Process for selecting a steam foam forming surfactant

Claim 1

In a process in which oil is displaced within a subterranean reservoir by injecting steam and surfactant-containing steam-foam-forming components to form a steam-containing fluid having less mobility than steam alone and thus having a greater tendency to avoid bypassing oil, an improved procedure for selecting which of a plurality of surfactant materials is the most effective for both avoiding oil bypassing and efficiently displacing the oil contained within a particular reservoir, comprising: mixing steam with each of a plurality of surfactant materials to form a plurality of steam foams which are substantially equivalent except for the compositions of the surfactant materials; displacing each of said foams into and through a pair of substantially equally available and equally permeable porous materials while concurrntly displacing an oil which is or is substantially equivalent to the reservoir oil through one of the permeable porous materials and measuring both the proportion of each of said foams which flows through the respective oil-free and oil-containing permeable material and the extent to which the foam removes the oil from the oil-containing material, in order to compare the capabilities of each of the surfactant materials with respect to both the mobility controlling and oil removing aspects when the foams formed by them have equal opportunities to flow through either a path which is oil-free or one which is oil-containing.

Claim 7

A method for formulating a steam-foam-forming mixture of steam and surfactant-containing steam-foam-forming components to be injected into an oil-containing subterreanean reservoir, comprising: arranging a pair of fluid conduits for conducting parallel flows of fluid through actual or simulated earth formations of substantially the same composition and permeability; flowing steam through the conduits and, to the extent required, adjusting the system to provide flow rates which are at least substantially equal within each of the two paths available to the steam; while flowing steam so that it can enter into both conduits at substantially the same rate, flowing the oil being treated into one conduit at a rate such that the oil contacts at least most of the steam that flows through that oil-containing conduit; while flowing the oil into the oil-containing conduit at the same rate, separately testing different mixtures by flowing them so that they can enter into both conduits at substantially the same rate and in the same way that the steam was inflowed into those conduits, using mixtures of the same quality and temperature of steam with each of at least two surfactant-containing steam-foam-forming components; determining the relative proportions of the total amounts of the steam-containing mixtures which flow through the respective oil-containing and oil-free conduits and the extent to which those steam-containing mixtures displace the oil from the oil-containing conduit; and formulating as said mixture to be injected into a subterranean reservoir a mixture of steam and steam-forming surfactant components which are effective for both causing a flow of steam-containing fluids into permeable materials containing the reservoir oil and for displacing that oil from those materials.

Claim 8

A method for formulating a steam-foam-forming mixture of steam and surfactant-containing steam-foam-forming components to be injected into an oil-containing subterreanean reservoir, comprising: arranging a pair of fluid conduits for conducting parallel flows of fluid through actual or simulated earth formations of substantially the same composition and permeability; flowing steam through the conduits and, to the extent required, adjusting the system to provide flow rates which are at least substantially equal within each of the two paths available to the steam; while flowing steam so that it can enter into both conduits at substantially the same rate, flowing the oil being treated into one conduit at a rate such that the oil contacts at least most of the steam that flows through that oil-containing conduit; while flowing the oil into the oil-containing conduit at the same rate, separately testing different mixtures by flowing them so that they can enter into both conduits at substantially the same rate and in the same way that the steam was inflowed into those conduits, using mixtures of the same quality and temperature of steam with each of at least two surfactant-containing steam-foam-forming components; determining the relative proportions of the total amounts of the steam-containing mixtures which flow through the respective oil-containing and oil-free conduits and the extent to which those steam-containing mixtures displace the oil from the oil-containing conduit; and formulating as said mixture to be injected into a subterranean reservoir a mixture of steam and steam-forming surfactant components which are effective for both causing a flow of steam-containing fluids into permeable materials containing the reservoir oil and for displacing that oil from those materials.