The aim of this study is to define the core soft skills of project manager that affect the success of the project in order to develop a framework for the core soft skills and competencies required for project managers. Oil and gas companies in Oman have been taken as a case study. The followed methodological approach involves reviewing literatures related to project objectives in order to understand the given problem and facilitate survey designing phase. A survey has been designed to highlight the importance of project manager soft skills to achieve project success. As well as, to address core soft skills that have vital effects on each phase in oil and gas projects.