Validating the Use of Experimental Design Techniques in Exploratory Evaluations

Abstract

fax 01-972-952-9435. AbstractThis work presents a validation of the use of Experimental Design (ED) techniques in exploratory evaluations. The results generated by a commercial software, which uses ED techniques combined with the Monte Carlo method, have been compared with 10,000 equivalent actual flow simulations. Several oil and gas real reservoirs were studied. The static and dynamic variables were selected from real prospect studies, as well as their respective range of variation. For each case studied, the commercial software planned a small number of flow simulations to run, applying different ED techniques. Based on the simulation results, a proxy model was generated using the Response Surface Method (RSM). Making use of this proxy model, it was possible to quickly simulate 10,000 experiments and to perform statistics calculations with the Monte Carlo method.In order to verify the quality of the proxy, 10,000 simulation files were generated, with the exact same combinations of parameters used in the Monte Carlo method. A script was written to run automatically all the files and to register their results. Besides comparing the statistics generated by these two methodologies, it was possible to compare the actual results of each one of the 10,000 simulations.The results indicate that the quadratic technique is the one with the best cost-benefit ratio and suggest that the proposed methodology generates reliable results in most cases. This reliability decreases when there are complexities in the flow model, such as well and group controls, water and/or gas reinjection, etc. However, results show that the range of possible results to be emulated by the proxy model is the most influential parameter in the quality of the results generated by it.The quality of the risk analysis performed with these ED techniques is obviously influenced by the ability of the proxy model to emulate the flow simulator response. The efficiency of different ED techniques, in different reservoirs, was analyzed and the reliability and limitations of this evaluation methodology has been accessed.