primary crack meaning in Chinese

主要裂缝

The gas generation of low mature source rocks has been simulated in the open system and close system respectively . the models of primary cracking gas ( gas from kerogen ) and secondary cracking gas ( gas from oil ) have been established . the ro value of primary cracking gas generation peak is ranged from 1 . 0 % to 1 . 5 % . the ro value of secondary gas generation peak is ranged from 1 . 5 % to 2 . 5 %
对低成熟(部分为成熟)的烃源岩在开放和密闭体系下的生气热模拟实验研究建立了热解气和油裂解气的生气模式，热解气的生气高峰在ro = 1 . 0 ? 1 . 5 ，油裂解气生气高峰是在ro = 1 . 5 ? 2 . 5之间，从热解气和油裂解气的相对含量来看热解气占总生气量的21 ，油裂解气可能占79 ，油裂解气产率为620m ~ 3吨