石油与天然气地质 ›› 2021, Vol. 42 ›› Issue (3): 627-638, 701.doi: 10.11743/ogg20210309

• 油气地质 • 上一篇    下一篇

四川盆地中部地区下寒武统龙王庙组混积特征及其地质意义

宋金民1(), 张亚雄2, 尹柯惟1,3, 刘树根1,4, 陈宗于5, 李智武1, 田艳红1,6, 孙玮1, 刘颖3, 金鑫1, 赵玲丽1   

  1. 1. 成都理工大学 油气藏地质及开发工程国家重点实验室, 四川 成都 610059
    2. 中国石化 石油勘探开发研究院, 北京 100083
    3. 中国石油 华北油田分公司 勘探开发研究院, 河北 任丘 062552
    4. 西华大学, 四川 成都 610039
    5. 中国石油 东方地球物理公司西南物探分公司, 四川 成都 610213
    6. 四川省地质矿产勘查开发局四零五地质队, 四川 成都 611830
  • 收稿日期:2018-10-10 出版日期:2021-06-28 发布日期:2021-06-23
  • 作者简介:宋金民(1983—),男,博士、副教授,碳酸盐岩沉积储层。E-mail: songjinmin@sohu.com
  • 基金资助:
    国家自然科学基金项目(41872150);国家自然科学基金项目(41472107);四川省科技厅重点研发项目(2018JZ0078);中石化前导性项目(P16109);成都理工大学中青年骨干教师培养基金项目(10912-KYGG201505)

Characteristics and geological significance of mixed sediments in the Lower Cambrian Longwangmiao Formation, central Sichuan Basin

Jinmin Song1(), Yaxiong Zhang2, Kewei Yin1,3, Shugen Liu1,4, Zongyu Chen5, Zhiwu Li1, Yanhong Tian1,6, Wei Sun1, Ying Liu3, Xin Jin1, Lingli Zhao1   

  1. 1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, Sichuan 610059, China
    2. Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China
    3. Exploration and Development Research Institute of Huabei Oilfield Company, PetroChina, Renqiu, Hebei 062552, China
    4. Xihua University, Chengdu, Sichuan 610039, China
    5. Southwest Branch Company of East Geophysical Company, CNPC, Chengdu, Sichuan 610213, China
    6. Sichuan Geology and Mineral Exploration and Development Bureau of 405 Geological Team, Chengdu, Sichuan 611830, China
  • Received:2018-10-10 Online:2021-06-28 Published:2021-06-23

摘要:

四川盆地中部地区下寒武统龙王庙组混合沉积较发育,但相关的研究和认识尚显薄弱。通过岩心观察描述和岩石学分析,对川中地区下寒武统龙王庙组混合沉积特征和地质意义进行研究。研究结果表明,研究区龙王庙组混合沉积主要为混积型碳酸盐岩,发育碳酸盐岩-混积岩层系与混积岩层系,具有渐变式混积和复合式Ⅱ型混积两种类型。纵向上,混合沉积受海平面变化控制,主要发育在三级海平面旋回的海侵期和海退早期,与风暴事件密切相关,且海侵期混积程度明显高于海退期;横向上,高石梯地区混积强度大于磨溪地区。通过四川盆地中部与北部地区龙王庙组混合沉积特征的对比,发现川北地区与古秦岭洋、摩天岭古陆相接,混积强度与混积颗粒粒度均大于川中地区,指示风暴潮流携带陆源碎屑经川北进入川中地区。四川盆地中部地区龙王庙组混积岩指示高石梯地区处于古地貌斜坡部位,粉砂级石英颗粒卸载形成混积中心。龙王庙组有利储层主要发育在弱混积或未混积颗粒滩微相中,混合沉积不利于优质储层的发育。

关键词: 混合沉积, 沉积环境, 地质意义, 龙王庙组, 寒武系, 四川盆地

Abstract:

The mixed siliciclastic and carbonate sediments that prevail the Lower Cambrian Longwangmiao Formation in the central Sichuan Basin are poorly understood.Their characteristics and geological significances are therefore focused in this study through core description and petrologic analysis.The results show that mixed carbonate-siliciclastic deposition dominates the formation as carbonate-mixed carbonate-siliciclastic sequences and mixed carbonate-siliciclasitic sequences in gradually mixing or type Ⅱ composite mixing styles.Vertically, the sediments are clearly storm-related and controlled by sea level variations in transgression and early regression stages of the third-order eustatic cycle with the mixing range much larger in transgression than that in regression stage.Horizontally, the sediments show higher mixing intensity in the Gaoshiti area than in the Moxi area.A characteristic comparison between the sediments of the formation in the central and northern Sichuan Basin reveals that sediments in the northern part of the basin have higher mixing intensity and greater granular size due to its adjacency to the Qinling Palaeocean and Motianling Palaeoland and a possible influx of terrigenous debris brought by storms through the north part to the center.The mixed sediments in the central Sichuan Basin indicate that Gaoshiti area was lying on a palaeo-slope where silty quartz grains were unloaded to form a mixing deposition center.It is also highly possible that quality reservoirs in the formation occur mostly in the weakly to non-mixing sediments of shoal facies, since highly mixed sediments are not suitable for the formation and development of such reservoirs.

Key words: mixed sediment, sedimentary setting, geological significance, Longwangmiao Formation, Cambrian, Sichuan Basin

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