Control of SCSSVs

Each well should have its subsurface controls located in the control panel, adjacent to the surface controls. A typical hydraulic circuit for an SCSSV is shown in Figure 1700-11.

To operate the control system in order to open the SCSSV and the SSV, the following sequence occurs:

1. By pulling the knob, the operator manually resets the pilot relay for the hydraulic system (MR-1). The pin will hold the relay open.
2. Instrument gas will flow through the ESD/Fire Loop pilot relay (R-2), and
a. Pressure up relay MR-1 and release its pin
b. Pressure up the hydraulic system latching relay (R-3) and allow gas to flow to the hydraulic pumps
c. Start the pneumatically driven hydraulic pump and
d. Close the hydraulic dump valve (R-4)
3. The selected SCSSVs will open and at the shut-in tubing pressure (SITP) the hydraulic low-pressure switch will allow instrument gas to flow to the hydraulic pressure pilot relay (R-5).
4. Instrument gas will flow through R-5 and through the process equipment S/D pilot relay (R-6) and will pressure up the field flowline instrument tubing up to the pressure-switch-low (PSL) switch.
5. After confirming that the first SCSSV is open, the operator pulls the knob to manually reset the pilot relay for the first SSV (MR-7-1). The pin will hold the relay open.
6. 100 psig instrument gas will flow through MR-7-1 to the quick exhaust valve and open the SSV.
7. After the first well is sending crude oil to the process equipment, instrument gas will flow through the PSL switch and the sand probe and back to the SSV pilot relay (MR-7-1), where the pin will release.
8. The second well is put onstream the same way by manually resetting the SCSSV selector and confirming that the SCSSV is open, then resetting the SSV pilot relay (MR-7-2), etc., until all the wells are flowing.

Typical Hydraulic Circuit for SCSSV

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