射线弹性阻抗致密气藏地震流体识别研究

发布时间：2018-03-20 17:55

  本文选题：射线弹性阻抗　切入点：致密砂岩气藏　出处：《西北大学》2017年硕士论文　论文类型：学位论文

【摘要】：致密气藏孔隙度低,渗透率低,地震识别难度大,找寻新技术识别致密储层流体一直是地球物理学研究的重要内容之一。鄂尔多斯盆地北部苏里格气田中生界和古生界储层流体分布规律复杂,井位部署难度大,现有地震预测方法难以有效识别流体,针对此问题,本文提出了一种基于孔隙介质岩石物理理论的AVO与射线弹性阻抗流体检测新技术,建立致密气藏地震流体检测的有效方法。首先,基于偶极横波测井资料建立一种改进的Xu-White方法预测孔隙介质气层段的横波速度;其次,通过模拟合理准确的岩石物理模型,分析岩石物理参数对弹性参数的影响程度及敏感性,完成角度域和射线参数域的两层模型和井模型射线弹性阻抗AVO正演模拟,分析含气饱和度对反射振幅的影响,通过研究AVO曲线分析REI和EI的精度;最后,根据理论研究以及交会图分析,找寻流体识别的敏感参数,在反演的射线弹性阻抗剖面上完成对岩性和流体的识别。研究表明:1)计算混合流体弹性参数时,Brie经验公式比Wood方程对含气饱和度的变化更为敏感,可以更好的模拟不同含气饱和度下的弹性参数;2)孔隙度、含气饱和度、泥质含量等的变化对弹性参数(纵波速度、横波速度、密度)的影响均较大;3)通过改进Xu-White方法中泥岩孔隙纵横比的计算,拟合泥岩孔隙纵横比与砂质含量的非线性公式,预测的孔隙介质气层段横波速度与实测横波平均误差为5.2%;4)建立角度域和射线参数域两层介质模型和井模型正演模拟,分析不同含气饱和度对射线弹性阻抗及反射振幅的影响,通过AVO分析研究REI和EI的精度,得到REI精度更高的结论;5)射线参数域随射线参数变化,反射系数的变化率更大,变化幅度更明显,较角度域来说,更能直观清楚的反映出反射振幅的变化规律和趋势;6)射线参数p=0.10的射线弹性阻抗REI值与纵波速度的交会图能很好的区分气层和非气层,可以在交会图上建立岩性和流体识别的敏感参数;7)使用流体识别的敏感参数,在射线参数p=0.10的射线弹性阻抗反演剖面上完成储层流体的识别,识别结果与单井日产气量相对应,效果较好。
[Abstract]:The porosity of tight gas reservoir is low, the permeability is low, and the seismic identification is difficult. Finding new techniques for identifying tight reservoir fluids has always been one of the important contents in geophysics. The fluid distribution of Mesozoic and Paleozoic reservoirs in Sulige gas field in the north of Ordos Basin is complicated and the well location is difficult to deploy. It is difficult to identify fluids effectively by existing seismic prediction methods. In this paper, a new technique of AVO and ray elastic impedance fluid detection based on rock physics theory in porous media is proposed. An effective method for seismic fluid detection in tight gas reservoirs is established. Firstly, an improved Xu-White method is established based on dipole shear wave logging data to predict the shear wave velocity of gas reservoirs in porous media. The influence degree and sensitivity of rock physical parameters on elastic parameters are analyzed. The forward modeling of ray elastic impedance (AVO) in angle domain and ray parameter domain is completed, and the effect of gas saturation on reflection amplitude is analyzed. The accuracy of REI and ei is analyzed by studying the AVO curve. Finally, according to the theoretical research and cross plot analysis, the sensitive parameters of fluid identification are found. The lithology and fluid are identified on the inverse ray elastic impedance profile. The results show that the Brie empirical formula is more sensitive to the change of gas saturation than the Wood equation in calculating the elastic parameters of mixed fluid. It can better simulate the change of porosity, gas saturation and mud content to elastic parameters (longitudinal wave velocity, shear wave velocity, etc.) under different gas saturation. By improving the calculation of the aspect ratio of mudstone porosity in the Xu-White method, the nonlinear formula of the ratio between the aspect ratio of the shale pore and the sand content is fitted. The predicted shear wave velocity of gas reservoir in porous media and the average error of measured shear wave are 5. 2 and 4) the forward modeling of two layers medium model and well model in angle domain and ray parameter domain are established, and the influence of different gas saturation on the elastic impedance and reflection amplitude of ray is analyzed. By AVO analysis, the accuracy of REI and ei is studied, and the conclusion that the precision of REI is higher than that of REI is obtained. The variation rate of reflection coefficient is larger and the range of variation is more obvious than that of angle domain. More intuitively and clearly reflects the reflection amplitude change law and trend (6) ray parameter p0. 10 ray elastic impedance REI value and longitudinal wave velocity cross plot can distinguish gas layer and non gas layer very well. The lithology and the sensitive parameters of fluid identification can be established on the intersection diagram. Using the sensitive parameters of fluid identification, the reservoir fluid can be identified on the ray elastic impedance inversion section of ray parameter p0. 10. The recognition results correspond to the daily gas production of a single well. The effect is good.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13;P631.4
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本文编号：1640173