Abstract: Method for increasing recovery of crude oil from a reservoir having an oil-bearing porous subterranean formation with a permeability of greater than 10 millidarcies, the formation including rock having pores with crude oil and connate water having a multivalent cation content present within the pores. The crude oil in the formation has an API gravity of less than 30°, a viscosity greater than 1 centipoise, and undissolved solids suspended therein. Injection water having undissolved solids suspended therein, a total dissolved solids content of 30,000 ppm or less and a multivalent cation content such that a ratio of the multivalent cation content of the injection water to the multivalent cation content of the connate water is less than 0.9, is injected into the formation, to produce an emulsion within the formation. The emulsion has an undissolved suspended solids content of at least 0.05% by weight of emulsion.

Abstract: A method for generating softened injection water (A) (i) introducing source water having a dissolved solids content of up to 15,000 mg/liter and a multivalent cation content of greater than 40 mg/liter to a bed of cation exchange resin in monovalent cation form, (ii) passing the water through the bed so that at least a portion of the multivalent cations in the water are replaced by monovalent cations from the resin, and (iii) withdrawing the softened injection water having a multivalent cation content of up to 40 mg/liter; (B) regenerating the cation exchange resin by (i) introducing a regenerating brine to the vessel, (ii) passing the brine through the bed and (iii) withdrawing a brine containing displaced multivalent cations, wherein the brine is a naturally occurring high salinity water having a concentration of cations such that the Softening Limit for the source water is up to 40 mg/liter of multivalent cations.

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: 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 increasing the recovery of crude oil from a reservoir comprising at least one oil-bearing porous subterranean formation having a permeability of greater than 10 millidarcies wherein (a) crude oil and connate water are present within the pore space of the formation rock, and (b) the crude oil that is present in the formation has an American Petroleum Institute (API) gravity of less than 30°, a viscosity under reservoir conditions of greater than 1 centipoise, and undissolved solids suspended therein, the method comprising: (A) injecting an injection water into the formation wherein the injection water has undissolved solids suspended therein, a total dissolved solids content (TDS) of 30,000 ppm or less, and a ratio of the total multivalent cation content of the injection water to the total multivalent cation content of the connate water of less than 0.

Abstract: A method for generating a softened injection water comprising: (A) generating the softened injection water by (i) introducing a source water having a total dissolved solids content of up to 15,000 mg/litre and having a multivalent cation content of greater than 40 mg/litre to a vessel that contains a bed of a cation exchange resin in its monovalent cation form, (ii) passing the source water through the cation exchange resin bed so that at least a portion of the multivalent cations in the source water are replaced by monovalent cations from the cation exchange resin, and (iii) withdrawing from the vessel the softened injection water having a multivalent cation content of up to 40 mg/litre; (B) regenerating the cation exchange resin by (i) introducing a regenerating brine to the vessel, (ii) passing the regenerating brine through the resin bed and (iii) withdrawing from the vessel a brine containing displaced multivalent cations, wherein the regenerating brine is a naturally occurring high salinity water having