In a previous publication we introduced a methodology to assist in choosing between polymer flooding and infill well drilling.

Fractional flow analysis of any reservoir system for the two cases and the results obtained by applying Welge's graphical technique, at breakthrough, were introduced in previous paper to identify whether it is suitable for any particular recovery process, before a decision is made to undertake detailed reservoir simulation studies. The objective of this paper is to conduct an economic analysis to investigate the impact of delaying the start of polymer flooding to identify whether it is better to start polymer flooding earlier or later in the life of the project, and to compare the polymer flooding scenario with a different scenario where infill well drilling is introduced. This is undertaken to illustrate the implementation of combined reservoir simulation and economic modelling.

It is achieved by performing a range of sensitivity calculations (reservoir simulation AND economic modeling), using Monte Carlo simulation (MCO) to establish confidence in the method and test uncertainties on key operational parameters input variables. These variables include oil, water and polymer production and injection costs, polymer concentration, timing, etc., and various economic factors such as; oil price, capital expenditure (CAPEX), polymer cost, etc. Sensitivity analysis graphs are developed to assess future engineering planning with regard to the economics of EOR projects. The analysis of uncertainty involves measuring the degree to which input contributes to uncertainty in the output.

These sensitivity calculations are numerous, and have been performed by developing a computer program, coded in Java. A total of 1,093,500 economic calculations were performed, based on 225 reservoir simulation calculations.