Compositions for enhanced oil recovery
Compositions and methods for increasing recovery, or flowback, of hydrocarbon compounds from hydrocarbon-containing subterranean reservoirs. The compositions include a dialkyl dimethyl ammonium surfactant, an amphoteric surfactant, and a solvent. The concentrated compositions are storage stable and easily diluted with a water source such as produced water to form injectates suitable for injecting into one or more hydrocarbon-bearing subterranean reservoirs. The injectates convert oil-wet rocks to water-wet but do not cause formation of emulsions with hydrocarbon compounds within the subterranean environment. Injection of the injectates into a reservoir results in an increase in the yield of hydrocarbons recovered, in particular from low permeability, low porosity reservoirs such as those formed by or encountered in hydraulic fracturing and/or in certain geographic locations.
1. A composition consisting essentially of:
(a) a dialkyl dimethyl ammonium surfactant or a mixture of two or more thereof;
(b) an amphoteric surfactant or a mixture of two or more thereof; and
(c) a solvent selected from a water source, a coupling agent, or a mixture of two or more thereof.
2. The composition of claim 1 wherein the composition is a concentrate, the concentrate comprising about 5 wt % to 90 wt % total surfactant based on the weight of the concentrate, wherein the concentrate and is storage stable and pumpable or pourable for about 24 hours to two years at temperatures between −40° C. and 100° C.
3. The composition of claim 2 wherein the concentrate comprises about 5 wt % to 30 wt % of a coupling agent based on the weight of the concentrate.
4. The composition of claim 1 wherein the composition is an injectate, the injectate comprising about 10 ppm to 10,000 ppm total surfactant based on the weight of the concentrate.
5. The composition of claim 1 wherein the water source is a high total dissolved solids water source, a high temperature water source, or a high total dissolved solids, high temperature water source.
6. The composition of claim 1 wherein the dialkyl dimethyl ammonium surfactant has the formula R 1 R 2 N + (CH 3 ) 2 X − , wherein R 1 and R 2 are independently selected from linear, branched, alicyclic, aryl, and alkaryl groups having 8 to 30 carbon atoms and X is a halide.
7. The composition of claim 1 wherein the dialkyl dimethyl ammonium surfactant is dicoco dimethylammonium chloride.
8. The composition of claim 1 wherein the amphoteric surfactant comprises a single internal cation, a single internal anion, and a hydrophobic moiety selected from linear, branched, alicyclic, aryl, and alkaryl groups having 6 to 50 carbon atoms.
9. The composition of claim 1 wherein the amphoteric surfactant is lauryl hydroxylsultaine.
10. The composition of claim 1 wherein the ratio of the dialkyl dimethyl ammonium surfactant to the amphoteric surfactant in the composition is about 10:1 to 1:3 by weight.
11. A method of increasing recovery of a hydrocarbon from a subterranean reservoir, the method comprising:
combining a concentrate consisting essentially of a dialkyl dimethyl ammonium surfactant or a mixture of two or more thereof, an amphoteric surfactant or a mixture of two or more thereof, and a coupling agent or a mixture of two or more thereof with a water source to form an injectate, the injectate comprising 10 ppm to 10,000 ppm total surfactant based on the weight of the injectate;
injecting the injectate into the subterranean reservoir; and
collecting a hydrocarbon from the subterranean reservoir.
12. The method of claim 11 wherein the subterranean reservoir comprises one or more of: tight rock, very tight rock, heavy hydrocarbon (heavy oil), high paraffin content hydrocarbon, high temperature, high pressure, high total dissolved solids water source.
13. The method of claim 11 wherein the combining further comprises combining a proppant with the injectate, further wherein the injecting is contemporaneous with an hydraulic fracturing.
14. The method of claim 11 wherein the injecting is into a first wellbore fluidly connected to the subterranean reservoir, and the collecting is from a second wellbore fluidly connected to the subterranean reservoir.
15. The method of claim 11 wherein the injecting and the collecting are carried out at the same wellbore.
16. The method of claim 11 wherein a wellbore is established prior to the injecting.
17. The method of claim 11 wherein the combining is diluting a concentrate with a water source, further wherein the method includes
forming a concentrate, the concentrate comprising about 5 wt % to 90 wt % total surfactant based on the weight of the concentrate and about 5 wt % to 30 wt % of the coupling agent based on the weight of the concentrate; and
optionally storing the concentrate in a container for a period of about 24 hours to two years before the diluting.
18. The method of claim 17 wherein the combining is carried out contemporaneously with the injecting.
19. A composition consisting essentially of:
(a) a dialkyl dimethyl ammonium surfactant or a mixture of two or more thereof;
(b) an amphoteric surfactant or a mixture of two or more thereof;
(c) a solvent selected from a water source, a coupling agent, or a mixture of two or more thereof; and
(d) a demulsifier, a proppant, or a combination thereof,
wherein the demulsifier is selected from the group consisting of polyethylenimine alkoxylates, alkoxylated alkylphenol formaldehyde resins, alkoxylated amine-modified alkylphenol formaldehyde resins, ethylene oxide/propylene oxide copolymers, crosslinked ethylene oxide/propylene oxide copolymers, and mixtures of two or more thereof.