Reservoir fluid recognizing method

Abstract

The invention provides a reservoir fluid recognizing method. The reservoir fluid recognizing method includes: logging a reservoir layer by double TE modes in long wait time, acquiring echo strings in long echo interval and short echo interval, inverting the echo strings to obtain a long echo interval T2 spectrum and a short echo interval T2 spectrum; shifting the short echo interval T2 spectrum to generate a simulating water spectrum according to the long echo interval supposing the short echo interval T2 spectrum measured under the condition of the short echo interval is all water course; subjecting the long echo interval T2 spectrum and the simulating water spectrum to spectrum differencing to generate a differential spectrum delta M, and judging the type of the reservoir fluid according to the differential spectrum delta M. Supposing the T2 spectrum under the condition of the short echo interval as the water spectrum, the long echo interval T2 spectrum is simulated, and oil gas water fluid in a pore medium in the reservoir layer can be recognized by subjecting the measured T2 spectrum and the simulated water spectrum at the long echo interval to differential spectrum processing and analyzing.

Description

technical field [0001] The invention relates to petroleum logging technology, in particular to a reservoir fluid identification method. Background technique [0002] In the field of oil exploration and logging technology, nuclear magnetic resonance logging technology is an important reservoir evaluation and fluid identification technology, which can provide reservoir information such as porosity, permeability, irreducible water saturation and pore distribution independent of lithology. Reservoir fluid properties can also be identified by difference spectrum method and shift spectrum method. When oil and water exist in the reservoir, the distribution of transverse relaxation time T2 is the comprehensive contribution of various fluids and pore structures. Due to the influence of porous media, oil-water NMR T2 signals overlap, which greatly increases the difficulty of oil-water identification. [0003] In the prior art, when NMR logging is used for oil-water identification, di...

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Problems solved by technology

Due to the complex pore structure, it is often encountered that the water signal in the pores cannot be completely polarized in a short waiting time. At this time, the water layer has a phenomenon of differential spectrum signals, which leads to misinterpretation of the oil layer by the water layer and reduces the coincidence rate of NMR logging. (See "Numerical Simulation of Nuclear Magnetic Resonance Logging Time-domain Analysis Method and Analysis of Influencing Factors" by Xie Ranhong, Xiao Lizhi, etc. in the journal "Journal of Geophysics" in August 2011, which records that the short waiting time of 1S cannot make large holes The water in the water is completely polarized, resulting in difference spectrum signals in the water layer, resulting in logging interpretation errors); for the shift spectrum method, which mainly relies on empirical methods, it is still quite far-fetched in theory, and it is difficult to realize the quantitative analysis of oil, gas and water in practical applications. Identification (see "Several Important Issues in the Application of Nuclear Magnetic Resonance Logging in my country" written by Xiao Lizhi in the "Logging Technology" magazine in October 2007, which records the limitations of spectral shifting technology based on experience)

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