Definition - What does Control Line mean?
A control line is a small diameter hydraulic line used to control downhole equipment such as the downhole safety valve (DHSV). It is kept pressurized at all times as the systems operated by the control line operate on a fail-safe basis.
The control line is designed to lose pressure when a system leaks or fails, resulting in the closure of the safety valve. This ensures that the well remains safe in the case of a leak or failure. In the oil and gas industry, control lines are run along the external of the production tubing to communicate between the ground surface and downhole.
Trenchlesspedia explains Control Line
Control lines enable the transmission of signals, allow downhole data acquisition, and permit control and activation of downhole instruments.
The command and control signals can be sent from a location on the surface to the downhole tool in the wellbore. Data from downhole sensors can be sent to the surface systems for evaluation or use in certain well operations.
Downhole safety valves (DHSVs) are surface controlled sub-surface safety valves (SCSSV) hydraulically operated from a control panel on the surface. When hydraulic pressure is applied down a control line, the pressure forces a sleeve within the valve to slide down, opening the valve. On releasing the hydraulic pressure, the valve closes.