Hydraulic stepping valve actuated sliding sleeve

An actuator for displacing a predetermined volume of fluid, said actuator comprising;

• (a) a cylinder (61) having first (68) and second (64) ends, a first fluid conduit (54) for supplying fluid to said first cylinder end (68) and a second fluid conduit (52) for transferring displacement fluid from said second cylinder end (64);
• (b) a piston (62) within said cylinder (61) disposed for axial translation within said cylinder, said piston having a first end proximate of said first cylinder end (68) and a second end proximate of said second cylinder end (64), said piston having an orifice plug (63) projecting from said second piston end for selectively obstructing entry of fluid into said second fluid conduit (52);
• (c) a force element (66) bearing upon said piston (62) second end to bias said piston toward said first cylinder end;
• (d) a first piston conduit (71) for transfer of fluid through said piston (62) between said first and second ends;
• and,
• (e) a first valve element (78) for controlling fluid flow through said first piston conduit (71), said valve element (78) being resiliently biased to a position that is open to flow between opposite ends of said piston and closed by abutment against said first cylinder end.

A system for controlling the flow of well fluid between a well annulus and an internal flowbore of a tubing string, said system comprising:

• (a) a tubular housing (12) in said tubing string having a fluid flow aperture (28) through a tubular wall thereof around said flowbore;
• (b) a substantially coaxial tubular sleeve (20) adjacent said housing for selectively obstructing the fluid flow area of said flow aperture (28);
• (c) a first actuator (50) for selectively displacing said sleeve in a first direction;
• and,
• (d) a second actuator (54) for incrementally displacing said sleeve (20) in a second direction wherein a fluid flow area through said aperture is changed in corresponding increments, and a force required to displace said sleeve from one flow rate increment to another increases incrementally.

A fluid actuator for displacing a predetermined volume of fluid comprising:

• a piston (62) disposed within a cylinder (61) for displacement of a predetermined fluid volume by translation from one end of said cylinder toward an opposite end;
• a force bias (66) of said piston toward said one cylinder end;
• a fluid supply (54) to said one cylinder end;
• and,
• a pressure differentially closed piston by-pass conduit (71) whereby said conduit is closed by a fluid pressure in said cylinder one end that is sufficient to displace said piston against said force bias.