砂岩岩石核磁共振T_2谱定量表征

基于统计学中的正态分布模型和地质混合经验分布模型,应用图解法和矩法2种数学算法,对核磁共振T2谱进行定量表征研究,提取出核磁共振T2谱反映自身孔隙结构及流体赋存状态信息的16项特征变量。在此基础上,结合压汞孔喉分布资料分析了核磁共振定量参数的岩石物理意义,验证了核磁共振定量参数表征储层微观孔隙结构方法的可靠性。在核磁共振定量表征参数相关性分析基础上,优选参数进行储层渗透率和束缚水饱和度求取,与实际岩心分析资料对比,新模型计算效果良好。进一步结合地区储层产能特征,利用核磁共振T2谱定量表征参数对储层进行分类综合评价,在冀东油田某井区的实际应用效果表明,核磁共振T2谱定量参数在储层微观孔隙结构特征研究、储层渗透率及束缚水饱和度计算、储层综合分类等方面均具有良好的评价效果。

Q uantitative characterization of sandstone NMR T2 spectrum

Based on the normal distribution model and hybrid geological empirical distribution model in statistics, two mathematical algorithms, i.e., graphic method and moment method, are used to study the quantitative characterization of nuclear magnetic resonance(NMR) T₂ spectrum, so as to extract 16 characteristic variables of NMR T₂ spectrum reflecting pore structure and fluid occurrence state. In combination with mercury-injection pore-throat distribution data, this study analyzes the petrophysical significances of NMR quantitative parameters and validates the reliability of the method that uses NMR quantitative parameters to characterize reservoir micro-pore structures. Based on the correlation analysis of NMR quantitative characterization parameters, the parameters are optimized to calculate reservoir permeability and irreducible water saturation. Compared with actual core analysis data, the new model shows favorable calculation results. In combination with regional reservoir capacity characteristics, the quantitative characterization parameters of NMR T₂ spectrum are applied for comprehensive classified evaluation. The practical application in a certain well block of Jidong oilfield demonstrates that the quantitative characterization parameters of NMR T₂ spectrum have favorable evaluation effects in the research of reservoir micro-pore structure characteristics, the calculation of reservoir permeability and irreducible water saturation, comprehensive reservoir classification and other aspects.