The Beschkent Depression in the Amu Darya Right Bank Block of Turkmenistan has a special depositional environment of low-energy deepwater gentle slopes where the geological understanding has been so little known currently that natural gas exploration there is quite difficult. In order to speed up the natural gas exploration in the Beschkent Depression, this paper analyzed the depositional characteristics of Callovian and Oxfordian of Middle–Upper Jurassic and the basal palaeogeomorphology. Then, from the perspective of geophysics, the characteristic investigation and seismic identification of reef beach in the depositional environment of low-energy deepwater slopes were carried out by means of reef-beach body thickness identification, discontinuous seismic attribution extraction and forward modeling based on wave equation, and accordingly the distribution of reef beach was confirmed. Finally, an integrated seismic and geologic identification method suitable for the Beschkent Depression was developed. And the following research results were obtained. First, in the Beschkent Depression, the rock types of Callovian–Oxfordian stage are mainly micrite grainstone, grain micrite and micrite. The depositional environment is mainly middle-outward gentle slope facies in the Callovian stage, and upper-lower slope facies in the Oxfordian stage, presenting obvious depositional characteristics of low-energy gentle slope. Second, three sub-palaeouplifts are developed in the basal palaeogeomorphology of the Beschkent Depression and the palaeogeomorphologic characteristics of being high in the northwest and low in the southeast are presented, which lays a geomorphologic foundation for the development of reef beach in the later stage. Third, based on 3D seismic data, 68 reef-beach bodies larger than 1 km2 are identified in the study area, with a total area of 187.3 km2. The northern and central-southern parts of the Beschkent Depression are the favorable zones for the development of reef beach. Fourth, it is revealed from the integrated geologic and seismic interpretation that Well block G22 and T21 in the northern part of Beschkent Depression and Well block B21–H21 in the central-southern part and its periphery zone are favorable zones. Two wells deployed and drilled in the favorable zones produce high-yield gas flow. In conclusion, this proposed integrated seismic and geologic identification method for subsalt small-scale reef beach in the depositional environment of deepwater gentle slope presents remarkable application effects. It promotes the significant breakthrough in the exploration of carbonate gas reservoirs in the Beschkent Depression and also provides some reference for the exploration of similar gas reservoirs.