样品扩充法识别火成岩

Igneous rock identification based on sample expansion method

以准噶尔盆地滴西地区火成岩为例,采用样品扩充法识别火成岩。首先挑选岩性稳定的深度段内的样品,然后将其扩充为岩性亚类样本,再利用正态分布函数、R型因子分析和层次分析法联合建立岩性亚类的模糊数学隶属函数,最后遵照最大隶属度原则进行岩性识别,并将识别结果与岩心薄片鉴定资料进行比较。结果表明:各种岩性平均解释符合率为82.77%;相同岩性的岩性亚类之间的误识对最终结果没有影响,误识的岩性主要为凝灰岩和火山角砾岩。该方法可应用于岩层厚度较大、测井曲线值相对稳定的复杂岩性识别中,其缺点是样品扩充时会舍弃部分岩性样品。

Sample expansion method was provided for lithologic identification of igneous rock in Dixi area,Jungger Basin.Firstly,the sample located in the thick formation which has the same lithology was picked up.Secondly,it was expanded in a specimen which represented an suborder of igneous rocks.Thirdly,the membership function was developed by means of normal distribution function,R-mode factor analysis and analytic hierarchy process.Finally,the igneous rock was identified by the principle of maximal membership grade based on fuzzy.The comparison between the identification results and the thin section analysis shows that the coincidence rate is 82.77%.However,error identification of suborders with the same lithology does not influence the final result,and the error rates of volcanic tuff and volcanic breccia are relatively high.Despite of the shortcoming of wasting some samples,this method can be used in mixed lithologic identification,especially when the layers are thick and the well logs are stable.