Abstract: In order to further explore the exploration potential of the nearly 4 000.0 km² exploration blank area in central platform of Mahu Sag, expand the exploration potential of Baikouquan Formation in Mahu Sag, and realize the breakthrough of Mahu Sag as a whole, the stratigraphic delineation of Baikouquan Formation in Mahu Sag has been refined by the comprehensive use of geological data, drilling data, and high-density seismic data. The sand bodies of the lowstand system tract in central platformof Mahu Sag have been defined as Baikouquan Formation 0 Member (T₁b₀). On this basis, combined with the regional sedimentary and tectonic backgrounds, the hydrocarbon accumulation conditions and controlling factors of the lowstand system tract T₁b₀ in Mazhong plateau area were analyzed in terms of the hydrocarbon source rock conditions, migration system, and depositional system. The study shows that the hydrocarbon source rocks of the Permian Fengcheng Formation have the bimodal characteristics of oil generation in an alkali lake conditions, the hydrocarbon potential is large, and T₁b₀ is closer to the source and more accessible to capture the deep oil and gas. The strike-slip faults in central platform of Mahu Sag directly inserted into the deep hydrocarbon source rocks during the Indo-Chinese epoch and formed an efficient migration system; the top and bottom plates of T₁b₀ have superior conditions, and T₁b₀ is superimposed on a large stratigraphical superposed background and develops multiphase lake invasion and retreating sand bodies, which form a large scale and effective reservoir-caprock association. T₁b₀ develops four large-scale fan bodies, and the tight zones, mudstones between fans, and tectonics of the fan delta plain subfacies are configured with each other to form a composite multi-faceted barrier, which lays the foundation for the large-scale formation of reservoirs in the front edge of the fan delta. The analogous study concluded that the subfacies of the leading edge of the central abduction fan has good upward-dipping and lateral barrier conditions and has a macro-integrated basis for the formation of reservoirs. The lithological target is superimposed and developed with a high degree of implementation, and it is the key exploration target for seeking breakthrough of the new stratigraphic system in T₁b₀ at present. The breakthrough of T₁b₀ is expected to open up the exploration situation in central platform of Mahu Sag, thus realizing the overall breakthrough of Baikouquan Formation in Mahu Sag.

Key words: fan-controlled large-scale accumulation, lowstand system tract, exploration potential analysis, Baikouquan Formation, central platform of Mahu Sag, Mahu Sag