Abstract: Disclosed are numerous downhole valves, systems, and a method that increases wellbore production and liquid lift efficiency and provides other benefits. The disclosed valves are designed to replace surface intermitted valves that waste reservoir energy and reduce liquid lift inefficiency in stop cocking and plunger lift systems. Additionally, the disclosure may be used to improve production and lift efficiency for surfactant lift systems and to raise liquids from below to above conventional liquid lift equipment. The disclosed valves open with energy supplied from the reservoir and utilize reservoir gas to lift liquids; therefore, no external gas injection or other energy is required. The design of the disclosed valves reduce or eliminate valve chatter, erosion and plugging issues that affect other downhole valves. Included in the disclosure are numerous valve embodiments comprising a tubular housing, an inlet and an outlet, a closing member, and a seat.

Abstract: A system and method for reducing the annular fluid volume in a wellbore to increase the lift efficiency of a lift system. In the preferred embodiment, a plunger lift system is installed in combination with a production tubing containing one or more joints with an increased outer diameter created by surrounding the joints by a material comprised of a differing composition than the composition of the joints. The increased outer diameter joints are placed in the liquid filled portion of the casing annulus above the setting depth of the plunger to reduce the accommodation space to liquids, resulting in a reduced annular liquid volume and an increase in the lift efficiency of the plunger lift system.