The main objective of this study was to develop a competency model and study the relationships of intensive training, quality assessment, motivation, and skill pool expert on the core competencies of workers serving in the oil and gas industry in Yemen to maintain sustainable productivity, development of the country's economy, employees' safety and clean environment in the O&G production. A preliminary study and questionnaire were used to assess the technical trainees' perceptions in operation, maintenance, and safety of five oil companies in Yemen. The sample was 350 trainees in this study. The data were analyzed by using SPSS software and Structural Equation Modelling (SEM). The result found that intensive training, quality assessment motivation has a significant positive effect on employees' core competence, however, the skill pool expert specifically in line supervisor and coach has a strong effect on employees' core competencies. Multiple linear regression analysis was used to test a hypothesis. This study was conducted in five oil companies and among 350 trainees only. For this reason, the results cannot be generalized to other contexts, where the other companies not interested and implemented conventional training programs, characteristics, and peer support from the work environment, were outside the scope of the study. This study will add value to the efforts of the oil exploration and production board in Yemen, by providing an increased understanding of the factors that create competent technicians based on the competency model