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塔里木盆地塔中地区的天然气碳同位素值与其他地区相比普遍偏低 ,用常规的气源对比方法难以确定其母质来源。选择苯、甲苯、甲基环己烷碳同位素作为有效的气源对比新指标 ,同时应用天然气生物标志物、天然气的δ13 C1—δ13 C4和实际地质资料进行气源综合对比 ,认为 :塔中主垒带上的天然气主要来源于寒武系—下奥陶统烃源岩 ,部分为中、上奥陶统与下奥陶统的混合气 ;塔中北斜坡的天然气主要来源于中、上奥陶统 ,部分来源于寒武系—下奥陶统烃源岩。对塔里木盆地相关气源岩进行热模拟实验 ,建立了Ro 与δ13 C1回归方程 ,应用该方程确定的塔中地区天然气成熟度为 :塔中主垒带上天然气的Ro 值约为 1 .4% ,塔中北斜坡的天然气Ro 值约为 1 .1 % ,烃源区均为塔中地区。图 3表 2参 4(李剑摘 )
Tazhong area of Tarim Basin natural gas carbon isotope values generally low compared with other regions, with conventional gas source contrast is difficult to determine the source of its parent material. The carbon isotopes of benzene, toluene and methylcyclohexane were selected as effective new indicators for gas source comparison. At the same time, the gas source δ13C1-δ13C4 was compared with the actual geological data by using biomarkers of natural gas and natural gas. It is concluded that: The natural gas on the base zone comes mainly from the Cambrian-Lower Ordovician source rocks, partly from the mixture of Middle and Upper Ordovician and Lower Ordovician. The natural gas from the northern and central slopes of Tarzan mainly comes from Middle and Upper Austria The Tao-tao, in part, comes from the Cambrian-Lower Ordovician source rocks. The thermal simulation experiments on the source rocks related to the Tarim Basin were carried out and the Ro and δ13C1 regression equations were established. The natural gas maturity in the Tazhong area determined by this equation is as follows: the Ro value of natural gas in the main base of the Tarim Basin is about 1.4% The Ro value of natural gas in the northern slope of Tazhong is about 1.1%, and all the hydrocarbon source areas are Tazhong area. Figure 3 Table 2 reference 4 (Li Jian picks)