Casing pipes are used to secure not stable the walls of the wells, restore the circulation of drilling fluid and separation of the rock strata. Bolted using threaded connections of the casing to form a casing. Casing pipe lowered into the well, corrosion. In accordance with the poor conditions of service drill pipes are manufactured from steel of strength class C and D, with a tensile strength of 550 and 650 MPa. Industry normal HE-41-68.Drilling company «Peter geo» uses drill pipe with a diameter of 127 mm wall 5 of article 5 group D and PVC pipes. These drill pipes are the type of connections without nipple i.e. at one end has male, the other female thread. When connecting with each other such drill pipe form the drill casing with smooth inner and outer surfaces. When running-in-hole drill pipe thread grease. Before lowering the drill string into the well on drill pipe bottom screw steel short Shoe «crown». The bottom of the Shoe is hardened. Purpose of Shoe is to protect the lower drill pipe from possible deformation during the descent of the drill string and to facilitate the descent of the drill string into the well, as the Shoe of the drill string cuts off the irregularities that may be on the walls of the borehole. To ensure descent of the drill string to a predetermined depth of the wellbore is pre-worked and calibrated. During the descent of the drill string, particular attention should be paid to the quality of threaded connections. Drilling in water has to deal with the aggressive (corrosive) waters. Therefore, along with mounting drilling steel pipes are widely used pipes made of rigid PVC (polyvinyl chloride) PVC.
Plastic tubes characterized by a small weight and have high corrosion resistance exceeding the resistance of high-alloy corrosion-resistant steels of the best brands. Plastics such as polyvinyl chloride and polyethylene, is chemically resistant to some organic and non-organic compounds.