石油与天然气地质 ›› 2021, Vol. 42 ›› Issue (5): 1146-1158.doi: 10.11743/ogg20210512

• 油气地质 • 上一篇    下一篇

鄂尔多斯盆地临兴区块上古生界致密砂岩气藏成藏条件及主控因素

刘畅1(), 张道旻2, 李超2, 路媛媛1, 于姗姗2, 郭明强1   

  1. 1. 中联煤层气有限责任公司, 北京 100011
    2. 中海油研究总院有限责任公司, 北京 100028
  • 收稿日期:2020-07-28 出版日期:2021-10-28 发布日期:2021-10-26
  • 作者简介:刘畅(1989-), 男, 博士、工程师, 石油地质。E-mail: liuchang23@cnooc.com.cn
  • 基金资助:
    中国海油重大项目(CNOOC-KJZDXM14)

Upper Paleozoic tight gas sandstone reservoirs and main controls, Linxing block, Ordos Basin

Chang Liu1(), Daomin Zhang2, Chao Li2, Yuanyuan Lu1, Shanshan Yu2, Mingqiang Guo1   

  1. 1. China United Coalbed Methane Corporation Ltd., CNOOC, Beijing 100011, China
    2. Research Institute Corporation Ltd., CNOOC, Beijing 100028, China
  • Received:2020-07-28 Online:2021-10-28 Published:2021-10-26

摘要:

鄂尔多斯盆地东缘临兴区块上古生界致密砂岩气资源潜力巨大,多层系发育优质气层,预测致密砂岩气资源量超千亿方,但构造背景特殊、储层非均质性强,造成气-水分布规律复杂,成藏地质条件及主控因素复杂多变,勘探开发难度较大。立足于系统梳理临兴区块致密砂岩气藏成藏条件,从平面上沉积模式、垂向上的生-储-盖组合及其耦合关系、时空上的气-水分布规律和天然气成藏过程中的差异聚集特征入手,揭示研究区整体非均质性背景下的差异富集规律,指导鄂尔多斯东缘千亿方大气田的勘探及高效开发。明确了烃源岩-储层-输导体系的配置关系:煤系烃源岩有机质丰度高,生烃潜力好,为大气田的形成奠定了基础;断裂的适度发育纵向沟通了煤系烃源岩及海相障壁海岸-潮坪及陆相河流-浅水三角洲沉积体系的砂岩储层,纵向上构成了下部源内、中部近源和上部远源3套成藏组合。深化了储层致密化成因及致密砂岩气成岩-成藏耦合关系,指出致密砂岩气藏具有“先致密后成藏”的特征。剖析了致密砂岩气藏天然气运移聚集机制,认为烃源岩生烃形成的超压是天然气运移的主要动力。建立了充足气源条件下、不同构造区带的多层系准连续选择性成藏模式,提出致密砂岩气具有“烃源控潜、构造控区、微相控储、物性控藏”的特点。天然气在烃源岩大量持续生烃背景下,优先选择断裂适度发育,构造活动强度适中,有利砂体及高渗物性条件背景下聚集成藏。

关键词: 成藏条件, 差异成藏机理, 成藏模式, 致密砂岩气藏, 上古生界, 临兴区块, 鄂尔多斯盆地

Abstract:

The Upper Palaeozoic tight sandstone in the Linxing block at the east margin of Ordos Basin is estimated to have a great gas potential of over 100 BCM.However, complex gas-water distribution by highly heterogeneous reservoirs against a special structural background and changing reservoir-forming settings with controls hinder the gas exploration and development in the block.From a perspective of tight sandstone gas reservoiring conditions, this study starts from establishing lateral sedimentary models, analyzing the vertical coupling relationship between source rocks, reservoirs and cap rocks, to summarizing the gas-water spatial-temporal distribution pattern and differential characteristics of gas accumulation process.The differential enrichment law in the block revealed throught the study can be used to guide an effective release of the huge gas potential from the east margin of Ordos Basin.The configuration of source rocks, reservoirs and carrier beds is defined as that the coal-measure source rocks characterized by high organic matter abundance and hydrocarbon generation potential is connected vertically with the sandstone reservoirs of marine barrier-coast tidal flat facies and continental rivers-shallow delta facies via the moderately developed faults, thus vertically constituting three plays that can be described as lower indigenous play, middle near-source rock play and upper far-source rock play.The study proposes that tight sandstone gas reservoirs in the block are formed after tightening-up process based on a deeper understanding of tightening-up mechanism of sandstone reservoirs and the coupling relationship between diagenesis and reservoir-forming.It suggests that it is overpressure that drives the gas to migrate after analyzing the migration and accumulation mechanism.It establishes a quasi-continuous selective accumulation model of multi-layer systems in different structural zones with sufficient gas source.It also summarizes the main controlling factors of multi-layer system and boils down the characteristics of the reservoirs as "source rock controlling gas potential, structure controlling play, micro-phase controlling reservoir, and physical property controlling accumulation".It finally concludes that high volume of gas continuously gushed from source rocks would preferentially migrate to and accumulate in areas with the right faults and high permeability sand bodies as well as moderate tectonic activities.

Key words: accumulation condition, differential accumulation mechanism, accumulation mode, tight sand gas, Upper Paleozoic, Linxing Block, Ordos Basin

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