摘要
煤体结构是判断煤层渗透性的有效标志,分为Ⅰ类原生结构、Ⅱ类碎裂煤、Ⅲ类碎粒煤、Ⅳ类糜棱煤,其判别大多采用岩心直接观察法,但如果同一研究区内煤体结构变化复杂,仅靠少量的勘探取心钻孔难以准确判别煤体结构。为提高煤体结构判别的准确性,提出借助测井曲线数据,应用贝叶斯(Bayes)判别法来判别煤体结构的方法。以鄂尔多斯盆地某煤层气田山西组2号煤层为例,对比分析不同煤体结构岩心与测井曲线的响应关系,通过统计分析选择深侧向电阻率曲线、密度测井曲线、井径曲线、浅侧向电阻率曲线、深浅侧向电阻率曲线差值、自然伽马曲线作为煤体结构判别的最优化测井组合;依据贝叶斯判别法,选取22组训练样本构建了Ⅰ类、Ⅱ类和Ⅲ类煤体结构类型的测井响应模型,通过15组样本验证了其在煤体结构判别中的准确性。所构建的煤体结构测井响应模型对煤层气选区评价、煤层气开发井位部署以及煤层气井产能差异性分析具有重要指导作用。
Coal structure is an effective index for the permeability of the CBM reservoir,which can be directly divided into type Ⅰprimary structure,type Ⅱ fragmented coal,type Ⅲ granulated coal and type Ⅳ mylonitized coal by core observation.However,the core structure is hard to be discriminated accurately by small amounts of exploration borehole for its complexity in the whole research area.In order to improve the discrimination accuracy for the coal structure,Bayesian discriminant approach（BDA） was applied based on plenty of log curves.No.2 coal seam in Shanxi Formation of certain CBM field in Ordos Basin was studied as a case.Re-sponses between the cores with different coal structures and log curves were compared.After statistic and analysis,curves including LLD,DEN,CAL,LLS,difference between LLD and LLS and GR were selected as the best log combination for the coal structure discrimination.According to the Bayesian discriminant ap-proach,log response models of the type Ⅰ,Ⅱ and Ⅲ coal structure were built respectively with 22 training samples,and their accuracy for the core structure discrimination were verified with 15 samples.The established models play an important role in guiding CBM area selection,CBM well deployment and CBM well productivity difference analysis.
出处
《中外能源》
CAS
2017年第12期29-35,共7页
Sino-Global Energy
关键词
煤体结构
判别方法
测井曲线
贝叶斯判别
测井响应模型
coal structure
discriminant approach
well log
Bayesian discriminant
log response model
