Abstract: An operating well such as an oil well is provided with a safety valve in the tubing thereof. A control cartridge controls the safety valve under the command of control signals transmitted from the surface. The control cartridge includes a housing mounted in the tubing and a receiver for receiving signals transmitted from the surface. A power supply is provided in the housing and is connected to an electronic control system, which control system is also connected to the receiver. A hydraulically operated actuator controls the safety valve, and a source of hydraulic fluid is provided in the housing and connected with the hydraulically operated actuator for operating the actuator. The source of hydraulic fluid is also connected to the power supply for operation thereof.