基于kHz~MHz频段电频谱的多孔介质中水合物饱和度评价方法:数值模拟研究  

Evaluation Method of Hydrate Saturation in Porous Medium Based on kHz-MHz Electrical Spectrum:A Numerical Simulation Study

作　　者：王硕[1] 邢兰昌[1] 魏伟[2] 韩维峰 朱作飞 苏丕波[3] WANG Shuo;XING Lanchang;WEI Wei;HAN Weifeng;ZHU Zuofei;SU Pibo(College of Control Science and Engineering,China University of Petroleum(East China),Qingdao 266580,Shandong,China;Department ofAlternative Energy,PetroChina Research Institute of Petroleum Exploration&Development,Langfang 065007,Hebei,China;Sanya Institute of South China Sea Geology,Guangzhou Marine Geological Survey,Sanya 572025,Hainan,China)

机构地区：[1]中国石油大学(华东)控制科学与工程学院,山东青岛266580 [2]中国石油勘探开发研究院新能源研究所,河北廊坊065007 [3]广州海洋地质调查局三亚南海地质研究所,海南三亚572025

出　　处：《新能源进展》2024年第6期671-680,共10页Advances in New and Renewable Energy

基　　金：山东省自然科学基金项目(ZR2024ME090);中石油“十四五”前瞻性基础性重大科技项目(2024DJ9601);三亚市“崖州湾”菁英人才科技专项项目(SCKJ-JYRC-2023-06);国家留学基金项目(202106455003)。

摘　　要：宽频电频谱蕴含了导电、电极化及其频散机制的信息,天然气水合物的介电常数在kHz~MHz频段呈现频散特性,提出了基于该频段的电频谱来反演水合物饱和度的新思路。首先建立含水合物多孔介质的电场有限元数值模型,然后探讨水合物饱和度、水合物微观赋存模式、电场频率等因素对宽频电频谱的影响规律,最后针对含悬浮型和包裹型水合物多孔介质分别提出基于两步法的三相介电混合模型,进而建立水合物饱和度计算模型。研究结果表明:(1)在含包裹型水合物多孔介质中,水合物将石英砂颗粒与孔隙水隔离,则多孔介质低频段(<kHz)电频谱不受双电层极化的影响;当频率高于水合物频散频率时,含悬浮型和包裹型水合物多孔介质的复电导率虚部和复介电常数实部随着水合物饱和度的增大而显著降低;(2)对于含悬浮型水合物多孔介质,先将孔隙水与水合物的混合物视为等效孔隙流体相,采用Bruggeman(BR)模型计算等效介电常数,后将等效孔隙流体相与骨架颗粒混合,采用Bruggeman-Hanai(BH)模型计算含水合物多孔介质的等效介电常数,利用该BR-BH三相介电混合模型计算水合物饱和度,最大绝对误差为0.08,最大相对误差为5.67%;(3)对于含包裹型水合物多孔介质,先将骨架颗粒与水合物的混合物视为等效骨架颗粒相,采用Maxwell Garnett(MG)或BR模型计算等效介电常数,后将等效骨架颗粒相与孔隙水混合,采用BH模型计算含水合物多孔介质的等效介电常数,利用MG-BH和BR-BH三相介电混合模型分别计算水合物饱和度,最大绝对误差均为0.04,最大相对误差均低于10%。该研究建立了一种新的水合物饱和度评价方法,为天然气水合物储层定量评价和动态监测技术的开发提供了理论基础。The broadband electrical spectrum contains information on conduction,polarization and its dispersion mechanisms.The dielectric constant of natural gas hydrate exhibits dispersion characteristics in the kHz-MHz frequency band.A new approach to evaluate hydrate saturation based on the electrical spectrum of this frequency band is proposed.Firstly,finite element numerical electric field models in porous media containing hydrates were established.Then,the influence of hydrate saturation,micro-distribution mode of hydrates,and electric field frequency on the broadband electrical spectrum was explored.Finally,three-phase dielectric mixing models based on a two-step method were proposed for porous media containing suspending and coating hydrates,and hydrate saturation evaluation models were established.It has been demonstrated that:(1)in the porous media containing coating hydrates,the hydrates isolate quartz sand particles from pore water,and the low-frequency(<kHz)electrical spectrum of the porous media is not affected by double layer polarization;when the frequency is higher than the dispersion frequency of hydrates,the imaginary part of the complex conductivity and the real part of the complex dielectric constant of porous media containing hydrates significantly decrease with the increase of hydrate saturation;(2)for the porous media containing suspending hydrates,the mixture of pore water and hydrates is first considered as an equivalent pore fluid phase,and the Bruggeman(BR)model is used to calculate the equivalent dielectric constant;then the equivalent pore fluid phase is mixed with the skeleton particles,and the Bruggeman Hanai(BH)model is used to calculate the equivalent dielectric constant of porous media containing hydrates;the BR-BH three-phase dielectric mixing model is used to calculate the hydrate saturation,with the maximum absolute error of 0.08 and the maximum relative error of 5.67%;(3)for the porous media containing coating hydrates,the mixture of skeleton particles and hydrates is first considered

关 键 词：天然气水合物 多孔介质 水合物饱和度 电学特性 宽频电频谱 数值模拟 

分 类 号：TK01[动力工程及工程热物理] P319[天文地球—固体地球物理学]