Compositions for enhanced oil recovery
Disclosed herein are compositions and methods for increasing recovery, or flowback, of hydrocarbon compounds from hydrocarbon-containing subterranean fractured rock formations (tight shale reservoirs). The flowback compositions include an anionic dimer surfactant, an anionic monomer surfactant, and a demulsifier. The flowback compositions convert oil-wet rocks to water-wet, yet exhibit a low tendency of composition components to sorb to the rock. The flowback compositions do not cause formation of emulsions with hydrocarbon compounds within the subterranean fractured rock formations. The flowback composition are useful for increasing the yield of hydrocarbons recovered from tight shale reservoirs.
1. A flowback composition comprising:
an anionic dimer surfactant selected from the group consisting of a compound having the formula
a compound having the formula
a compound having the formula
a compound having the formula
a compound having the formula
a compound having the formula
an anionic monomer surfactant; and
a water source, or a combination of the water source and a coupling agent, wherein the flowback composition is a flowback injectate, the injectate comprising about 99 wt % to 99.999 wt % of the water source, and wherein the water source is a produced water.
2. The flowback composition of claim 1 wherein the anionic moieties of the anionic monomer surfactant are selected from the group consisting of phosphate, sulfonate, carboxylate, and mixtures thereof.
3. The flowback composition of claim 1 wherein the anionic moiety of both the anionic dimer surfactant and the anionic monomer surfactant is sulfonate.
4. The flowback composition of claim 1 wherein the weight ratio of anionic dimer surfactant to the anionic monomer surfactant is about 3:1 to 1:3.
5. The flowback composition of claim 1 further comprising one or more clay stabilizers, proppants, or mixtures thereof.
6. The flowback composition of claim 1 , wherein the flowback composition comprises the combination of the water source and the coupling agent, and wherein the coupling agent is selected from the group consisting of linear, branched, or cyclic aliphatic alcohols having 1 to 6 carbon atoms, diols having 1 to 6 carbon atoms, alkyl ethers of alkylene glycols wherein the alkyl moiety has 1 to 6 carbon atoms, polyalkylene glycols, and mixtures of two or more thereof.
7. The flowback composition of claim 1 , wherein the flowback composition comprises the combination of the water source and the coupling agent.
8. The flowback composition of claim 7 wherein the flowback composition is storage stable.