潍北凹陷孔店组天然气成因类型及分布规律

根据天然气组分以及碳同位素和轻烃特征等资料,运用天然气成因理论并结合天然气成因类型判识图版和成藏条件,探讨了潍北凹陷孔店组天然气成因类型及分布规律。结果表明:潍北凹陷天然气CH₄体积分数大,重烃体积分数小,非烃组分极少;南部斜坡带的疃4井天然气属生物气;灶户鼻状构造带南部产出的天然气为混有生物气的油型伴生气;灶户鼻状构造带中部地区属典型的油型伴生气;北部洼陷区的东部和南缘产出的天然气具有煤型气,并有油型气混入;以昌1井为代表的北部深洼陷区是煤型气发育的有利地区。总之,潍北凹陷天然气可以划分为生物气、混有生物气的油型伴生气、典型的油型伴生气、混有油型气的煤型气、典型的煤型气等5种成因类型;孔店组天然气类型多样、分布复杂,这些与该区的烃源岩类型、成熟度等因素有关。

Genetic Type and Distribution Rule of Natural Gas of Kongdian Formation in Weibei Sag

Based on natural gas composition, carbon isotope and light hydrocarbon data, genetic type and distribution rule of natural gas of Kongdian Formation in Weibei Sag were discussed with the theory and discriminant diagram of natural gas genetic type and reservoir condition. The results showed that volume contents of CH₄, heavy hydrocarbon and nonhydrocarbon were high, low and extremely low for natural gas in Weibei Sag, respectively; natural gas from well Tuan-4 in southern clinoform zone was biogas; natural gas in the southern of Duhu nose tectonic zone was oil type associated gas with biogas; natural gas in the middle of Duhu nose tectonic zone was typical oil type associated gas; natural gas in southern rim and eastern of northern subsag was coal type gas with oil type gas; northern deep subsag was the prospecting area for coal type gas. In general, natural gas in Weibei Sag could be divided into five genetic types, which were biogas, oil type associated gas with biogas, typical oil type associated gas, coal type gas with oil type gas, typical coal type gas; types of natural gas in Kongdian Formation were numerous, distribution was complex, the reasons could be related to hydrocarbon source rock and maturation.