Multi-stage hydraulic fracturing tool and system

A system for controllably exposing selected locations along a wellbore to a pressurized fluid, the system comprising:

• a casing for disposal within the wellbore, the casing defining an internal borehole extending longitudinally within the wellbore, the casing having one or more geometrical profile locations provided on inner side thereof;
• and
• an actuation member for travelling down the borehole of the casing when disposed in the wellbore to engage with the one or more geometrical profile locations, the actuation member comprising:
• a generally cylindrical hollow body extending between an uphole end and a downhole end, and having two proximate edge portions extending between the uphole end and the downhole end, the two edge portions being separate and movable relative to one another to facilitate resilient deformation of the hollow body, said deformation causing a reduction of cross-sectional area of the hollow body;
• and
• a plug seat configured to receive a plug for blocking the borehole,
• wherein an outer surface of the hollow body comprises one or more protrusions and/or grooves configured to matingly engage with the one or more geometric profile locations provided in the casing, said mating engagement facilitated by said deformation of the hollow body.