Downhole and surface fluid sample acquisition demand customised sampling methods to overcome the following issues:
- low oil mobility
- sand production from unconsolidated formations
- high asphaltene content and resulting high gradients
- formation of water-in-oil emulsion and formation during production of the well
The high viscosity oils exhibit slower gas liberation below the bubble point and therefore delayed gas-phase formation, posing a huge problem to maintain equilibrium in the separator, thus making “true” oil property measurements a challenge. Difficulties associated with fluid modelling include characterising apparent bubble point behaviour, large viscosity changes with pressure and temperature, and high asphaltene content.
Additionally, Queiroz Galvão requires a substantial volume of reservoir hydrocarbon fluid for reservoir fluid characterization and process design. This provides them with good fluids property knowledge to preempt any flow assurance issues they might experience with the well and minimise problems with the completion string components.