One of the main applications of MRILab, the recently introduced NMR fluid analyzer, is the estimation of mud-filtrate contamination during the pump-out phase, prior to securing high quality fluid samples for PVT analysis. The NMR fluid analyzer utilizes T_1 saturation recovery measurements for contamination analysis. The main objective of this paper is to discuss the principles behind recently developed T_1 based novel methodologies that yield accurate and robust contamination estimates. The proposed algorithms were used to estimate the contamination levels in an offshore well drilled with OBM. Comparisons with laboratory assays on nine fluid samples show excellent agreement, thus proving the concept of using an NMR fluid analyzer for contamination analysis in sampling applications. A secondary objective of the paper is to illustrate the benefits of integrating fluid analyzer data with open-hole and NMR logs. Such integration leads to an overall improved interpretation, particularly in terms of hydrocarbon fluid properties.
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