济阳坳陷孤西断裂带深层天然气成因类型

Genetic Types of Deep Natural Gas in Guxi Fault Zone in Jiyang Depression

针对孤西断裂带深层天然气来源多、成因复杂的问题,以烃源岩特征分析为基础,利用天然气三元地球化学示踪体系,还考虑了伴生油生物标志物特征等,并结合成藏地质条件的分析,深入剖析了该区天然气的地球化学特征和成因类型。认为孤西断裂带深层天然气呈规律性变化,自西往东由油型气逐渐过渡到煤成气:其中渤深6潜山天然气由源自渤南洼陷Es4上高熟油型气和Es3下油型伴生气混合而成;渤古4潜山以Es4上生成的高成熟油型气为主,混有源自C-P的煤成气;孤北潜山第二排山天然气由煤成气和油型气混合而成;第三和第四排山则主要为C-P来源的煤成气。

The deep natural gas in Guxi fault zone is of the characteristics such as multisource and complex genesis. In view of this problem, based on the analysis of source rocks characteristics, the ternary geochemical-tracing system of natural gas and biomarkers of associated oil were used in order to clarify the geochemical characteristics and genesis of natural gas in the area, combining with analysis on geologic condition of gas pools. It is proposed that the natural gas in Guxi fault zone shows certain regularities and shifts from oil-typed gas to coal-type gas from west to east. Gas in Boshen 6 buried hill is the mixture of high-matured oil-type gas from upper Es4 source rocks in Bonan subsag and oil- associated gas from lower Es3 source rocks. Natural gas from Bogu 4 buried hill mainly consists of high-matured oil- type gas sourced by upper Es4 source rocks, mixed with coal-typed gas. Gas in the second row of Gubei buried hill is the mixture of coal-type and oil-type gas, and natural gas from the third and forth rows is mainly composed of coaltype gas generated by the upper Paleozoic source rocks.