| 摘要: |
| 世界整装大油气田均以海相盆地为主,储集类型首推碳酸盐岩岩溶孔洞+裂缝。岩溶发育的程度除相控外,层序不整合界面与区域性地层不整合面的复合面,在表生成岩作用环境下可形成碳酸盐岩古风化壳型岩溶。塔里木盆地和鄂尔多斯盆地奥陶系古喀斯特油气藏的重大突破,佐证了碳酸盐岩岩溶储层的特殊意义。我国海相盆地碳酸盐岩风化壳岩溶的形成和演化,均与加里东构造旋回中的幕次古隆起和海平面下降共耦,埋藏期和热水溶蚀的叠加可改善岩溶的储集性能。在大面积覆盖的油气田区预测古风化壳型的岩溶储层,可通过地震剖面追踪区域性地层不整合面和层序界面,圈出古岩溶的时空展布、推测古岩溶地貌以及与不同层位岩性相的关系。孔洞充填方解石与碳酸盐围岩的氧碳同位素有别,前者的Z值小于120,是反馈淡水岩溶环境的重要标志之一。 |
| 关键词: 风化壳岩溶储层 碳酸盐岩 不整合面 地震界面 氧碳同位素 |
| DOI： |
| 附件 |
| 投稿时间：2005-07-30 |
| 基金项目: |
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| The palaeoweathering crust-type karst reservoir rocks in carbonate rocks |
| XU Xiao-song, DU Bai-wei |
| (Chengdu Instiutute of Geology and Mineral Resources, Chengdu 610082, Sichuan, China) |
| Abstract: |
| The giant oil and gas fields are totally hosted in marine basins in the world.The reservoir spaces mainly include pore spaces and fissures of carbonate karsts.The palaeoweathering crust-type karsts tend to be developed on the composite surfaces between sequence unconformity and regional stratigraphic unconformity in the epidiagenetic environments.The breakthrough in the studies of the Ordovician palaeokarst oil and gas accumulations in the Tarim Basin,Xinjiang and Ordos Basin,Nei Mongol is circumstantial evidence in favour of special significance of carbonate karst reservoir rocks.The formation and evolution of the carbonate palaeoweathering crust-type karsts in the marine basins in China are all coupled with episodic paleo-uplifts and sea-level falls in the Caledonian tectonic cycles.The burial stages and hydrothermal corrosion may improve the reservoir capacity of carbonate karsts.The prediction of the palaeweathering crust-type karst rerservoir rocks in large-scale oil and gas fields may be implemented by tracing the regional stratigraphic unconformity and sequence boundary with the aid of seismic profiles,delineating the spatio-temporal distribution of palaeokarsts,and reconstructing the palaeokarst geomorphology and its relations with different lithofacies.The oxygen and carbon isotopes are different for pore space-filled calcite and carbonate rocks as wall rocks:Z values are less than 120 for the former,which may be an important indicator for fresh-water karst environments. |
| Key words: palaeoweathering crust-type karst rerservoir rock carbonate rock unconformity seismic boundary oxygen and carbon isotopes |
