Page 158 - Physical Principles of Sedimentary Basin Analysis

140 Heat flow

0
h =790m x = 0.5 km
x = 4.9 km

1
depth [km] h =910m h =180m Sandstone

2

Sandstone
Salt
3
0 25 50 75 100 125
temperature [°C]
Figure 6.16. Geotherms through the center of the diapir and at the left side of the model. The positions
of the geotherms refer to Figure 6.15.

z 1 ^ z = 1

water water

silt
z 2 ^ z = 0
shale

Figure 6.17. Meteoric fluid flow in an island of permeable sediments. Notice that the dimensionless
ˆ z-axis points upwards.

Hudec and Jackson (2007) presents the field salt tectonics in terms of observations and
mechanisms. How salt structures alter the thermal field has been studied by several authors,
for instance Lerche (1990b), Mello et al. (1995) and Petersen and Lerche (1995).

Exercise 6.14 Verify the average heat conductivities λ 1 and λ 2 using the data from
Figure 6.16 and the heat conductivities for shale, sandstone and salt given above.

6.11 Forced convective heat transfer
Areas with sufficiently “strong” fluid flow have heat convected by the fluid in addition to
transfer by conduction through the rock. This kind of heat transfer is called forced heat
convection. The fluid flow is important for the temperature, but the temperature has a neg-
ligible feedback on the fluid flow. We will now look at forced heat convection by vertical
fluid flow, for instance vertically into the ground from a high water table (see Figure 6.17),