Sidetrack/Recompletion Time Evaluation by Proxy Model

Abstract

Sidetrack during field development and ongoing production arises to exploit bypassed reserves, unexploited zones and to tackle unforeseen conditions that are likely to occur due to uncertainties and heterogeneity in initially characterizing a reservoir. Whereas recompletion is due to sequential production of stacked reservoirs or multiple pay zones that is caused by regulation on commingling. The purpose of this paper is to investigate the application of experimental design (ED) in optimizing sidetrack/recompletion time of multiple pay zones in view of maximizing returns on investment by net present value (NPV) and expected monetary value (EMV). A hypothetical reservoir of two pay zones with uncertainties associated with pay thickness, porosity, permeability and time to perform the sidetrack was considered. The ED method of Box-Behnken response surface design was used to reduce the number of runs made by generating the most effective combination of variables for the experiment. Experimental runs were conducted with a Black Oil reservoir simulator to give production profile and the computed NPV was used afterwards to produce the Proxy model in ED. NPV computed from the Proxy Model was reasonable compared to that of the production profile from the simulator. However, a higher level D-Optimal or factorial design may be required for a reasonable match of EMV with respect to obtaining a realistic sidetrack/recompletion time.