PVT Properties in the IGI Property Model

The Bulk group now contains fluid behaviour properties (Oil density, GOR, oil content properties e.g. %S, %N etc.) reported specifically from a geochemical laboratory. 

Taking account of the analysis location, well site surface test results are captured in the PVT-Flow group, while results from tests undertaken in a PVT laboratory on collected fluids are reported in the appropriate PVT groups (Figure 1).  

The renamed PVT (formerlyBulkPVT) and PVT-GC groups are the main PVT property groups containing parameters derived from laboratory tests.   

The source of core PVT properties (Table 1) in the PVT group is designated to come from the routinely run validation single-stage separation test (aka Atmospheric Flash test).  

The depressurised oil and gas fractions obtained from the single-stage separation test are used to conduct fluid composition analysis. By preference, the PVT-GC property group should be used to store the normalised molar fractions for the recombined reservoir fluid. The phase used should be stored in the Comp phase.PVT-GC property.  Along with the capacity to store information on individual molecules, the property group also supports a range of plus faction compositions. 

Where core PVT properties (Table 1) are derived from alternative laboratory PVT tests, test-specific property groups have been provided. An unknown test group is also available where the laboratory test is unknown: 

Oil density (Oil dens.PVT) is routinely reported at atmospheric conditions, equivalent to stock tank oil. Provision in the model has also been made for oil density values reported at saturation and reservoir pressure (both at reservoir temperature);Oil dens pSat & Oil dens pReserv respectively. Accommodation of values routinely reported relative to different pressures also applies to a sample’s formation volume factor.  

The gas-oil-ratio (GOR) property has several aliases in PVT analysis based on whether data has been measured from PVT on-site tests or laboratory tests (GOR, GLR, GVF, Rs, GOR/Rs). The model uses the common term GOR throughout its naming, with aliases to assist property discovery and linking where appropriate.   

Fluid viscosity values are recorded in the PVT-Visc group. Sample viscosity is given its own group, as the group contains three separate schemas depending on the test set-up used. The three schemas present are: 

1. Viscosity is reported relative to saturation and reservoir pressure with the temperature fixed at the reservoir value (reported in the tReserv.PVT property) 
2. Viscosity is reported relative to saturation and reservoir pressure with the temperature fixed at a value different to that in thereservoir (reported in the Alt Temp.PVT-Visc property) 
3. Viscosity is reported relative to user-defined pressure and temperature values (reported in the User Temp.PVT-Visc & User Pressure.PVT-Visc properties). 

In the Fluid-Interp group, users can record fluid contamination levels and assign PVT samples to a fluid class. This property group also allows the user to record an associated comment and interpretation confidence level. 

Figures 2 and 3 provide a full overview of the PVT property groups & properties. We hope you find the new PVT model extension useful.