Maintaining a downhole valve in an open position

A method of adjusting a downhole valve, comprising:

• positioning a downhole valve assembly in a wellbore, the downhole valve assembly comprising a downhole valve coupled to a downhole valve actuator that comprises a pressure chamber enclosing a pressurized fluid at a closing pressure, the downhole valve actuator maintaining the valve in a closed position as long as the closing pressure is greater than an annulus pressure in an annulus between the downhole valve assembly and the wellbore;
• circulating a fluid in the annulus to set the annulus pressure at a first fluid pressure;
• based on the annulus pressure greater than the closing pressure of the pressurized fluid, activating the downhole valve actuator to adjust the valve to an open position from the closed position;
• circulating the fluid in the annulus to set the annulus pressure at a second fluid pressure greater than the first fluid pressure to break a rupture disk of the downhole valve actuator;
• and
• upon breaking of the rupture disk, locking the valve in the open position independent of the relative values of the closing pressure and the annulus pressure.