Integrated Hydrocarbon System Analysis in SPDC

Herwig H. Ganz¹, Uzor Aneke¹, Charles Anowai², Joe Ejedawe², Beni Lehner², and Kehinde Ladipo^1
1 SPDC, Port Harcourt, Nigeria
² SIEP Rijswijk, Rijswijk, Netherlands

SPDC's oil and gas reserves are distributed over more than 4000 reservoirs. Although some areas have been classified as predominantly oil or gas prone, occurrence of oil and gas reservoirs seems random and unpredictable. Particularly the occurrence of high CGR (condensate-gas-ratio) gas is very poorly understood and condensate reserves are often not even properly evaluated since historically they were not considered valuable commodities. However, with the rapidly developing Nigerian gas market and ambitious plans to ever increasing NLNG capacity with strong and very specific gas quality criteria, hydrocarbon type and quality is one of the major risks and uncertainties of most exploration and development targets. Thus, understanding and predicting hydrocarbon type and distribution and particularly CGR are of prime economic importance. The following four processes are critical to understanding oil and gas distribution in the Niger Delta:

1. The hydrocarbon system (mainly: source rocks and maturity) 2. Processes that control CGR 3. Processes that control GOR 4. Processes that control biodegradation and occurrence of biogenic gas.

During the last years a pragmatic but effective model has been developed in SPDC. The model itself and examples to predict hydrocarbon type and distribution in the Niger Delta will be presented.