A method and device for acquiring nuclear magnetic resonance logging t2 spectrum

Abstract

The embodiment of the invention provides a nuclear magnetic resonance logging T2 spectrum collecting method and device. The method comprises the steps that (1) the porosity of a sample is acquired; (2) a 90-degree pulse is applied to the magnetized sample; (3) 180-degree pulses of a predetermined number are applied to the magnetized sample to acquire a first echo string; (4) 180-degree pulses are continuously applied to the magnetized sample until the magnetization of the sample disappears to acquire a second echo string; (5) the first echo string and the second echo string are integrated to acquire a nuclear magnetic resonance T2 spectrum echo string; (6) the T2 spectrum porosity of the sample is acquired according to the inversion of the nuclear magnetic resonance T2 spectrum echo string; and (7) whether the deviation between the T2 spectrum porosity and the porosity is less than a preset threshold is judged, and if the judgment result is NO, the predetermined number is changed and steps from (2) to (7) are repeated until the judgment result is YES. According to the embodiment of the invention, a small data amount is considered, and the micro-nanopore measurement accuracy is improved.

Description

technical field [0001] The present application relates to the technical field of petroleum logging, in particular to a method and device for acquiring T2 spectrum of nuclear magnetic resonance logging. Background technique [0002] The method of using the NMR properties of matter to study rock properties in boreholes is called NMR logging or NMR logging. In the field of oil exploration and logging technology, nuclear magnetic logging is an important reservoir evaluation and fluid identification method, which can provide reservoir information such as porosity, permeability, irreducible water saturation and pore distribution independent of lithology, and also Fluid information can be provided. The above information is mainly obtained from the transverse relaxation time T2 of nuclear magnetic resonance, and the value of T2 directly determines the accuracy of reservoir parameters and the coincidence rate of fluid identification. [0003] In the prior art, the transverse relaxa...

AI Technical Summary

Problems solved by technology

However, blindly reducing the echo interval between two 180-degree pulses will lead to too much echo signal data, which will cause the subsequent inversion processing speed to be too slow. At the same time, a small echo interval will increase the power of the instrument, making it Heat and reduce accuracy

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