四川盆地涪陵地区五峰组-龙马溪组含气页岩段纵向非均质性及其发育主控因素

doi:10.11743/ogg20160605

摘要/Abstract

摘要： 四川盆地涪陵地区下志留统龙马溪组发育一套富有机质泥页岩，勘探证实为一套优质含气页岩储层。该套页岩具较强的纵向非均质性，直接影响了储层含气量及储层可改造性。研究首先建立了页岩等时层序地层对比格架；在等时地层格架中，分析了页岩储层在岩矿组成、黄铁矿含量、沉积构造、有机质丰度等方面的非均质性特征。在海侵期，页岩中主要发育自生硅质和沉积成因的自生黄铁矿，页理发育，有机碳含量高，与硅质之间呈现特殊的正相关耦合关系。早期高位域时期，页岩中主要包含陆源粉砂，发育小型波纹层理和透镜状层理；粘土质含量较海侵期有所增加，有机碳含量中等；兼有沉积成因的自生黄铁矿和后期次生成因的黄铁矿。晚期高位域时期，粘土质含量进一步增加；粉砂质含量减少；有机碳含量低；兼有沉积成因的自生黄铁矿和后期次生黄铁矿。从沉积作用、古海洋生产力和氧化还原环境等方面探讨了非均质性的影响因素，明确其主要受控于陆源供给速率、古生产力、水体氧化还原性和古洋流等因素。

关键词: 页岩非均质性, 页岩气, 五峰组, 龙马溪组, 涪陵地区, 四川盆地

Abstract: The organic shales in the Lower Silurian Longmaxi Fm in Fuling area,the Sichuan Basin are proved to be shale gas reservoirs of high quality.Nevertheless,they have relatively strong vertical heterogeneity,directly influencing its gas content and reservoir fracability.An isochronal sequence stratigraphic framework is first established.Then,the heterogeneities of the shale are analyzed in respects of petrological and mineralogical compositions,the content of pyrite,sedimentary structures and organic matter abundance within this framework.The shales deposited during TST are characterized by authigenic siliceous minerals and pyrites of sedimentary origin,obvious lamellation,high TOC and special positive relationship between TOC and siliceous mineral content.The shales deposited in the early HST feature in the occurrence of terrigenous silts,small wavy lamination and lenticular bedding,higher clay content than that of TST,moderate TOC,and the existence of both authigenic and secondary pyrites.The shales deposited during the late HST feature in even higher clay content but lower silt content,low TOC and the existence of both authigenic and secondary pyrites.The factors influencing shale heterogeneity are discussed in respects of sedimentology,paleo-marine productivity and redox conditions and they mainly include the influx rate of terrestrial deposits,paleo-marine productivity,redox conditions and paleo-current.

Key words: shale heterogeneity, shale gas, Wufeng Formaiton, Longmaxi Formation, Fuling area, Sichuan Basin

中图分类号:

TE122.2

孟志勇. 四川盆地涪陵地区五峰组-龙马溪组含气页岩段纵向非均质性及其发育主控因素[J]. 石油与天然气地质, 2016, 37(6): 838-846. doi: 10.11743/ogg20160605 Meng Zhiyong. Vertical heterogeneity and its controlling factors of the gas shale in the Wufeng-Longmaxi Fms in Fuling area,the Sichuan Basin[J]. Oil & Gas Geology, 2016, 37(6): 838-846. doi: 10.11743/ogg20160605

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