松辽盆地南部长岭地区青山口组原油的地球化学特征及油源分析

松辽盆地南部长岭地区中、新生界地层中有登娄库组、营城—火石岭组、青山口组、嫩江组 4套主要烃源层 ,目前已在长岭地区北部及东部地区的青山口组中发现了工业性的油气层或含油气显示。分析了主要烃源层的分布特征和地球化学条件 ,并系统地剖析了青山口组原油的地球化学特征。结果表明 ,青山口组存在两类地球化学特征不同的原油 (Ⅰ类、Ⅱ类 ) ,其中Ⅰ类原油主要分布在大情字井的青二段—青三段的中部 ,Ⅱ类原油主要分布在大情字井的青二段—青三段的上部及大老爷府—双坨子构造中。通过油源对比分析表明 ,Ⅰ类原油主要来源于青山口组的中部 (青二段、青三段 ) ,并与储层互层的烃源岩。Ⅱ类原油与青山口组下部的青一段烃源岩有很好的对应关系 ,推测其油源主要为这套烃源岩 ,其次可能是下白垩统烃源岩 ,嫩江组烃源岩的贡献不大。

GEOCHEMICAL CHARACTERISTICS AND SOURCE ANALYSIS OF OILS FROM THE QINGSHANKOU GROUP IN THE CHANGLING REGION,THE SONGLIAO BASIN

There are four series of source rocks, including the Nen jiang Group, Qingshankou Group, Denglouku Group and Yingcheng-Huoshiling Group of the Cretaceous, in the Changling region, the Songliao Basin. Hydrocarbon rese rvoir or oil and gas shows have been found in the east and north parts of the Ch angling region. In this paper, the organic geochemical characteristics of the so urce rocks mentioned above have been studied in detail. The geochemical characte ristics of the crude oil samples collected from the Qingshankou Group have been investigated. It is shown that there are two types of the crude oils (type Ⅰ and type Ⅱ) in the Qingshankou Group, which have di fferent compositional characteristics. The type Ⅰ oil occurs in the middle of the K_2qn 2-3 section in the Daqingzijing structure, and the type Ⅱ oil at the top of the K_2qn 2-3 section in the Daqingzijing , Dalaoyefu and Shuangtuozi structures. The correla tion between oils and source rocks reveals that the type Ⅰ oil i s mainly derived from the source rocks in the middle of K_2qn (K_2qn 2-3 section), and the type Ⅱ oil mainly from the source rock s in the bottom of K_2qn (K_2qn1 section).