Abstract: The Cambrian-Ordovician carbonate rocks in the Gucheng area of Tadong are key exploration fields in the Tarim Basin. The paleogeographic pattern of "two platforms clamping one basin" determines the superior source-reservoir assemblage and hydrocarbon migration direction in the study area. However, in recent years, exploration activities have not achieved the expected results and the exploration potential of the area has again become the focus of attention. Based on a large number of cores, thin sections, CT scanning data, geochemical data, well logging, and seismic data, this paper examines the types and evolution processes of carbonate platforms in different geological periods of the Cambrian-Ordovician in the Tadong area, analyzes their controlling effects on sedimentary reservoirs, and evaluates the exploration potential of Cambrian-Ordovician carbonate rocks in the area. The results show that: Under the influence of tectonic movements and sea level change, the evolution characteristics of Cambrian-Ordovician platform types in the Gucheng area of Tadong is from ramp platform to rimmed platform to weak-rimmed platform to ramp platform to weak-rimmed open platform. This has resulted in the large-scale development of five sets of reservoirs: ramp microbial mound-shoal in the Cambrian subsalt Xiaoerbulake-Wusonggeer Formations, platform-margin mound-shoal in the Middle-Upper Cambrian, slope gravity flow in the Middle-Upper Cambrian and Middle-Lower Ordovician, ramp dolomitic shoal in the Lower Yingshan Formation, and grain limestone shoal in the Upper Yingshan-Yijianfang Formations. Based on the platform types, evolution processes, and favorable facies belts of reservoir, with prediction and evaluation of reservoir distribution as the core objective, it is indicated that ramp dolomitic shoal in the Lower Yingshan Formation and platform margin mound-shoal in the Middle-Upper Cambrian are the key exploration fields for reserves and production increase in the Tadong area in the near future. There are also three risk exploration fields worth exploring, which are the grain limestone shoal in the Upper Yingshan-Yijianfang Formations, the ramp microbial mound-shoal in the Cambrian subsalt Xiaoerbulake-Wusonggeer Formations, and the slope gravity flow in the Middle-Upper Cambrian and Middle-Lower Ordovician.

Key words: ramp microbial mound-shoal reservoir, mound-shoal reservoir in rimmed platform margin belt, ramp dolomitic shoal reservoir, weak-rimmed grain-limestone shoal reservoir, slope gravity flow reservoir, platform types, Cambrian-Ordovician, Tadong area, Tarim Basin