We know that underground rock formations can't all be the same. Some are soft and a little hard. According to this situation, we choose the drilling machine, and use the drilling method, also have to change in time.
Let's take a detailed division of the underground rock formations, as well as the corresponding drilling methods. Salt formation: is a water-soluble formation, relatively soft.
But the drill erstwhile is easy to stick to mud, and the holes that come out are easy to drop and even collapse.
Soil adhesion layer, shale: is a water-sensitive formation, drill bit easy to form a mud bag, drilling out of the hole will generally be over-diameter.
Sand, gravel, loose lysing formation: is a loose pore formation, easy to leak, leak ingesta.
High-pressure oil and gas well formations: underground storage of oil, natural gas, etc. , easy to blow out, causing serious consequences.
High temperature formation: geothermal well, ultra-deep well encountered formation, mud treatment agent failure, formation instability. Due to the complex formation, we must look into it when drilling.
Above, just list a few single formations, some are complex, in a layer, you may encounter the above several situations.