Geological Characteristics Analysis of the Taiyuan Limestone Gas Reservoir in Zizhou-Qingjian Area, Ordos Basin

In Zizhou-Qingjian area, Ordos Basin, the Taiyuan limestone of Early Permian has good exploration prospects. The breakthrough of well A*1H has heighten confidence in limestone reservoir exploration. Geological conditions of the reservoir are complex, and the analyzing of geological characteristics based on existing data is of great significance for further exploration and development. In study area, the reservoir geological characteristics such as hydrocarbon supply, reservoirs development, principal stress, micro structure, mudstone sealing conditions were studied. The results showed that: ① With the characteristics of wide coverage and high hydrocarbon-generating intensity, the research area had sufficient hydrocarbon supply; ② The high areas of ancient landforms were subjected to atmospheric fresh water leaching which promoted the development of high-quality reservoirs; ③ The maximum principal stress is negatively correlated with gas production, productive wells are mainly distributed in 39.5–41.5 MPa of maximum principal stress; ④ Micro structures are the key factors for natural gas enrichment, high-yield wells are distributed in the high parts of the nose structure; ⑤ The effective sealing of the overlying mudstone is essential for preservation of the gas reservoir. In general, ancient landforms, principal stress, effective sealing are key geological factors for reservoir formation. Based the above research exploration target over 1000 km2 were notably provided.