基于NMR和X-CT的页岩储层孔隙结构研究

Application of NMR and X-CT Technology in the Pore Structure Study of Shale Gas Reservoirs

为了定量表征页岩储层孔隙结构,应用NMR和CT扫描技术研究中扬子地区陡山沱组页岩储层孔隙结构特征。研究结果表明:①陡山沱组页岩横向弛豫时间(T2)谱为非对称不连续双峰结构,且T2谱的谱峰小,代表页岩孔隙直径小;②发育微孔隙、微裂缝的页岩密度最小,在CT灰度图像中表现为黑色,CT灰度图像经伪彩色增强,可以更直接地观察页岩内部孔隙发育特征;③页岩的三元组构中,矿物、有机组分和孔隙分别具有不同的CT数分布区间,通常孔隙的CT数都小于300 HU,因此可通过CT数来定量识别孔隙;④根据NMR的T2截止值计算了页岩有效孔隙度,并分析了页岩储层中可动流体百分数。

From the angle of refinement, nondestructive and quantitative characterization, NMR and CT scanning techniques were used for shale reservoir of pore structure. The results show that： ①The shale T2 spectrum as the asymmetric continuous double peak structure, no single peak T2 spectrum, spectral peak is the peak representing the development of pores; ② The shale micro pore, micro cracks is in the minimum density, CT in gray image is black, gray image by pseudo color enhancement, can more directly observe of shale internal porosity characteristics; ③ The three tuple shale structure, minerals, organic components and pore are of different CT number and CT distribution interval, CT number of pores are usually less than 300 HU, so it can be through the CT number to quantitatively identify pore; ④According to the shale NMR resonance experiment T2 cutoff value of the effective porosity calculation of shale, mobile fluid percent in shale reservoirs was analyzed.