Hydrodynamic water-oil separation breakthrough

A water-oil separation apparatus comprising:

• an upright separation vessel,
• a central tube provided in the separation vessel;
• inlet piping attached to a central inlet disposed along an upper portion of the central tube, the inlet piping adapted to introduce a fluid mixture into a separation portion of the vessel where the fluid mixture separates into a gas, which gas collects in a gas layer at a top portion of the upright separation vessel, and into an oil layer and a water layer, which oil and water layers collect within the upright separation vessel below the gas layer;
• an upper baffle provided within the vessel below the central inlet;
• means for skimming oil off of the oil layer provided within the vessel above the upper baffle, wherein the means for skimming oil fluidly communicates with an oil outlet for removing the skimmed oil from the vessel;
• a lower baffle located below the upper baffle within the vessel;
• a central outlet for the water layer provided below the lower baffle;
• a water leg operably associated with the upright separation vessel;
• wherein the central outlet for the water layer communicates with an inlet of the water leg that regulates a level of interface between the oil layer and water layer within the vessel, and an outlet provided on the water leg for discharging water out of the water leg, and
• wherein the water leg is provided with an inner tube concentrically located within an outer tube and an adjustable height upper end of the inner tube serving as a flow over weir allowing water within the annulus to flow out of the upper end of the annulus and into the inner tube and from there downward within the inner tube to the outlet provided on the water leg and wherein the adjustable height upper end is adjusted in height external to the water leg inner and outer tubes.