Advanced fluid-typing methods for NMR logging

Abstract

In recent years, nuclear magnetic resonance (NMR) has been increasingly used for fluidtyping in well-logging because of the improved generations of NMR logging tools. This paper first discusses the applicable conditions of two one-dimensional NMR methods: the dual TW method and dual TE method. Then, the two-dimensional (T2, D) and (T2, T1) NMR methods are introduced. These different typing methods for hydrocarbon are compared and analyzed by numerical simulation. The results show that the dual TW method is not suitable for identifying a macroporous water layer. The dual TE method is not suitable for typing gas and irreducible water. (T2, T1) method is more effective in typing a gas layer. In an oil-bearing layer of movable water containing big pores, (T2, T1) method can solve the misinterpretation problem in the dual TW method between a water layer with big pores and an oil layer. The (T2, T1) method can distinguish irreducible water from oil of a medium viscosity, and the viscosity range of oil becomes wide in contrast with that of the dual TW method. The (T2, D) method is more effective in typing oil and water layers. In a gas layer, when the SNR is higher than a threshold, the (T2, D) method can resolve the overlapping T2 signals of irreducible water and gas that occurs due to the use of the dual TE method. Two-dimensional NMR for fluid-typing is an important development of well logging technology.