石油与天然气地质 ›› 2024, Vol. 45 ›› Issue (5): 1275-1288.doi: 10.11743/ogg20240506

• 油气地质 • 上一篇    下一篇

干旱型浅水三角洲沉积特征及沉积模式

宋璠1(), 孔庆圆1, 张学才2, 曹海防2, 焦国华3, 杨悦1   

  1. 1.深层油气全国重点实验室(中国石油大学(华东),山东 青岛 266580
    2.中国石化 胜利油田分公司 西部油气勘探项目部,山东 东营 257017
    3.中国石化 新疆新春石油开发有限责任公司,山东 东营 257017
  • 收稿日期:2024-03-18 修回日期:2024-07-17 出版日期:2024-10-30 发布日期:2024-11-06
  • 第一作者简介:宋璠(1982—),男,博士、副教授,沉积储层、油藏描述。E-mail:songfan0026@163.com
  • 基金项目:
    国家自然科学基金项目(41702158);山东省自然科学基金项目(ZR2022MD014)

Sedimentary characteristics and models of shallow-water deltas in arid settings: A case study of the Jurassic Qigu Formation in the Yongjin area within the hinterland of the Junggar Basin

Fan SONG1(), Qingyuan KONG1, Xuecai ZHANG2, Haifang CAO2, Guohua JIAO3, Yue YANG1   

  1. 1.State Key Laboratory of Deep Oil and Gas,China University of Petroleum (East China),Qingdao,Shandong 266580,China
    2.Western Oil and Gas Exploration Project Department,Shengli Oilfield Branch Company,SINOPEC,Dongying,Shandong 257017,China
    3.Xinjiang Xinchun Petroleum Development Co. ,Ltd. ,SINOPEC,Dongying,Shandong 257017,China
  • Received:2024-03-18 Revised:2024-07-17 Online:2024-10-30 Published:2024-11-06

摘要:

浅水三角洲是沉积学研究领域的热点,但是干旱气候背景、水体间歇振荡、沉积特征与沉积过程较为复杂的浅水三角洲研究报道较少。综合利用岩心、测井、分析化验和地震等资料,根据现代沉积分析与沉积数值模拟,对准噶尔盆地腹部永进地区侏罗系齐古组开展系统的沉积相研究,建立了齐古组沉积模式。研究表明:① 中-晚侏罗世准噶尔盆地气候转为干旱,齐古组沉积水体变浅且频繁振荡, 1砂组—3砂组发育浅水辫状河三角洲沉积,4砂组物源供给减弱、气候持续干旱,沉积相转变为曲流河三角洲。② 与湿润气候背景下的浅水三角洲相比干旱型浅水三角洲,水下分流河道变化较快,随着河道延伸逐渐分叉、改道出多种类型的河道砂。三角洲砂体颜色呈红灰间互的变化规律,砂岩岩性较细、成熟度低、分布规模不大。持续干旱的气候条件导致湖盆可容空间不断减小,三角洲朵叶体中几乎不发育河口砂坝,沉积砂体主要为多种形态类型的水下分流河道砂。③ 单一供给河道控制的沉积体规模有限且顺水流方向分异明显,发育高能水下主干河道、中-高能网状分流河道和低能改造型分流河道3种沉积微相。单砂体间连通性较差、储集空间非均质性强,油气勘探开发难度大。

关键词: 干旱气候, 沉积模式, 浅水三角洲, 齐古组, 侏罗系, 永进地区, 准噶尔盆地

Abstract:

Shallow-water deltas represent a hot research topic in sedimentology. However, there is a lack of studies and reports on shallow-water deltas featuring an arid climate, intermittently oscillating water bodies, and complex sedimentary characteristics and processes. Using data from core observation, logging, analyses, assays, and seismic surveys, along with modern analogs and sedimentary numerical simulations, we systematically investigate the sedimentary facies of the Jurassic Qigu Formation (J3q) in the Yongjin area within the hinterland of the Junggar Basin. Accordingly, the sedimentary models of the shallow-water deltas formed in arid settings (also referred to as arid shallow-water deltas) in the J3q are established. The results indicate that as the Junggar Basin’s climate grew to be arid during the Middle-to-Late Jurassic, the sedimentary water bodies in the J3q became shallow and oscillated frequently. Consequently, shallow-water braided river deltas were deposited in sand sets 1‒3 of this formation. In contrast, the sedimentary facies of sand set 4 of the formation shifted to meandering-river deltas due to reduced provenance supply and persistent drought. In contrast, shallow-water deltas formed in a humid climate frequently feature rapidly varying subaqueous distributary channels, with various channel sand sets coming into being as the channels gradually bifurcated and diverted while extending. These deltaic sand bodies display alternating red and gray colors, with sandstones proving fine-grained, low-maturity, and locally distributed. Persistent drought leads to a constant decrease in the lacustrine basin accommodation space. As a result, mouth sandbars are rarely found in the deltaic lobes, and the sedimentary sand bodies are dominated by subaqueous distributary channel sands of various morphologies. The sedimentary bodies with single-channel provenance supply exhibit limited scales and pronounced lithofacies differentiation along water flow directions, leading to the development of three sedimentary microfacies: high-energy subaqueous trunk channels, medium- to high-energy reticular distributary channels, and low-energy modified distributary channels. The low connectivity among individual sand bodies and the strong heterogeneity of storage spaces complicate the hydrocarbon exploration and production in arid shallow-water deltas.

Key words: arid climate, sedimentary model, shallow-water delta, Qigu Formation (J3q), Jurassic, Yongjin area, Junggar Basin

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