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本文建立了能够考虑孔喉特征的储层岩石三维非规整网络模型,用数值模拟方法进一步研究饱含水岩样的核磁T_2谱特征。通过模拟储层岩石孔喉核磁共振T_2谱的特征,表明核磁共振T_2谱同岩心孔喉半径分布具有很好的相似性,对T_2谱中孔隙体、喉道信号的分解可以评价储层岩石孔隙体、喉道的半径大小及分布情况。分别模拟喉道半径、孔喉比以及孔隙连通性等孔隙结构特征对T_2谱的影响,发现:1.随着喉道半径的增大,T_2谱峰值向右移动,而且峰值处的驰豫信号强度增大;2.随着孔喉比的增大,T_2谱峰值向右移动,峰值处的驰豫信号强度增大,而且孔隙体T_2谱和喉道T_2谱逐渐分开;3.随着连通性的增大,曲线左端上升,短驰豫时间信号所占比列增大,右边的峰值有所降低。
In this paper, a three-dimensional non-regular network model of reservoir rock considering the pore-throat characteristics is established and the characteristics of NMR T_2 spectra of water-saturated rock samples are further studied by numerical simulation. By simulating the characteristics of nuclear magnetic resonance T_2 spectrum of pore throat in reservoirs, it is shown that the T_2 NMR spectrum has a good similarity with the core pore throat radius distribution. The decomposition of pore and throat signals in T_2 spectrum can be used to evaluate reservoir rock porosity Body, throat radius and distribution. The effects of pore structure, such as throat radius, pore throat ratio and pore connectivity, on the T_2 spectrum were simulated. The results show that: 1. As the throat radius increases, the peak of T_2 moves to the right, and the relaxation signal at the peak 2. With the increase of pore-to-throat ratio, the peak value of T_2 moves to the right, the signal intensity at the peak increases, and the T_2 spectrum of the pore and the throat T_2 spectrum gradually separate. 3. As the connectivity Sex increases, the left end of the curve rises, the proportion of short relaxation time signals increases, and the right peak decreases.