深层高压页岩气藏吸附气含量评价新方法  

A new evaluation method for adsorbed gas contents of deep high-pressure shale gas reservoirs

作　　者：赵玉龙[1] 刘香禺 张烈辉[1] 张鉴 常程 赵圣贤 张帆[1] ZHAO Yulong;LIU Xiangyu;ZHANG Liehui;ZHANG Jian;CHANG Cheng;ZHAO Shengxian;ZHANG Fan(State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation//Southwest Petroleum University,Chengdu,Sichuan 610500,China;Shale Gas Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610051,China)

机构地区：[1]“油气藏地质及开发工程”国家重点实验室·西南石油大学 [2]中国石油西南油气田公司页岩气研究院

出　　处：《天然气工业》2021年第10期69-82,共14页Natural Gas Industry

基　　金：国家自然科学基金面上项目“深层海相页岩气藏气水赋存机制及跨尺度流动模拟研究”(编号:52074235),“耦合压裂缝网扩展机制的页岩气藏动态模拟研究”(编号:51874251);中国石油—西南石油大学创新联合体项目“川南深层与昭通中浅层海相页岩气整体动用理论与技术”(编号:2020CX020202),“不同构型页岩储层流体流动规律及开发优化理论与方法”(编号:2020CX030202);国家自然科学基金青年基金项目“页岩气藏耦合地层—井筒流动的压裂水平井生产动态模拟方法研究”(编号:52004237)。

摘　　要：目前对于深层高压页岩气藏储层真实吸附气含量的研究不深入、计算欠准确、报道较罕见。为了解决上述问题,基于广泛使用的微孔充填Dubinin-Astakhov模型,结合不同温度下的超临界甲烷高压吸附实验数据,研究了高压下甲烷在页岩中的超临界吸附特征,探讨了常用吸附相密度计算方法在高压下页岩气过剩吸附量校正中的适用性,结合Gibbs公式和Dubinin-Astakhov模型开展了过剩吸附量校正研究,基于循环迭代和最优化思路提出了结合吸附特征曲线优化Dubinin-Astakhov模型参数的新方法。研究结果表明:(1)常用的过剩吸附量校正方法对于求取高压(大于等于20 MPa)条件下甲烷在页岩中的绝对吸附量并不适用,主要误差出现在高压段;(2)吸附相甲烷密度受温度影响较小,受页岩样品影响显著,不同井区和层位页岩中吸附相甲烷密度可能存在着较大的差异;(3)基于该新方法可以开展深层高压页岩气藏储层吸附气含量评价,计算结果满足吸附势理论且可以获得唯一的吸附特征曲线,计算得到的页岩气过剩吸附量与实测结果具有很好的一致性。结论认为,该新方法可以为深层高压页岩气藏储量评估提供依据并支撑深层页岩气藏经济高效开发。At present,the real adsorbed gas content of a deep high-pressure shale gas reservoir is not researched deeply,its calculation is not accurate enough and there are few related reports.In order to solve these problems,this paper studies the supercritical adsorption characteristics of methane in shale under high pressure based on the widely used Dubinin-Astakhov model with micropore filling,combined with experimental data of supercritical high-pressure methane adsorption under different temperatures.Then,the applicability of the commonly used calculation method of adsorption phase density to the correction of excessive adsorption capacity of shale gas under high pressure is discussed,and the correction of excessive adsorption capacity is researched using the Gibbs formula and Dubinin-Astakhov model.Finally,based on cyclic iteration and optimization concept,a new method for optimizing the parameters of Dubinin-Astakhov model by combining with adsorption characteristic curve is proposed.And the following research results are obtained.First,the commonly used correction method of excessive adsorption capacity is not suitable for calculating the absolute adsorption capacity of methane in shale under high pressure(≥20 MPa),and the main error occurs in the high-pressure section.Second,the density of adsorbed methane is less affected by temperature,but significantly by shale samples.The density of adsorbed methane in shale may vary greatly in different well blocks and horizons.Third,this new method can be used to evaluate the adsorbed gas content of deep high-pressure shale gas reservoirs.The calculation results satisfy the adsorption potential theory and can provide the unique adsorption characteristic curve.The calculated excessive adsorption capacity of shale gas is in agreement with the measurement results.In conclusion,this new method can provide a basis for the reserve estimation of deep high-pressure shale gas reservoirs and support the economical and efficient development of deep shale gas reservoirs.

关 键 词：页岩气 吸附气含量 高压 超临界吸附 过剩吸附量 绝对吸附量 Dubinin-Astakhov模型 参数优化 

分 类 号：P618.13[天文地球—矿床学]