基于聚类分析的多煤层煤层气产层组合选择

多煤层煤层气产层组合是后期多层合采的关键。以云南老厂雨旺区块煤层气开发井为例,选取多煤层的煤层厚度、埋深、储层压力梯度,渗透率和含气量5个关键参数,运用SPSS软件,采用Q型聚类,输出树状谱图,进行多层次产层组合分析。依据类间距远近,聚类结果可以分为大的4个层次,对应4个组合,级别越高,产层相似度越高,组合越好,一般3级组合或者4级组合是最优组合。分析发现聚类类别界面煤层大部分对应于区域煤系地层分段的关键界面煤层或者是区域盖层附近,其实质反映了地质作用的内在控制。采用Q型聚类对雨旺区块煤层气勘探开发井进行了产层组合划分,结果与其他方法划分的产层组合较为吻合,且对前期煤层气开发井聚类分析发现,多产层相似度越高,类间距越近,产气效果越好。综合说明聚类分析方法是一种间接有效的产层组合判别方法。

Production layer combination selection for coalbed methane development in multi-coal seams based on cluster analysis

In multi-coal seams,coalbed methane(CBM) production layer combination is a key to the latter multi-layer co-production.Taking the CBM development well in Yuwang block from Laochang in Yunnan as an example,five key parameters including thickness,burial depth,reservoir pressure gradient,permeability and CBM content of multi-coal seams were selected,using SPSS software and Q-type clustering method,outputting tree-like spectra,multi-level production layer combination were analyzed.According to the distance between classes,the clustering results could be divided into four major levels,corresponding to four combinations,the higher the level,the higher the similarity between production layers,the better the combination.Generally,the combination of level 3 or level 4 was the optimal combination.It was found that most of the interface coal seams in the clustering category correspond to the key interface coal of coal seams measures or the regional caprocks,which essentially reflected the inherent control of geological processes.The Q-type clustering was used to divide the production layer combination of the CBM exploration and development wells in Yuwang block.The research showed its results were more consistent with those by other methods.According to the clustering analysis of CBM development wells in the previous period,the higher the similarity,the closer the class spacing,the better the CBM producing effect.In summary,clustering analysis method was an indirect and effective method of production layer combination.