Determination of connectivity in reservoirs using downhole fluid analysis

Abstract

Downhole Fluid Analysis (DFA) is a concept that utilizes downhole optical spectroscopy to provide laboratory quality measurements as part of advanced formation tester (FT) operations. With DFA, several fluid properties including GOR, hydrocarbon composition, contamination estimation, and color can be determined. Recent advances in asphaltene science have related the fluid color to the asphaltene content of the fluid. Asphaltenes have been shown to grade continuously in an oil column; therefore a continuous asphaltene gradient would indicate a reservoir with a higher probability of fluid communication while a deviation from this gradient would indicate a reservoir which would likely not have fluid communication and is likely not connected. DFA-enabled FT operations can be used to determine the asphaltene gradient in an oil and gas column. The Flory-Huggins-Zuo (FHZ) equation of state (EOS) has been developed to predict the asphaltene gradient. In this study, the predicted asphaltene gradient determined from the FHZ EOS for low GOR crudes is compared to the DFA and laboratory data in order to determine connectivity in a reservoir.