海拉尔盆地乌尔逊凹陷幔源CO_2充注对下白垩统砂岩储层质量的影响  

Impacts of mantle-genetic CO, influx on the reservoir quality of Lower Cretaceous sandstone from Wuerxun depression, Hailaer basin.

作　　者：刘立[1] 朱德丰[2] 曲希玉[1] 金镇龙[2] 王小琴[1] 董林森[1] 

机构地区：[1]吉林大学地球科学学院,长春130061 [2]大庆油田有限责任公司勘探开发研究院,大庆163712

出　　处：《岩石学报》2009年第10期2311-2319,共9页Acta Petrologica Sinica

基　　金：国家自然科学基金(批准号:40672074和40372060 );教育部高等学校博士学科点专项科研基金 (课题编号:20070183137)资助.

摘　　要：海拉尔盆地乌尔逊凹陷下白垩统含片钠铝石砂岩部分记录了幔源CO_2-砂岩相互作用历史。为揭示幔源CO_2充注对储层质量的影响,通过偏光显微镜、扫描电镜观察和孔隙度、渗透率数据研究了海拉尔盆地乌尔逊凹陷含片钠铝石砂岩的岩石学和储层特征。幔源CO_2的充注导致了长石的部分溶解和片钠铝石及铁白云石的沉淀。长石的溶解形成了次生孔隙。片钠铝石以针状晶形为特征,其集合体呈束状、簇状、扇状和玫瑰花状。部分片钠铝石呈板状。片钠铝石以充填孔隙为主,少量交代长石和其他骨架碎屑颗粒。片钠铝石局部被铁白云石交代,说明铁白云石的形成晚于片钠铝石。片钠铝石的含量为1%～20%。相同深度段的含片钠铝石砂岩(n=597,h=1309.15～2140.71m)与普通砂岩(n=1550,h=1323.72～2141.3m)的孔隙度、渗透率数据统计表明,含片钠铝石砂岩的物性整体上低于普通砂岩,说明CO_2的充注导致了储层质量的改变。片钠铝石含量-孔隙度和片钠铝石含量-渗透率之间的关系,揭示片钠铝石含量是引起储层质量改变的主要因素。片钠铝石含量10%似乎是储层质量发生变化的界限,当片钠铝石含量>10%,随片钠铝石含量增加,砂岩的孔隙度和渗透率降低;当片钠铝石含量<10%,随片钠铝石含量增加,部分砂岩的孔隙度和渗透率表现出增加趋势。作者认为,片钠铝石含量高的砂岩长期处于高CO_2分压成岩环境,而片钠铝石含量低的砂岩则处于高CO_2分压成岩环境的时间相对较短。The history of mantle-genetic CO2-sandstone interactions are partly recorded in the dawsonite-bearing sandstone from Wuerxun depression, Hailaer basin. The petrology and reservoir characteristics of dawsonite-bearing sandstone from Wuerxun depression, Hailaer basin have been investigated using polarizering microscope, scanning electron microscope and core analysis data of porosity and permeability to unravel effect of mantle-genetic CO2 influx on the reservoir quality. The mantle-genetic CO2 influx leads to the partly dissolution of feldspar and the precipitation of dawsonite as well as ankerite. The secondary porosity has been formed as a result of Vie feldspar dissolution. Dawsonite that filled pores and replaced feldspar and other framework grain is distinguished by its acicular habit, typically forming bundles, tufts, fans and rosetes. Locally, dawsonite also forms tabular crystals. Dawsonite is locally replaced by ankerite suggesting that dawsonite grew before ankerite. Dawsonite generally comprises 1% similar to 20% of the sandstone volume. The statistics of porosity and permeability measured from the dawsonite-bearing sandstone(n = 597, h = 1309.15 similar to 2140.71m) and common sandstone(n = 1550, h = 1323.72 similar to 2141.3m) with the almost same burial depth show that the reservoir quality of the dawsonite-bearing sandstone is lower than those of common sandstone as a whole suggesting that the mantle-genetic CO2 influx resulted in the change of reservoir quality. The plots of dawsonite volume versus porosity and permeability reveal that dawsonite volume is the main factor caused the change of reservoir quality. Dawsonite volume of 10% seems to a limit changed reservoir quality, when dawsonite volume > 10%, porosity and permeability of sandstone are reduced with the dawsonite volume increasing, when Dawsonite volume < 10%, porosity and permeability of some sandstones show the raising trend with the dawsonite volume increasing. Authors suggest that the sandstone with higher volume of dawsonite be in th

关 键 词：海拉尔盆地 乌尔逊凹陷 幔源 下白垩统 砂岩 储层质量 Lower Cretaceous 片钠铝石 含量增加 孔隙度和渗透率 铁白云石 成岩环境 扫描电镜观察 长石 质量的改变 渗透率降低 偏光显微镜 主要因素 质量改变 相互作用 

分 类 号：P58[天文地球—岩石学]