OXIDIZER ENHANCED EMULSIFIED SOLVENT SYSTEMS TO DISSOLVE AND REMOVE TAR
A system and methods for dissolving tar for removal are provided. An exemplary system provides a treatment fluid for dissolving tar for removal. The treatment fluid includes an emulsion of solvent-in-water, and an oxidizer in the water phase. The emulsion can include a surfactant as a stabilizer. The treatment fluid can be used for hydrocarbon recovery from oil sands, or for removing tar deposits from oil reservoirs in sandstone rock or carbonate rock, among others.
1 . A treatment fluid for dissolving tar for removal, comprising:
an emulsion of solvent-in-water; and
an oxidizer in the water phase.
2 . The treatment fluid of claim 1 , wherein the solvent comprises a single solvent or a mixture of solvents.
3 . The treatment fluid of claim 1 , wherein the solvent comprises xylene, toluene, n-methyl pyrrolidone, ethylene glycol monobutyl ether, acetone, diesel or kerosene, or any combination thereof.
4 . The treatment fluid of claim 1 , wherein the solvent comprises a mixture of mutual solvents.
5 . The treatment fluid of claim 1 , wherein the oxidizer comprises a salt of BrO 3 − , ClO 3 − , or both.
6 . The treatment fluid of claim 5 , wherein the salt comprises lithium, sodium, potassium, magnesium, calcium, strontium, or barium, or any combination thereof.
7 . The treatment fluid of claim 1 , wherein the oxidizer comprises hydrogen peroxide, sodium persulfate. ammonium persulfate, sodium perborate, sodium percarbonate, potassium sulfate, calcium peroxide, magnesium peroxide, t-butyl hydroperoxide, or sodium hypochlorite, or any combination thereof.
8 . The treatment fluid of claim 1 , wherein the oxidizer comprises sodium persulfate.
9 . The treatment fluid of claim 1 , comprising a surfactant.
10 . The treatment fluid of claim 9 , wherein the surfactant has a hydrophobic-lipophilic balance (HLB) of greater than about 12.
11 . The treatment fluid of claim 9 , wherein the surfactant comprises about 0.1 vol. % to about 5 vol. %.
12 . The treatment fluid of claim 1 , wherein the oxidizer is active at a temperature of between about 38° C. and about 177° C.
13 . The treatment fluid of claim 1 , wherein the oxidizer is active at a temperature of between about 60° C. and about 95° C.
14 . The treatment fluid of claim 1 , wherein the oxidizer is active at a temperature of greater than 38° C.
15 . The treatment fluid of claim 1 , wherein the oxidizer is active at a temperature of greater than 116° C.
16 . The treatment fluid of claim 9 , wherein:
the solvent comprises xylene and n-methyl pyrrolidone;
the surfactant comprises alkyl sorbitan ethoxylates, alkyl alcohol ethoxylates, fatty acid ethoxylate, alkyl aryl sulfonates, or alkyl sulfonates, or any combinations thereof; and
the oxidizer comprises sodium bromate, sodium chlorite, or a mixture thereof.
17 . A method for dissolving tar for removal, comprising:
dissolving an oxidizer into water;
forming an emulsion of solvent in the water;
injecting the emulsion into a reservoir; and
producing dissolved tar from the reservoir.
18 . The method of claim 17 , comprising selecting the oxidizer based, at least in part, on a reservoir temperature.
19 . The method of claim 18 , comprising selecting a bromate to be the oxidizer.
20 . The method of claim 19 , comprising selecting a persulfate to be the oxidizer.
21 . The method of claim 17 , comprising selecting xylene, toluene, N-methyl pyrrolidone, ethylene glycol monobutyl ether, acetone, diesel or kerosene, or any combination thereof, as the solvent.
22 . The method of claim 17 , comprising selecting a mixture of xylene and n-methyl pyrrolidone, a mixture of n-methyl pyrrolidone and ethylene glycol monobutyl ether, or a mixture of diesel and n-methyl pyrrolidone as the solvent.
23 . The method of claim 17 , comprising adding a chemical dispersant to the emulsion, wherein the chemical dispersant is selected to decrease agglomeration of broken tar molecules.
24 . The method of claim 17 , comprising injecting the emulsion into an oil sands reservoir.
25 . The method of claim 17 , comprising injecting the emulsion into a sandstone reservoir containing oil, or a carbonate reservoir containing oil, or a hydraulically fractured shale reservoir.
26 . The method of claim 24 , comprising producing bitumen from the oil sands reservoir, sandstone reservoirs containing oil, or carbonate reservoirs containing oil, or a hydraulically fractured shale reservoir.
27 . The method of claim 17 . comprising injecting the emulsion into a reservoir through an injection well during an enhanced oil recovery process.
28 . The method of claim 27 . comprising producing hydrocarbons and broken tar molecules from the reservoir through a production well.