Abstract A process for recovering oil from an oil-bearing subterranean reservoir penetrated by at least one injection well and at least one production well which comprises the steps of: (1) injecting into the oil-bearing subterranean reservoir through the injection well a first injecting fluid consisting essentially of (a) 1% to 30% by weight of an internal olefin sulfonate having 10 to 26 carbon atoms and a disulfonate content of 20% by weight or less, (b) 0.1% to 20% by weight of a cosurfactant, and (c) a brine; (2) injecting, as a second injecting fluid, an aqueous polymer solution having a viscosity higher than that of the first injecting fluid into the oil-bearing subterranean reservoir; and (3) recovering oil replaced with the first and second injecting fluids through the production well. This process can recover oil from subterranean reservoirs at a high oil recovery efficiency without destroying a micro-emulsion during sweeping in the subterranean reservoir even when the salt concentration of the formation water is widely changed.
Inventors
👤 Toshiyuki Ukigai
👤 Masaaki Hagiwara
👤 Junichi Yamada
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-11-01 23:44
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/58; C09K8/584
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
129 words
A process for recovering oil from an oil-bearing subterranean reservoir penetrated by at least one injection well and at least one production well which comprises the steps of: (1) injecting into the oil-bearing subterranean reservoir through the injection well a first injecting fluid consisting essentially of (a) 1% to 30% by weight of an internal olefin sulfonate having 10 to 26 carbon atoms and a disulfonate content of 20% by weight or less, (b) 0.1% to 20% by weight of a cosurfactant, and (c) a brine; (2) injecting, as a second injecting fluid, an aqueous polymer solution having a viscosity higher than that of the first injecting fluid into the oil-bearing subterranean reservoir; and (3) recovering oil replaced with the first and second injecting fluids through the production well.
Claim 2
Dependent Claim
129 words
A process for recovering oil from an oil-bearing subterranean reservoir penetrated by at least one injection well and at least one production well which comprises the steps of: (1) injecting into the oil-bearing subterranean reservoir through the injection well a first injecting fluid consisting essentially of (a) 1% to 30% by weight of an internal olefin sulfonate having 10 to 26 carbon atoms and a disulfonate content of 20% by weight or less, (b) 0.1% to 20% by weight of a cosurfactant, and (c) a brine; (2) injecting, as a second injecting fluid, an aqueous polymer solution having a viscosity higher than that of the first injecting fluid into the oil-bearing subterranean reservoir; and (3) recovering oil replaced with the first and second injecting fluids through the production well.
Claim 3
Dependent Claim
21 words
A process as claimed in claim 1, wherein said surfactant is an internal olefin sulfonate having 12 to 24 carbon atoms.
Claim 4
Dependent Claim
84 words
A process as claimed in claim 1, wherein said surfactant is prepared by sulfonating internal olefins containing as a main constituent vinylene-type monoolefin having 10 to 26 carbon atoms and having a general formula: R--CH═CH--R' wherein R and R' are independently straight- or branched-chain saturated hydrocarbon radicals having 1 or more carbon atoms, provided that the total carbon atom number of R and R' is 8 to 24, followed by neutralizing the sulfonated products with appropriate bases and then, optionally, hydrolyzing the neutralized products.
Claim 5
Dependent Claim
68 words
A process as claimed in claim 1, wherein said cosurfactant has the general formula; R"O(CH.sub.2 CH.sub.2 O).sub.n H wherein n is a number of from 0 to about 4 and R" is an alkyl or alkenyl group having 3 to 8 carbon atoms when n is zero and an alkyl, alkenyl, a phenyl, or an alkylphenyl group having 6 to 15 carbon atoms when n is not zero.
Claim 6
Dependent Claim
26 words
A process as claimed in claim 1, wherein said brine is contained in an amount of 50% to 98.9% by weight in the first injecting fluid.