Significance of the Isotopic Composition of He and Ar in Natural Gases

To identify the oil-gas source rocks is very important for the prospection of oil and gas, and it is a key method to detect the isotopic composition of He and Ar in natural gases for retracing source rocks. The detection of Ar isotopic composition was started in 1973 by Gavrigov et al., then the time-accumulating effect of radiogenic Ar was recognized by Chinese researchers after the discovery of the fact that the content of radiogenic Ar (i. e. 40Ar) increases with the increase of the age of source rocks, and the formula to estimate the age of source rocks was established with the consideration of the K

烃源岩测井识别在渤海湾石油开发中的应用

研究沉积盆地油气总量及分布规律,有必要首先了解烃源岩的分布。受取心样品数量的限制,一般不可能获得整段连续烃源岩有机碳的实验室测定值,常采用间隔一定距离的有机碳含量测定值的几何平均值,无法反映生油岩的全貌。为获取单井连续有机碳含量,准确确定烃源岩厚度,有必要开展测井烃源岩评价研究。渤海沙河街组地层具有高伽马、高孔隙度、高电阻率等典型烃源岩测井响应特征,可通过测井曲线特征定性识别烃源岩。建立测井信息与烃源岩有机碳含量间的定量关系模型,计算出烃源岩有机碳含量的连续分布。对不同有机碳含量计算方法结果对比表明,用Passey模型计算的有机碳含量与岩心有机地化分析有机碳含量趋势一致、相对误差小,证实该方法基本满足渤海地区烃源岩评价需求。通过对渤海湾研究区20口井测井处理结果的对比,该区沙河街组湖相地层有机碳含量最高,有利烃源岩厚度大,其中沙三中段是最有利烃源岩分布层位。