Deep well simulator

An apparatus for determining the permeability and changes in permeability to fluids as a function of time of a solid at a particular temperature and pressure and flow rate, said apparatus comprising a precision plunger-type pump, means for controlling the flow rate of liquid from the pump, a fluid reservoir housing a movable piston that divides the interior of the reservoir into two sides, a fluid side and a test fluid side, said pump connected to the fluid side of the fluid reservoir to permit said piston to be actuated by the fluid pressure exerted on the movable piston of the reservoir by the pump, a solid or core holder with an inlet and exit means, the test fluid side of the reservoir connected to an inlet connection for the solid holder, a heater adjacent to the solid holder with means for maintaining a solid in the solid holder at any temperature, a differential pressure transducer, the transducer is connected to the entrance and exit means for the solid holder to measure and record differential pressure continuously as a function of time, a receiver with a movable piston housed therein that divides the interior of the receiver into two sides, a test fluid side and an oil side, means for passage of the test fluid from the reservoir to the inlet of the solid holder, means for passage of the test fluid from the exit of the solid holder to the test fluid side of the receiver, a pressure transducer, a pressure let-down capillary connected through the pressure transducer to the oil side of the receiver, a heater adjacent to the pressure let-down capillary for heating the oil in the capillary, means for connecting to said pressure transducer and said heater for controlling the heat provided by the heater to permit a constant pressure downstream of the solid holder by providing a controlled pressure to the receiver piston to control the exit pressure of the fluid from the solid holder.