Measurement of phase behavior or pressure/volume/temperature (PVT) analysis is a key component of optimum utilization of hydrocarbon resources. Representative fluid samples are required to enable advanced physical and chemical analyses to be carried out in specialized fluid testing lab. Fluid samples are collected in the field either subsurface in the wellbore or at surface separator. Collected samples are then transferred from the field to the PVT lab under controlled conditions. Once in the lab, the following QA/QC tests are conducted to make sure the samples are representative:
- Opening Pressure
- Saturation Pressure at Separator Temperature
- Air/Water contents
- Compositional Analysis
Although thorough sample-checking procedures can identify some of the most obvious problems, there is never absolute certainty that the fluid under study is truly representative of the reservoir fluid. On occasion, laboratory measurements can show that a fluid is definitely not representative (e.g., saturation pressure is significantly higher than reservoir pressure
