Solar powered control panels

A Solar Powered Wellhead Control Panel is a cabinet that is a free-standing type and it is used to operate all safety valves that are attached to one or more Christmas Trees including the Downhole Safety Valve, which is installed below the surface in the Well. However for this panel the power source is coming from a Solar package (Photovoltaic Cells, Battery pack and charge controller). This is also a limitation in sizing as the motor will run on 12 or 24VDC the power rating of the motor cannot be selected to high. Further the running time of the motor must be limited as much as possible otherwise a the Solar package will become too big. The solar package can be supplied for use in safe area, but also suitable for use in a zone 1 area.

• Controlled valves could be as follows:
• SSSV = Subsurface Safety Valve / DHSV = Downhole Safety Valve
• SSV = Surface Safety Valve
• UMV = Upper Master Valve
• WV = Wing Valve

The built up of this panel can be split in several section, namely the hydraulic power unit and the control section.

The hydraulic power unit consist out of a hydraulic reservoir, a pump that can be either air/gas or electric driven. Accumulators to store the generated hydraulic energy for later use and to maintain pressure.

The HPU will have various pressure levels required to operate the system, the various levels can be achieved by use of pressure regulators or various pumps with different outputs.

The control section is usually operated at a low pressure, which most likely be hydraulic due to the solar package. It consist out of various possible sequences in operation and various shutdown levels, but in the end will be open/close the safety valves in the field in the correct way.

WHCPs may have multiple applications, which include, but are not limited to

• Safe and Sequential Operation of Wellhead Valves (SCSSV/SSV/Wing Etc.)
• Emergency (ESD station) and Fire Shutdown (Fusible Loop)
• Safe Operation of Riser Valves
• Flow line Pressure control (High/Low Pilot)
• Well Test Operation (Wireline Bypass)
• Hydraulic supply to SDV (HIPPS) /ESD/ Choke Valve
• Partial Stroking of field installed actuators
• Depending upon the pressure requirement for valves, HP, MP, and LP headers are envisaged.

The WHCP internal hydraulic circuit has tubing (small bore pipe), tube fittings (twin ferrule or threaded), check valves, isolation valves, quick exhaust valves, etc. as per requirement.

A fusible loop with fusible plugs are used to hold hydraulic pressure and installed around the wellhead. In case of heat (fire), the fusible plug melts and oil pressure will be released and will cause a shutdown in the panel which will ensure that the Safety Valves will be closed.

Sizing of the hydraulic lines between the WHCP and the Safety Valves, swept volume of each actuator and required closing times are important for overall WHCP design, but also the amount of accumulators and the running time of the electro motor.