Gas shale profiling
Shale gas is a hot item in the USA. Now there is major activity in Europe and elsewhere. GeoS4 is already providing specialist services for evaluating gas-in-place in potential and proven gas shales worldwide.
The relative proportion of oil and gas in conventional petroleum systems is highly variable, and depends initially on the nature of the parent source rock organic matter and its level of maturity at the time of expulsion, and subsequently upon the pressure, temperature and biology of the source-carrier-reservoir system during expulsion, migration and accumulation. Clearly, reservoir quality, the timing of trap formation, and seal integrity must also be in harmony, and economic viability depends upon the cumulative influence of all four elements.
Broadly the same scenario applies to unconventional shale gas plays. Except in this case source rock properties are of paramount importance because the resource is contained within the shale itself; hence it is an organic-rich reservoir as well as source rock in which the gas is stored in the matrix/fracture porosity and sorbed on the surface of the organic fraction. Some gas shales have been said to be dysfunctional source rocks, in that they have retained a high proportion of the gas they have generated, rather than simply expelling it into adjacent carrier- and reservoir-facies rocks.
Our gas shale profiling services
Estimate gas-in-place: We use compositional kinetics, including PhaseKinetics to do this. In fact, gas is sourced by 3 processes : the first one (early gas) is associated to oil generation; the second one (late gas) results from mature kerogen cracking at maturities beyond the oil window; the last one (secondary gas) is due to oil cracking within the source rock. The compositional kinetic model predicts GOR, viscosity, API gravity, and saturation pressure as function of maturity and OM type. We also use compositional mass balances where maturity series are available.
Identify methane sources: We use individual stable carbon isotopes of gases as function of maturity and OM type to do this.
Shale Gas Profiling: Organic matter - the critical component of gas shales - laid out in a simple profiler system.
Unravel vertical and lateral heterogeneities: High density profiling is a must, considering the heterogeneity of many gas shales, when developing production strategies.
Related resources
Click here to learn more about GASH, an interdisciplinary Gas Shale research program run by a multinational expert task force drawn from research institutions, geological surveys, universities and consultants with the goal of predicting shale gas formation and occurrence in time and space.