Research
Analytical Determination of Subsurface Temperature Using Two Layers Model in Part of Niger Delta Sedimentary Basin, Nigeria
The solution of Fourier's one-dimensional steady state conduction heat flow equation for two layers-model has been solved using the analytical techniques and applied to part of Niger Delta sedimentary basin. The temperature-depth profile obtained shows a linear increase in temperature with depth. The internal properties affecting the thermal structures are the thermal conductivity and heat production. Comparison of measured and computed temperatures for some wells showed good agreement with minor variation ranging between -4.0 to 5.0 oC. This model can be used to determine thermal properties of other parts of the basin with little adjustment of the rock properties values.
Radiogenic Heat Production from Well Logs in Part of Niger Delta Sedimentary Basin, Nigeria.
The radiogenic heat produced from radioactive elements has been investigated in some parts of Niger Delta sedimentary basin. The heat production was computed from gamma ray logs for three oil producing wells. The major lithology observed in the gamma ray log is alternation of sand and shale. The computed value ranges between0.35 to 2.0μWm-3 for well 1, 0.34 to 1.78μWm-3 for well 2 and 0.24 to 2.0μWm-3 for well 3. The average radiogenic heat production ranges between 0.3 to 1.93μWm-3. It was observed that the heat production within the sand lithology ranges from 0.24 to 0.7μWm-3.Whilethe computed value for the shale lithology ranges from 0.8 to 2.0 μWm-3. The high radiogenic heat production in shale was as a result of high concentration of radioactive elements. The sandstone zone was deficient of radioactive elements and this resulted in the low value. The plot of depth against radiogenic heat production was scattered and it also showed an increase with depth. The increase was due to high shale lithology at greater depth of the Agbada Formation and the shale in the Akata Formation. A linear relationship was established for the radiogenic heat production and the product of gamma ray and density logs for the study Area. The relationship can be used if gamma ray spectral logs are not available.
