Lexicographic approach to well placement optimization for short, medium and long term investment decision

This thesis presents an investigation of the effect of production time in well placement optimization as well as the effect of adding well spacing constraints, and the use of lexicographical multi objective approach considering short, medium and long term net present values (NPV) as different objectives.;Adding minimum well spacing constraints to the optimization problem is necessary although it affects the results. We found this effect is varying from negligible to more noticeable depending on the density of wells to be completed in the reservoir.;The results of the study showed that well placement optimization results in short, medium and long term are affected by changing the simulated period. When short period NPV is used as the objective function the optimum results for medium and long term are not guaranteed.;We proposed the use of lexicographic approach in well placement optimization to simultaneously optimize the NPVs for different suggested project life times. The results of this approach compared to the regular single objective optimization found to achieve a well configuration that ensures better results in short, medium and long term investment scenarios. A drawback of this approach is that it involves sequential optimization which requires more function evaluation and therefore more time and computational cost.