石油学报 ›› 2011, Vol. 32 ›› Issue (1): 70-76.DOI: 10.7623/syxb201101010

• 地质勘探 • 上一篇    下一篇

四川盆地雷口坡组台内滩与台缘滩沉积特征差异及对储层的控制

李  凌 1  谭秀成 1  丁  熊 1  吴晓庆 1  邹  春 1  周素彦 1  黄先平 2  石学文 2   

  1. 1西南石油大学资源与环境学院  四川成都  610500; 2中国石油西南油气田分公司勘探开发研究院  四川成都  610051
  • 收稿日期:2010-06-25 修回日期:2010-09-20 出版日期:2011-01-25 发布日期:2011-03-23
  • 通讯作者: 李 凌
  • 作者简介:李 凌,女,1973年6月生,2010年获西南石油大学博士学位,现为西南石油大学副教授,长期从事储层沉积学的教学与科研工作。
  • 基金资助:

    四川省教育厅省级重点学科建设项目(SZD0414)资助。

Difference in depositional characteristics between intra-platform and marginal-platform shoals in Leikoupo Formation, Sichuan Basin and its impact on reservoirs

LI Ling 1  TAN Xiucheng 1  DING Xiong 1  WU Xiaoqing 1  ZOU Chun 1  ZHOU Suyan 1  HUANG Xianping 2  SHI Xuewen 2   

  • Received:2010-06-25 Revised:2010-09-20 Online:2011-01-25 Published:2011-03-23

摘要:

四川盆地在中三叠统雷口坡组沉积时期处于局限—蒸发台地—台地边缘沉积环境,勘探实践证明雷口坡组的储层发育台内滩和台缘滩两类颗粒滩,不同类型的颗粒滩储层具有明显分异。通过对两类颗粒滩特征及形成条件的深入分析,指出台缘环境浪基面影响深度最大可达20m,沉积物可容空间大,形成的单滩体厚度大,早期暴露几率小,较大的上覆地层静压易使颗粒呈格架支撑,喉道减小,有利于滩体内部粒间孔保存,储集空间以(溶扩)残余粒间孔为主;而由于台缘环境的遮挡,台内环境的浪基面影响深度一般为2~3m,颗粒滩在局部微地貌高地发育,厚度较小,暴露几率大,早期大气淡水可影响单旋回台内滩中上部,储集空间以粒内溶孔和铸模孔为主。沉积环境形成的物质基础是后期成岩演化与孔隙演化的关键,影响了颗粒滩储层最终的储集面貌。

关键词: 四川盆地, 雷口坡组, 台内滩, 台缘滩, 碳酸盐岩, 储层成因

Abstract:

The Leikoupo Formation in Sichuan Basin was deposited in a restricted evaporative platform or margin platform environment. Exploration practice has indicated that in the Leikoupo reservoir developed two kinds of grain shoals, i.e. intra-platform shoal and marginal-platform shoal, which are distinctly different. With thorough analyses on characteristics and formation conditions of these two shoals, the present paper showed that the marginal-platform shoal had a wave base up to 20 m in maximum and a large available space for sediments, forming shoals with big thickness for an individual one and less exposure. Greater static pressure of overlying formations resulted readily in a trellis support for grains and the decreased throat port, favoring the preservation of intergranular space within shoals and the formation of reservoir space dominated by residual intergranular pores (dissolved enlargement). While the intra-platform shoal had a wave base ranging generally between 2~3 m due to a shelter of the marginal-platform environment and grain shoals developed in local micro-topographic highland with minor thickness and frequent exposure. Fresh water in the early atmosphere might influence the middle and upper parts of a mono-cyclic intra-platform shoal, resulting in the reservoir space dominated by intragranular karst and moldic pores.A material basis laid by environments is a key to diagenetic and porous evolutions at the late stage, exerting an effect on the final reservoir features of grain shoals.

Key words: Sichuan Basin, Leikoupo Formation, intra-platform shoal, marginal-platform shoal, carbonate rock, reservoir genesis