梨树断陷主力烃源岩判定及其地球化学特征

Identification of chief hydrocarbon source rocks in Lishu Fault Depression and their geochemical characteristics

通过对梨树断陷4套潜在烃源岩生烃潜力特征分析,确定了沙河子组为其主力烃源层,其次为营城组,火石岭组和登娄库组仅在局部地区发育有效烃源岩。采用20余项变量对梨树断陷有机碳含量大于0.5%的烃源岩进行聚类分析,结果表明梨树断陷有效烃源岩可以划分为4类,4类烃源岩的沉积环境、生烃潜力、母质来源及成熟度方面均存在一定的差异,以C类和D类源岩生烃潜力最高,与原油的可比性较好。从平面分布来看,C类源岩主要分布在四五家子、皮家及桑树台深洼深湖相沉积区域;A、B、D类源岩主要分布在苏家屯、双龙次洼及盆地边缘太平庄、七棵树、秦家屯等地区浅湖—半深湖及三角洲平原上的沼泽相沉积区域。

Based on the hydrocarbon generation potential of 4 sets of source rocks developed in the Lishu Fault Depression, the results illustrated that the chief hydrocarbon source layer is K^sh and the secondary layer is Klyc; meanwhile, the effective source rocks of K1 h and K1 d formations only developed in some certain areas. We made a cluster analysis to source rock samples （TOC〉0.5%） based on more than 20 variables, and the results have shown that the source rock samples can be divided into 4 types and the geochemical characteristics of 4 types of source rocks are different in many respects, such as sedimentary environment, hydrocarbon generation potential, origin of organic matters and maturity stages. Type C and D source rocks have the highest hydrocarbon generation potential and they have good comparability with crude oils. Taking into account the plane distribution of source rocks, type C source rocks mainly distribute in Siwujiazi, Pijia and Sangshutai deep depressions with deep lake facies. Meanwhile, type A, B and D source rocks mainly distribute in Sujiatun sag, Shuanglong sag and Taipingzhuang, Qikeshu, Qinjiatun areas along the basin margins with shallow lake facies, semi-deep lake facies and swamp subfacies within delta plain sedimentary environment.