Texaco Inc.

Joseph T Carlin

Ricardo L Cardenas

Timothy N Tyler

Kenoth H Flournoy

Melvin E Mills, Jr

John A Wells

James W Ware

Richard H Widmyer

Jack H Park

Robert G Pindell

Gilbert L Haferkamp

This invention relates to a process for enhanced recovery of hydrocarbons from a subterranean hydrocarbon-bearing formation penetrated by an injection well and a production well wherein, before injection, the surfactant fluid is separated into two phases by the addition of small amounts of polymer and the portion having the higher sulfonate content is used as the surfactant slug. As an improvement we disclose the step of adding the phase of surfactant fluid with the lower sulfonate content to the polymer slug which is used to drive the surfactant fluid to further increase recovery.

Method of increasing enhanced oil recovery by using a novel low

An improved fluid for enhanced hydrocarbon recovery in a subterranean oil-bearing reservoir comprising:

Method of increasing enhanced oil recovery by using a higher sulfonate

In a method wherein valuable substances are recovered from a subterranean reservoir comprising the injection of a two phase fluid into the reservoir, uniform injectivity of the two separate phases is achieved by conducting the injected fluid to a point below the bottom of the injection interval in the well bore of the injection well through a tubing to which is attached a terminal device which is penetrated by a plurality of holes, each such hole being of sufficient diameter to reduce the bubble size of the gas phase to less than about 0.5 inches.

Method for injecting a two phase fluid into a subterranean reservoir

Disclosed is an oil recovery process for recovering oil from subterranean formations containing relatively high salinity water, said process employing an aqueous surfactant fluid containing at least two surfactants, one primary anionic surfactant such as petroleum sulfonate and a solubilizing cosurfactant such as an alkyl or alkylaryl, polyethoxy sulfate or sulfonate. The process comprises injecting a plurality of slugs of surfactant fluids followed by a low salinity fluid containing a viscosifying amount of a hydrophilic polymer. The salinity and concentration of solubilizing cosurfactant of each surfactant slug are both decreased from the maximum level in the first slug of the surfactant fluid and in successive slugs to a minimum level at the last slug of the surfactant fluid.

Double tapered surfactant waterflood oil recovery process

Disclosed is a novel aqueous surfactant-containing fluid suitable for use in surfactant flooding oil recovery processes, and an oil recovery process using the fluid. The fluid contains petroleum sulfonates alone or in combination with solubilizing co-surfactants such as ethoxylated alkyl or alkylaryl compounds, alkyl or alkylaryl polyethoxy sulfates, or alkyl or alkylaryl polyethoxy sulfonates. The petroleum sulfonate is a mixture of petroleum sulfonates of varying equivalent weights ranging from 250 to 700, with an average equivalent weight between 325 and 425 and preferably between 350 and 400. Additionally, the distribution of equivalent weights is relatively uniform, with from 40 to 70 percent being less than 400 and from 60 to 30 percent of the petroleum sulfonates having equivalent weights being 400 or greater; and preferably from 15 to 35 percent of the petroleum sulfonates having equivalent weights less than 350, and 30 to 50 percent having equivalent weights from 350 to less than 500 and from 10 to 40 percent of the petroleum sulfonates having equivalent weights of 500 and above. The especially preferred embodiment employs a mixture of petroleum sulfonates in which 5 to 15 percent have equivalent weights less than 300, from 25 to 50 percent have equivalent weights the range of from about 300 to less than 400, from 15 to 25 percent fall in the range of from about 400 to less than 500 and from 5 to 20 percent have equivalent weights greater than 500.

Surfactant flooding oil recovery process

An oil recovery process comprising injecting a fatty alcohol into the oil phase of the reservoir followed by the injection of a soap which effectively emulsifies the oil-fatty alcohol mixture followed by further water injection to displace and produce the emulsified oil.

Oil recovery process: injection of fatty alcohol followed by soap

A method for transporting viscous hydrocarbons which involves introducing into a pipeline or well-bore with the viscous hydrocarbons a solution containing (1) an anionic surfactant such as sodium tridecyl sulfate, sodium oleate, etc., or an oxyalkylated anionic surfactant of the sulfonate or sulfate type, and mixtures of the surfactants mentioned and (2) an alkalinity agent such as sodium hydroxide, thereby forming a low viscosity, salt-tolerant, oil-in-water emulsion. Optionally, the solution may contain a small amount of a guanidine salt or a water-soluble oxyalkylated, nitrogen-containing aromatic compound such as ethoxylated-8-hydroxy quinoline.

Oil-in-water emulsion

In the recovery of oil from an oil-bearing formation having a high salinity connate water wherein an aqueous surfactant slug containing a commercially available petroleum sulfonate is injected followed by the injection of an aqueous drive agent, improved recovery is obtained, if a cosurfactant and a mono-unsaturated secondary alcohol are added to the surfactant slug.

Surfactant oil recovery process usable in a formation having high

Solution for transporting hydrocarbons in a pipeline

Primary anionic surfactants such as organic sulfonates, specifically petroleum sulfonates as well as synthetic alkyl or alkylaryl sulfonates are effective for recovering oil from subterranean, oil-containing formations only if the salinity and/or concentration of divalent ions in the formation water is relatively low. Many petroleum formations contain water whose salinity is in excess of the tolerance level of organic sulfonates, and either the high salinity water must be displaced by a preflush or the primary anionic organic sulfonate surfactants must be used in conjunction with an effective solubilizing co-surfactant in order to increase the solubility of the organic sulfonate in the high salinity and/or hard water. Suitable solubilizing co-surfactants include ethoxylated alcohols, alkyl phenols, and alkyl or alkylaryl thiols, as well as sulfated or sulfonated, ethoxylated alcohols or alkyl phenols. Optimum performance in any particular field is achieved if the ratio of primary anionic surfactant to solubilizing co-surfactant is carefully chosen so the surfactant combination exhibits borderline solubility in the particular formation water in which the surfactants are to be employed. The concentration ratio of primary and solubilizing surfactants which results in the desired borderline solubility may be identified by preparing a number of samples in the formation water using different ratios of primary surfactant concentration to solubilizing co-surfactant concentration, measuring the electrical conductivity of the samples and choosing the concentration ratio corresponding to the sample which produced the minimum electrical conductivity, or at which point the conductivity vs. concentration ratio curve exhibited an inflection point.

Salinity tolerant surfactant oil recovery process

Disclosed is an aqueous, saline surfactant-containing fluid and an oil recovery process using the fluid for recovering oil from formations containing high salinity and/or high hardness water, the fluid comprising an anionic surfactant such as organic sulfonate especially petroleum sulfonates as well as synthetic alkyl or alkylaryl sulfonates and a solubilizing co-surfactants such as an ethoxylated alcohol, alkyl phenol, or alkyl or alkylaryl thiol, or sulfated or sulfonated, ethoxylated alcohols or alkyl phenols. Optimum performance in any particular field is achieved if the ratio of primary anionic surfactant to solubilizing co-surfactant is carefully chosen so the surfactant combination exhibits borderline solubility in the particular formation brine in which the surfactants are to be employed. The concentration ratio of primary and solubilizing surfactants which results in the desired borderline solubility may be identified by preparing a number of samples in the formation water using different weight ratios of primary surfactant to solubilizing co-surfactant concentration, and visually noting the minimum co-surfactant needed to avoid separation of the surfactant fluid into separate phases, or which gives the surfactant fluid a pearlescent, a swirl-silver appearance which is characteristic of fluids having the proper balance of primary anionic surfactant and solubilizing co-surfactant.

Pipeline method for transporting viscous hydrocarbons

Surfactant oil recovery process in which an aqueous fluid containing petroleum sulfonate is injected into an oil formation containing water which is naturally fresh or which has been reduced to an acceptable salinity level by a pre-flush with fresh water is disclosed. Optimum oil recovery is achieved by determining the average equivalent weight petroleum sulfonate which produces the minimum interfacial tension in an oil-brine system similar to that present in the formation in which the surfactant is to be injected, and a petroleum sulfonate sample having an average equivalent weight which is from 2 to 20 percent and preferably from 5 to 15 percent less than the average equivalent weight of the sample which produced the minimum interfacial tension, or from 20 to 100 and preferably from 30 to 70 equivalent weight units less than the average equivalent weight of the sample which produced the minimum interfacial tension is used in the oil recovery process.

Surfactant oil recovery process

Primary anionic surfactants such as organic sulfonates are effective for recovering oil from subterranean formations only if the salinity and/or hardness of the formation water is relatively low. In petroleum formations containing high salinity, or hard water, either the high salinity water must be displaced by a preflush or the primary anionic surfactant must be used in conjunction with an effective solubilizing co-surfactant, such as ethoxylated alcohols or alkyl phenols, or alkyl or alkylaryl thiols, as well as sulfated or sulfonated, ethoxylated alcohols or alkyl phenols. Optimum performance is achieved if two or more samples of petroleum sulfonate having different equivalent weight ranges and distributions are blended in a ratio which requires the minimum amount of solubilizing cosurfactant to achieve a condition of borderline solubility in the particular formation water in which the surfactants are to be employed. This ratio may be identified by preparing a number of blended petroleum sulfonate samples in the formation water using different ratios of total primary surfactant concentration to solubilizing co-surfactant concentration, and determining whether borderline solubility is achieved, by direct observation or by identifying the sample which produced the minimum electrical conductivity, or at which point the conductivity vs. concentration ratio curve exhibits an inflection point.

A method of transporting viscous hydrocarbons which involves introducing into a pipeline or well-bore with the viscous hydrocarbons a solution containing an anionic surfactant or soap such as sodium tridecyl sulfate or sodium oleate together with a guanidine salt and optionally with an alkalinity agent and/or a nonionic surfactant such as a polyethoxylated alcohol thereby forming a low viscosity salt tolerant oil-in-water emulsion.

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Houston, TX, United States of America

Joseph T Carlin