松辽盆地朝长地区原油的成熟度普遍较低，大多数原油仍保留正烷烃奇偶优势，这主要与半咸水咸水环境中藻类母质生源输入有关。长２０井的原油既具有正烷烃奇偶优势，又具有较低甾萜烷异构体比值，属于典型的低熟原油。从长２０井低熟原油中检测到了一定量的２８，３０二降藿烷，这说明源岩形成于极度厌氧的环境。此外，在原油中还发现了藿１７（２１）烯系列，这进一步揭示了原油的低熟性。其它原油虽具有正构烷烃的奇偶优势，但甾萜烷参数均比较高，可能为低熟油与成熟油的混合作用所致。 The maturity of the crude oil in the North Face of the Songliao Basin is generally low, most of the crude oil still retains the odd-even advantage of n-alkanes, which is mainly related to the input of algae parent biomass in brackish water. The crude oil from Well Chang20 shows both the odd-even advantage of n-alkane and the lower ratio of isoprostane-isomer, belonging to the typical low-mature crude oil. A certain amount of 28, 30 butanediol was detected from the low-mature well of Well Chang 20, indicating that the source rock formed in an extremely anaerobic environment. In addition, the series of hopaxes (17) have also been found in crude oils, further revealing the low ripeness of crude oils. Although other crude oil has the odd-even advantage of n-paraffins, but the parameters of sterol-terpanes are relatively high, which may be due to the mixing effect of low-mature oil and mature oil.