In many shallow petroleum prospects the original composition of petroleum is subjected to post-filling alteration through biotic and abiotic effects such as biodegradation and –synthesis, cap rock leakage, evaporative fractionation or water washing. These processes have strong economic consequences since they lead to a decrease in oil quality and producibility.
The overall goal of the Industry-Partnership-Program project BioPetS Flux is to develop integrated models for the prediction and quantification of the extent of those post-filling alteration processes in reservoirs.
Specific objectives of this project are:
- Characterisation, evaluation and interpretation of vertical and lateral variability of petroleum composition within reservoirs at high resolution.
- Developing integrated models for predicting and quantifying the extent of post-filling alteration in reservoirs.
- Using asphaltenes to reconstruct the original compositions and volumes of oils in reservoirs
- Recognition and quantification of dynamic in-reservoir processes through geological time
- Calculation of mass balances of chemical and biological alteration
The compositional heterogeneity of crude oils as well as bitumens from reservoir cores are analytically characterised using advanced petroleum geochemical techniques. Thereby particular attention is paid to the distribution of polar non-hydrocarbon constituents, containing nitrogen, sulphur and oxygen, such as carbazoles, fluorenones and xanthones which are expected to provide suitable insights into the role of partitioning processes on the reservoir scale. Also the carbon and hydrogen isotopic signatures of petroleum hydrocarbons will be determined as quantitative tracers of alteration processes in the investigated reservoirs.
Reservoir asphaltenes are investigated in order to reconstruct the original composition of trapped oil in the different reservoir levels and to estimate how much and what type of petroleum is lost due to the post-filling alteration processes. Analysis of asphaltenes isolated from rock samples will reveal small scale variations within the reservoir while asphaltenes of produced oils represent a mixture from an undefined part of the reservoir.
Haltenbanken (Norway), Campos Basin (offshore Brazil)
Raingard M. Haberer
Rolando di Primio
Sponsors: BG Group, DevonEnergy, ExxonMobil, Petrobras, Repsol, Shell, StatoilHydro