The invention provides a variable-
diameter casing scraper. The variable-
diameter casing scraper is characterized in that an
upper joint and a lower joint are arranged at two ends of a mandrel, and a
pressure transmission hole is formed in the mandrel. The end, close to the
upper joint, of the mandrel is sleeved with a guide cylinder, the guide cylinder is sleeved with a plate spring, and the middle of the plate spring is sleeved with a scraping knife. One end of the plate spring is connected with the
upper joint, and the other end of the plate spring is connected with a push cylinder. The push cylinder is connected with a
piston, the
piston and the mandrel are pre-fixed, and a
hydraulic cylinder sleeve is arranged on the
piston in a sleeving mode and located at the position close to the
pressure transmission hole. The guide cylinder has a certain
radian so as to guide the plate spring and the scraping knife to radially expand, and the plate spring is of an arch structure with the certain
radian so as to drive the scraping knife to radially expand. According to the variable-
diameter casing scraper, scraping of a combined casing of a technical casing and a
tail pipe can be completed by adopting a scraping
pipe column, and the purposes of shortening the scraping operation period, reducing the operation cost and improving the operation efficiency can be achieved on the premise of ensuring the safety of the scraping operation.