Assessment of the source rocks from the Dongying Formation in the Liaozhong depression, Liaodong Bay

The present paper deals with the organic geochemical analysis and assessment of the source rocks from the lower submember of the 2nd member of the Dongying Formation (Ed^2-1) and the 3rd member of the Dongying Formation (Ed³) in the Liaozhong depression, Liaodong Bay, with the emphasis on organic matter abundance, type and maturity based on the organic geochemical parameters such as total organic carbon (TOC), hydrocarbon potential (S₁ + S₂), hydrogen index (I_H), hydrogen/carbon ratios (H/C), oxygen/carbon ratios (O/C), maximum temperatures of thermolysis (T_max) and vitrinite reflectance (Ro). The analytical results indicate that the source rocks from the lower submember of the 2nd member of the Dongying Formation (Ed^2-1) display 0 to 3 mg/g for S₁ + S₂, 0% to 1.5% for TOC, Ro < 0.5% and III to II₂ types of organic matter, indicating immature or poor source rocks. The source rocks from the 3rd member of the Dongying Formation (Ed³) display 4 to 9 mg/g for S₁ + S₂, 1% to 1.25% for TOC, Ro < 0.5 and II₁ to II₂ types of organic matter, indicating mature or better source rocks.