The present invention is directed to a process for producing and separating oil. An aqueous fluid having an ionic content of at most 0.15 M and a total dissolved solids content of from 200 ppm to 10,000 ppm is introduced into an oil-bearing formation. Oil and water are produced from the formation subsequent to the introduction of the aqueous fluid into the formation. A demulsifier and a brine solution having a total dissolved solids content of greater than 10,000 ppm are mixed with the oil and water produced from the formation. Oil is then separated from the mixture of oil, water, demulsifier, and brine solution.

A method of treating contaminated materials such as oil and gas production waste sludges to recover crude oil hydrocarbons. The method includes the inversion of water-in-oil emulsions, and subsequent separation steps. These may involve the separation and removal of asphaltenes, petroleum waxes and/or solid particles from the crude oil hydrocarbons. The treatment method uses the physical phenomena of hydrodynamic cavitation and hydraulic shock, which produce different effects upon a mixture of water and the contaminated material being treated. These are deployed either as single or combined stage(s) of treatment or as a repeated series of single/combined treatment stages, with or without additional processing operations between each single/combined treatment stage. The method may be implemented with suitable plant including hydrodynamic cavitation units (103, 106) and hydraulic shock units (104, 107), followed by separators (105, 108).

A hydrothermal liquefaction (HTL) system has a biomass slurry flow path with a first pump and a first heat exchanger network downstream of the first pump. The first heat exchanger network includes plurality of heat exchangers in a parallel, series, and/or series-parallel flow arrangement. The biomass slurry flow path extends through cold flow sides of the heat exchangers of the first heat exchanger network. The biomass slurry flow path includes a second pump downstream of the first heat exchanger network, and a second heat exchanger network downstream of the second pump. The biomass slurry flow path extends through cold flow sides of the heat exchangers of the second heat exchanger network. A hydrothermal liquefaction (HTL) reactor is downstream of the second heat exchanger network. Heat transfer liquid in a heat transfer liquid circuit flows through hot flow sides of the heat exchangers of the second heat exchanger network.