煤层气选区评价方法探讨——以准噶尔盆地南缘为例

煤层气选区评价历来是煤层气勘探的一个重要环节,其中评价方法的选择关系到能否准确命中目标靶区,近年来的选区评价方法从定性评价逐渐发展为定量评价。以准噶尔盆地南缘为评价区,从定性—半定量—定量评价的思路方法着手,首先选取了典型的5种评价方法,系统地论述了其在煤层气评价选区中的利弊,发现定性评价方法仍有着其广泛运用的空间,虽然现有的定量评价方法进一步降低了主观因素影响,但这5种评价方法均不同程度地存在着主观性、经验性判断。在对这5种方法进行异同点总结的基础之上,笔者进一步引进了主成分分析法这一定量评价方法,避免了主观因素影响,优选出四工河—大黄山区段为有利区段,与前述5种方法结果相同,表明主成分分析法运用于煤层气选区评价是合理可靠的,完全避免了主观因素的影响成为其选区评价的最大优点。在综合分析了各评价方法的优缺点之后,提倡运用初步定性判断—定量评价研究—定性评价验证的思路来进行煤层气的选区评价。

Discussion on methods for selected areas evaluation of coalbed methane:A case study of southern Junggar Basin

Selected areas evaluation of coalbed methane has always been an important link in the process of coalbed methane (CBM) exploration，in which the evaluation method is the key to favorable area.The methods gradually developed from the qualitative evaluation to quantitative evaluation in recent years.This paper uses southern Junggar Basin as an appraisal area.Firstly，five typical kinds of evaluation methods are discussed，in which the merits and demerits are systematically expounded.It is founded that qualitative evaluations are still practical，although quantitative evaluations have improved the veracity of evaluation，subjectivism and empirical judgments are still existed in the process of quantitative evaluations to some extent.Based on the differences and similarities of the five evaluation methods，principal component analysis (PCA) has been proposed for the purpose that avoids the subjectivism and empirical judgments.The Sigonghe to Dahuangshan area has been selected as a favorable area by PCA method，the same result is generated by the five evaluation methods，which proves that the PCA method is feasible in selecting the favorable CBM areas，and its greatest advantage is to avoid the subjectivism.The authors advocate that the thought of “first qualitative judgment，second quantitative analysis，and final qualitative verification” should be used to select favorable CBM areas.