Well logs-derived radiogenic heat production in the sediments of the Chad Basin, NE Nigeria

Abstract

Radiogenic heat production estimated from the concentrations of the radioactive elements obtained from log data from a well drilled in the Chad Basin, NE Nigeria range between 0.17 and 1.90, have an average of 0.90±0.01 and a standard deviation of 0.34 μW m-3. The data also indicated that the sediments are low in the concentration of the radioactive element potassium, normal in thorium and higher-than normal in uranium, with potassium contributing only about 7.5% to the production. The Chad, Kerri Kerri, Gombe, Fika, Gongila and Bima Formations are estimated to have average heat productions of 1.02±0.03, 0.62±0.01, 1.21±0.02, 0.93±0.01, 0.94±0.01 and 0.76±0.01 μW m-3, respectively, values observed to be smaller than those of neighbouring basins. Heat production estimated from gamma ray intensity moderately correlated with those estimated from the concentrations of radioactive elements, while only low correlation was observed with heat production estimated from fractional proportion of quartz in matrix. Radiogenic heat is estimated to contribute between 14 and 27% of the surface heat flow, while map view of well site heat production revealed trend that decrease with increasing sediment thickness. Further analysis also suggests that up to 366 m of the bima formation may have been derived from the same source. © 2010 Asian Network for Scientific Information.