Rock core holder compatible with nuclear magnetic resonance

Abstract

The invention relates to a rock core holder compatible with nuclear magnetic resonance, which can simulate pressures and temperatures of deep reservoirs, perform oil water displacement of a rock core under simulated formation conditions, and simultaneously perform nuclear magnetic resonance on-line measurement. According to the invention, a radio frequency coil is embedded in the rock core holder, and the signal to noise ratio is greatly increased when the rock core holder is compared with a conventional rock core holder. The rock core holder is made of nonmagnetic nonmetal materials, which avoids the damage of the magnetic field uniformity caused by magnetic materials, and also avoids the generation of eddy current in the holder by a pulse gradient. Compared with a conventional rock core holder, the invention not only greatly increases the signal to noise ratio, but also fully ensures the accuracy of nuclear magnetic resonance measurement results at a high temperature and a high pressure. The holder is applicable to on-line measurement of nuclear magnetic resonance relaxation spectra, diffusion-relaxation two-dimensional spectra, and imaging methods during rock core oil water displacement at a high temperature and a high pressure. In addition, the invention performs real-time tracking compensation of temperatures and pressures of ring-crush fluid, and thus ensures the reliability of rock core simulated formation conditions.

Description

technical field [0001] The invention relates to a nuclear magnetic resonance compatible rock core holder, which is mainly used for analyzing the physical properties of rock cores by using nuclear magnetic resonance one-dimensional relaxation spectrum, diffusion relaxation two-dimensional spectrum and imaging method in petroleum exploration and development research. technical background [0002] In the exploration and development research of oil and natural gas, it is necessary to take out relevant formation cores from the ground, conduct core physical property analysis experiments, measure the relevant physical parameters such as porosity and permeability, and conduct displacement experiments related to exploration and development. As a means of analysis, nuclear magnetic resonance technology has developed rapidly and been widely used because it can non-destructively detect the properties of hydrogen-containing fluid inside the sample, and has the advantages of rapidity, accu...

AI Technical Summary

Problems solved by technology

When the conventional core holder structure is applied to nuclear magnetic resonance measurement, there will be three disadvantages: (1) If the conventional core holder structure is used for nuclear magnetic resonance measurement, the nuclear magnetic resonance radio frequency coil must be placed in the conventional core holder. Externally, the filling factor of the sample (referring to the ratio of the volume of the sample to the volume of the NMR RF coil) is very low, which makes the signal-to-noise ratio of the NMR measurement very low

(2) If the conventional core holder structure is used for NMR measurement, the electric heating method of the conventional core holder will bring a lot of noise to the NMR measurement signal, and the heating speed is also very slow

(3) Because the conventional core holders are made of paramagnetic metal materials, these paramagnetic metal materials will destroy the uniformity of the magnetic field when placed in the magnetic field, and at the same time, it is easy to generate a large eddy current, which can only be achieved by pulse gradients. NMR measurements cause large adverse effects

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