核磁共振测井T2cutoff确定方法及适用性分析

T2cutoff是核磁共振测井中的一个重要参数,它决定了核磁共振测井测量的有效孔隙度、渗透率、自由流体饱和度、束缚水饱和度等参数的精确程度.目前国内外普遍选取的T2cutoff为:砂泥岩储层取33ms,碳酸盐岩储层取92ms.实际研究发现T2cutoff应是变化的量而并非单一值.简单的运用单一的T2cutoff来计算各种地层参数势必会产生误差甚至得出错误的解释结论.叙述了33ms作为T2cutoff的由来及其不合理性,同时分析了目前国内外确定T2cutoff的各种方法及其适用性.

Analysis of methods for determining NMR T2cutoff and Its Applicability

T2cutoff is a very important parameter in NMR logging.By which,effective porosity,permeability,free fluid saturation and irreducible water saturation can all be calculated accurately.Log analyst all use 33ms in sandstone and 92ms in carbonate rock as its value at home and abroad.But actual analysis find that it should be various but not unitary value.Error even incorrect interpretation result of reservoir parameter should be get by single T2cutoff.In this paper,give the origin of 33ms and analyze its absurdity.And also give the methods of determining T2cutoff and these availability.