| 四川盆地北缘灯影组深埋白云岩优质储层形成与保存机制 |
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| 引用本文： | 王国芝,刘树根,李娜,王东,高媛.四川盆地北缘灯影组深埋白云岩优质储层形成与保存机制[J].岩石学报,2014,30(3):667-678. |
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| 作者姓名： | 王国芝 刘树根 李娜 王东 高媛 |
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| 作者单位： | 成都理工大学油气藏地质及开发工程国家重点实验室, 成都 610059;成都理工大学地球科学学院, 成都 610059;成都理工大学油气藏地质及开发工程国家重点实验室, 成都 610059;成都理工大学地球科学学院, 成都 610059;中国地质调查局成都地质调查中心, 成都 610081;成都理工大学地球科学学院, 成都 610059 |
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| 基金项目： | 本文受国家自然科学基金项目（41072082、41273060）和国家“973”项目（2012CB214805）联合资助. |
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| 摘 要： | 叠合盆地深埋碳酸盐岩优质储层的形成和保存机理是一个复杂而又有争议的议题。大量的地质地球化学证据表明,四川盆地北缘灯影组深埋白云岩在灯四段和灯二段末期先后发生了两期古岩溶作用,在灯影组内形成了大小不等的晶洞和次生孔隙。在后期的深埋-隆升过程中,表生期的岩溶孔洞被不同世代的矿物充填,先存的孔洞被不同程度的改造和破坏,随埋藏深度的增加先存孔洞的体积变小;同时CO2、有机酸、H2S和多期外来酸性热液流体的溶蚀改造又形成了部分新的次生孔洞;油气藏主要赋存于残余的表生岩溶孔洞和新生次生溶孔内。研究表明,灯影组深埋白云岩优质储层的形成和保存不仅受表生岩溶作用、古岩溶地貌和沉积微相的影响和控制,而且还受深埋隆升过程中多期流体充注、溶蚀-沉淀和石油热裂解的复合控制。其中,表生岩溶作用是影响优质储层形成的最为关键性因素,古岩溶地貌和沉积微相控制了优质储层的时空分布,表生岩溶作用影响的深度最深达500m左右。多期侵蚀性流体的溶蚀和石油热裂解所引起的超压使先存表生岩溶孔洞能得以保存。
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| 关 键 词： | 深埋白云岩 优质储层 表生岩溶 深埋溶蚀-沉淀 石油热裂解 灯影组 四川盆地北缘 |
| 收稿时间： | 2013/8/17 0:00:00 |
| 修稿时间： | 2013/12/16 0:00:00 |
Formation and preservation mechanism of high quality reservoir in deep burial dolomite in the Dengying Formation on the northern margin of the Sichuan basin |
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| WANG GuoZhi,LIU ShuGen,LI N,WANG Dong and GAO Yuan.Formation and preservation mechanism of high quality reservoir in deep burial dolomite in the Dengying Formation on the northern margin of the Sichuan basin[J].Acta Petrologica Sinica,2014,30(3):667-678. |
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| Authors: | WANG GuoZhi LIU ShuGen LI N WANG Dong and GAO Yuan |
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| Institution: | State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China;School of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China;School of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China;Chengdu Center of Geological Survey, China Geological Survey, Chengdu 610081, China;School of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China |
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| Abstract: | The formation and preservation mechanism of a high quality reservoir in deep burial carbonate rocks in a superimposed basin is a complicated and controversial issue. A great deal of geologic and geochemical evidence shows that two phases of subaerial karstification of deep burial dolomite on the northern margin of the Sichuan basin occurred successively at the end of the fourth and second Member of the Dengying Formation. The subaerial karstification plays a very important role in the development of a great number of secondary dissolution vugs and pores beneath the kastification surface. During the late deep burial-uplift process, the epigenetic karst vugs were filled by different minerals formed at different stages, and the pre-existing vugs were transformed and destroyed inordinately, becoming smaller as they were buried deeper. At the same time, some new secondary vugs were formed by corrosive fluids such as CO2, organic acid, H2S, and multi-phased exotic acidic hydrothermal fluids. Hydrocarbon was chiefly accumulated in the residual karst vugs and new secondary pores. This study manifests that the formation and preservation of high quality reservoirs in deep burial dolomite in the Dengying Formation are controlled not only by epigenetic karstification, paleokarst topography, and sedimentary microfacies, but also by multi-phase fluid filling, dissolution-precipitation, and oil thermal cracking. Among these factors, subaerial karstification plays the most important role in the formation of the high quality reservoir, the impact of this process can reach as deep as 500m downward. The other factors of paleokarst topography and sedimentary microfacies are responsible for the distribution of high quality reservoirs. The pre-existing epigenetic karst vugs could be preserved on account of multi-phased corrosive fluid and overpressure caused by oil thermal cracking. |
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| Keywords: | Deep-burial dolomite High quality reservoir Epigenetic karstification Deep burial dissolution-precipitation Oil thermal cracking Dengying Formation Northern margin of the Sichuan basin |
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