基于核磁共振二维谱技术识别储层流体类型

IDENTIFY RESERVOIR FLUID TYPES WITH TWO DIMENSIONAL NMR TECHNIQUES

在梯度磁场的作用下,测量流体的CPMG脉冲回波时间间隔的平方与表观弛豫时间的倒数之间存在线性关系。通过一维反演方法得到了流体的表观弛豫时间T2,利用线性拟合的方法得到了流体的扩散系数和弛豫时间;通过二维反演方法得到核磁共振二维谱(D-T2),建立了多孔介质中饱和流体类型的识别方法。研究表明:在一定温度下,油的弛豫时间和扩散系数存在线性关系,气和水的扩散系数在一定条件下是常数。由于油、气、水弛豫时间和扩散系数的不同,在核磁共振二维谱上得到很好的表征,因此可以快速、直观地识别它们,为识别流体类型提供了一种新方法。

This paper discloses a new technique which can be used to identify fluid type based on two dimensional NMR techniques.The relationship between the reciprocal of apparent relaxation time and the square of CPMG echo spacing is linear.Apparent relaxation time is computed through one dimensional NMR inversion and diffusion coefficient and relaxation time are obtained through linear regression.Two dimensional NMR inversion is applied to obtain two dimensional NMR map(D-T2) and to establish recognition methods of fluids saturated in the porous medium.Studies show that the diffusion coefficient and relaxation time of oil is linear relation at a given temperature and the diffusion coefficient of gas and water are constant in some conditions.Due to different relaxation time and diffusion coefficient of oil,gas and water,it can be well characterized by two dimensional NMR map and this offers a new fluid type identification method.