湘鄂西地区下寒武统石龙洞组古岩溶发育及储层特征
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摘要
四川盆地下寒武统龙王庙组天然气勘探近期取得的重大发现,引起了对同期沉积的石龙洞组的广泛关注。通过对鄂西渝东—湘鄂西地区石龙洞组多个野外露头的研究,观察到在平面上石龙洞组顶部存在典型的风化岩溶现象,推测在该区内存在与早寒武世末兴凯运动有关的区域性岩溶不整合面。以湖北恩施咸丰背斜庙梁子—丁寨剖面为例,石龙洞顶部的表层岩溶带厚度为3 m,主要为风化壳层和垮塌角砾岩层。同时,受大气淡水和裂缝影响,表层岩溶带下部地层在较深范围内都受到大气淡水淋滤作用影响,属于岩溶改造带。根据胶结物类型及溶蚀特征可分为大气淡水垂向渗滤溶蚀区及潜流溶蚀区。此外,初步探讨了表生岩溶与储层发育的关系。研究区整体岩性较致密,但局部存在优质储层,尤其是表层岩溶带孔洞发育十分丰富,连通性良好。而岩溶改造带由于后期埋藏阶段成岩作用的影响,尤其是晚期硅化作用的破坏,现存孔洞相对较少。研究区优质储层的形成主要受表生及埋藏期溶蚀作用和白云化作用控制。
Significant gas discovery in the Lower Cambrian Longwangmiao Formation in Sichuan basin has received wide attention on the time-equivalent Shilongdong Formation in Western Hunan-Hubei area. In order to provide guidance to the regional evaluation of reservoir in Western Hunan-Hubei area, detailed research has been carried out with methods including observation of outcrop, thin section, casted thin section, and cathode luminescence analysis. Based on the research of several outcrops in Eastern Hubei- Chongqing and Western Hunan-Hubei area, typical weathering crust karst features have been observed. Miaoliangzi-Dingzhai cross section has been chosen as the typical section in Enshi Xianfeng area for detailed research. The surface karstificated zone is 3 meters in thickness, composed of weathering layer and collapse breccia layer. The underlying strata have been affected by meteoric water leaching and dissolution due to faults and fracture system. And the meteoric water dissolution reaches as far as hundreds meters. According to the cement types and dissolution features, the vertical seepage flow zone and horizontal subsurface flow zone have been distinguished. Lithology is overall dense in the research area, but high quality reservoir with high porosity and permeability exists in some area, especially in the surface karstificated zone.In the vertical seepage flow zone and horizontal subsurface flow zone, pore space is lost due to late silicification, and only minor pore space is preserved. According to the discussion of diagenesis process and reservoir development, high quality reservoir is mainly controlled by supergene karstification, burial dissolution, and dolomitization. It is speculated that regional unconformity karsts are present in the research area, which are related to Xingkai movement during early Cambrian. This research is important to the regional evaluation of reservoir in Eastern Hubei-Chongqing and Western Hunan-Hubei area.
Significant gas discovery in the Lower Cambrian Longwangmiao Formation in Sichuan basin has received wide attention on the time-equivalent Shilongdong Formation in Western Hunan-Hubei area. In order to provide guidance to the regional evaluation of reservoir in Western Hunan-Hubei area, detailed research has been carried out with methods including observation of outcrop, thin section, casted thin section, and cathode luminescence analysis. Based on the research of several outcrops in Eastern Hubei- Chongqing and Western Hunan-Hubei area, typical weathering crust karst features have been observed. Miaoliangzi-Dingzhai cross section has been chosen as the typical section in Enshi Xianfeng area for detailed research. The surface karstificated zone is 3 meters in thickness, composed of weathering layer and collapse breccia layer. The underlying strata have been affected by meteoric water leaching and dissolution due to faults and fracture system. And the meteoric water dissolution reaches as far as hundreds meters. According to the cement types and dissolution features, the vertical seepage flow zone and horizontal subsurface flow zone have been distinguished. Lithology is overall dense in the research area, but high quality reservoir with high porosity and permeability exists in some area, especially in the surface karstificated zone.In the vertical seepage flow zone and horizontal subsurface flow zone, pore space is lost due to late silicification, and only minor pore space is preserved. According to the discussion of diagenesis process and reservoir development, high quality reservoir is mainly controlled by supergene karstification, burial dissolution, and dolomitization. It is speculated that regional unconformity karsts are present in the research area, which are related to Xingkai movement during early Cambrian. This research is important to the regional evaluation of reservoir in Eastern Hubei-Chongqing and Western Hunan-Hubei area.
引文
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[12]纪友亮,陈丽华,涂强,等.油气储层地质学[M].北京:中国石油大学出版社,2009:111.Ji Youliang,Chen Lihua,Tu Qiang,et al.Petroleum Reservoir Geology[M].Beijing:China University of Petroleum Press,2009:111.
[13]甯濛,郝斌斌,张九园,等.混合水白云石化和埋藏白云石化作用的是与非——以四川盆地飞仙关组白云岩成因为例[J].地球科学前沿,2012(2):193-198.Ning Meng,Hao Binbin,Zhang Jiuyuan,et al.The rationality of mixedwater dolomitization and buried dolomitization—Taking the genesis ofdolostone of Feixianguan Formation in the Sichuan Basin as an example[J].Advances in Geosciences,2012(2):193-198.
[14]盛贤才,王韶华,文可东,等.鄂西渝东地区石柱古隆起构造沉积演化[J].海相油气地质,2004,9(1-2):43-52.Sheng Xiancai,Wang Shaohua,Wen Kedong,et al.Tectonics and sedi-mentology of Shizhu Palaeohigh in Western Hubei-Eastern Chongqingarea[J].Marine Origin Petoleum Geology,2004,9(1-2):43-52.
[15]黄汲清,任纪舜,姜春发,等.中国大地构造及其演化[M].北京:科学出版社,1980.Huang Jiqing,Ren Jishun,Jiang Chunfa,et al.Geotectonic Evolution ofChina[M].Beijing:Science Press,1980.
[16]王剑,刘宝珺,潘桂堂.华南新元古代裂谷盆地演化——Rodinia超大陆解体的前奏[J].矿物岩石,2001,21(3):135-145.Wang Jian,Liu Baojun,Pan Guitang.Neoproterozoic rifting history ofSouth China:Significance to Rodinia breakup[J].Journal of Mineralogyand Petrology,2001,21(3):135-145.
[17]钟勇,李亚林,张晓斌,等.四川盆地下组合张性构造特征[J].成都理工大学学报:自然科学版,2013,40(5):498-510.Zhong Yong,Li Yalin,Zhang Xiaobin,et al.Features of extensionalstructures in pre-Sinian to Cambrian strata,Sichuan Basin,China[J].Journal of Chengdu University of Technology(Science&Technology Edi-tion),2013,40(5):498-510.
[18]刘树根,孙玮,罗志立,等.兴凯地裂运动与四川盆地下组合油气勘探[J].成都理工大学学报:自然科学版,2013,40(5):511-520.Liu Shugen,Sun Wei,Luo Zhili,et al.Xingkai taphrogenesis and petro-leum exploration from Upper Sinian to Cambrian Strata in Sichuan Basin,China[J].Journal of Chengdu University of Technology:Science&Tech-nology Edition,2013,40(5):511-520.
[19]宋金民,刘树根,孙玮,等.兴凯地裂运动对四川盆地灯影组优质储层的控制作用[J].成都理工大学学报:自然科学版,2013,40(6):658-670.Song Jinmin,Liu Shugen,Sun Wei,et al.Control of Xingkai taphrogene-sis on Dengying Formation high quality reservoirs in Upper Sinian of Si-chuan Basin,China[J].Journal of Chengdu University of Technology:Sci-ence&Technology Edition,2013,40(6):658-670.
[20]刘宝珺,许效松,潘杏南,等.中国南方古大陆沉积地壳演化与成矿[M].北京:科学出版社,1993.Liu Baojun,Xu Xiaosong,Pan Xinnan,et al.Paleo-continental sedimen-tary evolution and mineralization in South China[M].Beijing,:SciencePress,1993.
[21]田望学,潘龙克,江林生.早寒武世早期鄂中古岛异议[J].湖北地矿,2001,15(4):7-11.Tian Wangxue,Pan Longke,Jiang Linsheng.A discussion on"paleo-is-land of central Hubei"in early stage of Lower Cambrian epoch[J].HubeiGeology&Mineral Resources,2001,15(4):7-11.
[2]李忠雄,陆永潮,王剑,等.中扬子地区晚震旦世-早寒武世沉积特征及岩相古地理[J].古地理学报,2004,6(2):151-162.Li Zhongxiong,Lu Yongchao,Wang Jian,et al.Sedimentary characteris-tics and lithofacies palaeogeography of the Late Sinian and Early Cambri-an in middle Yangtze region[J].Journal of Palaeogeography,2004,6(2):151-162.
[3]李昌鸿.江汉平原加里东期古隆起对震旦系-下古生界成藏条件的控制作用[J].石油实验地质,2008,30(6):564-567.Li Changhong.Controls of the Caledonian paleouplift to the Sinian-LowerPaleozoic reservoiring conditions in Jianghan Plain[J].Petroleum Geology&Experiment,2008,30(6):564-567.
[4]罗顺社,高振中,李建明,等.湘鄂西地区震旦系至奥陶系有利储集层段的储层特征及分布规律研究[J].石油天然气学报,2002,24(4):4-7.Luo Shunshe,Gao Zhenzhong,Li Jianming,et al.Reservoir characteris-tics and distribution of Sinian to Ordovician in Western Hunan and Hubei[J].Journal of Oil and Gas Technology,2002,24(4):4-7.
[5]郭战峰,陈绵琨,付宜兴,等.鄂西渝东地区震旦、寒武系天然气成藏条件[J].西南石油大学学报:自然科学版,2008,30(4):39-42.Guo Zhanfeng,Chen Miankun,Fu Yixing,et al.Natural gas reservoiringconditions of Sinian and Cambrian in from Western Hubei to EasternChongqing area[J].Journal of Southwest Petroleum University:Science&Technology Edition,2008,30(4):39-42.
[6]刘莉.江汉盆地海相探区中寒武统盐下层勘探潜力浅析[J].海相油气地质,2011,16(1):26-32.Liu Li.Exploration potential of Middle Cambrian subsalt formations inmarine origin formation area,Jianghan Basin[J].Marine Origin PetroleumGeology,2011,16(1):26-32.
[7]王必金,包汉勇,郭战峰,等.湘鄂西区寒武系层序划分及其对油气勘探的意义[J].石油实验地质,2013,35(4):372-377.Wang Bijin,Bao Hanyong,Guo Zhanfeng,et al.Sequence stratigraphic di-vision of Cambrian in western Hunan-Hubei and applications for petro-leum exploration[J].Petroleum Geology&Experiment,2013,35(4):372-377.
[8]盛贤才,郭战峰,陈学辉,等.江汉平原及邻区海相碳酸盐岩的古岩溶特征及控制因素[J].海相油气地质,2007,12(2):17-22.Sheng Xiancai,Guo Zhanfeng,Chen Xuehui,et al.Palaeokarst character-istics and controlling factors of marine carbonate rocks in Jianghan Plainand its neighboring areas[J].Marine Origin Petroleum Geology,2007,12(2):17-22.
[9]牛晓燕,李建明,李冬冬.中扬子西部地区石龙洞组古岩溶储层控制因素分析[J].石油仪器,2010,24(2):69-72.Niu Xiaoyan,Li Jianming,Li Dongdong.Analyses on fossil karst reservoircontrolling factors in Shilongdong formation of Middle Yangtze WesternRegion[J].Petroleum Instruments,2010,24(2):69-72.
[10]马永生.碳酸盐岩微相——分析、解释及应用[M].北京:地质出版社,2006:191-196.Ma Yongsheng.Microfacies of Carbonate Rocks:Analysis,Interpretationand Application[M].Beijing:Geological Publishing House,2006:191-196.
[11]黄思静.碳酸盐矿物的阴极发光性与其Fe,Mn含量的关系[J].矿物岩石,1992,12(4):74-79.Huang Sijing.Relationship between cathodoluminescence and concen-tration of iron and manganese in carbonate minerals[J].Journal of Mineralogy and Petrology,1992,12(4):74-79.
[12]纪友亮,陈丽华,涂强,等.油气储层地质学[M].北京:中国石油大学出版社,2009:111.Ji Youliang,Chen Lihua,Tu Qiang,et al.Petroleum Reservoir Geology[M].Beijing:China University of Petroleum Press,2009:111.
[13]甯濛,郝斌斌,张九园,等.混合水白云石化和埋藏白云石化作用的是与非——以四川盆地飞仙关组白云岩成因为例[J].地球科学前沿,2012(2):193-198.Ning Meng,Hao Binbin,Zhang Jiuyuan,et al.The rationality of mixedwater dolomitization and buried dolomitization—Taking the genesis ofdolostone of Feixianguan Formation in the Sichuan Basin as an example[J].Advances in Geosciences,2012(2):193-198.
[14]盛贤才,王韶华,文可东,等.鄂西渝东地区石柱古隆起构造沉积演化[J].海相油气地质,2004,9(1-2):43-52.Sheng Xiancai,Wang Shaohua,Wen Kedong,et al.Tectonics and sedi-mentology of Shizhu Palaeohigh in Western Hubei-Eastern Chongqingarea[J].Marine Origin Petoleum Geology,2004,9(1-2):43-52.
[15]黄汲清,任纪舜,姜春发,等.中国大地构造及其演化[M].北京:科学出版社,1980.Huang Jiqing,Ren Jishun,Jiang Chunfa,et al.Geotectonic Evolution ofChina[M].Beijing:Science Press,1980.
[16]王剑,刘宝珺,潘桂堂.华南新元古代裂谷盆地演化——Rodinia超大陆解体的前奏[J].矿物岩石,2001,21(3):135-145.Wang Jian,Liu Baojun,Pan Guitang.Neoproterozoic rifting history ofSouth China:Significance to Rodinia breakup[J].Journal of Mineralogyand Petrology,2001,21(3):135-145.
[17]钟勇,李亚林,张晓斌,等.四川盆地下组合张性构造特征[J].成都理工大学学报:自然科学版,2013,40(5):498-510.Zhong Yong,Li Yalin,Zhang Xiaobin,et al.Features of extensionalstructures in pre-Sinian to Cambrian strata,Sichuan Basin,China[J].Journal of Chengdu University of Technology(Science&Technology Edi-tion),2013,40(5):498-510.
[18]刘树根,孙玮,罗志立,等.兴凯地裂运动与四川盆地下组合油气勘探[J].成都理工大学学报:自然科学版,2013,40(5):511-520.Liu Shugen,Sun Wei,Luo Zhili,et al.Xingkai taphrogenesis and petro-leum exploration from Upper Sinian to Cambrian Strata in Sichuan Basin,China[J].Journal of Chengdu University of Technology:Science&Tech-nology Edition,2013,40(5):511-520.
[19]宋金民,刘树根,孙玮,等.兴凯地裂运动对四川盆地灯影组优质储层的控制作用[J].成都理工大学学报:自然科学版,2013,40(6):658-670.Song Jinmin,Liu Shugen,Sun Wei,et al.Control of Xingkai taphrogene-sis on Dengying Formation high quality reservoirs in Upper Sinian of Si-chuan Basin,China[J].Journal of Chengdu University of Technology:Sci-ence&Technology Edition,2013,40(6):658-670.
[20]刘宝珺,许效松,潘杏南,等.中国南方古大陆沉积地壳演化与成矿[M].北京:科学出版社,1993.Liu Baojun,Xu Xiaosong,Pan Xinnan,et al.Paleo-continental sedimen-tary evolution and mineralization in South China[M].Beijing,:SciencePress,1993.
[21]田望学,潘龙克,江林生.早寒武世早期鄂中古岛异议[J].湖北地矿,2001,15(4):7-11.Tian Wangxue,Pan Longke,Jiang Linsheng.A discussion on"paleo-is-land of central Hubei"in early stage of Lower Cambrian epoch[J].HubeiGeology&Mineral Resources,2001,15(4):7-11.