oil reservoirs by waterflooding employing a multicomponent anionic-nonionic surfactant system in combination with a Xanthomonas polysaccharide thickening agent. The surfactant system and polysaccharide provide for an enhanced thickening action in the injected aqueous liquid at relatively low shear rates. The anionic surfactant employed is an amide-linked sulfonate and the nonionic component is a polyethylene oxide type surfactant.

Abstract: An improved process for the production of a heteropolysaccharide by fermentation of a methanol containing culture medium with a microorganism of Methylomonas mucosa NRRL B-5696 wherein an alkali metal glycerophosphate is incorporated into the culture medium to provide a source of assimilable phosphate. An iron chelating agent selected from the group consisting of the alkali metal and the ferric/alkali metal salts of ethylenediaminetetraacetic acid may be added to the culture medium and N-tris-(hydroxymethyl)methyl glycine may be employed as a buffering agent. The heteropolysaccharide thus produced may be employed in the in vivo form to provide a viscous aqueous solution injected into a subterranean oil reservoir for mobility control purposes.