Abstract: A differential pressure operated gas lift includes a valve element movable in a tubular body to open and close a gas flow passage having flow restricting orifices upstream thereof. A coil spring tends to open the valve element. In the open position of the valve element an external pressure responsive surface engages a seat which is axially adjustable to vary the spring force and change the length of travel of the valve element between its open and closed positions. The reopening differential pressure can be changed while maintaining the same closing pressure differential. Very large injection rates can be implemented at low differential pressures.

Abstract: A device for draining a nickel cadmium or other battery prior to recharging the battery includes first and second input terminals for connecting the device to a battery to be discharged, and first and second circuits coupled to the input terminals for draining current from the battery for deep cycle discharge purposes. The first circuit has sufficient resistance to drain current from the battery without damage to the battery when the battery has an output voltage above a predetermined threshold level (e.g., 3.3 volts), and the second circuit presents a low resistance in order to drain current from the battery when the battery has an output voltage no greater than the threshold level. The device includes a relay coupled to the input terminals for decoupling the second circuit from the battery when the battery has an output voltage greater than the threshold level.

Abstract: A three-phase well test apparatus and method using a two-phase separator. A separator is used to separate well fluid into gas and liquid constituents. The gas constituent is measured by a gas flow meter, and a pressure control valve is used to prevent surging of the gas beyond the range of the meter A pump is used to pump liquid out of the separator through a liquid flow line. A recirculating line is provided, and a valve may be acutated between a flow position and a recirculating position in response to a liquid level in the separator. When liquid is not being flowed for measurement, it is recirculated to the separator and thereby continuously mixed to maintain the liquid in a homogeneous condition. Downstream from the valve is a liquid meter and a meter prover connection. The recirculation mixes the liquid A mixer may be positioned downstream from the pump to additionally mix the liquid flowing therethrough.