Mardon D, Prammer M G, Coates G R
NUMAR Corp., Houston, TX 77032, USA.
Magn Reson Imaging. 1996;14(7-8):769-77. doi: 10.1016/s0730-725x(96)00162-2.
New methods for acquiring and processing gradient NMR well log data enable signals from gas, light oil, and water to be unambiguously separated and, in many cases, quantified. These methods exploit the combined effects of T1-based and diffusion-based contrast on log response. T1 contrast, which separates the water and light hydrocarbon (oil or gas) signals, is measured by subtracting spin-echo decays measured at different, appropriately chosen wait times. Gas and oil signals are then separated based on the large contrast in the diffusion-induced T2 relaxation times for gas vs. liquid. Practical application of these principles is illustrated with new log examples that also highlight the advantages of NMR over traditional logging methods for detecting and typing light hydrocarbons, especially in mineralogically complex rocks.
获取和处理梯度核磁共振测井数据的新方法能够明确分离并在许多情况下量化来自天然气、轻质油和水的信号。这些方法利用了基于T1和基于扩散的对比度对测井响应的综合影响。通过减去在不同的、适当选择的等待时间测量的自旋回波衰减来测量分离水和轻质烃（油或气）信号的T1对比度。然后根据气体与液体在扩散诱导的T2弛豫时间上的巨大差异来分离气体和油信号。新的测井实例说明了这些原理的实际应用，这些实例还突出了核磁共振在检测和识别轻质烃方面相对于传统测井方法的优势，特别是在矿物成分复杂的岩石中。
