Fleury M, Deflandre F
Institut Français du Pétrole, 92852 Rueil-Malmaison, France.
Magn Reson Imaging. 2003 Apr-May;21(3-4):385-7. doi: 10.1016/s0730-725x(03)00145-0.
We propose a new method to determine wettability indices from NMR relaxometry. The new method uses the sensitivity of low field NMR relaxometry to the fluid distribution in oil-water saturated porous media. The model is based on the existence of a surface relaxivity for both oil and water, allowing the determination of the amount of surface wetted either by oil or by water. The proposed NMR wettability index requires the measurement of relaxation time distribution at four different saturation states. At the irreducible water saturation, we determine the dominant relaxation time of oil in the presence of a small amount of water, and at the oil residual saturation, we determine the dominant relaxation time of water in the presence of a small amount of oil. At 100% water and 100% oil saturation, we determine the surface relaxivity ratio. The interaction of oil with the surface is also evidenced by the comparison of the spin-lattice (T1) and spin-locking (T1rho) relaxation times. The new NMR index agrees with standard wettability measurements based on drainage-imbibition capillary pressure curves (USBM test) in the range [-0.3-1].
我们提出了一种从核磁共振弛豫测量法确定润湿性指数的新方法。该新方法利用低场核磁共振弛豫测量法对油水饱和多孔介质中流体分布的敏感性。该模型基于油和水均存在表面弛豫率，从而能够确定被油或水润湿的表面量。所提出的核磁共振润湿性指数需要测量四种不同饱和状态下的弛豫时间分布。在残余水饱和度下，我们确定在少量水存在时油的主导弛豫时间，而在残余油饱和度下，我们确定在少量油存在时水的主导弛豫时间。在100%水饱和度和100%油饱和度下，我们确定表面弛豫率比。通过比较自旋晶格（T1）和自旋锁定（T1rho）弛豫时间，也证明了油与表面的相互作用。新的核磁共振指数在[-0.3 - 1]范围内与基于排驱-吸入毛细管压力曲线（美国矿务局试验）的标准润湿性测量结果一致。
