Abstract: A catalyst system of the Ziegler-Natta type suitable for producing ethylene copolymers having a reduced hexane extractable content comprising (a) an organoaluminum component and (b) a titanium trichloride component which has been prepared by reducing titanium tetrachloride with magnesium metal.

Abstract: A well pumping system uses a closed gas cycle to periodically unload a pumping chamber in a well. The system includes a tubing string having a downhole pumping chamber providing a check valve at the lower end. A packing assembly defines the upper end of the pumping chamber and includes a dip tube having a check valve allowing upward liquid movement through the dip tube. A conduit passes through the packing assembly. Pressurized gas is periodically pumped down the conduit to force liquid upwardly through the dip tube and tubing string. Cycling of the pressurized gas is controlled by a liquid seal control assembly at the surface. When the pumping chamber has been unloaded, the gas therein flows up the conduit and through the seal control assembly to a suction tank. The pressurized gas is thus maintained in a closed cycle.