摘要
深部煤层处于高温高压环境,甲烷呈超临界态,实验获得过剩吸附量与实际的绝对吸附量存在较大偏差,二者之间的校正显得尤为重要。但目前校正系数中的吸附相密度大多采用了饱和液相密度或van der Waals密度这一定值,与甲烷吸附相密度随压力和温度变化的事实不符。本研究首先基于前人实验数据和理论分析建立了深部煤层中甲烷吸附相密度随温度和压力变化的数学模型;然后提出了吸附模型参数确定方法,优选出了考虑变吸附相密度的深部煤层气吸附解吸模型;最后进行了实例应用。研究表明,甲烷吸附相与游离相的密度差随压力先快速上升后缓慢上升并逐渐趋于一定值,随温度呈指数型渐进下降趋势;考虑变吸附相密度的深部煤层气吸附解吸模型,借助8个误差函数优选而来,可以准确表征深部煤层气吸附解吸特征;对于目标深部煤层气藏,Langmuir-Freundlich模型为最优的吸附解吸模型。研究成果可为深部煤层气藏类型划分、不同气体含量占比评价及排采制度优化确定提供理论基础。
Deep coal seams exist in high-temperature and high-pressure environments,where methane exists in a supercritical state,experimental measurements of excess adsorption exhibit substantial deviations from the true absolute adsorption,making the correction between excess and absolute adsorption critically important.However,existing correction methods predominantly use fixed values for adsorption phase density,such as saturated liquid phase density or van der Waals density,which is inconsistent with the fact that the density of methane adsorption phase varies with pressure and temperature.This study first developed a mathematical model for methane adsorption phase density as a function of pressure and temperature in deep coal seams,based on prior experimental data and theoretical analysis.Then,the parameter determination methods for the adsorption models were proposed,and an optimized adsorption-desorption model incorporating variable adsorption phase density was selected for deep CBM.Finally,a case study was conducted.Results show that:(1)The density difference between adsorption phase and free phase of methane derived in this study initially increases rapidly with pressure,then rises slowly before gradually approaching a constant value,but exhibits an exponential asymptotic decline with increasing temperature.(2)The adsorption-desorption model considering variable adsorption phase density,optimized using 8 error functions,accurately characterizes the adsorption-desorption behavior of methane in deep coal seams.(3)For the given deep CBM reservoir,the Langmuir-Freundlich model was identified as the optimal adsorption desorption model.This research provides theoretical support for classifying reservoir types,evaluating gas content ratios,and optimizing production strategies.
作者
石军太
吉义天宇
贺甲元
陈明
黄红星
王凯
张硕
SHI Juntai;JI Yitianyu;HE Jiayuan;CHEN Ming;HUANG Hongxing;WANG Kai;ZHANG Shuo(National Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing 102249,China;Coalbed Methane Research Center,China University of Petroleum(Beijing),Beijing 102249,China;Sinopec Petroleum Exploration and Production Research Institute,Beijing 100083,China;Linfen Branch,PetroChina Coalbed Methane Corporation Limited,Linfen,Shanxi 042200,China;China United Coalbed Methane National Engineering Research Center Co.Ltd.,Beijing 100059,China)
出处
《钻采工艺》
北大核心
2025年第3期127-138,共12页
Drilling & Production Technology
关键词
深部煤层气
吸附相密度
吸附模型
过剩吸附量
绝对吸附量
deep coalbed methane
adsorption phase density
adsorption model
excess adsorption amount
absolute adsorption amount
