Safe production is one of the most important issues in oil and gas plants. Oil and gas companies lose enormous amounts of money and trust once they experience accidents such as explosions and oil spills. They have to make clear production rate limits to mitigate the human related risks that cause accidents. In this study, we model plant workers using an agent-based simulation to estimate the limits. The proposed model represents that plant workers solve problems with risks, and that the probability of the occurrence of a problem is proportional to three main factors, the production rate, the plant size, and the plant equipment degradation rate. The experimental results show that the proposed model can estimate the limits for different sizes of the three factors. The results imply that the limit estimation made by the proposed model is very crucial for plant operations to mitigate human-related accidents. © Springer-Verlag Berlin Heidelberg 2014.