The basic concept of the Earth structure and Plate Tectonic is good to know for drilling oil and gas wells.
The image below (Figure 1) shows the Earth structure. There are tree compositional layers which are curst, mantel and core. At the center of the Earth, the center core is a solid iron core which is surrounded by a liquid iron core. Core has a range between 2,900 – 6,370 km from surface. Mantel which has its range between 100 – 2,900 km consists of upper and lower mantel. Lower mantle (Meshosphere) is hot but strong due to high pressure however upper mantle is weak, hot and molten. Crust is a surface of the Earth and a majority of the Earth crust is made up of iron, silicon, oxygen and magnesium.
Figure 1 – Earth Structure