This article presents the evolution of the Downhole Fluid Analysis technology (DFA) to support better downhole fluid sampling operations and its tremendous increasing potential in the understanding of the reservoir fluids distribution and reservoir continuity trough the use of tracers.
When sampling formation water or hydrocarbons with wireline formation testers (WFT) in wells drilled with WBM and SBM respectively, it is important to track mud filtrate contamination by distinguishing between formation fluid and mud filtrate. Among the DFA techniques that have been recently used for continuous monitoring of the formation fluid sampling cleanup process in wireline operations is the use of fluorescence sensors. These help to differentiate between formation water and a WBM filtrate that has been marked with fluorescent tracers or SBM filtrates and formation hydrocarbons that have particular fluorobores that may allow its differentiation. In case this differentiation is not clear there is room to emphasize it by adding fluorescent tracers to the drilling fluid. This method that has been proved at single well operations can be expanded for multiwell fluid dynamics analysis by monitoring production wells nearby injectors that had received traced water or gas in slugs or continuous injection processes (Interwell Fluorescence Tracer Testing, IFWT). The monitoring can be performed mounting the DFA fluorescence sensor in a Production Logging tool, deploying permanent DFA sensors in the well completion or temporally selective tests via wireline / slick line. The existing modeling techniques for interwell tracers modeling support the fluorescence tracers planning and evaluation.
Field examples compared with laboratory results that confirm the success of this real-time monitoring solution at single well scale are presented for heterogeneous formations.