A method for enhanced or improved oil recovery includes injecting a miscible injection fluid comprising an unfractionated hydrocarbon mixture through an injection well into a hydrocarbon bearing reservoir at a structurally higher position to initiate gravity-stable displacement and gas cap expansion processes. Residual hydrocarbons in the hydrocarbon bearing reservoir are mobilized and displaced by the miscible injection fluid to a structurally lower position within the hydrocarbon bearing reservoir adjacent a production well through which they are produced to the surface.

A method for enhanced or improved oil recovery includes injecting a miscible injection fluid comprising an unfractionated hydrocarbon mixture through an injection well into a hydrocarbon bearing reservoir at a structurally higher position to initiate gravity-stable displacement and gas cap expansion processes. Residual hydrocarbons in the hydrocarbon bearing reservoir are mobilized and displaced by the miscible injection fluid to a structurally lower position within the hydrocarbon bearing reservoir adjacent a production well through which they are produced to the surface.

Method of modelling the evolution of the pH value of a porous medium after injection of an alkaline agent solution into this medium. The alkaline agent is considered as a soda pseudo-constituent of concentration equal to an OH— concentration corresponding to the pH value of the alkaline agent solution injected. An adsorption equation calibrated to experimental data is then used to determine an amount of soda pseudo-constituent adsorbed, from the concentration of the soda pseudo-constituent. Finally, the evolution of the pH value is modelled by modelling the transport of the alkaline agent solution by means of a soda transport simulator, by replacing the soda by the soda pseudo-constituent.

Method of modelling the evolution of the pH value of a porous medium after injection of an alkaline agent solution into this medium. The alkaline agent is considered as a soda pseudo-constituent of concentration equal to an OH— concentration corresponding to the pH value of the alkaline agent solution injected. An adsorption equation calibrated to experimental data is then used to determine an amount of soda pseudo-constituent adsorbed, from the concentration of the soda pseudo-constituent. Finally, the evolution of the pH value is modelled by modelling the transport of the alkaline agent solution by means of a soda transport simulator, by replacing the soda by the soda pseudo-constituent.

Disclosed techniques include a method of obtaining an enhanced oil recovery fluid from a hydrocarbon reservoir, comprising producing a hydrocarbon stream from the hydrocarbon reservoir, separating an associated gas stream from the hydrocarbon stream, and condensing at least a portion of the associated gas stream to obtain an enriched hydrocarbon fluid suitable for injecting into a liquid layer of the hydrocarbon reservoir to enhance recovery of hydrocarbons from the hydrocarbon reservoir.

Disclosed techniques include a method of obtaining an enhanced oil recovery fluid from a hydrocarbon reservoir, comprising producing a hydrocarbon stream from the hydrocarbon reservoir, separating an associated gas stream from the hydrocarbon stream, and condensing at least a portion of the associated gas stream to obtain an enriched hydrocarbon fluid suitable for injecting into a liquid layer of the hydrocarbon reservoir to enhance recovery of hydrocarbons from the hydrocarbon reservoir.

A method of enhanced oil recovery may comprise placing into a subterranean formation a production enhancement fluid comprising a short chain hydrocarbon phase and a silane based wettability modifier, wherein the short chain hydrocarbon phase comprises hydrocarbons having 5 or less carbon atoms; allowing the production enhancement fluid to remain in the subterranean formation for a shut-in period; and producing hydrocarbons from the subterranean formation.

A method of enhanced oil recovery may comprise placing into a subterranean formation a production enhancement fluid comprising a short chain hydrocarbon phase and a silane based wettability modifier, wherein the short chain hydrocarbon phase comprises hydrocarbons having 5 or less carbon atoms; allowing the production enhancement fluid to remain in the subterranean formation for a shut-in period; and producing hydrocarbons from the subterranean formation.

A method for producing oil, comprising injecting water and a solvent into a formation; producing a mixture comprising water, solvent, oil, and gas from the formation; separating the mixture into a first stream comprising oil, water, and a first portion of the solvent, and a second stream comprising gas and a second portion of the solvent, and exposing the second stream to water to remove the second portion of the solvent from the gas.

A method for producing oil, comprising injecting water and a solvent into a formation; producing a mixture comprising water, solvent, oil, and gas from the formation; separating the mixture into a first stream comprising oil, water, and a first portion of the solvent, and a second stream comprising gas and a second portion of the solvent, and exposing the second stream to water to remove the second portion of the solvent from the gas.