三塘湖盆地石炭系烃源岩评价

摘要

三塘湖盆地石炭系烃源岩分布具有南厚北薄的特点，且以马朗凹陷和条湖凹陷的烃源岩厚度最大。烃源岩类型主要包括滨浅海相一海陆交互相的暗色泥岩、凝灰质泥岩和碳质泥岩。盆地内部石炭系烃源岩有机碳含量、生烃潜量及氯仿沥青A的含量均较丰富。干酪根稳定碳同位素值及岩石热解分析结果指示石炭系烃源岩有机质来源广泛，干酪根类型以Ⅱ型为主，也有少量Ⅰ型和Ⅲ型。大部分烃源岩样品实测镜质体反射率大于0．7％，对应的最大热解温度大于435℃，达到了有机质热演化的成熟至高成熟阶段。研究表明，三塘湖盆地石炭系烃源岩为一套好至极好的烃源岩，具有很高的生烃潜力。%The distribution of the Carboniferous source rocks in Santanghu basin is characterized by thick in south and thin in north, in which Malang and Tiaohu sags have the maximum thickness of them. The lithologic types of source rocks mainly include dark mudstone, tuffaceous mudstone and carbonaceous medstone deposited in littoral-neritic or marine-continental alternating environment. The total or- ganic carbon content, potential hydrocarbon generation amount and bitumen extraction abundance in them are all higher. RockEval pyroly- sis parameters suggest that the organic matter in Carboniferous source rocks is dominated by Type-Ⅱ kerogen, with minor Type-Ⅰ and -Ⅲ kerogen contribution. Vitrinite reflectance （Ro） values for most source rock samples are bigger than 0.7%, corresponding Tmax values is over 435℃, indicating a mature to high-mature stage for most source rocks. The study shows that all the Carboniferous source rocks in Santang- hu basin are high quality source rocks, with a good potential for hydrocarbon generation.