Reservoir characterization of Yolde Formation, Kolmani Field, Gongola Basin, Nigeria using pressure, temperature, PVT, and well log data.

The reservoir characterization of the Yolde Formation was conducted to assess the hydrocarbon potential of the Kolmani field in the Gongola Basin, Upper Benue Trough. This evaluation utilized Pressure, Temperature, PVT, mobility, and well log data. Data from repeated formation testers (RFT), modular formation testers (MDT), PVT laboratory results, and well logs were analyzed to achieve a comprehensive understanding of the Yolde Formation reservoir. The pressure data and PVT analysis revealed the presence of gas and water in the Yolde Formation at depths of 6916 ft and 6997 ft, respectively. This led to the identification of the gas-water contact at 6997 ft. Further analysis of the gas type using PVT analysis and the Soave-Redlich-Kwong (SRK) equation of state (EOS) model indicated that 80% of the gas in the reservoir was condensate gas. Temperature data ranged from 104 to 270 °F at the bottom hole and 109 °F to 281 °F in the formation. The calculated geothermal gradients of 0.0228 deg F/ft (52.49 °C/Km) and 0.0234 deg F/ft (42.62 °C/Km) suggested favorable conditions for gas reservoirs and hydrocarbon generation. The highest fluid mobility was observed at depths of 6916 ft, 7116.5 ft, and 7186.9 ft, indicating the presence of gas. The gamma ray log and resistivity log of the Kowell-1 well characterized the Yolde Formation as a substantial system of thin to medium sand/shale laminae. This research provides valuable insights into the hydrocarbon potential of the area, supporting future exploration and development efforts.