Based on 115 wells logging data statistics and processing,distribution characteristics of dark mudstone of Chang 9 was studied.Mudstone of Chang 91 thickness and distributed area are greater than Chang 92 in the study area,distribution of mudstone thickness is in an average of 6 to 40 m,up to 70 m;Thicker mudstone areas are in Gucheng-Taerwan and Qingyang- Maling;According to mudstone thickness and average organic carbon content in the study area,the distribution of hydrocarbon source rock of Chang 9 in the...