Abstract: The Shaximiao Formation is currently a key target for exploration and development of continental tight oil and gas in the Sichuan Basin,and the main gas-bearing series is the channel sand bodies of J₂s¹₂.However,the research on the coupling relationship between the channel sand bodies and palaeogeomorphology is scarce,which restricts further fine exploration and development of tight gas.To address this issue,based on the establishment of an isochronous framework in the central Sichuan Area and employing the principle of sedimentary compensation,the paleogeomorphology of the J₂s¹₂ was semi-quantitatively restored using the impression method while fully considering the differential compaction of strata.An integrated analysis of core,well logging,and seismic data was conducted on the J₂s¹₂ section of the sedimentary system,which then serves as the basis for analyzing the coupling relationships between various ancient landform units and sedimentary microfacies.The seismic multi-attribute integration method was utilized to predict the thickness of the sand bodies,proposing that palaeogeomorphology controls the distribution of channel sand bodies and the preferential pathways for sediment transport,namely "the valley transporting sand,interfluvial hill separating sand,and gentle slope stopping the sand".Research results indicate that J₂s¹₂ in the central Sichuan Area features ancient landform pattern of alternating valleys and hills,with higher elevations in the westsouth and lower elevations in the eastnorth,and an overall gentle slope.The area primarily consists of major river valleys,tributary valleys, interfluves,and gentle slopes.The main morphological units developed include primary valleys,tributary valleys,interfluvial hills,and gentle slopes.The J₂s¹₂ section in the study area features a continental river sedimentary system,with channel sand bodies distributed in a banded pattern.The ancient landform units of the J₂s¹₂ section control the distribution of sedimentary microfacies,with channel deposits concentrated in the valleys and floodplain deposits more frequently occurring on the gentle slopes. This research provides valuable insights for the subsequent exploration of tight gas.

Key words: palaeogeomorphology, channel sand body, impression method, sedimentary system, sand control mechanism, Shaximiao Formation, Sichuan Basin