Estimation of Fluid Properties Using NMR Correlations in Berea Rocks SPE 69608
Rodrigues, Patricia Romero, Pedro
Estimation of Fluid Properties Using NMR Correlations in Berea Rocks SPE 69608 - Dallas, Texas Society of Petroleum Engineers 2001 - Rodrigues, Patricia .
Fluid viscosity is one of the most important parameters necessary to establish reservoir production and economic potential. Until the appearance of Nuclear Magnetic Resonance (NMR) techniques in the oil industry, oil viscosity determination was limited to laboratory tests and correlations with API gravity. Nuclear Magnetic Resonance response is the consequence of fluid properties, as viscosity and density, and its interactions with its surroundings. In water wet rocks, oil NMR behavior depends only on its properties, since it has not contact with the pore surface. However, the water attached to the surface has an effect on the global NMR signal. The technique used to overcome this situation is the NMR differential spectrum, which consists in implementing two different polarization times during NMR measurements, one that polarizes all present fluids and the other, which only polarizes the water. This technique has shown good results for sand reservoirs saturated with light oil, since the polarization time of light oil is much greater than the polarization time of water in sandstone. However, this technique cannot be used with confidence, in presence of heavier oil or in rocks where the water has greater polarization time, since both signals can be overlapped. This study is based on the idea of generating correlations to determine fluid properties through the use of mixed NMR signals of oil and water. In the study, we used Berea rocks to determine correlations for API gravity and oil viscosity vs. logarithmic average and 1 st quartile of the NMR T2 distribution, for three different echo times (300, 600 and 1200 µs). These correlations were determined in a general form as function of the echo time for free fluids and in saturated samples. API gravity correlations for free fluids and fluids inside the porous media showed similar results, while viscosity results showed the need of a specific correlation for fluids inside the porous media. This work constitutes a preliminary step on the generation of correlations to determine fluid properties inside the porous media.
Estimation of Fluid Properties Using NMR Correlations in Berea Rocks SPE 69608 - Dallas, Texas Society of Petroleum Engineers 2001 - Rodrigues, Patricia .
Fluid viscosity is one of the most important parameters necessary to establish reservoir production and economic potential. Until the appearance of Nuclear Magnetic Resonance (NMR) techniques in the oil industry, oil viscosity determination was limited to laboratory tests and correlations with API gravity. Nuclear Magnetic Resonance response is the consequence of fluid properties, as viscosity and density, and its interactions with its surroundings. In water wet rocks, oil NMR behavior depends only on its properties, since it has not contact with the pore surface. However, the water attached to the surface has an effect on the global NMR signal. The technique used to overcome this situation is the NMR differential spectrum, which consists in implementing two different polarization times during NMR measurements, one that polarizes all present fluids and the other, which only polarizes the water. This technique has shown good results for sand reservoirs saturated with light oil, since the polarization time of light oil is much greater than the polarization time of water in sandstone. However, this technique cannot be used with confidence, in presence of heavier oil or in rocks where the water has greater polarization time, since both signals can be overlapped. This study is based on the idea of generating correlations to determine fluid properties through the use of mixed NMR signals of oil and water. In the study, we used Berea rocks to determine correlations for API gravity and oil viscosity vs. logarithmic average and 1 st quartile of the NMR T2 distribution, for three different echo times (300, 600 and 1200 µs). These correlations were determined in a general form as function of the echo time for free fluids and in saturated samples. API gravity correlations for free fluids and fluids inside the porous media showed similar results, while viscosity results showed the need of a specific correlation for fluids inside the porous media. This work constitutes a preliminary step on the generation of correlations to determine fluid properties inside the porous media.
