井研地区下寒武统烃源岩发育特征及对灯影组成藏的影响  

The Development Characteristic of Lower Cambrian Source Rock and Its Impact on the Hydrocarbon Accumulation of Dengying Formation in Jingyan Area

作　　者：赵姗姗[1,2] 王海军[1] 王同[1] 

机构地区：[1]中国石化西南油气分公司勘探开发研究院,四川 成都 [2]中国石化西南油气分公司地质中心实验室,四川 成都

出　　处：《地球科学前沿（汉斯）》2023年第7期709-721,共13页Advances in Geosciences

摘　　要：为深入评价下寒武统烃源岩特征及对灯影组成藏的影响,通过对井研地区6口典型钻井岩心、岩屑及天然气样品的地球化学分析,发现井研地区下寒武统发育麦地坪组和筇竹寺组两套烃源岩,TOC含量高,烃源品质中等–好,整体处于高–过成熟阶段,有机质类型均为生烃潜力极强的腐泥型。但麦地坪组有效烃源岩仅局限发育于研究区东部,供烃能力有限;而筇竹寺组有效烃源岩厚达百米,横向分布稳定,是区内最主要的烃源岩。这一差异分布特征可能与原始沉积的古地貌格局和沉积水体有关。气源对比结果表明,灯影组天然气为典型的原油裂解气,主要来源于筇竹寺组泥页岩,灯影组含气性与构造没有必然的联系,旁生侧储的源储配置样式和保存条件是灯影组成藏的关键,研究区南部近东西向正断层上升盘一侧可能是未来勘探的有利区域。Six drilling wells were selected for the geochemical analysis to evaluate the characteristic of Lower Cambrian source rock and its impact on hydrocarbon accumulation of Dengying formation in Jingyan area. Two sets of Lower Cambrian source rocks are present in Jingyan area, that is Maidiping mudstone and Qiongzhusi mudstone and shales, which are rich in organic matter with high to post mature stage. The type of organic matter for these source rocks is sapropelic kerogen with unexceptionable hydrocarbon potential. However, the occurrence of efficient source rocks of Maidiping formation is merely limited in the eastern area, with finite hydrocarbon supply. In contrast, the efficient source rocks of Qiongzhusi formation, as the main source rock, were pervasively distributed with a thickness of over 100 meters across the whole study area. The palaeogeomorphology and depositional water depth during organic matter deposition may be the main reason for this discrepancy. The natural gas of Dengying formation is typical crude oil cracking gas and is mainly sourced from Qiongzhusi source rock based on the gas-source comparison. No consequent relationship between hydrocarbon accumulation and the structural setting is present. On the contrary, the configuration of source rock and reservoir together with preservation condition are the critical factors for the hydrocarbon accumulation of Dengying formation. The hanging wall of nearly EW-trending normal faults may be the most favorable hydrocarbon exploitation area in the future.

关 键 词：井研地区 下寒武统 烃源岩 腐泥型 原油裂解气 侧向成藏 

分 类 号：P61[天文地球—矿床学]