Nigeria is a critical player in the energy industry. However, the industry has concerns over the under performance of Nigerian oil and gas projects. This study involved comprehensive and quantitative analysis of Nigerian oil and gas project performance from technical and non-technical perspectives with data from 65 projects. Nigerian projects have a high average cost overrun of 38% with an SD of 39%, time overrun of 37% with an SD of 41%, fatality rate of 0.027, and oil spillage ratio of 18.51. The overall performance of Nigerian projects is much worse than that for their global peers. The results demonstrate that Nigerian oil and gas projects are of low subsurface complexity and present low technology challenges, which are advantages for field development; therefore, subsurface complexity and technology challenges are not the major causes of the poor performance. However, non-technical factors (local content, community, security, and partnership) play a significant role. In the study, the degree of the factor's effect is quantified and categorized into groups for guidance. Further, a set of recommended practices was developed based on the risk level to assist project planners, international companies, investors, and policymakers to mitigate risks of developing oil and gas projects. (C) 2018 Elsevier Ltd. All rights reserved.