The invention relates to the technical field of threaded connection of oil casings, in particular to a basically flush type
coupling-free air-tight seal oil casing joint
assembly which comprises an external thread joint and an internal thread joint, and after the external thread joint and the internal thread joint are screwed together, the external thread joint and the internal thread joint are screwed together. An outer
metal sealing structure, an outer elastic sealing structure, meshing threads, an inner elastic sealing structure, an inner
metal sealing structure, a torque shoulder and the like are sequentially formed. Through the cooperation of the external thread connector, the internal thread connector, the external
metal sealing structure, the external elastic sealing structure, the meshing thread and the internal metal sealing structure, the connecting and sealing functions are provided, the connector is basically flush with the
pipe body, the oil casing can enter a well easily, the well cementation gap is large, and the connector connecting efficiency can reach 65%-70%; and 2) the inner and outer seals are both metal / metal seal and elastic seal, and the double-seal structure greatly improves the sealing effect, and is suitable for ultra-deep wells and high-pressure
natural gas wells with harsh conditions.