Method of secondary extraction of oil from a well

Abstract

The invention discloses a method to enhance flow of oil bearing crude from a stripper well, by sealing the concentric well casing and tubing components together across the annular space between these components, at a level generally above any liquid in the casing, to define a sealed space open via perforations in the casing to the surrounding oil bearing formation; by evacuating gases from the defined sealed space to establish subatmospheric pressure conditions therein that may be reduced only by flow of fluids including the crude through the well casing perforations from the surrounding oil bearing formation; by discontining these conditions and immediately thereafter injecting a fluid into the defined sealed space, to pressurize the defined space to superatmospheric pressure conditions; by repeating both phases of the cycle between the subatmospheric and superatmospheric pressure conditions, sequentially over and over; and by operating a lift pump means in the well tubing, at least part of the time during each cycle or between each sequential cycle, to recover oil bearing crude drawn into the well casing.