NMR Well-logging

M. D. Hiirlimann, D. D. Griffin 2000, (Spin dynamics of Carr-Purcel-Mei-bohm-Gill-like sequences in grossly inhomogeneous B0 and Bj fields and applications to NMR well logging), J. Magn. Reson. 143, 120-135. 

Fig. 2.7.6 Left A representation of a Schlum- that dearly separate and correspond to the berger NMR well-logging tool [56], The long oil and water signals, respectively. The lower cylinder is the tool body and the shaded areas peak corresponds to the oil phase, the higher contain permanent magnets. The multiple peak corresponds to the water phase. Note that sensitivity regions are shown as the colored the T2 distribution of the oil and water peaks sheets that are outside the tool body. Right overlap significantly. From the map, a water...

J. A. Jackson, (ed.) 2001, Concepts in Magnetic Resonance, Special Issue The History of NMR Well Logging (vol. 13), Wiley, Chichester. 

NMR Well Logging and Fluid Analysis 3.6.2.1 NMR Wire-line Logging... 

Interpretation of NMR well logs is usually made with the assumption that the formation is water-wet such that water occupies the smaller pores and oil relaxes as the bulk fluid. Examination of crude oil, brine, rock systems show that a mixed-wet condition is more common than a water-wet condition, but the NMR interpretation may not be adversely affected [47]. Surfactants used in oil-based drilling fluids have a significant effect on wettability and the NMR response can be correlated with the Amott-Harvey wettability index [46]. These surfactants can have an effect on the estimation of the irreducible water saturation unless compensated by adjusting the T2 cut-off [48]. 

G. Taicher and A. Reiderman, NMR well logging apparams and method. United States Patent 6,018,243, 1997. 

C.M. Edwards and D.T. Georgi, High-resolution high-speed NMR well logging device. United States Patent, 7,012,426, 2006. 

Despite the limitations discussed in earlier Subsections, relaxation time data are useful for characterizing porous media. For instance, NMR well logging experiments provide valuable information that may be critical in determining whether a particular borehole will be profitable. As well as pore size information, other parameters characterizing the pore space have also been obtained from relaxation data. 

Sedimentary rocks from oil reservoirs exhibit significant porosity where crude oils and water often coexist to share the pore space. The characterization of the pore structure and the fluids in situ is essential in the development of oilfields and specifically in the design of the production strategy and the facility. NMR has become an increasingly important well-logging and laboratory technique to quantify rock and fluid properties. 2D NMR has recently been introduced to the petroleum industry as a commercial well-logging service [58]. We will first review a few examples of the 2D NMR experiments on the sedimentary rocks in laboratory and well-logging applications. 

NMR has proven to be a valuable tool for formation evaluation by well logging, downhole fluid analysis and laboratory rock characterization. It gives a direct measure of porosity as the response is only from the fluids in the pore space of the rock. The relaxation time distribution correlates with the pore size distribution. This correlation makes it possible to estimate permeability and irreducible water saturation. When more than one fluid is present in the rock, the fluids can be identified based on the difference in the fluid diffusivity in addition to relaxation times. Interpretation of NMR responses has been greatly advanced with the ability to display two distributions simultaneously. 

S. Godefroy, M. Fleury, F. Deflandre, J.-P. Korb 2002, (Temperature effect on NMR surface relaxation in rocks for well logging applications),/. Phys. Chem. B 106, 11183-11190. 

J. C. Goswami, A. Sezginer, and B. Luong, On the design of NMR sensor for well-logging applications, IEEE Antennas Propag., 48(9), 1393-1402 (2000). 

In addition to the above suite of well logs, the newest type of log was obtained via NMR (here called CMR) as shown in Figure 7.37. In this new method, the capillary, clay-bound, and free water (on the right) as determined by the NMR log, are subtracted from the total porosity as determined by the density tool (not shown) to obtain the hydrate saturation in the middle column. 

R 327 M. Auger, Biological and Pharmaceutical Applications of Solid-State NMR Spectroscopy , Can. J. Anal. Sci. Spect., 2002, 47,184 R 328 K. Awazu and H. Kawazoe, Strained Si-O-Si Bonds in Amorphous SiOa Materials A Family Member of Active Centers in Radio, Photo, and Chemical Responses , J. Appl. Phys., 2003,94, 6243 R 329 T. Babadagli and S. Al-Salmi, A Review of Permeability-Prediction Methods for Carbonate Reservoirs Using Well-Log Data , SPE Reserv. Eval. Eng., 2004, 7, 75... 

The T2 distribution has applications as diverse as petroleum geology and bread making. It distribution has been applied in the petroleum industry for many years to characterize rock cores to obtain pore size distributions in well-logging operations. Rock cores from oil wells are filled with water or oil. The NMR CPMG echo train is acquired in a TD-NMR instrument and the T2 distribution is obtained. This is essentially a mirror image of pore size distribution, as water in small pores is more restricted it is less mobile (short T. Water in large pores has more freedom to move (long Tj). 

Kleinberg RL (1996) Well logging. In Encyclopedia of NMR. Wiley-Liss, New York, pp 4960 969... 

Two models are used to derive permeability from NMR measurements. For both models, it is assumed that the volume investigated by NMR measurement is completely water filled. In well-logging applications, this is given because the volume investigated by NMR is so shallow that it is completely flushed by drilling fluid if other fluids are present, a hydrogen index correction must be applied. 

Vinegar, H.J., 1995. Lecture notes, SPWLA Short Course on NMR Logging, Paris, 26-29 June. Society of Petrophysicists and Well Log Analysts, Houston. 

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