基于核磁共振与电阻率测井的煤储层孔隙性评价

Coal seam porosity evaluation based on nuclear magnetic experiment and resistivity log

针对实验方法获取孔隙度存在单点性和成本昂贵等问题,文章在核磁共振实验分析煤储层孔隙结构和探讨阿尔奇公式在煤层评价中适用性的基础上,创新性地提出了利用核磁数据校正电阻率资料求取的煤储层裂隙孔隙度,获得了电阻率资料有效评价煤储层裂隙孔隙度的方法,取得了较好的效果。实例工区的研究结果表明:该地区核磁T2谱呈现明显的双峰形态,左峰表示吸附孔隙,在离心前后变化小;阿尔奇法计算得到的孔隙度主要反映的是煤储层的裂隙孔隙度;通过核磁技术校正的煤储层裂隙孔隙度精度更高。

Aiming at the disadvantages of NMR experiment to obtain porosity, such as high cost and spot measurement, we propose the new method to effectively evaluate the fracture porosity of coal seam by electrical resistivity logging data and NMR experiment, in which the porosity from the resistivity is corrected by the NMR data, based on the pore structure and fracture porosity of coal seams from NMR experiments and applicability of Archie formula in the coal. The results showed that the T2 spectrum clearly showed two peaks, the left peak indicates adsorption pore, and the morphology change is small after centrifugation; the porosity calculated by Archie method largely reflects the fracture porosity of coal seam; the precision of coal fracture porosity corrected by NMR experiments is higher.