Natural gas helium extraction system and helium extraction process

The invention discloses a natural gas helium extraction system and a helium extraction process, and belongs to the technical field of natural gas helium extraction, the helium extraction process is divided into a low-temperature workshop section and a lower-temperature workshop section, two different working medium circulating refrigeration processes are matched, and two refrigerants methane with different boiling points and nitrogen are used for compression expansion refrigeration to provide cooling capacity for the two workshop sections. And cold energy is provided according to the required low temperature level, that is, cold energy at a relatively high temperature level is prevented from being provided for a working section requiring low temperature, and cold energy at a relatively low temperature level is prevented from being provided for a working section requiring relatively high temperature, so that the amount of cold energy required by the working section requiring relatively low temperature is great