Reservoirs with temperatures of 150 degrees C or more. Producing oil or gas from such fields means constantly pushing back the technological frontier. HPHT can also cause a hole to collapse and danger of a blowout. When oil is produced from very deep wells it comes out of the ground at a very high temperature cooling quickly on its way out and causing paraffin to form and clog the pipes. In addition, the oil is produced at extremely high pressure (about 230 times the pressure of air in a car’s tire)