The mobile full-diameter NMR system is capable of analyzing large-diameter core samples, providing a comprehensive and highly representative characterization of the true pore structure in strongly heterogeneous reservoirs.It enables rapid, continuous, non-destructive, and high-precision 1D T₂ and 2D T₁–T₂ NMR measurements immediately after core retrieval. With fast data processing and interpretation, it delivers near in-situ, high-fidelity results, allowing on-site access to reliable information on formation porosity, pore structure, fluid properties, and oil saturation.

Free relaxation, surface relaxation, and diffusion relaxation are three distinct mechanisms present in the NMR relaxation of fluids in rock pores, and generally, all three behaviors coexist simultaneously.

Nuclear Magnetic Resonance (NMR) is a rapid, non-destructive method for pore characterization. By measuring the NMR T₂ spectra of cores saturated with hydrogen-containing fluids, it provides information on rock properties and fluid distribution, such as porosity, permeability, pore size distribution, and movable fluid fraction. The key to characterizing full-scale pore size distribution lies in determining the conversion factor, C, between the transverse relaxation time T₂ and the pore radius r.

How can more oil and gas resources be unlocked? How can reservoir enhancement and protection be effectively evaluated? As an advanced analytical technique, what role can Nuclear Magnetic Resonance (NMR) play in these processes?

Two-dimensional NMR logging is a novel nuclear magnetic resonance method developed by applying the concepts of 2D NMR spectroscopy to petroleum logging. By distinguishing oil and water signals on a two-dimensional spectrum according to their different diffusion coefficients, it enables clear phase identification. As domestic exploration and development increasingly focus on deep and complex reservoirs, two-dimensional NMR logging has become an essential advanced technology for rapidly and early assessing the hydrocarbon potential of complex reservoirs.

The NMR freeze–thaw method detects a greater variety of pore types, including both open and closed pores, and covers a wider pore size range, providing more complete information on pore size distribution. Compared with conventional pore measurement techniques, the NMR freeze–thaw method not only offers unique advantages in the quantitative identification of “total porosity” in coal, but also presents practical benefits such as non-contamination of samples, preservation of sample structure, ease and speed of testing, and low sample preparation requirements. Therefore, it is a promising method with potential for extended application in pore characterization of unconventional reservoirs.

Using NMR to determine shale pore size distribution offers two major advantages: first, it is non-destructive, allowing multiple repeated measurements on the same core; second, it can measure full-diameter cores, providing a macroscopic representation of the true subsurface formation.

The effect of liquid nitrogen on permeability enhancement varies with coal rank, primarily influenced by the initial porosity of the coal. In general, the enhancement follows the trend: lignite > anthracite > bituminous coal.

In order to investigate the evolution characteristics of pore structures during the leaching process of ionic rare earths and to analyze the influence mechanism of ion-exchange percolation on the microscopic structure of the ore, a saturated leaching experiment was designed using reconstructed rare earth samples.

Using low-field nuclear magnetic resonance (NMR) technology, experiments were conducted to investigate how liquid nitrogen freezing time, freeze–thaw cycles, coal moisture content, and coal rank affect the modification of coal physical properties under freeze–thaw conditions.