DOWNHOLE SEPARATION AND INJECTION OF PRODUCED WATER IN HYDROCARBON WELLS USING PARTIAL GAS LIFT

摘要

A method and system for the downhole separation and injection of a predominately water component of the mixture produced from a naturally flowing or gas-lifted hydrocarbon well. The produced mixture is delivered to a separator located in the wellbore above an injection formation, the separator comprising a gas-liquid separator and an oil-water separator. The produced mixture is admitted to a gas-liquid separator to separate the free gas from the produced mixture. The gas-depleted produced mixture is then admitted to an oil-water separator where the produced mixture is separated into a predominately water component and a predominately hydrocarbon component. The separated gas and the predominately hydrocarbon component are delivered to the surface, separately or commingled. The predominately water is injected in the injection formation accessible through the same wellbore, and located below the separator. The predominately water component is separated at a sufficiently elevated location with respect to the injection formation to permit the predominately water component to be delivered to the injection formation under the force of gravity. This invention achieves downhole water separation and injection without having to install downhole pumps to re-inject the water contained in the produced mixture.