摘要
储层中裂缝的发育影响着油气运移和储存,因此识别裂缝以及得到裂缝性储层的表征参数与物理性质对于预测天然气的产量有重要的意义.本文主要通过实验和数值模拟研究了低频段(100 Hz~1 MHz)内均质岩样和不同裂缝参数的裂缝性岩样的复电阻率频散特性.利用有限元模拟计算简易岩样模型的复电阻率,研究了完全饱和水状态下均质岩样与裂缝岩样复电阻率频散特性的区别.并重点研究了100 Hz、1 kHz和10 kHz下均质岩样以及不同裂缝宽度、密度、倾角岩样含水饱和度S_(W)与电阻增大率I_(R)、含水饱和度S_(W)与介电常数变化率Iε的变化关系.实验结果显示完全饱含水的情况下裂缝的出现,使得岩样的复电阻率实部降低,复电阻率虚部的幅值减小;不同频率(100 Hz、1 kHz和10 kHz)下I_(R)-S_(W)曲线发生分离.裂缝密度和裂缝倾角的增加,导致岩样的复电阻率实部降低,复电阻率虚部的幅值减小;并使得不同频率下的I_(R)-S_(W)和Iε-S_(W)分离程度变大.讨论了阿尔奇公式中饱和度指数n与系数b以及仿阿尔奇公式中介电饱和度指数n′与系数b′与裂缝参数的关系,说明在高含水饱和度时,导电与介电的幂指数规律基本一致.通过对裂缝性岩石上述参数的研究,为多频复电阻率测井仪的研发提供理论与实验支撑,进而提高裂缝性储层含气性识别以及定量评价含气饱和度的可靠性.
The fracture can be a good channel for oil and gas migration,which has a great influence on the permeability of the reservoir.It is of major significance to identify fractures and determine the characterization parameters and physical properties of fractured reservoirs.In this study,the complex resistivity dispersion characteristics of homogeneous rock samples and fractured rock samples with different fracture parameters in the low-frequency band(100 Hz~1 MHz)were studied mainly by experiment and numerical simulation.The complex resistivity of homogeneous rock sample model and fractured rock sample models at 100%saturated water was calculated by finite element simulation.The relationship between the resistivity index I_(R) and the water saturation S_(W) of homogeneous rock samples and rock samples with different fracture widths,densities and dip angles were mainly studied at 100 Hz,1 kHz and 10 kHz.The relationship between the dielectric constant change rate Iεand the water saturation S_(W) were also studied.The experimental results show that the real part of complex resistivity decreases and the amplitude of the imaginary part of complex resistivity decreases due to the appearance of fracture in the case of 100%water saturation of rocks.It also leads to the separation of I_(R)-S_(W) curves at three frequencies.With the increase of fracture density and fracture dip angle,the real part of complex resistivity decreases,and the amplitude of the imaginary part of complex resistivity decreases.As the fracture width,density and dip angle increased,the separation of I_(R)-S_(W) and Iε-S_(W) curves increased.The relationship between the saturation exponent n or coefficient b which is in Archie Equation and pseudo-Archie Equation and the fracture parameters were discussed.It is shown that the power exponent law of conductivity and dielectric is basically the same at high water saturation.Through the study of the above parameters of fractured rocks,provides theoretical and experimental support for the development of multi-frequency complex resistivity logging tools,which further improves the reliability of gas-bearing identification and quantitative evaluation of gas saturation in fractured reservoirs.
作者
潘保芝
阿茹罕
郭宇航
张丽华
魏伯阳
周伟一
PAN BaoZhi;A RuHan;GUO YuHang;ZHANG LiHua;WEI BoYang;ZHOU WeiYi(College of Geo-exploration Science and Technology,Jilin University,Changchun 130061,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2021年第10期3774-3787,共14页
Chinese Journal of Geophysics
基金
吉林省科技发展计划优秀青年人才项目(20190103150JH)资助.
关键词
裂缝性岩石
复电阻率
含水饱和度
导电
介电常数
裂缝参数
Fractured rock
Complex resistivity
Water saturation
Conductivity
Dielectric constant
Fracture parameters
