Combination downhole tubing circulating valve and fluid unloader and

Abstract

A combination circulating valve and fluid unloader adapted for connecting in a tubing string disposed within the well bore of a producing well which is closed to downward flow of fluids therethrough. The valve includes a tubular member with ports through the wall thereof having a sliding sleeve disposed around the outside surface which is also provided with ports through the wall thereof for passage of fluid into the annulus. Opening and closing of the valve is accomplished by shifting the sliding sleeve between three positions by changing the pressure of the fluids contained in the tubing string to overcome the force exerted by a spring biasing the sliding sleeve toward a first, closed position. When the pressure of the fluid is increased to a first selected pressure, the sliding sleeve is shifted with respect to the tubular member to a second, circulating position in which the ports of the tubular member are in fluid communication with the ports of the sliding sleeve. When the pressure is further increased to a second selected pressure, the sliding sleeve is shifted to the third, unloading position in which the ports are also in fluid communication for the passage of fluid without regard to pressure. A spring-biased pin is provided for locking the sliding sleeve in the third position to allow the draining of fluid from the tubing string.