Reservoir Fluid Geodynamics and
A New Thermodynamic Treatment of Reservoir Crude Oils

March 25 , 2019

VIDEO LECTURES PART 1 OF 3:

VIDEO LECTURES PART 2 OF 3:

VIDEO LECTURES PART 3 OF 3:

Doctor Oliver Mullins

Schlumberger Limited

ABSTRACT

Reservoir crude oils consist of dissolved gases, liquids and dissolved solids, the asphaltenes. Cubic equations of state, variants of the van der Waals equation, have been used to treated gas-liquid equilibria of reservoir crude oils for 45 years. Until recently, there had been no 1st-principles treatment of solution-solid equilibria for reservoir crude oils. With the resolution of the three asphaltene nanostructures in crude oil (and laboratory solvents) codified in the Yen-Mullins model, the gravity and other terms are resolved and the first asphaltene EoS has been developed, the Flory-Huggins-Zuo EoS. Reservoir case studies show that this treatment is valid over 100 kilometer lengths scales and over 50 million year time lines. Moreover, the asphaltene EoS is critically important to address a wide variety of reservoirs concerns and will be reviewed.
Until recently, there had been little accounting for the chemistry and physics processes of reservoir fluids over geologic time after entry into the reservoir. With the routine ability to identify equilibration of reservoir fluids, it is now possible to identify disequilibrium processes; “Reservoir Fluid Geodynamics” (RFG) is a new technical discipline that accounts for these dynamics. The technology advance of downhole fluid analysis provides data sets that can then be interpreted within a thermodynamic construct of the Flory-Huggins-Zuo EoS. 40 oilfield case studies provide tremendous insight into an array of RFG processes. For robust analysis, this thermodynamic treatment is best coupled with high resolution compositional analysis with geochemical interpretation. Two-dimensional gas chromatography (GCxGC) is the method of choice for liquid-phase compositional analysis. Oilfield case studies are reviewed starting with simple thermodynamic equilibrium of light oils, black oils, and heavy oils, associated with the three asphaltene nanostructures. Equilibration of asphaltenes implies the oil is in a single producing unit addressing the most important reservoir concern in all deepwater markets globally. Ongoing RFG processes associated gas charge into oil and also biodegradation of oil are shown to cause significant disequilibrium persisting for long geologic times. The industry’s first “movie” of tar mat formation is shown (albeit only two time frames). The coupling of science and technology advances is leading to an explosion of oilfield applications.

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