Technique for increased retention time in oil field settling tanks

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
1 is a side view of the apparatus of the instant invention.
The apparatus employs a large volume settling tank 103, a flow direction means 108, an oil outlet means 105, and a water outlet means 107.
(An oil-water inlet pipe 122 is connected to the flow direction means and is not shown in FIG.
1).
The tank employed can be of a standard cone bottom design to facilitate settling of sediments contained in the fluids to be separated.
FIG.
1 also shows a tank fluid level 102 which indicates the oil level of the fluids in the tank.
Level 104 is the oil-water interface of the separated fluids in the tank.
Volume 106 is the water volume portion of the fluids in the tank.
In the method of the instant invention an oil-water emulsion mixture is continually introduced into the tank through the flow direction means 108 so that the mixture enters the tank substantially tangential to the tank wall 120.
Then, simultaneously with the introduction of additional fluid into the tank through the flow direction means, separated oil is continuously withdrawn through oil outlet means 105 and water is continuously withdrawn through the bottom-center located water outlet means 107.
In an alternate embodiment it is possible to introduce the fluid mixture into the tank substantially tangential to the tank wall through a plurality of flow direction means The tangential entry of the fluids creates a slow vortex-like flow pattern of fluid in the tank which interferes with adverse fluid channeling.
The induced flow pattern establishes long circular-like flow paths in the tank which interfere with the direct channeling of the unseparated fluids from the mixture inlet to the water outlet.
This in effect increases the reaction time of the fluid mixture in the settling tank.
In addition, the desired gravity separation of oil and water in the settling tank requires a period of time.
This required time period can be obtained by the induced slow vortex-like flow pattern thus allowing the desired gravitational separation