Downhole Fluid Analysis and Gas Chromatography; a Powerful Combination for Reservoir Evaluation
- Oliver C. Mullins (Schlumberger) | Julia C. Forsythe (Schlumberger) | Andrew E. Pomerantz (Schlumberger) | Tim Wilkinson (TALOS) | Ben Winkelman (TALOS) | Vinay K. Mishra (Schlumberger) | Jesus A. Canas (Schlumberger) | Li Chen (Schlumberger) | Richard Jackson (Schlumberger) | Soraya S. Betancourt (Schlumberger) | Julian Y. Zuo (Schlumberger) | Armin Kauerauf (Schlumberger) | Ken E. Peters (Schlumberger)
- Document ID
- Society of Petrophysicists and Well-Log Analysts
- Publication Date
- October 2018
- Document Type
- Journal Paper
- 649 - 671
- 2018. Society of Petrophysicists & Well Log Analysts
- 2 in the last 30 days
- 184 since 2007
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Downhole fluid analysis (DFA) accurately measures light absorption (optical density or OD) in different optical wavelength channels vertically and laterally in reservoirs providing accurate fluid gradients especially for dissolved gas, liquids and dissolved solids, the asphaltenes. DFA data can then be used for thermodynamic analysis using the cubic equation of state for gas-liquid equilibria, and the Flory-Huggins-Zuo equation of state (FHZ EoS) for solution-asphaltene equilibria. Thermodynamically equilibrated reservoir asphaltenes imply reservoir connectivity. Disequilibrium can imply recent or ongoing reservoir fluid geodynamic (RFG) processes, which impact major production concerns. Compositional analysis of the reservoir fluids using conventional gas chromatography (GC) and two-dimensional gas chromatography (GC×GC) can be used to validate the thermodynamic analyses, especially within a geochemical context.
Several reservoirs are examined here with DFA, GC and GC×GC methods exploring many different reservoir concerns. Connectivity and its inverse compartmentalization are recurring concerns and are effectively addressed. GC×GC is shown to support simple thermodynamic modeling enabling connectivity analysis, which is then validated in production. Viscosity profiles throughout reservoirs are accounted for using simple modeling of asphaltene gradients. Biodegradation is shown to yield three endmember viscosity profiles, no in-reservoir gradients versus large in-reservoir gradients at the OWC or large gradients at the top of the oil column, and the governing RFG processes are clearly identified. Water washing is measured over a large range and has a secondary effect on oil quality; factors that control the extent of water washing are shown. A universal protocol is used for reservoir evaluation that elucidates key reservoir concerns efficiently. This protocol is generally applicable for reservoirs in all stages of exploration, appraisal and development.
|File Size||23 MB||Number of Pages||23|