四川盆地二叠系火成岩分布及含气性
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摘要
基于露头、地震、测井和钻井资料分析,结合勘探实践成果,对四川盆地二叠系火成岩特征、分布、储集性能及含气性进行研究。分析表明,盆地内二叠系发育中心式火山喷发岩相,其岩性组合及分布特征表现出明显差异性;火成岩主要分布于3个区域:盆地西南部,主要为大面积溢流相玄武岩;盆地中西部的简阳—三台地区,发育侵入岩、火山熔岩(玄武岩)和火山碎屑岩;川东达州—梁平地区,则仅为辉绿岩和玄武岩。研究得出以下5方面的认识:①上二叠统火成岩可分为侵入岩和喷出岩两大类,以喷出岩占主体,在化学成分上既具有碱性玄武岩特点,也具有拉斑玄武岩特点,属偏碱性的过渡型玄武岩浆喷发;②溢流相的玄武岩在纵向上具有明显的韵律结构,单韵律层自下而上为火山碎屑岩(不发育)→深灰、灰色斑状玄武岩(不稳定)→深灰带紫色微晶-隐晶玄武岩→深灰绿色气孔状、杏仁状玄武岩;中心式火山喷发也具有韵律性,纵向上自下而上为火山碎屑岩(集块岩、角砾岩)→火山熔岩→凝灰质熔岩的演化序列;③玄武岩和火山碎屑岩的孔隙类型具多样性,以溶蚀孔、脱玻化微孔为主,但物性差异大,玄武岩储集层表现为超低孔渗,厚度小,分布于旋回中上部及顶部,横向可对比性较差;火山碎屑岩为中—高孔储集层(YT1井:孔隙度8.66%～16.48%,平均值为13.76%),厚度较大,储集层品质较好;④盆地西南部玄武岩中的天然气主要来源于中二叠统,盆地中西部火山碎屑岩中天然气来自于寒武系筇竹寺组;⑤分析不同地区火成岩成藏条件,盆地西南部气源相对不足、储集层欠发育,保存条件差异性较大,含气性较复杂;盆地中西部简阳—三台地区烃源充足、储集层发育、保存条件优越,天然气地质条件优越,是天然气勘探有利区。
Based on the analysis of outcrop, seismic, logging and drilling data, combined with exploration practice, the characteristics,distribution, reservoir performance and gas-bearing properties of Permian igneous rocks in Sichuan Basin are studied. The study shows that central volcanic eruptive facies are developed in Sichuan Basin, and their lithological assemblages and distribution characteristics show obvious differences. The igneous rocks are mainly distributed in three regions: the southwestern part of the basin has dominantly largescale overflow facies basalts; the central and western part of the basin, Jianyang-Santai area, develop intrusive rocks, volcanic lavas(basalts)and pyroclastic rocks; and the eastern part of Sichuan, Dazhou-Liangping area, only develop diabase and basalts. Five aspects of understandings are achieved:(1) The Upper Permian igneous rocks can be divided into intrusive rocks and extrusive rocks, with the extrusive rocks as the main body. The chemical compositions of the extrusive rocks are characterized by both alkaline basalt and tholeiitic basalt, and belong to the subalkaline type of transitional basalt magma eruption.(2) There are obvious rhythmic structures vertically among overflow facies basalt, and the single rhythmic layer consists of, from bottom up, pyroclastic rocks(undeveloped), gray and dark gray porphyritic basalts(unstable), dark gray and purple microcrystalline-cryptocrystalline basalts, dark greyish green porous and amygdaloid basalts; the central volcanic eruption shows the rhythm and the vertical sequence of volcanic clastic rocks(agglomerates and breccias), volcanic lava,tuffaceous lava from bottom to top.(3) The pore types of basalt and pyroclastic rocks are diverse, mainly dissolution pore and de-vitrification micropore, but their physical properties are different. Basalt is characterized by ultra-low pore permeability, small reservoir thickness, and reservoirs are distributed in the upper and middle parts of the cycle, with poor lateral comparability. Volcanic clastic rocks are medium to high porous reservoirs(Well YT1: porosity: 8.66%-16.48%, average 13.76%) with large thickness and good reservoir quality.(4) Natural gas in basalts in southwestern basin mainly comes from Middle Permian, and natural gas in volcanic clastic rocks in central and western basin comes from Cambrian Qiongzhusi Formation.(5) Analysis of igneous reservoir-forming conditions in different areas shows that there are relatively insufficient gas sources and great differences in preservation conditions in southwestern basin. Reservoirs are poorly developed and gas-bearing is complex. The Jianyang-Santai area in the central and western part of Sichuan Basin has abundant hydrocarbon sources, developed reservoir, favorable preservation conditions and favorable gas geological conditions,and it is a favorable area for gas exploration.
Based on the analysis of outcrop, seismic, logging and drilling data, combined with exploration practice, the characteristics,distribution, reservoir performance and gas-bearing properties of Permian igneous rocks in Sichuan Basin are studied. The study shows that central volcanic eruptive facies are developed in Sichuan Basin, and their lithological assemblages and distribution characteristics show obvious differences. The igneous rocks are mainly distributed in three regions: the southwestern part of the basin has dominantly largescale overflow facies basalts; the central and western part of the basin, Jianyang-Santai area, develop intrusive rocks, volcanic lavas(basalts)and pyroclastic rocks; and the eastern part of Sichuan, Dazhou-Liangping area, only develop diabase and basalts. Five aspects of understandings are achieved:(1) The Upper Permian igneous rocks can be divided into intrusive rocks and extrusive rocks, with the extrusive rocks as the main body. The chemical compositions of the extrusive rocks are characterized by both alkaline basalt and tholeiitic basalt, and belong to the subalkaline type of transitional basalt magma eruption.(2) There are obvious rhythmic structures vertically among overflow facies basalt, and the single rhythmic layer consists of, from bottom up, pyroclastic rocks(undeveloped), gray and dark gray porphyritic basalts(unstable), dark gray and purple microcrystalline-cryptocrystalline basalts, dark greyish green porous and amygdaloid basalts; the central volcanic eruption shows the rhythm and the vertical sequence of volcanic clastic rocks(agglomerates and breccias), volcanic lava,tuffaceous lava from bottom to top.(3) The pore types of basalt and pyroclastic rocks are diverse, mainly dissolution pore and de-vitrification micropore, but their physical properties are different. Basalt is characterized by ultra-low pore permeability, small reservoir thickness, and reservoirs are distributed in the upper and middle parts of the cycle, with poor lateral comparability. Volcanic clastic rocks are medium to high porous reservoirs(Well YT1: porosity: 8.66%-16.48%, average 13.76%) with large thickness and good reservoir quality.(4) Natural gas in basalts in southwestern basin mainly comes from Middle Permian, and natural gas in volcanic clastic rocks in central and western basin comes from Cambrian Qiongzhusi Formation.(5) Analysis of igneous reservoir-forming conditions in different areas shows that there are relatively insufficient gas sources and great differences in preservation conditions in southwestern basin. Reservoirs are poorly developed and gas-bearing is complex. The Jianyang-Santai area in the central and western part of Sichuan Basin has abundant hydrocarbon sources, developed reservoir, favorable preservation conditions and favorable gas geological conditions,and it is a favorable area for gas exploration.
引文
[1]罗志立.峨眉地裂运动的厘定及其意义[J].地质学报,1989,9(1):1-17.LUO Zhili.Determination of the Emei taphrogenesis and its significance[J].Acta Geologica Sinica,1989,9(1):1-17.
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[4]黄勇,郝家栩,邓贵标,等.滇西施甸地区二叠纪卧牛寺组大陆溢流玄武岩的发现[J].地质通报,2012,31(2):314-320.HUANG Yong,HAO Jiaxu,DENG Guibiao,et al.The discovery of terrestrial extrusive basalt of Permian Woniusi Formation in Shidian area,western Yunnan Province[J].Geological Bulletin of China,2012,31(2):314-320.
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[7]肖龙,徐义刚,梅厚钧,等.云南宾川地区峨眉山玄武岩地球化学特征:岩石类型及随时间演化规律[J].地质科学,2003,38(4):478-494.XIAO Long,XU Yigang,MEI Houjun,et al.Geochemistry of Emeishan flood basalts at Binchuan Area,SW China:Rock types and temporal evolution[J].Scientia Geologica Sinica,2003,38(4):478-494.
[8]曹昌磊,梅红波,胡光道,等.云南建水官厅峨眉山玄武岩喷发旋回划分及其意义[J].地质学刊,2014,38(3):352-358.CAO Changlei,MEI Hongbo,HU Guangdao,et al.Division and implications of Emeishan basalt volcanic cycles in Guanting of Jianshui in Yunnan[J].Journal of Geology,2014,38(3):352-358.
[9]潘杏南,赵济湘,张选阳,等.康滇构造与裂谷作用[M].重庆:重庆出版社,1987.PAN Xingnan,ZHAO Jixiang,ZHANG Xuanyang,et al.Tectonics and rifting in Kangdian region[M].Chongqing:Chongqing Publishing Group,1987.
[10]马永生,陈洪德,王国力,等.中国南方层序地层与古地理[M].北京:科学出版社,2009.MA Yongsheng,CHEN Hongde,WANG Guoli,et al.Sequence stratigraphy and paleogeography of southern China[M].Beijing:China Science Publishing and Media Ltd,2009.
[11]张若祥,王兴志,蓝大樵,等.川西南地区峨眉山玄武岩储层评价[J].天然气勘探与开发,2006,29(1):17-20.ZHANG Ruoxiang,WANG Xingzhi,LAN Daqiao,et al.Reservoir evaluation of Emeishan basalts in Southwest Sichuan[J].Natural Gas Exploration and Development,2006,29(1):17-20.
[12]何松林.玄武岩储层特征及气源分析:以川西南上二叠统峨眉山玄武岩为例[J].有色金属文摘,2016,31(1):1-5.HE Songlin.Basalt reservoir characteristics and gas source analysis:Taking the Upper Permian Emeishan basalt in southwest Sichuan Basin as an example[J].Nonferrous Metals Abstract,2016,31(1):1-5.
[13]杜金虎,汪泽成,邹才能.上扬子克拉通内裂陷的发现及对安岳特大型气田形成的控制作用[J].石油学报,2016,37(1):1-16.DU Jinhu,WANG Zecheng,ZOU Caineng.Discovery of intra-cratonic rift in the Upper Yangtze and its coutrol effect on the formation of Anyue giant gas field[J].Acta Petrolei Sinica,2016,37(1):1-16.
[2]罗志立.略论地裂运动与中国油气分布[J].中国地质科学院院报,1984,6(3):99-107.LUO Zhili.A discussion of taphrogenesis and hydrocarbon distribution in China[J].Bulletin of the Chinese Academy of Geological Sciences,1984,6(3):99-107.
[3]沈军辉,王兰生,徐林生,等.峨眉山玄武岩的岩相与岩体结构[J].水文地质工程地质,2001,28(6):1-4.SHEN Junhui,WANG Lansheng,XU Linsheng,et al.The lithofacies and the rock mass structure of Emei Mountain basalt rock mass[J].Hydrogeology and Engineering Geology,2001,28(6):1-4.
[4]黄勇,郝家栩,邓贵标,等.滇西施甸地区二叠纪卧牛寺组大陆溢流玄武岩的发现[J].地质通报,2012,31(2):314-320.HUANG Yong,HAO Jiaxu,DENG Guibiao,et al.The discovery of terrestrial extrusive basalt of Permian Woniusi Formation in Shidian area,western Yunnan Province[J].Geological Bulletin of China,2012,31(2):314-320.
[5]玄力,李君.滇黔交界地区峨眉山玄武岩地质特征及其与铜矿化关系探讨[J].西部探矿工程,2014,26(1):156-160.XUAN Li,LI Jun.Geological characteristics of Emei Mountain basalt in the border of Yunnan and Guizhou province and its relationship with copper mineralization[J].West-China Exploration Engineering,2014,26(1):156-160.
[6]黎琪.川滇峨眉山玄武岩杏仁体中矿物共生组合特征及成因[D].桂林:桂林理工大学,2015.LI Qi.The characteristic and genesis of mineral assemblages in the amygdaloidal structure in basalt of Sichuan and Yunnan province[D].Guilin:Guilin University of Technology,2015.
[7]肖龙,徐义刚,梅厚钧,等.云南宾川地区峨眉山玄武岩地球化学特征:岩石类型及随时间演化规律[J].地质科学,2003,38(4):478-494.XIAO Long,XU Yigang,MEI Houjun,et al.Geochemistry of Emeishan flood basalts at Binchuan Area,SW China:Rock types and temporal evolution[J].Scientia Geologica Sinica,2003,38(4):478-494.
[8]曹昌磊,梅红波,胡光道,等.云南建水官厅峨眉山玄武岩喷发旋回划分及其意义[J].地质学刊,2014,38(3):352-358.CAO Changlei,MEI Hongbo,HU Guangdao,et al.Division and implications of Emeishan basalt volcanic cycles in Guanting of Jianshui in Yunnan[J].Journal of Geology,2014,38(3):352-358.
[9]潘杏南,赵济湘,张选阳,等.康滇构造与裂谷作用[M].重庆:重庆出版社,1987.PAN Xingnan,ZHAO Jixiang,ZHANG Xuanyang,et al.Tectonics and rifting in Kangdian region[M].Chongqing:Chongqing Publishing Group,1987.
[10]马永生,陈洪德,王国力,等.中国南方层序地层与古地理[M].北京:科学出版社,2009.MA Yongsheng,CHEN Hongde,WANG Guoli,et al.Sequence stratigraphy and paleogeography of southern China[M].Beijing:China Science Publishing and Media Ltd,2009.
[11]张若祥,王兴志,蓝大樵,等.川西南地区峨眉山玄武岩储层评价[J].天然气勘探与开发,2006,29(1):17-20.ZHANG Ruoxiang,WANG Xingzhi,LAN Daqiao,et al.Reservoir evaluation of Emeishan basalts in Southwest Sichuan[J].Natural Gas Exploration and Development,2006,29(1):17-20.
[12]何松林.玄武岩储层特征及气源分析:以川西南上二叠统峨眉山玄武岩为例[J].有色金属文摘,2016,31(1):1-5.HE Songlin.Basalt reservoir characteristics and gas source analysis:Taking the Upper Permian Emeishan basalt in southwest Sichuan Basin as an example[J].Nonferrous Metals Abstract,2016,31(1):1-5.
[13]杜金虎,汪泽成,邹才能.上扬子克拉通内裂陷的发现及对安岳特大型气田形成的控制作用[J].石油学报,2016,37(1):1-16.DU Jinhu,WANG Zecheng,ZOU Caineng.Discovery of intra-cratonic rift in the Upper Yangtze and its coutrol effect on the formation of Anyue giant gas field[J].Acta Petrolei Sinica,2016,37(1):1-16.
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