南襄盆地襄樊-枣阳凹陷油气勘探前景探讨

襄樊-枣阳凹陷位于南襄盆地的南部,与北部＂小而肥＂的南阳、泌阳凹陷相比,该区油气勘探一直未获得突破。通过对凹陷内核桃园组烃源岩特征的研究及油气资源评价表明,核桃园组烃源岩未成熟,生烃量和聚集烃量均较少,且已施钻的以核桃园组为主要目的层的钻井均未获得油气成果。因此,襄樊-枣阳凹陷核桃园组不能作为油气勘探的主要目的层。凹陷东部的部分盐井提供了区内白垩系烃源岩具有生油气潜力的信息,而且土壤地球化学勘探也指示了该区白垩系具有一定的勘探前景;襄参1井揭示区内震旦—寒武系碳酸盐岩有机质丰度高,其生油气潜力值得进一步探索,土壤地球化学勘探也显示,存在与震旦—寒武系有关的热演化气;土壤地球化学勘探显示区内存在幔源成因天然气。综合分析认为,中生界白垩系、幔源天然气及震旦—寒武系碳酸盐岩是襄樊-枣阳凹陷油气勘探值得探索的新层位和新领域。

Oil and Gas Exploration Prospects in Xiangfan-Zaoyang Sag of Nanxiang Basin

Xiangfan-Zaoyang sag lies on the south of Nanxiang basin. Compared with the northern small but prolific Nanyang and Biyang sags, the breakthrough of exploration activity is always obtained in this area. Through the research on the characteristics of Cenozoic Hetaoyuan group source rock and the hydrocarbon resource evaluation, we know that the source rock is immature, and the quantity of hydrocarbon generation and resources is very little, the total quantity of hydrocarbon generation is 2. 97×10^8t, the largest resources quantity is only 130 × 10^4t. Moreover, the wells of aiming at Hetaoyuan group don＇t obtain the hydrocarbon accomplishment in Xiangfan-Zaoyang sag. Therefore, Hetaoyuan group can＇t be taken as the exploration objective formation. Some salt wells provided a little information on Cretaceous source rock, and soil geochemistry exploration also showed that Cretaceous has exploration prospect. The exploration of carbonate and mantle derived gas is the fields of being concerned both at home and abroad over a long period of time, and some breakthroughs have been made. Some soil geochemistry exploration information has revealed that there are some exploration prospects of carbonate and mantle derived gas. Then based on multidisciplinary analyzing research accomplishment of salt exploration and soil geochemistry exploration, Mesozoic Cretaceous, mantle derived gas and Sinian-Cambrian carbonate are the new horizon and fields of hydrocarbon exploration in Xiangfan-Zaoyang sag.