Sedimentary evolution and petroleum geological significance of Permian Maokou Formation in eastern and northern Sichuan Basin
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摘要: 近年来,四川盆地二叠系茅口组的勘探思路和布井原则由原来的“占高点、沿长轴”转变为以寻找滩相孔隙型规模储层为目标,并取得了新突破,使其成为了勘探热点层系,这就需要详细的沉积演化研究来支撑。川东—川北地区是茅口组构造—沉积分异最为明显,也是勘探潜力较大的区域。对茅口组386口钻井的测井资料进行系统梳理,并利用野外剖面和钻井取心进行沉积相分析,结合测井曲线与沉积相,分析研究区茅口组的沉积演化。研究认为,川东—川北地区茅口组一段到茅口组二下亚段总体为碳酸盐缓坡,地层厚度和沉积相总体受川中古隆起的影响,局部发育低能滩;茅二上亚段到茅三段转变为具有镶边性质的碳酸盐台地,地层厚度和沉积相带展布转变为北西—南东向,自西向东依次发育台地相、台缘带、斜坡和陆棚相,台缘带发育高能滩相。研究区茅口组沉积期相对海平面总体经历了两次升降过程,对应地层分别为茅一段到茅二下亚段和茅二上亚段到茅三段。受区域海平面升降、区域构造活动以及碳酸盐台地类型的控制,茅一段到茅二下亚段缓坡发育具有岩溶和云化的滩相储层;茅二上亚段到茅三段海槽内发育潜在烃源岩,是非常规油气勘探潜在有利区,而海槽西侧则发育具重要勘探价值的规模性台缘带高能滩。Abstract: In recent years, the Permian Maokou Formation of the Sichuan Basin shifted focus. Previously, targeting high points and exploring along the long axis were common. Now, the strategy emphasizes finding shoal grainstone reservoirs with pores, leading to significant breakthroughs and making the Maokou Formation a hotspot for exploration. This change requires strong support from sedimentary evolution studies. The eastern and northern Sichuan regions are notable for distinct tectonic and sedimentary features within the Maokou Formation, suggesting promising exploration potential. Analysis of the logging data from 386 wells was conducted and sedimentary facies analysis was carried out using field profiles and drilling cores. Combining the logging curves with sedimentary facies, the sedimentary evolution of the Maokou Formation in the study area was analyzed. Findings reveal a gentle carbonate slope from the first member to the lower submember of the second member. The stratigraphic thickness and sedimentary facies are generally influenced by the ancient Central Sichuan Palaeouplift, with low-energy shoals developing locally. A transition to a rimmed carbonate platform occurs from the upper submember of the second member to the third member, with stratigraphic thickness and sedimentary facies showing a northwest to southeast orientation. The platform develops sequentially from platform facies to platform margin, slope, and shelf facies from west to east, with high-energy shoals developing in the platform margin. Sedimentation history indicates two distinct rise to fall processes of the relative sea level during the Maokou Formation sedimentary period, corresponding to the first member to the lower submember of the second member, and the upper submember of the second member to the third member. The formation of shoal grainstone reservoirs with karst and dolomitization in the gentle slope during the first period was controlled by regional sea level changes, tectonic activities, and the type of carbonate platform. Potential hydrocarbon source rocks developed in submarine troughs during the second period. The region holds promise for unconventional oil and gas exploration, particularly on the west side of the trough with high-energy shoals on platform margins.
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图 4 川东—川北地区二叠系茅口组镜下照片及岩石、岩心照片
a.双河口剖面,茅二上亚段,含放射虫泥质灰岩,盆地相;b.西北乡剖面,茅二上亚段,薄层硅质岩夹泥质灰岩,盆地相;c.DY1井,4 391.72 m,茅二上亚段,含生屑泥质灰岩,斜坡相;d.C12井,3 385 m,茅二上亚段,生屑团块,斜坡相;e.C12井,3 343.2 m,茅二上亚段,亮晶颗粒灰岩,台缘高能滩相;f.雪玉洞剖面,茅二上亚段,晶粒云岩,台缘高能滩相;g.老黄轩剖面,茅二上亚段,生屑灰岩,开阔台地相;h.老黄轩剖面,茅三段,含生屑泥晶灰岩,局限台地相;i.L7井,4 476 m,茅二上亚段,亮晶—微亮晶颗粒灰岩,低能滩相;j.长江沟剖面,茅一段,眼皮灰岩,含生屑泥质泥晶灰岩,缓坡相。据参考文献[24]。
Figure 4. Microscopic photographs and photographs of rocks and cores of Permian Maokou Formation in eastern and northern Sichuan Basin
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[1] 胡朝伟, 胡广, 张玺华, 等. 川西北地区茅口组上部黑色岩系的层位、沉积环境及生烃潜力评价[J]. 石油实验地质, 2020, 42(2): 202-214. doi: 10.11781/sysydz202002202HU Chaowei, HU Guang, ZHANG Xihua, et al. Sedimentary environment, hydrocarbon potential and development of black rocks in Upper Maokou Formation, northwestern Sichuan[J]. Petroleum Geology & Experiment, 2020, 42(2): 202-214. doi: 10.11781/sysydz202002202 [2] PANG Qian, ZHANG Xihua, CHEN Cong, et al. Extraordinarily high organic matter enrichment during the Late Guadalupian in northwestern Sichuan Basin, China[J]. Journal of Petroleum Science and Engineering, 2022, 210: 110058. doi: 10.1016/j.petrol.2021.110058 [3] 韩月卿, 李双建, 韩文彪, 等. 川东南地区中二叠统茅口组灰泥灰岩储层孔隙特征[J]. 石油实验地质, 2022, 44(4): 666-676. doi: 10.11781/sysydz202204666HAN Yueqing, LI Shuangjian, HAN Wenbiao, et al. Pore characteristics of marl reservoir in Maokou Formation of Middle Permian, southeastern Sichuan Basin[J]. Petroleum Geology & Experiment, 2022, 44(4): 666-676. doi: 10.11781/sysydz202204666 [4] 胡东风, 王良军, 张汉荣, 等. 碳酸盐岩烃源岩气藏的发现及其油气地质意义: 以四川盆地涪陵地区中二叠统茅口组一段气藏为例[J]. 天然气工业, 2020, 40(7): 23-33. doi: 10.3787/j.issn.1000-0976.2020.07.003HU Dongfeng, WANG Liangjun, ZHANG Hanrong, et al. Discovery of carbonate source rock gas reservoir and its petroleum geolo-gicalimplications: a case study of the gas reservoir in the firs t member of Middle Permian Maokou Formation in the Fuling area, Sichuan Basin[J]. Natural Gas Industry, 2020, 40(7): 23-33. doi: 10.3787/j.issn.1000-0976.2020.07.003 [5] 杨明磊, 诸丹诚, 李涛, 等. 川南地区中二叠统茅口组颗粒滩对早成岩期岩溶储层的控制[J]. 现代地质, 2020, 34(2): 356-369. https://www.cnki.com.cn/Article/CJFDTOTAL-XDDZ202002016.htmYANG Minglei, ZHU Dancheng, LI Tao, et al. Control of eogenetic karst reservoir by shoals in Middle Permian Maokou Formation, southern Sichuan Basin[J]. Geoscience, 2020, 34(2): 356-369. https://www.cnki.com.cn/Article/CJFDTOTAL-XDDZ202002016.htm [6] 王兴志, 李博, 杨西燕, 等. 四川盆地北部中二叠世晚期"广元—旺苍"海槽特征及其油气地质意义[J]. 石油勘探与开发, 2021, 48(3): 562-574. https://www.cnki.com.cn/Article/CJFDTOTAL-SKYK202103012.htmWANG Xingzhi, LI Bo, YANG Xiyan, et al. Characteristics of "Guangyuan-Wangcang" trough during Late Middle Permian and its petroleum geological significance in northern Sichuan Basin, SW China[J]. Petroleum Exploration and Development, 2021, 48(3): 562-574. https://www.cnki.com.cn/Article/CJFDTOTAL-SKYK202103012.htm [7] 何登发, 李德生, 张国伟, 等. 四川多旋回叠合盆地的形成与演化[J]. 地质科学, 2011, 46(3): 589-606. doi: 10.3969/j.issn.0563-5020.2011.03.001HE Dengfa, LI Desheng, ZHANG Guowei, et al. Formation and evolution of multi-cycle superposed Sichuan Basin, China[J]. Chinese Journal of Geology, 2011, 46(3): 589-606. doi: 10.3969/j.issn.0563-5020.2011.03.001 [8] 罗志立. 峨眉地裂运动和四川盆地天然气勘探实践[J]. 新疆石油地质, 2009, 30(4): 419-424. https://www.cnki.com.cn/Article/CJFDTOTAL-XJSD200904008.htmLUO Zhili. Emei taphrogenesis and natural gas prospecting practices in Sichuan Basin[J]. Xinjiang Petroleum Geology, 2009, 30(4): 419-424. https://www.cnki.com.cn/Article/CJFDTOTAL-XJSD200904008.htm [9] 田景春, 曾允孚. 中国南方二叠纪古海洋锶同位素演化[J]. 沉积学报, 1995, 13(4): 125-130. https://www.cnki.com.cn/Article/CJFDTOTAL-CJXB504.013.htmTIAN Jingchun, ZENG Yunfu. The revolution of the isotopic composition of strontium in the Permian Paleo-ocean in South China[J]. Acta Sedimentologica Sinica, 1995, 13(4): 125-130. https://www.cnki.com.cn/Article/CJFDTOTAL-CJXB504.013.htm [10] 胡世忠. 论东吴运动构造事件与二叠系分统界线问题[J]. 地层学杂志, 1994, 18(4): 309-315. https://www.cnki.com.cn/Article/CJFDTOTAL-DCXZ404.015.htmHU Shizhong. On the event of Dongwu movement and its relation with Permian subdivision[J]. Journal of Stratigraphy, 1994, 18(4): 309-315. https://www.cnki.com.cn/Article/CJFDTOTAL-DCXZ404.015.htm [11] 刘树根, 童崇光, 罗志立, 等. 川西晚三叠世前陆盆地的形成与演化[J]. 天然气工业, 1995, 15(2): 11-15. doi: 10.3321/j.issn:1000-0976.1995.02.001LIU Shugen, TONG Chongguang, LUO Zhili, et al. The formation and evolution of Late Triassic Foreland Basin in west Sichuan[J]. Natural Gas Industry, 1995, 15(2): 11-15. doi: 10.3321/j.issn:1000-0976.1995.02.001 [12] 梁兴, 徐政语, 栗维民, 等. 蜀南—渝西地区中二叠统茅一段灰质源岩气储层特征及主控因素: 以DB1井为例[J]. 石油实验地质, 2023, 45(4): 714-725. doi: 10.11781/sysydz202304714LIANG Xing, XU Zhengyu, LI Weimin, et al. Characteristics and main controlling factors of the limy source rock gas reservoir in the first member of the Middle Permian Maokou Formation in the southern Sichuan and western Chongqing area: a case study of well DB 1[J]. Petroleum Geology & Experiment, 2023, 45(4): 714-725. doi: 10.11781/sysydz202304714 [13] 汪泽成, 江青春, 黄士鹏, 等. 四川盆地中二叠统茅口组天然气大面积成藏的地质条件[J]. 天然气工业, 2018, 38(1): 30-38. https://www.cnki.com.cn/Article/CJFDTOTAL-TRQG201801007.htmWANG Zecheng, JIANG Qingchun, HUANG Shipeng, et al. Geolo-gical conditions for massive accumulation of natural gas in the Mid-Permian Maokou Fm of the Sichuan Basin[J]. Natural Gas Industry, 2018, 38(1): 30-38. https://www.cnki.com.cn/Article/CJFDTOTAL-TRQG201801007.htm [14] 江青春, 胡素云, 姜华, 等. 四川盆地中二叠统茅口组地层缺失量计算及成因探讨[J]. 天然气工业, 2018, 38(1): 21-29. https://www.cnki.com.cn/Article/CJFDTOTAL-TRQG201801006.htmJIANG Qingchun, HU Suyun, JIANG Hua, et al. Calculation and inducement of lacuna in the Mid-Permian Maokou Fm of the Sichuan Basin[J]. Natural Gas Industry, 2018, 38(1): 21-29. https://www.cnki.com.cn/Article/CJFDTOTAL-TRQG201801006.htm [15] 沈树忠, 王玥, 金玉玕. 二叠系全球界线层型和点位(GSSP)研究进展[J]. 地层学杂志, 2005, 29(2): 138-146. doi: 10.3969/j.issn.0253-4959.2005.02.009SHEN Shuzhong, WANG Yue, JIN Yugan. Progress report on the global stratotype sections and points (GSSPs) of the Permin system[J]. Journal of Stratigraphy, 2005, 29(2): 138-146. doi: 10.3969/j.issn.0253-4959.2005.02.009 [16] SHEN Shuzhong, ZHANG Hua, ZHANG Yichun, et al. Permian integrative stratigraphy and timescale of China[J]. Science China Earth Sciences, 2019, 62(1): 154-188. doi: 10.1007/s11430-017-9228-4 [17] 邱威挺, 古鸿信. 试论川东北地区下二叠统孤峰组燧石(硅质岩)的沉积环境[J]. 岩相古地理, 1991(6): 1-8. https://www.cnki.com.cn/Article/CJFDTOTAL-TTSD199106000.htmQIU Weiting, GU Hongxin. Sedimentary environments of the chert (siliceous rocks) from the Lower Permian Gufeng Formation in northeastern Sichuan[J]. Lithofacies Paleogeography, 1991(6): 1-8. https://www.cnki.com.cn/Article/CJFDTOTAL-TTSD199106000.htm [18] 高平, 李双建, 何治亮, 等. 四川盆地广元—梁平古裂陷构造—沉积演化[J]. 石油与天然气地质, 2020, 41(4): 784-799. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT202004013.htmGAO Ping, LI Shuangjian, HE Zhiliang, et al. Tectonic-sedimentary evolution of Guangyuan-Liangping paleo-rift in Sichuan Basin[J]. Oil & Gas Geology, 2020, 41(4): 784-799. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT202004013.htm [19] 彭金宁, 杜崇娇, 李龙龙, 等. 四川盆地中二叠世岩相古地理及其油气地质意义[J]. 石油实验地质, 2023, 45(1): 49-59. doi: 10.11781/sysydz202301049PENG Jinning, DU Chongjiao, LI Longlong, et al. Lithofacies palaeogeography of Middle Permian in the Sichuan Basin and its petroleum geological significance[J]. Petroleum Geology & Experiment, 2023, 45(1): 49-59. doi: 10.11781/sysydz202301049 [20] JONES D L, MURCHEY B. Geologic significance of Paleozoic and Mesozoic radiolarian chert[J]. Annual Review of Earth and Planetary Sciences, 1986, 14: 455-492. doi: 10.1146/annurev.ea.14.050186.002323 [21] 史晓颖, 梅仕龙, 孙岩, 等. 黔南斜坡相区二叠系层序地层序列及其年代地层对比[J]. 现代地质, 1999, 13(1): 1-10. https://www.cnki.com.cn/Article/CJFDTOTAL-XDDZ901.000.htmSHI Xiaoying, MEI Shilong, SUN Yan, et al. Permian sequence successions of slope facies in southern Guizhou and their chronostratigraphic correlation[J]. Geoscience, 1999, 13(1): 1-10. https://www.cnki.com.cn/Article/CJFDTOTAL-XDDZ901.000.htm [22] BURCHETTE T P, WRIGHT V P. Carbonate ramp depositional systems[J]. Sedimentary Geology, 1992, 79(1/4): 3-57. [23] HAQ B U, SCHUTTER S R. A chronology of Paleozoic sea-level changes[J]. Science, 2008, 322(5898): 64-68. doi: 10.1126/science.1161648 [24] PANG Qian, HU Guang, ZHANG Xihua, et al. Organic geoche-mistry, sedimentary environment, and organic matter enrichment of limestone-marlstone rhythms in the Middle Permian northern Sichuan Basin, China[J]. Marine and Petroleum Geology, 2021, 134: 105306. doi: 10.1016/j.marpetgeo.2021.105306 [25] 王成善, 李祥辉, 陈洪德, 等. 中国南方二叠纪海平面变化及升降事件[J]. 沉积学报, 1999, 17(4): 536-541. https://www.cnki.com.cn/Article/CJFDTOTAL-CJXB199904004.htmWANG Chengshan, LI Xianghui, CHEN Hongde, et al. Permian sea-level changes and rising-falling events in South China[J]. Acta Sedimentologica Sinica, 1999, 17(4): 536-541. https://www.cnki.com.cn/Article/CJFDTOTAL-CJXB199904004.htm [26] 江青春, 胡素云, 汪泽成, 等. 四川盆地茅口组风化壳岩溶古地貌及勘探选区[J]. 石油学报, 2012, 33(6): 949-960. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB201206006.htmJIANG Qingchun, HU Suyun, WANG Zecheng, et al. Paleokarst landform of the weathering crust of Middle Permian Maokou Formation in Sichuan Basin and selection of exploration regions[J]. Acta Petrolei Sinica, 2012, 33(6): 949-960. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB201206006.htm [27] 梅庆华, 何登发, 文竹, 等. 四川盆地乐山—龙女寺古隆起地质结构及构造演化[J]. 石油学报, 2014, 35(1): 11-25. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB201401002.htmMEI Qinghua, HE Dengfa, WEN Zhu, et al. Geologic structure and tectonic evolution of Leshan-Longnvsi paleo-uplift in Sichuan Basin, China[J]. Acta Petrolei Sinica, 2014, 35(1): 11-25. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB201401002.htm