Wellbore casing scraper

A controllable downhole scraper comprising:

• a fluid reservoir having a pressure wall positioned and movable within the fluid reservoir to define a first portion of the fluid reservoir that includes a first fluid, the pressure wall exerting a force on the first fluid to maintain a first pressure;
• a scraper blade movable between a retracted position and an extended position;
• a sleeve positioned on a tubular and slidable between a first position and a second position, the sleeve in the first position engaging the scraper blade to move the scraper blade into the retracted position, the sleeve in the second position engaging the scraper blade to move the scraper blade into the extended position, wherein the sleeve is configured to move between the retracted position and the extended position through a reduction in the first pressure of the first fluid;
• a restrictor fluidly coupled between the fluid reservoir and a pressure reservoir;
• and
• a gas reservoir selectively operable to reduce the first pressure of the first fluid.