Most maturity calculations carried out by existing software, including Novva, are based on the Easy%Ro algorithm developed by Lawrence Livermore National Laboratory (Sweeney and Burnham, 1990). We also find that this method works quite well. At present we don’t include any effects of either fluid pressure or tectonic stress in Novva.
Voldman et al. (2008) have published a method for calculating CAI (Conodont Alteration Index) values for any given thermal history, but this method is not included in any existing commercial software. However, their CAI algorithms will be included in a future version of our Novva software.
Of course, calculating maturity correctly requires an accurate reconstruction of the thermal history of the rocks, as well as a good algorithm for converting a thermal history into an Ro value. In our modeling work we pay particular attention to reconstructing unconformities as correctly as possible, since maximum temperature is often reached at maximum burial, prior to erosion. We also focus on linking our burial and heat-flow histories to the tectonic history, since tectonic events are often (but not always!) associated with conductive and/or convective thermal events.