Deltaic systems represent one of the major hydrocarbon reservoir types worldwide. However, limited studies of braided-meandering transitional deltas hinder accurate characterization of deltaic sedimentary systems and the efficient development of associated tight-gas reservoirs. Furthermore, this will influence tight-gas recovery during the late development stage of the gas field. To address this issue, this study focuses on the H8 member of the Guadalupian Shihezi Formation in the Su X block of the Sulige Gas Field, Ordos Basin, China. An integrated approach combining core observations, well-logging interpretation, seismic inversion, and dynamic data validation is employed to investigate the sedimentary evolution pattern of the braided-meandering transitional delta system. The main findings are as follows: 1) The delta plain is dominated by braided and meandering distributary channels, which are classified into braided channels (sinuosity index 1.3) according to channel sinuosity index. 2) As the base level rises, the braided distributary channels on the delta plain gradually transition to meandering distributary channels. 3) The sand bodies of braided distributary channels are characterized by a cut-and-fill pattern, containing gas-rich reservoirs with higher productivity than those in meandering channels. This study proposes a pattern in which the distributary channels on the delta plain undergo an overall transition from braided to meandering patterns with the local coexistence of both channels. The findings provide a robust theoretical basis for characterizing analogous river-dominated deltaic sedimentary systems and offer meaningful geological guidance for enhancing tight-gas recovery efficiency and optimizing reservoir development strategies in similar petroliferous basins worldwide. • Establishes a sedimentary model for braided–meandering transition and coexistence in delta plains. • Integrates drilling, 2D seismic, and production data with intelligent seismic inversion. • Identifies base-level variation as the primary driver of distributary-channel transformation. • Demonstrates that braided-channel reservoirs have higher gas content and productivity.
Li et al. (Wed,) studied this question.