Fluid filled drill pipe plug

A wiper plug for downhole use is disclosed. It features an inflatable structure that allows it to ride inside tubulars that change or gradually vary in inside diameter. In a preferred embodiment the bladder is actuated by fluid displaced by a biased piston. The piston is capable of moving in opposite directions to allow original insertion into a launcher and subsequent bladder expansion. In another embodiment, the piston can be fluid driven in opposed directions by a pump and an on board control system which can regulate, on a real time basis, the contact pressure of the bladder to a predetermined level or range, as the bladder encounters varying interior wall diameters of the tubular string or associated equipment.