@wikipedia

Natural subsurface temperature distribution  $//<![CDATA[ \begin{array}{l}T_G({\bf r})\end{array} //]]>$, where $//<![CDATA[ \begin{array}{l}{\bf r}\end{array} //]]>$ is position vector.

It is formed by the upward vertical heat conduction from Earth's centre towards Earth's surface with account of subsurface rock inhomogeneity, local immovable heat sources and lateral/vertical heat-mass flows.

In Basin Analysis scales the Geothermal Temperature Field can be quite complex, while at a scales of a typical Petroleum Field it usually simplifies to the laterally constant Geothermal Temperature Profile.

See Also

Geology

[ Petroleum Geology ][ Geological Model (GM) ] 

[ Geothermal Temperature Profile ]

[ Geothermal Temperature Field @model ][ Geothermal Temperature Profile @model ]