Systems and methods for treating produced water

1. A method for treating produced water, comprising:

separating the produced water to form a gas, an oil emulsion, and water;

recovering heat energy from the produced water during separation of the produced water by using an integrated separator-heat exchanger;

converting the recovered heat energy to mechanical and/or electrical energy; and

using the mechanical and/or electrical energy to directly drive treatment of the produced water.

2. The method of claim 1 , further comprising converting the mechanical energy to electrical energy.

3. The method of claim 1 , comprising using a heat engine in fluid communication with a generator to convert the recovered heat energy to electrical energy.

4. The method of claim 1 , comprising using a thermoelectric generator to convert the recovered heat energy to electrical energy.

5. The method of claim 1 , further comprising delivering excess recovered heat energy to a distribution network.

6. The method of claim 1 , further comprising using an energy network to supplement the recovered heat energy or as a backup source of power.

7. A system for providing energy to treat produced water, comprising:

a source of produced water having heat energy;

a water treatment subsystem having an energy requirement and comprising an oil-water separator fluidly connected downstream of the source of produced water; and

an energy recovery subsystem comprising a heat exchanger and configured to convert a portion of the heat energy from the produced water to mechanical and/or electrical energy, and to supply at least a portion of the energy requirement of the water treatment subsystem,

the oil-water separator being integrated with the heat exchanger and configured to separate the produced water to form a gas, an oil emulsion, and water while recovering heat energy from the produced water.

8. The system of claim 7 , wherein the energy recovery subsystem comprises a generator disposed in communication with a turbine to generate electrical energy.

9. The system of claim 8 , wherein the turbine comprises a two-phase turbine.

10. The system of claim 7 , wherein the water treatment subsystem comprises at least one of a microfiltration unit, an activated carbon media unit, a reverse osmosis unit, and an electrodialysis unit.

11. The system of claim 7 , wherein the energy recovery subsystem comprises a heat engine configured to operate in accordance with a trilateral thermodynamic energy conversion cycle.

12. The system of claim 7 , wherein the heat energy is used in a heating or cooling application.

13. The method of claim 1 , wherein the mechanical and/or electrical energy is used to directly drive a desalination operation associated with treatment of the produced water.

14. The method of claim 13 , wherein the mechanical and/or electrical energy supplies at least 90% of a total energy requirement of the desalination operation.

15. The system of claim 7 , wherein the oil-water separator has an inlet fluidly connected downstream of the source of produced water, a gas outlet, an oil emulsion outlet, and a water outlet fluidly connected to at least one of a microfiltration unit, an activated carbon media unit, a reverse osmosis unit, and an electrodialysis unit.

16. The system of claim 7 , wherein the system is associated with an oil and gas extraction operation.

17. The system of claim 10 , wherein the energy recovery subsystem is configured to supply at least 90% of a total energy requirement of the electrodialysis unit.