二连盆地阿尔凹陷下白垩统烃源岩地球化学特征及油源对比  

Geochemical characteristics and source rocks and oil-source correlation of the Lower Cretaceous in Aer Sag, Erlian Basin

作　　者：卢学军 高平[2,3] 丁修建[2,3] 陈哲龙 柳广弟[2,3] 

机构地区：[1]中国石油华北油田分公司勘探开发研究院,河北任丘062552 [2]中国石油大学(北京)地球科学学院,北京102249 [3]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249

出　　处：《岩性油气藏》2014年第3期101-108,共8页Lithologic Reservoirs

摘　　要：阿尔凹陷是二连盆地的一个次级构造单元,勘探程度较低。下白垩统为二连盆地的主力烃源岩和产油层,在阿尔凹陷广泛发育。有机地球化学分析表明,阿尔凹陷下白垩统烃源岩有机质丰度高,以Ⅰ—Ⅱ型为主,低成熟—成熟,已进入大量生烃阶段,其中腾一段烃源岩生烃能力最强,阿四段烃源岩生烃能力稍差;下白垩统烃源岩主要为淡水—微咸水环境,腾一段为偏强还原—弱氧化环境,阿四段为偏弱氧化环境;烃源岩常规甾烷分布特征为C29>C27>C28,表明其具有以藻类输入为主、陆源有机质输入为辅的生源特征,而腾一段生源输入的差异可能与湖侵及湖退引起的水体深度变化有关。下白垩统油砂和烃源岩样品的生物标志化合物特征对比表明,腾一段原油来源于腾一段烃源岩,阿尔善组原油可能主要来源于腾一段烃源岩,混有阿四段的油源。Aer Sag is one of the sub-structural units in Erlian Basin, with a lower exploration degree. The Lower Creta- ceous is proved the major source rocks and oil-producing intervals in Erlian Basin, which is also widely developed in Aer Sag. The organic geochemical analysis indicates that the Lower Cretaceous source rocks in Aer Sag possess high contents of organic matter, its organic matter type is mainly type Ⅰ and type Ⅱ, and its source rock maturity ranges from low-mature to mature indicating the phase of large amounts of hydrocarbon generating. Among them, the first member of Tenger Formation （K1 bt^1） has the greatest potential of hydrocarbon generation, and followed by the fourth member of Aershan Formation （K1bt^4）. The Lower Cretaceous source rocks were mainly deposited in the freshwater to brackish water environment. The redox of K1bt^1 preferred to a strongly reducing-weakly oxidizing environment, but K1bt^4 tended to a weakly oxidizing environment. The distribution characteristics of regular steranes of the Lower Cretaceous source rocks is ＂C29〉 C27〉 C28＂. It is shown that the biogenic sources are dominated by algae input, secondly by terrestrial input. In addition, the correlation of biomarker characteristics of oil sands and source rocks from the Lower Cretaceous suggest that K1bt^1 oil originated from K1bt^1 itself, but Aershan Formation oil might come from K1bt^1 and mixed with the oil from K1b^4 source rocks.

关 键 词：地球化学特征 生物标志物 油源对比 下白垩统 二连盆地 

分 类 号：TE122.113[石油与天然气工程—油气勘探]