Oil-in-water-in-oil emulsion
An oil-in-water-in-oil emulsion (O/W/O) comprising a first oil-in-water emulsion dispersed in a second oil, and a method of preparing the same. The O/W/O emulsion can be used as a drive fluid in an enhanced oil recovery process. The O/W/O emulsion of this invention may also be used as a lubricant, and has the beneficial property of being resistant to shear forces.
1. A method for recovering hydrocarbons from a subterranean formation, said method comprising the steps of:
(a) preparing an oil-in-water-in-oil emulsion;
(b) injecting said oil-in-water-in-oil emulsion into a subterranean formation;
(c) displacing hydrocarbons from said subterranean formation to at least one producing well, wherein the oil-in-water-in-oil emulsion is used as a drive fluid; and
(d) recovering hydrocarbons from the at least one producing well.
2. The method of claim 1 , wherein said step of preparing said oil-in-water-in-oil emulsion comprises:
(a) forming a first oil-in-water emulsion comprising a first oil, water, about 0.1 wt % to about 10 wt % of an organic acid, and about 0.01 wt % to about 10 wt % of a salt of an organic acid, all based on the weight of said first oil-in-water emulsion;
(b) dispersing said first oil-in-water emulsion in a second oil.
3. The method of claim 2 , further comprising the step of diluting said oil-in-water-in-oil emulsion to reduce the viscosity of said emulsion prior to said step of injecting said emulsion into said subterranean formation.
4. The method of claim 3 , wherein said step of diluting said oil-in-water-in-oil emulsion comprises adding hydrocarbon gas.
5. The method of claim 3 , wherein said dispersing step comprises mixing said first oil-in-water emulsion with said second oil.