The invention relates to a device which enables two
petroleum casing pipes with different diameters to be hanged and connected by expanding the casing pipes underground, and a construction technology.The device comprises a drilling string, an expansion
pipe hanging body, a length-adjusting scroll cover set, an expansion transmitting room and a
tail pipe connection pair and is characterized in that the drilling string consists of an adjusting-centering
pipe nipple, a transition
drill pipe, a push-pull central pipe and a bearing
screw cap; the expansion pipe hanging body consists of a casing pipe, a hanging pipe, a hanging projection and a hanging
rubber ring; the length-adjusting scroll cover set consists of a length-adjusting scroll cover and a clamping nut; the expansion transmitting room consists of a pull cap, a propelling
piston, an expansion head, an upper expansion pipe cavity body, a lower expansion pipe cavity body, a
steel ball, a transmitting seat, an O-shaped seal rig and acirclip for a hole; and the
tail pipe connection pair consists of a lower expansion pipe, a
tail pipe connection hoop and tail pipes. The invention has the advantages that hanging
modes of hydraulicpush,
lubrication expansion head and hard and soft combination are adopted, thereby having reliable tightness and strong hanging capability; and circulation of
drilling fluid, injection of
cement paste and hanging connection can be completed in one construction, and thereby convenient operation is achieved.