STACKED PISTON SAFETY VALVE WITH DIFFERENT PISTON DIAMETERS

Certain aspects are directed to a subsurface safety valve. The subsurface safety valve includes a closure mechanism and a piston assembly for actuating the closure mechanism. The piston assembly includes a first piston disposed in a first chamber, a second piston disposed in a second chamber adjacent to the first chamber, and first and second control lines. The second chamber has a second diameter that is smaller than a first diameter of the first chamber. The first control line selectively communicates pressure to the first piston in a downhole direction. The first piston applies force to the second piston in response to pressure being communicated to the first piston. The force can cause the closure mechanism to be actuated. The second control line communicates a second pressure to the first piston in an uphole direction that reduces an amount of force for displacing the second piston an uphole direction.