Yuanba gas field lies in the weak deformation area with super-deep negative structure. The major carrier system is a 3D network complex that consists of porous-type dolomite reservoirs in Changxing formation and fractures (interbedded fracture, joint fissures and so on) , which is different from that in Puguang gas field. The multidirectional migration and near-source hydrocarbon accumulation are the favorable conditons of the carrier system. It can help the gas generated from the underlying Wujiaping Formation and lateral Dalong Formation to realize vertical and lateral hydrocarbon migration. The oil and gas accumulation zones are mainly controlled by the height and density of fractures and the distribution ranges and scales of high quality dolomite reservoirs that are characteristic of reef and shoal facies in the Changxing Formation.