Variable orifice gas lift valve for high flow rates with detachable power source and method of using

A valve in a well conduit for variably controlling the flow of a first fluid into the well conduit from a well annulus disposed about the well conduit, comprising:

• a valve body with a longitudinal bore therethrough for insertion in a mandrel;
• a variable orifice valve in the body for controlling flow of the first fluid from the well annulus into the well;
• a moveable hydraulic piston fixedly connected to the variable orifice valve;
• and,
• a valve-open and a valve-closed hydraulic control line in fluid communication with the hydraulic piston for providing dual supplies of pressurized fluid thereto;
• whereby the variable orifice valve is opened by applying pressure to the hydraulic piston through the valve-open control line and bleeding off pressure from the valve-closed control line;
• the variable orifice valve is closed by applying pressure to the hydraulic piston through the valve-closed control line and bleeding off pressure from the valve-open control line;
• and,
• the amount of the first fluid flowing through the variable orifice valve and the mandrel is controlled by varying the amount of pressurized fluid being applied to and bled off from the hydraulic piston through the control lines.