Oil and gas casing test tool

The invention provides an oil and gas casing test tool. The test tool comprises an upper transition plate mounted on the upper flange surface of an oil-gas casing flange and a lower transition plate mounted on the lower flange surface of the oil-gas casing flange, the upper transition plate is connected with a flange of a hollow composite insulator; the top end of the hollow composite insulator isconnected with an upper cover; a section of circular tube extends into the hollow composite insulator from the inside of the upper cover, a circular tube contact finger is arranged on the inner wallof the circular tube, an aluminum tube is installed in the circular tube and is in equipotential contact with the circular tube through the circular tube contact finger, and the circular tube extendsdownwards to the gas end of the oil-gas casing and is in equipotential contact with the gas end of the oil-gas casing. The bottom of the lower transition plate is connected with an oil storage device,the bottom of the oil stora