Method for identifying thickened oil reservoir by utilizing nuclear magnetic resonance well logging

Abstract

The invention discloses a method for identifying a thickened oil reservoir by utilizing nuclear magnetic resonance well logging and belongs to the field of reservoir fluid identification.The method comprises the steps that a well having nuclear magnetic resonance well logging data is processed to obtain a standard T2 distribution spectrum; the nuclear magnetic porosity of the reservoir is calculated, and a nuclear magnetic T2 spectrum cutoff value method is utilized to calculate irreducible water saturation SBVI; a spectrum coefficient method is utilized to calculate irreducible water saturation SSBVI; finally, reservoir fluid identification factors are calculated; a fluid identification chart is established according to the fluid identification factors, and accordingly a reservoir fluid is accurately judged.The method utilize the characteristic that the two calculated irreducible water saturations have remarkable difference when thickened oil exists in the reservoir to effectively identify the reservoir, can adopt a method of utilizing the nuclear magnetic T2 spectrum cutoff value method and the spectrum coefficient method to calculate the difference of the irreducible water saturations to achieve accurate and reliable identification of the thickened oil reservoir in a thickened oil distribution area and is an effective fluid identification method for exploration and evaluation of large-area thickened oil reservoirs of our country at present.

Description

technical field [0001] The invention relates to the field of reservoir fluid identification in oil testing exploration, in particular to a nuclear magnetic resonance logging method for identifying heavy oil reservoirs. Background technique [0002] Fluid identification in heavy oil reservoirs is one of the difficult problems in logging interpretation and evaluation. Nuclear magnetic resonance logging is a logging method for studying the natural content and occurrence state of hydrogen in fluids. It is currently the only logging method that can evaluate the physical properties of crude oil. well method. However, a large number of experiments on heavy oil reservoirs have confirmed that after heavy oil (viscosity η>50cP / 50°C) is saturated with rock samples, its T 2 The spectrum is basically distributed in the range of bound fluid. When the crude oil reaches a certain viscosity, the T of heavy oil 2 The value is even smaller than that of the bound fluid. At this time, it is...

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Problems solved by technology

[0004] In order to solve the problem that conventional NMR logging cannot be used to identify heavy oil reservoirs in the prior art, the present invention provides a method using T 2 Method of identifying heavy oil reservoirs by calculating irreducible water saturation of reservoirs with cut-off value and spectral coefficient method

This method can avoid the unfavorable factors that the heavy oil signal cannot be identified due to the overlapping of the heavy oil signal and the bound fluid signal

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