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济阳坳陷孤南洼陷低熟油的地质储量可达数千万吨，类似的由沙一段和沙四段烃源岩形成的低熟油在渤海湾盆地普遍可见。以孤南洼陷为例，讨论了低熟油勘探中的有关问题。明确提出判别低熟原油的指标是其Ｃ２９甾烷的异构化系数（其值０．３０～０．３５可作为上限值），ＯＥＰ及Ｐｒ／ｎＣ１７和Ｐｒ／ｎＣ１８可作为辅助指标。低熟原油可以是中等密度的高蜡油，其组分特征是高饱芳比和高非沥比。孤南洼陷生成低熟油的沙一段烃源岩为富含藻类有机质的油页岩，形成于半咸水—咸水、强还原的沉积环境。孤南洼陷低熟油形成阶段的Ｒｏ值上限为０．４０％～０．４５％，相应的深度为２３００～２５００ｍ；Ｒｏ值下限为０．６０％～０．６５％，相应的深度为３０００～３２００ｍ。咸水环境由富含藻类的有机质早期生烃，可能是最主要的低熟油形成机制。图２表４参８（邓春萍摘）
Geological reserves of low-mature oil in Gunnan depression in Jiyang depression can reach tens of millions of tons. Similar low-mature oil formed from source rocks of Sha-1 and Sha 4 Member is generally visible in Bohai Bay basin. Taking Lunnan depression as an example, the related problems in low-mature oil exploration are discussed. Clearly put forward to judge low-maturity crude oil is the index of its C29 sterane isomerization (the value of 0.30 to 0.35 can be used as the upper limit), OEP and Pr / nC17 and Pr / nC18 can be used as a secondary indicator. Low-maturity crude oil may be a medium-density, high-wax oil whose component characteristics are high satiety ratios and high non-leaching ratios. The source rocks of the first member of Shahejie Formation of low-mature oil in Gunnan sag are oil shale rich in algae organic matter and are formed in the sedimentary environment of brackish water-salt water and strong reduction. The upper limit of Ro value during low-mature oil formation in Gunnan sag is 0.40% -0.45%, the corresponding depth is 2300-2500m, the lower Ro value is 0.60% -0.65%, and the corresponding depth is 3000 ~ 3200m. Salt water environment by the algae-rich organic matter early hydrocarbon generation, may be the most important low-maturing oil formation mechanism. Figure 2 Table 4 Reference 8 (Deng Chunping pick)