川北地区下寒武统龙王庙组沉积相及与储层的关系
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摘要
以四川盆地北部下寒武统龙王庙组为研究对象,利用野外露头、测井及岩心等资料,探讨了川北地区下寒武统龙王庙组的沉积相类型及特征,并分析了其对储层的影响。研究认为:川北地区在早寒武世龙王庙期的沉积环境为碳酸盐台地,发育潮坪、局限台地和开阔台地等3种相带,这些相带又进一步细分为混积潮坪、台内点滩、潟湖和滩间海等4种亚相。其中,混积潮坪亚相主要发育砂质白云岩坪、白云岩坪等,部分地区可见潮道;台内点滩亚相以砂屑白云岩最为常见,沉积厚度不大;潟湖亚相以白云质潟湖沉积和白云质灰质潟湖沉积为主,分布面积大;滩间海亚相沉积物以深灰色块状石灰岩为主,局部夹白云质豹斑灰岩。纵向上,大部分地区龙王庙组沉积由2次海退旋回构成,潟湖主要发育在单个沉积旋回的中下部;台内点滩主要发育在沉积旋回的中、上部,单个滩体厚度较薄;混积潮坪发育在旋回顶部,即旋回末期。平面上,由于受古陆影响,研究区自西向东具有物源供应减少、沉积水体逐渐变深,以及沉积相从潮坪—局限台地—开阔台地过渡的特征,台内点滩主要围绕局限潟湖分布。结合不同沉积相带储层物性的分析,认为台内点滩的颗粒白云岩储集性能最好,晶粒白云岩次之,膏盐岩最差。龙王庙组储层发育的最有利沉积环境为台内点滩。
Based on the analysis of field outcrops, well logging and core data, the sedimentary facies types and features of the Lower Cambrian Longwangmiao Formation in northern Sichuan Basin are discussed, and their influences on reservoirs are analyzed. During Early Cambrian Longwangmiao period, the sedimentary environment in northern Sichuan Basin was carbonate platform, which developed three types of facies including tidal flat, restricted platform and open platform, which were further subdivided into four types of subfacies: mixed tidal flat, intra-platform shoal, lagoon and interbank sea. The mixed tidal flat was mainly composed of sandy dolomite and dolomite, and tidal channels were visible in some areas. The intra-platform shoal was mainly composed of doloarenite with small deposition thickness. The lagoon mainly consisted of dolomite lagoon and dolomiticlimy lagoon with large distribution area. The deposition of interbank sea was mainly composed of dark gray massive limestone with intercalated dolomitic mottled limestone. The Longwangmiao period is composed of two regressive cycles in most areas,and lagoon mainly developed in the middle and lower part of a single sedimentary cycle, and intra-platform shoal mainly developed in the middle and upper part of a sedimentary cycle with thin single layer, and the mixed tidal flat mainly developed at the top of a sedimentary cycle. Due to the influence of paleocontinents, the sediment source supply decreased and the water depth gradually deepened, and the sedimentary facies translated from tidal flat to restricted platform to open platform successively from west to east in the study area. The intra-platform shoal mainly distributed around the restricted lagoon. Combined with the analysis of reservoir property of different sedimentary faces, it is concluded that grain dolomite depositing on the intraplatform shoal have the best reservoir property, followed by the crystalline dolomite, and the gypsum was the worst. Therefore,the most favorable sedimentary environment for reservoir development in Longwangmiao Formation is intra-platform shoal.
Based on the analysis of field outcrops, well logging and core data, the sedimentary facies types and features of the Lower Cambrian Longwangmiao Formation in northern Sichuan Basin are discussed, and their influences on reservoirs are analyzed. During Early Cambrian Longwangmiao period, the sedimentary environment in northern Sichuan Basin was carbonate platform, which developed three types of facies including tidal flat, restricted platform and open platform, which were further subdivided into four types of subfacies: mixed tidal flat, intra-platform shoal, lagoon and interbank sea. The mixed tidal flat was mainly composed of sandy dolomite and dolomite, and tidal channels were visible in some areas. The intra-platform shoal was mainly composed of doloarenite with small deposition thickness. The lagoon mainly consisted of dolomite lagoon and dolomiticlimy lagoon with large distribution area. The deposition of interbank sea was mainly composed of dark gray massive limestone with intercalated dolomitic mottled limestone. The Longwangmiao period is composed of two regressive cycles in most areas,and lagoon mainly developed in the middle and lower part of a single sedimentary cycle, and intra-platform shoal mainly developed in the middle and upper part of a sedimentary cycle with thin single layer, and the mixed tidal flat mainly developed at the top of a sedimentary cycle. Due to the influence of paleocontinents, the sediment source supply decreased and the water depth gradually deepened, and the sedimentary facies translated from tidal flat to restricted platform to open platform successively from west to east in the study area. The intra-platform shoal mainly distributed around the restricted lagoon. Combined with the analysis of reservoir property of different sedimentary faces, it is concluded that grain dolomite depositing on the intraplatform shoal have the best reservoir property, followed by the crystalline dolomite, and the gypsum was the worst. Therefore,the most favorable sedimentary environment for reservoir development in Longwangmiao Formation is intra-platform shoal.
引文
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[16]杨雪飞,王兴志,杨跃明,等.川中地区下寒武统龙王庙组白云岩储层成岩作用[J].地质科技情报,2015,34(1):35-41.
[17]XIAO Di, TAN Xiucheng, XI Aihua, et al. An inland faciescontrolled eogenetic karst of the carbonate reservoir in the Middle Permian Maokou Formation, southern Sichuan Basin, SW China[J]. Marine and petroleum geology, 2016, 72:218-233.
[18]冯增昭,彭勇民,金振奎,等.中国南方寒武纪和奥陶纪岩相古地理[M].北京:地质出版社,2001:2,87-101.
[19]马腾,谭秀成,李凌,等.四川盆地早寒武世龙王庙期沉积特征与古地理[J].沉积学报,2016,34(1):33-48.
[20]李皎,何登发.四川盆地及邻区寒武纪古地理与构造-沉积环境演化[J].古地理学报,2014,16(4):441-460.
[21]杨威,谢武仁,魏国齐,等.四川盆地寒武纪—奥陶纪层序岩相古地理、有利储层展布与勘探区带[J].石油学报,2012,33(增刊2):21-34.
[22]周慧,李伟,张宝民,等.四川盆地震旦纪末期—寒武纪早期台盆的形成与演化[J].石油学报,2015,36(3):310-323.
[23]四川油气区石油地质志编写组.中国石油地质志(卷十):四川油气区[M].北京:石油工业出版社, 1989:80-109.
[24]冯增昭.单因素分析多因素综合作图法:定量岩相古地理重建[J].古地理学报,2004,6(1):3-19.
[25]张满郎,谢增业,李熙喆,等.四川盆地寒武纪岩相古地理特征[J].沉积学报,2010,28(1):128-139.
[2]沈安江,陈娅娜,潘立银,等.四川盆地下寒武统龙王庙组沉积相与储层分布预测研究[J].天然气地球科学,2017,28(8):1176-1190.
[3]魏国齐,杨威,谢武仁,等.四川盆地震旦系—寒武系大气田形成条件、成藏模式与勘探方向[J].天然气地球科学,2015,26(5):785-795.
[4]周进高,徐春春,姚根顺,等.四川盆地下寒武统龙王庙组储集层形成与演化[J].石油勘探与开发,2015,42(2):158-166.
[5]杜金虎,张宝民,汪泽成,等.四川盆地下寒武统龙王庙组碳酸盐缓坡双颗粒滩沉积模式及储层成因[J].天然气工业,2016,36(6):1-10.
[6]杨雪飞,王兴志,唐浩,等.四川盆地中部磨溪地区龙王庙组沉积微相研究[J].沉积学报,2015,33(5):972-982.
[7]赵文智,沈安江,胡安平,等.塔里木、四川和鄂尔多斯盆地海相碳酸盐岩规模储层发育地质背景初探[J].岩石学报,2015,31(11):3495-3508.
[8]朱祥,李毕松,梁子锐,等.四川盆地龙王庙期岩相古地理及有利相带特征[J].天然气技术与经济,2015,9(6):5-8.
[9]王龙,沈安江,陈宇航,等.四川盆地下寒武统龙王庙组岩相古地理特征和沉积模式[J].海相油气地质,2016,21(3):13-21.
[10]代林呈,朱祥,李毕松,等.川东地区龙王庙组颗粒滩发育特征及分布规律[J].地质科技情报,2017,36(6):181-189.
[11]杨雪飞,王兴志,代林呈,等.川中地区下寒武统龙王庙组沉积相特征[J].岩性油气藏,2015,27(1):95-101.
[12]姚根顺,周进高,邹伟宏,等.四川盆地下寒武统龙王庙组颗粒滩特征及分布规律[J].海相油气地质,2013,18(4):1-8.
[13]沈安江,佘敏,胡安平,等.海相碳酸盐岩埋藏溶孔规模与分布规律初探[J].天然气地球科学,2015,26(10):1823-1830.
[14]朱东亚,张殿伟,李双建,等.四川盆地下组合碳酸盐岩多成因岩溶储层发育特征及机制[J].海相油气地质,2015,20(1):33-44.
[15]刘树根,宋金民,赵异华,等.四川盆地龙王庙组优质储层形成与分布的主控因素[J].成都理工大学学报(自然科学版),2014,41(6):657-670.
[16]杨雪飞,王兴志,杨跃明,等.川中地区下寒武统龙王庙组白云岩储层成岩作用[J].地质科技情报,2015,34(1):35-41.
[17]XIAO Di, TAN Xiucheng, XI Aihua, et al. An inland faciescontrolled eogenetic karst of the carbonate reservoir in the Middle Permian Maokou Formation, southern Sichuan Basin, SW China[J]. Marine and petroleum geology, 2016, 72:218-233.
[18]冯增昭,彭勇民,金振奎,等.中国南方寒武纪和奥陶纪岩相古地理[M].北京:地质出版社,2001:2,87-101.
[19]马腾,谭秀成,李凌,等.四川盆地早寒武世龙王庙期沉积特征与古地理[J].沉积学报,2016,34(1):33-48.
[20]李皎,何登发.四川盆地及邻区寒武纪古地理与构造-沉积环境演化[J].古地理学报,2014,16(4):441-460.
[21]杨威,谢武仁,魏国齐,等.四川盆地寒武纪—奥陶纪层序岩相古地理、有利储层展布与勘探区带[J].石油学报,2012,33(增刊2):21-34.
[22]周慧,李伟,张宝民,等.四川盆地震旦纪末期—寒武纪早期台盆的形成与演化[J].石油学报,2015,36(3):310-323.
[23]四川油气区石油地质志编写组.中国石油地质志(卷十):四川油气区[M].北京:石油工业出版社, 1989:80-109.
[24]冯增昭.单因素分析多因素综合作图法:定量岩相古地理重建[J].古地理学报,2004,6(1):3-19.
[25]张满郎,谢增业,李熙喆,等.四川盆地寒武纪岩相古地理特征[J].沉积学报,2010,28(1):128-139.