Chalcedony, also known as Chert, is a sedimentary rock and is composed of microcrystalline quartz which means that the quartz crystals are so small that they can only be viewed with a microscope. Chalcedony occurs in nature in a variety of colors but is commonly found white, brown, red, orange, gray, black and white. Trenchless technology used for oil and gas drilling and pipeline installation often pass through different layers of rocks and sediments.
Depending on the type of soil and rock encountered, the right drill bit is used to prevent damage to downhole equipment.
Trenchlesspedia Explains Chalcedony
Chalcedony is very hard having a hardness rating of seven on the Mohs scale of hardness. It breaks with a conchoidal fracture and broken pieces are smooth with a non-granular structure. Geotechnical soil investigation can give a fair idea of the type of rock that will be encountered during the drilling process. Drill bits are chosen depending on the hardness of rock to be drilled through, preventing damage to drill head and other equipment downhole.
Many drilling projects fail because of unforeseen sub-surface rock conditions.