Question

Q.2. What is the role of basin modeling in prospect appraisal?

Answer 1

The Role of Basin Modeling

Basin modeling should not be overlooked as a tool for assessing unconventional resources. As discussed in Chapter 7, unconventional plays are maturity driven. In the lower maturity plays, natural gas liquids and condensate are desirable products. But below a vitrinite reflectance of 1.3% Ro, PVT behavior of the hydrocarbons present will influence producibility (GOR, liquid dropout potential). In higher maturity plays, phase behavior is less of a problem. However, above a vitrinite reflectance of 2.5% Ro, loss of porosity and permeability from early metamorphism will likely limit gas available for production. Basin modeling can be used as a means of predicting maturity where data are lacking or filling in gaps in data-poor areas.

In addition, these models can be used to estimate temperature and pressure conditions in target intervals that can assist in predicting the phase behavior of reservoir fluids. And time–temperature histories from the models can be useful for predicting potential diagenetic mineral transformation, such as the opal-CT to quartz transition (Dralus et al., 2011), quartz cementation (Lander and Walderhaug, 1999), and the smectite to illite transformation (Velde and Vasseur, 1992), that can effect porosity, permeability, geomechanical properties, and fluid sensitivity.

Basin modeling is also important in understanding the impact of the burial history on unconventional resources. Many of the successful shale gas plays, including the Barnett, Eagle Ford, Haynesville, and Marcellus, have experienced significant uplift after going into the gas window and reaching maximum burial depth. Uplift likely assists in the development of overpressure in the stored gas and aids in production.