NIUMAG
NMR technology can be used to determine the distribution of H proton transverse relaxation time T2 and longitudinal relaxation time T1, which represent the pore structure around spin molecules (such as pore water). NMR technology has been widely used in food, petroleum and soil fields because of its non-destructive and high efficiency. In recent years, rock core NMR device has been used to detect core pore structure, identify the synthesis and decomposition of natural gas hydrate, and measure the unfrozen water content in frozen soil. Compared with traditional testing methods (CT, scanning electron microscopy and time domain reflectometry), NMR is the only method that can directly and non-destructively detect the content of water molecules.
At present, NMR logging is based on one-dimensional NMR technology, which only measures the lateral relaxation time information of formation pore fluids and cannot distinguish whether these signals come from oil or water. When oil, gas and water exist at the same time, their T2 signals overlap. The fluid identification methods such as Difference Spectrum Method (DSM), Shift Spectrum Method (SSM), Time Domain Method (TDA), Diffusion Method (DIFAN) and Diffusion Enhancement Method (EDM) proposed earlier have certain limitations in practical applications.
Two-dimensional NMR logging expands the distribution of the number of hydrogen nuclei in the pore fluid from one-dimensional single T2 relaxation variable to two-dimensional two variables, making full use of the information from NMR observations to open up a new field of NMR logging rock physics research .
Two-dimensional NMR logging is a new NMR logging method developed by applying the concept of 2D NMR spectroscopy to petroleum logging. According to the difference of oil-water diffusion coefficient, the oil-water signal can be distinguished on the two-dimensional spectrum. As the focus of domestic exploration and development gradually shifts to deep and complex oil and gas reservoirs, two-dimensional NMR logging will be an indispensable high and new technology for quickly and early judging the hydrocarbon prospects of complex oil and gas reservoirs.
