珠江口盆地陆相原油轻烃环优势及其成因

珠江口盆地淡水中深湖相烃源岩所生成原油的轻烃中三环优势（3PR）大于五环优势（5PR）和六环优势（6PR）,而其煤系烃源岩所生成原油的轻烃中三环优势（3PR）较小,五环和六环优势（5PR+6RP）较大;淡水中深湖相烃源岩中过渡金属及其配位体结构有利于速率常数k^3_,Ⅰ型和Ⅱ₁型干酪根有利于形成三环优势（3PR）,生成的原油C₇轻烃中链烷烃含量较高,而煤系烃源岩中过渡金属及其配位体结构有利于速率常数k⁵+k^6_,Ⅱ₂型和Ⅲ型干酪根有利于形成五环和六环优势（5PR+6RP）,生成的原油C₇轻烃中环烷烃和芳烃含量较高。

Origin of Ring Preference of Light Hydrocarbons in Continental Petroleum, Pearl River Mouth Basin

Based on the data of the 28 continental oils in Pearl River Mouth Basin, the three-ring preference (3RP) is greater than 5RP and 6RP in LHs from fresh water lacustrine facies source rocks. The three-ring preference (3RP) is less than 5RP and 6RP in LHs from coal-measures source rocks. The transition metals and their structures of the surrounding ligands in fresh water lacustrine facies source rocks are favor to k3(velocity constant).Kerogen Ⅰand Ⅱ₁ are favorable to forming the 3RP, higher content of C₇-isoalkanes exist in the LHs. The transition metals and their structures of  the surrounding ligands in coal-measures source rock are favor to k⁵ and k⁶,kerogenⅡ₂ and III are likely to form 5RP and 6RP,LHs contain high amount of C₇-cycloalkanes and toluene.