沁水盆地柿庄地区构造煤定量分析及其物性特征

构造煤由于煤体结构不稳定及低渗透率的特点影响了煤层气的开发,基于测井资料的煤体结构定量分析有利于识别构造煤,有效预防构造煤对煤层气的不利影响。利用煤岩地球物理响应特征及地质录井资料,对构造煤进行了识别。针对柿庄地区煤岩特点,首先进行测井响应参数与煤体结构之间地相关性探讨,主成分分析结果表明,柿庄地区构造煤的测井响应特征主要与声波时差、补偿中子、密度及井径等4个测井参数相关性较大,相关性均高达0.8以上,相比而言,电阻率测井参数与构造煤体之间相关性较弱。基于以上4种高相关性参数响应特点并结合柿庄地区煤岩骨架测井参数基值进一步提出了煤体结构指数e作为判识构造煤的指标,当e1.8时,煤体结构普遍为构造煤。不同煤岩结构物性对比研究表明:与原生构造煤及碎裂结构煤相比,研究区构造煤具有低含气量、高演化程度及高黏土矿物含量的特点。

Quantitative analysis on tectonically deformed coal and its physical properties in Shizhuang area of Qinshui Basin

Due to its unstable coal structure and low permeability,the tectonically deformed coal affects the development of coalbed methane.The quantitative analysis based on logging data is in favor of coal structure identification and then has an effective prevention for the adverse effects caused by the tectonically deformed coals.With the characteristics of the geophysical response of coals and the geological logging data,the tectonically deformed coal is identified.According to the characteristics of coal in Shizhuang area,this paper firstly discusses on the correlation between logging response parameters and coal structure.The results of principal component analysis show that the logging response characteristics of tectonically deformed coal in Shizhuang area have a high correlation with four loggings including sonic,compensated neutron,density and caliper and the value of correlation is above 0.8.In comparison,the correlation between resistivity logging parameter and structural coal is weak.Based on the response characteristics of four logging curves and combined with logging basic values of coal skeleton,it presents the coal structure index e as the identification index of tectonically deformed coal.When the value of e is above 1.8,the tectonically deformed coals are generally developed.The comparison study of different coal structures shows that the tectonically deformed coal in the study area has the characteristics of low gas content,high evolution degree and high clay mineral content.