Weatherford Laboratories, Houston, TX, USA.
J Magn Reson. 2013 Aug;233:17-28. doi: 10.1016/j.jmr.2013.04.014. Epub 2013 May 4.
Unconventional petroleum resources, particularly in shales, are expected to play an increasingly important role in the world's energy portfolio in the coming years. Nuclear magnetic resonance (NMR), particularly at low-field, provides important information in the evaluation of shale resources. Most of the low-field NMR analyses performed on shale samples rely heavily on standard T1 and T2 measurements. We present a new approach using solid echoes in the measurement of T1 and T1-T2 correlations that addresses some of the challenges encountered when making NMR measurements on shale samples compared to conventional reservoir rocks. Combining these techniques with standard T1 and T2 measurements provides a more complete assessment of the hydrogen-bearing constituents (e.g., bitumen, kerogen, clay-bound water) in shale samples. These methods are applied to immature and pyrolyzed oil shale samples to examine the solid and highly viscous organic phases present during the petroleum generation process. The solid echo measurements produce additional signal in the oil shale samples compared to the standard methodologies, indicating the presence of components undergoing homonuclear dipolar coupling. The results presented here include the first low-field NMR measurements performed on kerogen as well as detailed NMR analysis of highly viscous thermally generated bitumen present in pyrolyzed oil shale.
非常规石油资源，特别是页岩中的资源，预计在未来几年将在世界能源组合中发挥越来越重要的作用。核磁共振（NMR），特别是在低场条件下，为页岩资源的评估提供了重要信息。大多数在页岩样品上进行的低场 NMR 分析严重依赖于标准的 T1 和 T2 测量。我们提出了一种新的方法，在测量 T1 和 T1-T2 相关时使用固体回波，以解决在与常规储层岩石相比对页岩样品进行 NMR 测量时遇到的一些挑战。将这些技术与标准的 T1 和 T2 测量相结合，可以更全面地评估页岩样品中含氢成分（如沥青质、干酪根、粘土结合水）。这些方法应用于未成熟和热解油页岩样品，以检查在石油生成过程中存在的固体和高粘性有机相。与标准方法相比，固体回波测量在油页岩样品中产生了额外的信号，表明存在经历同核偶极耦合的成分。这里呈现的结果包括首次在干酪根上进行的低场 NMR 测量，以及对热解油页岩中存在的高粘性热生成沥青质的详细 NMR 分析。
