关于页岩含气量确定方法的探讨

Determination of Gas Content in Shale

页岩含气量是页岩气资源评价和有利区优选的关键性参数,也是评价页岩是否具有开采价值的一个重要标准。对页岩含气量的获取方法进行了介绍,其一是通过解吸法分别测量解吸气、残余气和损失气;其二是利用等温吸附实验、测井解释等方法分别计算页岩中的吸附气、游离气含量。分析认为:解吸法测量结果容易受到取心方式、测定方法、损失气量计算方法、气体解吸温度等因素的影响,所测得的总含气量比间接法更接近于真实值;吸附气量的估算需要综合考虑有机碳含量、粘土矿物组分、成熟度、温度和压力等因素对页岩吸附能力的影响,建立适当的吸附气含量计算模型,游离气量估算的关键是确定页岩的有效孔隙度和含气饱和度。建立针对页岩含气量测试技术和等温吸附实验技术标准,量化各种控制因素对页岩含气量的影响,对准确评价页岩含气量具有重要意义。

Gas content in shale is key parameter for shale gas resource evaluation and favorable area preferential selection and also is an important standard for shale exploitation value evaluation. Introduced are such acquisition methods for shale gas content as desorption,isothermal adsorption experiment and well logging interpretation. Applied is desorption method to measure desorption gas,residual gas and loss gas respectively,and applied are isothermal adsorption experiment and well logging interpretation methods to calculate desorption gas and free gas content respectively. Analysis results suggest that results measured by desorption method are affected easily by such factors as core-taking way,measurement method,loss gas volume calculation method and gas desorption temperature and total gas content obtained by these methods is more close to the real value than indirect methods. Determination of testing technology for gas content in shale and establishment of technical standard for isothermal adsorption experiment and quantization of effects of various control factors on shale gas content have important significance for accurate evaluation of shale gas content.