石油与天然气地质 ›› 2021, Vol. 42 ›› Issue (4): 829-840, 862.doi: 10.11743/ogg20210405

• 油气地质 • 上一篇    下一篇

四川盆地川西坳陷上三叠统须家河组三段和五段“甜点”储层特征及分布

叶素娟(), 杨映涛, 张玲   

  1. 中国石化 西南油气分公司勘探开发研究院, 四川 成都 610041
  • 收稿日期:2020-10-18 出版日期:2021-08-28 发布日期:2021-08-27
  • 作者简介:叶素娟(1969-), 女, 博士、研究员, 储层地质与油气成藏。E-mail: sujuan_ye@hotmail.com
  • 基金资助:
    国家科技重大专项(2016ZX05002-004)

Characteristics and distribution of "sweet spot" reservoirs in the third and fifth members of Upper Triassic Xujiahe Formation, Western Sichuan Depression, Sichuan Basin

Sujuan Ye(), Yingtao Yang, Ling Zhang   

  1. Exploration and Production Research Institute, SINOPEC Southwest Oil&Gas Company, Chengdu, Sichuan 610041, China
  • Received:2020-10-18 Online:2021-08-28 Published:2021-08-27

摘要:

四川盆地川西坳陷须家河组三段和五段烃源岩厚度大、有机质丰度高,同时发育规模较大的三角洲分流河道和席状砂沉积,具有较好的源内成藏潜力。根据储层岩石学、微观孔隙结构和物性特征等方面的综合分析,结合录井与测井解释成果,系统研究了川西坳陷须三段和须五段“甜点”储层的特征、成因机制和分布规律。研究表明,川西坳陷须三段和须五段以三角洲前缘-滨浅湖细粒碎屑岩沉积为主,主要发育薄层砂岩型储层,但在成都凹陷南部地区须三段发育单层及累计厚度均较大的三角洲分流河道厚层砂岩型储层。薄层砂岩型储层岩石类型多样,沉积物粒度细,碳酸盐矿物和粘土含量较高,强烈的压实和胶结作用导致储层异常致密;“甜点”储层的形成主要受生烃作用、溶蚀作用和破裂作用控制,主要由富含有机质的泥页岩和中-细砂岩(高石英、低碳酸盐岩岩屑)组合形成。厚层砂岩型储层的储集空间类型以溶蚀孔隙和裂缝占主导,“甜点”储层形成主要受岩石粒度和易溶、脆性矿物组分含量以及溶蚀作用强度的控制,其中溶蚀作用是关键因素。龙门山中段和新场构造带以南地区须五段具有烃源岩品质较好、石英(长石、粘土矿物)含量较高、碳酸盐矿物含量较低的特点,有利于薄层砂岩型“甜点”储层的发育;成都凹陷南部须三段厚层砂岩型“甜点”储层主要分布在与泥页岩相邻(纵/侧向)的高石英(长石)中-粗砂岩中。

关键词: 陆相烃源岩, 成因机制, “甜点”储层, 须家河组, 川西坳陷, 四川盆地

Abstract:

The third and fifth members of Xujiahe Formation in Western Sichuan Depression are characterized by thick source rocks with high TOC and medium- to large-scale delta distributary channel and sheet sandstones of huge in-source accumulation potential.A systematic study was carried out on the characteristics, formation mechanism and distribution of "sweet spot" reservoirs in the two members based on an integration of petrography, pore structure, and petrophysical property analyses with well logging interpretations.The results show that fine-grained thin sandstone interbeds against a delta front to shore-shallow lacustrine environment dominate the two members, with the third member in southern Chengdu Sag containing some single- or multiple-layered thick sandstone against delta distributary channels.The thin sandstone reservoirs are characterized by diverse rock types, fine grain size, and high contents of clay matrix and carbonate minerals, and rather tight due to intensive compaction and carbonate cementation."Sweet spot" reservoirs in the thin sandstones are mainly the results of hydrocarbon generation, dissolution and fracturing processes.Assemblages of organic-rich shale and fine- to medium-grained sandstone with high content of quartz (feldspar) and small amount of carbonate debris (cement) are considered potential sweet spots.The thick sandstone reservoirs are dominated by secondary pores and fractures.Sweet spots are mostly controlled by granularity, the content of feldspar (quartz) and other soluble (brittle) minerals as well as dissolution intensity, of which the latter is the key factor.The fifth member in the south of Longmenshan front structural belt and Xinchang structural belt is most likely to contain thin sandstone sweet spots because of its high-quality source rocks, high content of quartz (feldspar and clay), and low content of carbonate minerals.While the third member in southern Chengdu Sag is ideal for the thick sandstone sweet spots to develop in quartz (feldspar)-rich medium- to coarse-grained sandstones adjacent to shales vertically and laterally.

Key words: continental source rock, formation mechanism, "sweet spot" reservoir, Xujiahe Formation, Western Sichuan Depression, Sichuan Basin

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