Mathematics, Physics and Computer SciencesTemperature variations in the Niger Delta subsurface from continuous temperature logs.

Abstract

Continuous temperature data from 126 wells allowed to attain a state of thermal equilibrium for several months and 134 wells (stabilisation within thirty days) were used to determine the variations in temperature in the Niger Delta.




At about 8,000 ftss., high temperatures of 80 - 120 ºC exist in the Northern and Ughellis depobelts, low temperatures of 46 – 88 ºC are recorded in the Central and Coastal depobelts, moderate temperatures 80 – 100 ºC are seen in the Offshore depobelt. At 6,000 and 4,000 ftss. similar trends are also evident.




Regional geothermal gradients range from 1.5 – 2.5 ºC/100 m in the Coastal depobelt and Offshore regions and increases northward to 4.5 ºC/100 m. Vertical geothermal gradients show a continuous but non linear function with depth and increases with diminishing sand percentage from less than 1.0 ºC/100 m in the continental sands through 2.5 ºC/100 m in the paralic section to 5.0 ºC/100 m in the continuous shaly section. Higher gradients are associated with shaly formations primarily because of low thermal conductivity.

Global Journal of Pure and Applied Sciences Volume , No 1 January (2001) pp. 137-142




KEY WORDS:

Temperature variations, subsurface, temperature logs, sand percentage, depobelts.