In order to explore the characteristics of rich accumulation and the exploration potential of transitional shale gas

the lower Carboniferous shale in southern Guizhou is taken as the research object. Based on the data of two investigation wells and two exploration wells

the analysis is conducted from the aspects of stratigraphic sequence and sedimentary facies

occurrence characteristics of shale

accumulation conditions and favorable area evaluation. The research result shows that: ① The lower Carboniferous shale deposits in western Guizhou are controlled by the NW-SE Shuicheng-Ziyun synsedimentary fault and the Shuicheng-Liuzhi uplift partition

which can be divid

ed into weining shuicheng tidal flat lagoon-transition sedimentary facies and Shuicheng-Ziyun shallow-water shelf marine sedimentary facies

forming Weining and Ziyun depositional central areas with deposition thickness ranging from 30 m to 200 m. The sedimentary thickness of Weining-Shuicheng is 119 m

and the embedded depth of floor is between 1 500 m and 3 000 m

which is a favorable area for exploration. ② Influenced by multi-stage structure and controlled by syndeposition

the gas accumulation type controlled by the combination of folds and faults is relatively developed in this area

which is a typical gas accumulation mode controlled by the structure of anticlinal combination blocked by reverse fault. ③ On the plane

the accumulation zone of Weishui anticline and Shuicheng-Ziyun fault structure is a favorable exploration area for shale gas research in Weining-Shuicheng

the sedimentary center of Jiusi Formation

with an area of about 944 km

2

. There are at least three sets of organic-rich shale gas bearing beds vertically in the shale

which have good exploration potential