Estimation of Gas Volumes in Shale Gas Systems: Mass Balances and Kinetic Modeling
F. Behar1 and F. Haeseler1
Results show that the amount of gas associated to oil ranges between 20 and 40 mg/g C and any kerogen type is capable to generate late dry gas in amount between 60 and 80 mg/g C. Moreover, the same amount of late gas is generated either from an immature kerogen than from a mature kerogen. This means that it is possible to anticipate from immature samples both the volume and the gas composition for maturities higher than 1.2% Ro. For instance, assuming an initial organic carbon content of 2%, the gas volume originating from retained compounds represents 3 to 5 Scf/ton whereas the late gas range between 40 and 60 Scf/ton. Consequently, due to these successive reactions the molecular gas composition varies continuously with increasing maturity. At Ro = 1.0% the dryness being 60% sharply increases to 90% at maturities between 2 and 3% Ro.
AAPG Search and Discovery Article #90188 ©GEO-2014, 11th Middle East Geosciences Conference and Exhibition, 10-12 March 2014, Manama, Bahrain