Petroleum development optimization under uncertainty : integrating multi-compartment tank models in mixed integer non-linear programs

A field development plan is an important document used to tell the share holders and investors that every aspect of the project has been carefully evaluated. The field development plan should include the objectives of the development, petroleum engineering data, operating and maintenance principles, description of engineering facilities, cost and manpower estimates, project planning and budget proposal. But to arrive at decisions concerning the contents of the field development plan many concept and ideas would have to be screened so that the best ideas and concepts are carried forward for detailed analysis. This screening process can be daunting as there is no limit to the number of viable concepts and ideas. To add to this, for a new field there is hardly ever enough data to fully characterize the reservoir at the time the field development plan is being formulated because there are only a handful of wells in the reservoir. This lack of information about the reservoir introduces uncertainty in the analysis done during the screening process of the concept selection and can have a significant impact on the quality of the project. In this work, we present a simple integrated asset model that can be used in conjunction with a proposed framework at the concept screening and selection phase of a project to evaluate the impact of uncertainty in the input variables on key project drivers. The model can be used to screen multiple concepts to arrive at a few promising concepts that point the direction for detailed studies. The application of the model is demonstrated with synthetic cases formulated for a deep water field which is at the concept selection phase. In the demonstration, we investigated how uncertainty in the reservoir thickness (NTG) and the degree of heterogeneity affect the optimal choices for initial facility size, the number of rigs and the number of pre drilled wells.