Method for treating petroleum well pumping power fluid

Abstract

A separation compartment of a multiphase separation vessel receives production fluid from a petroleum well and that fluid separates by gravity into the gas, oil and water phases in the vessel. An adjustable siphon leads from a water space in the separation compartment to a discharge compartment of the vessel. The level of the discharge from the siphon determines the elevation of an oil phase-water phase interface within the separation compartment and the presence of the desired of the fluid phases at a pickup for power fluid. The siphon includes a removable line that permits a change in the elevation of the outlet of the line into the discharge compartment. Preferably, the discharge compartment comprises an upstanding pipe, the top of which acts as a weir for receiving oil from the separation compartment. Oil from the vessel may pass through a cyclone for further separation of solids from the oil and then introduced by a pump back into the well to act as the power fluid for the well. Excess oil is taken off as product in a product stream together with production gas and water. An alternate embodiment employs an upstream surge vessel that takes surges in production fluid from the well of a greater flow rate than an established rate and directs excess flow directly to the dicharge to bypass the siphon.