Soil pollution from waste crude oil in emergency pits is a major problem at petroleum industry sites. In this work, extra-heavy waste crude oil was recovered from emergency pits and underwent many pre-purification processes to remove water and impurities. This type of oil was subjected to thermal cracking reactions in a semi-batch reactor constructed from stainless steel, with a volume of 500 mL. The cracking reactions were tested at operating temperatures of 400, 425, and 450 °C, with operating pressures of 1, 3, 5, and 7 bar. The results indicated that during thermal cracking, the reaction mechanism was highly dependent on the heat and mass transfer processes that occurred in the reactor. It was noted that the interaction between the optimal reaction temperature and operating pressure enhanced the product distribution and formation of high-quality liquid fuel with low gaseous and coke formations. The highest API of 30.5 was achieved for the liquid product at an operating temperature of 400 °C and a pressure of 3 bar. Additionally, an evaluation of the thermal cracking mechanism found that the transport processes that occurred in the reactor were the chief factor in providing a high-performance thermal cracking process.