Under subsurface reservoir conditions, petroleum may exist as a single vapour phase, as in gas accumulations, a single liquid phase, as exemplified by undersaturated crude oils, or a two-phase system where a gas cap is in equilibrium with an underlying oil leg.
Being able to predict gas-oil ratio and bulk petroleum phase volumes ahead of drilling is a crucial yet very poorly constrained element of exploration strategy. Predicting the composition of the liquid phase is also critical because sulphur contents, wax contents and TAN all directly affect viscosity, recovery and price per barrel.
In order to be able to address the probability of encountering petroleum in the subsurface, as well as estimating phase state and physical properties ahead of drilling, the integration of basin and petroleum system evolution of the study area is required.
No Black Boxes
Our conceptual approach to pre-drill pay definition is science-based and relies on published results. The figure below visualizes the development of concept by presenting important publications on the way. Full references are given here.