Improved type self-adaptive method for T2-G acquisition parameter t0 of CPMG sequence

A technology for collecting parameters and T2-G, which is applied in the direction of analysis by using nuclear magnetic resonance, which can solve the problems of cumbersome and time-consuming adjustment, and achieve the effect of avoiding disorderly adjustment and reducing the difficulty of experimental operation.

Active Publication Date: 2015-01-21
CHINA UNIV OF PETROLEUM (EAST CHINA)
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Problems solved by technology

[0044] In order to solve the current improved CPMG sequence acquisition parameter t 0 To solve problems such as cumbersome and time-consuming adjustments, the present invention provides an improved CPMG sequence T 2 -G acquisition parameter t 0 adaptive method

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  • Improved type self-adaptive method for T2-G acquisition parameter t0 of CPMG sequence
  • Improved type self-adaptive method for T2-G acquisition parameter t0 of CPMG sequence
  • Improved type self-adaptive method for T2-G acquisition parameter t0 of CPMG sequence

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Embodiment Construction

[0073] The improved CPMG sequence is a commonly used NMR pulse sequence for measuring the magnetic field gradient distribution inside rocks. The duration of the first window is t 0 It is a key acquisition parameter that affects the loading effect of internal magnetic field gradient information. For manual adjustment of t 0 Due to the tedious and time-consuming limitations, the present invention discloses an improved CPMG sequence T 2 -G acquisition parameter t 0 an adaptive method. this kind of t 0 Rationale for Adaptive Methods: Defining t 0 Adaptive discriminant factor σ, T 2 -G Before the formal experiment, change t 0 The NMR pre-acquisition is performed to obtain the σ curve, and the optimal t is realized through the σ maximum value condition combined with the signal-to-noise ratio constraint condition 0 automatic search and match. The improved CPMG sequence T designed by the present invention 2 -G acquisition parameter t 0 The adaptive method can effectively redu...

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Abstract

The invention discloses an improved type self-adaptive method for T2-G acquisition parameter t0 of a CPMG sequence. The self-adaptive method comprises the following basic steps: defining a t0 self-adaptive discriminant factor sigma; before formal experiment of the T2-G, changing the t0 to carry out nuclear magnetic resonance preacquisition to obtain a sigma curve, and by combination of the maximum-value condition of sigma and the constraint condition of the signal-to-noise ratio, realizing automatic searching and matching of the optimized t0. The improved type self-adaptive method disclosed by the invention has the advantages that the operation difficulty of the experiment can be effectively reduced; and by application of the improved type self-adaptive method, the experiment efficiency of the T2-G is greatly improved, and the application prospect is wide on the oil-field site.

Description

technical field [0001] The invention relates to the field of low-field nuclear magnetic resonance core analysis, in particular to the improved CPMG sequence T 2 -G acquisition parameter t 0 An adaptive method design for . Background technique [0002] When the reservoir rock framework contains paramagnetic or ferromagnetic substances, the magnetic susceptibility of the rock framework and pore fluid is significantly different (as shown in Table 1), and this difference in magnetic susceptibility will form an additional magnetic field in the pore space under the condition of an external magnetic field Gradient, called the internal magnetic field gradient. [0003] Kleinberg and Vinegar (1996) gave an approximate calculation formula for the gradient of the internal magnetic field: [0004] G = ΔH R ≈ μ 0 H 0 ...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N24/08
Inventor 范宜仁吴飞邢东辉葛新民巫振观
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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