Due: 3/28/02
Geodynamics
Problem Set 4
1. Temperatures at the interfaces between sedimentary layers of different rock types as determined from a well log are given below. The measured thermal conductivity of each layer is also given. Determine the heat flow through each layer.
Depth (m) | Temp (°C) | Rock Type | k (W/m-°K) |
380 | 18.362 | Sandstone | 3.2 |
402 | 18.871 | Shale | 1.7 |
412 | 19.330 | Sandstone | 5.3 |
465 | 20.446 | Salt | 6.1 |
475 | 20.580 | Sandstone | 3.4 |
510 | 21.331 | Shale | 1.9 |
515 | 21.510 |
3. Assume that the yearly temperature variation is periodic. What is the skin depth? At what depth is the temperature 180° out of phase with the surface variation? Assume that k = 1 mm2/s.
4. The ocean ridges are made up of a series of parallel segments connected by transform faults, as shown below. Because of the difference of age there is a vertical offset on the fracture zones. What is the vertical offset (a) at the ridge crest and (b) 100 km from the ridge crest. (rm = 3300 kg/m3, k = 1 mm2/s, a = 3x10-5, Tm-To = 1300 °K, u = 50 mm/yr).
5. If petroleum formation requires temperatures between 100 °C and 150 °C, how deep would you drill in a sedimentary basin 20 Myr old? Assume To = 10 °C, Tm = 1300 °C, km = 1 mm2/s, ks = 2 W/m-°K, and km = 3.3 W/m-°K.