地下复杂火山岩岩性测井识别方法——以准噶尔盆地克拉美丽气田为例

Study on lithologic identification of the underground complex volcanics:taking Kelameili Gasfield in Junggar Basin as an example

以准噶尔盆地克拉美丽气田为例,利用常规测井响应和常规测井交会图识别地下复杂火山岩岩性,以微电阻率扫描成像测井识别火山岩结构构造.结果表明:熔岩和次火山岩以高电阻率、低声波时差和低中子的特征区别于火山碎屑岩.根据从基性到酸性熔岩自然伽马增大的特征可以区分各种熔岩.次火山岩以高自然伽马和低密度的特征区别于玄武岩和安山岩,二长玢岩以低自然伽马的特征区别于流纹岩和花岗斑岩,进一步以自然伽马-电阻率交会图区分花岗斑岩和流纹岩.火山角砾岩以较高的密度和电阻率以及锯齿状声波时差和中子曲线区别于凝灰岩.在FMI图像上,熔岩特有的气孔构造、杏仁构造、流纹构造、块状构造、熔结结构等特征区别于火山碎屑岩的凝灰结构和火山角砾结构以及火山沉积-碎屑岩的层理构造.可以根据气孔构造、杏仁构造区分熔岩与次火山岩.

The lithology of the underground complex volcanics in Kelameili Gasfield,Junggar Basin is identified by the conventional logging data and cross plots,and the structure of the volcanics is identified by FMI.The results show that the lava and subvolcanic rocks are different from the pyroclastic rocks by high resistivity,low interval transit time and low neutron.Different kinds of lava can be distinguished by the characteristic of gradually increasing gamma from basic lava to acidic lava.Subvolcanic is different from basalt and andesite by higher gamma and lower density.Mangerite porphyrite is different from granite porphyry and rhyolite by lower gamma.Granite porphyry can further be distinguished with rhyolite by gamma——resistivity cross-plot.Volcanic breccia can be distinguished with tuff by higher density and resistivity and serrated interval transit time curve and neutron curve.In the image of FMI,the stomatal structure,almond structure,fluxion structure and welded texture et al of lava are obviously different from the tuff texture and volcanic breccia texture of pyroclastics and the bedding structure of volcanic sedimentary clastic rocks.Lava can be distinguished with subvolcanic by stomatal structure and almond structure.