Fig.1

Map showing structures and study area location and the stratigraphic column of the Upper Paleozoic strata in the Hangjinqi area， northern Ordos Basin （after reference ［31］）"

Fig.2

Single-well （high-frequency） sequences and sedimentary facies of the Lower Shihezi Formation in the Jin-77 well block within the Dongsheng gas field， Hangjinqi area， northern Ordos Basin"

Fig.3

Synthetic seismograms of well Jin-77 in the Dongsheng gas field， Hangjinqi area， northern Ordos Basin"

Fig.4

Core， logging， and seismic response characteristics and division of the Upper Paleozoic sequence boundaries in the Jin-77 well block and its adjacent area in the Dongsheng gas field， Hangjinqi area， northern Ordos Basin"

Fig.5

Sequence correlation cross-section with well-to-seismic calibration crossing wells J77P5-Jin6-Jin75-Jin77-Jin122 in the Dongsheng gas field， Hangjinqi area， northern Ordos Basin （see Fig. 1 for the location of section AB）"

Fig.6

Core and logging curve characteristics for the identification of high-frequency sequence boundaries in well Jin-77 in the Dongsheng gas field， Hangjinqi area， northern Ordos Basin"

Fig.7

Cross-well correlation of （high-frequency） sequences in the Lower Shihezi Formation， Dongsheng gas field， Hangjinqi area， northern Ordos Basin （see Fig. 1b for the location of section）"

Fig.8

Pictures showing the lithofacies characteristics of the He 1 Member in the Jin-77 well block within the Dongsheng gas field， Hangjinqi area， northern Ordos Basin"

Fig. 9

Logging curve patterns and seismic response characteristics reflecting the sedimentary microfacies of the He 1 Member in the Jin-77 well block within the Dongsheng gas field， Hangjinqi area， northern Ordos Basin"

Fig.10

Correlation of cross-well seismic section （a） and sedimentary microfacies （b） for the He 1 Member in the Dongsheng gas field， Hangjinqi area， northern Ordos Basin （see Fig. 1 for the location of section CD）"

Fig. 11

Forward modeling results of the geological model of varying sand-body thicknesses （a） and the relationship between sand body thickness and the maximum trough amplitude （b） for the He 1 Member in the Dongsheng gas field， Hangjinqi area， northern Ordos Basin"

Fig.12

Forward modeling results of the geological model of varying sedimentary microfacies （a） and the relationship between sedimentary microfacies and the maximum trough amplitude （b） for the He 1 Member in the Dongsheng gas field， Hangjinqi area， northern Ordos Basin"

Fig.13

Characteristic comparison between and stratal slicing setting for zero-phase （a） and converted 90°-phase （b） seismic sections crossing wells from Jin-701 to Jin 76 in the Dongsheng gas field， Hangjinqi area， northern Ordos Basin （see Fig. 1 for the location of section C—D）"

Fig.14

Planar distributions of the seismic attributes （a） and sedimentary microfacies （b） of the H1-2 sublayer and the attributes of H1-1 （c） and H1-3 （d） sublayers in the Dongsheng gas field， Hangjinqi area， northern Ordos Basin"