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Scientificity Of Core Nuclear Magnetic Resonance
Jun 08, 2017

The scientific and accurate selection of nuclear magnetic resonance of rock core directly affects the measurement results of parameters such as saturation of magnetic fluid and magnetic fluid saturation of rock samples. Centrifugal method is widely used at home and abroad to determine the T2 cut-off value of the method, most domestic and foreign experts and scholars selected 100psi as the standard sandstone and carbonate core T2 cut off the best centrifugal force. The results show that the T2 cutoff value of the core of the sedimentary rock reservoir is less than 33ms, and the core T2 of the volcanic reservoir is not seen, Rock Core NMR & MRI and the core of the volcanic rocks is not more than 33ms. Cut-off reports.

The experimental results show that the centrifugal force of 100psi as the cutoff value of the core T2 may not be applicable to the low porosity, low permeability gritstone core and the special lithic core such as carbonate rock and volcanic rock. In this paper, a certain number of representative sandstone, Rock Core NMR & MRI carbonate rock and volcanic core were selected for the best centrifugal force calibration experiment. Each core was subjected to nuclear magnetic resonance measurement after centrifugal centrifugation. For the core selected in this paper, the optimum centrifugal force of the low-hole, low-permeability and conglomerate core T2 is approximately 200psi, and the best centrifugal force of the carbonate and volcanic core is about 400psi, and the corresponding effective seepage The lower limit of the throat radius is 0.1μm, and the carbonate and volcanic rocks are 0.05um.

In the best centrifugal force, a large number of representative sandstone, carbonate rock and volcanic core were selected for centrifugal experiment and NMR T2 measurement, and the corresponding cutoff value of core T2 was determined. In this paper, a certain number of representative The results show that the original wetting property of the core has an effect on T2 cutoff value. In the core of this study, the T2 cutoffs of the conglomerate core are mostly concentrated between several ms and 30ms, and the cutoff value of the carbonate core T2 is about 100ms. The T2 cutoff value of the volcanic rock core varies greatly with the lithology of the rock. Rock Core NMR & MRI The average value of rhyolite in the heart is 87.91ms, the average value of tuff is 52.02ms, and the average value of volcanic breccia is 36.28ms.

On the basis of accurate T2 cut-off value, this paper analyzes the correlation between the water saturation and the porosity and permeability of the core NMR, and establishes the core water saturation of the volcanic rock, Rock Core NMR & MRI the movable fluid saturation And the results of core magnetic analysis of core volcanic rocks in Daqing Oilfield were compared with those of corresponding reservoir test results and core CT analysis.

Core NMR is widely used in carbonate reservoir pore structure, fluid properties and other aspects of discrimination. However, due to the heterogeneity of carbonate reservoirs, the multi - solution and complexity of conventional logging responses are combined. The use of nuclear magnetic resonance logging to comprehensively reflect reservoir pore structure and fluid properties can overcome the shortcomings of conventional logging. Based on a large number of core nuclear magnetic resonance experiments, the relationship between the transverse relaxation T2 spectrum, the relationship between T2 spectrum and pore throat structure, the influence of particle size, the influence of fracture hole, the change rule of T2 cutoff The relationship between porosity and permeability parameters of nuclear magnetic analysis and pore parameters of conventional analysis has been achieved. Rock Core NMR & MRI The experimental results show that the magnetic resonance T2 distribution spectrum reflects the pore structure of the rock, which reflects the pore size distribution and has a good effect in evaluating the pore structure and reservoir effectiveness of carbonate rocks. The effect of resonance measurement is very small and the lower limit of particle size is 2mm. The cuttings drilled by the grinding PDC bit or with the breaker are not suitable for the application of nuclear magnetic resonance technology. The T2 cutoff value of the carbonate formation is not The T2 distribution spectrum can not effectively reflect the parameters of fractured porosity, but the T2 spectrum can qualitatively identify the reservoirs of pore development.