Polymer-Flooding Economics, From Pilot to Field Implementation

Abstract

SummaryPolymer flooding of oil fields has not reached the same maturity as waterflooding. Hence, implementing polymer projects at field scale requires a workflow comprising several steps. The workflow starts with screening of the portfolio of an organization for oil fields potentially amenable for this enhanced-oil-recovery (EOR) method. Next, laboratory and field testing is required, followed by sector and field implementation and finally rollout in the portfolio.Going through the workflow, not only is the subsurface uncertainty reduced, but also the knowledge regarding the cost structure and operating capabilities of the organization is improved.Analyzing the economics of polymer-injection projects shows that costs can be split into costs dependent on the polymer injector/producer (polymer pattern) and costs that are independent. Knowing these costs, a minimum economic number of patterns (MENP) is defined to achieve net present value (NPV) of zero. This number is used to determine a minimum economic field size (MEFS) for polymer injection, which is taken into account in the screening of the portfolio.A robustness criterion for economic-evaluation purposes is defined as the minimum number of patterns required for economic polymer injection. By use of this criterion, a diagram is derived allowing for screening of fields for polymer economics by use of pattern-dependent and pattern-independent costs and the utility factor (UF).The cost structure reveals how the NPV of polymer projects changes with the number of patterns, incremental oil, and injectivity. Injectivity is particularly important because it determines the chemical-affected reservoir volume (CARV) or speed of production.A sensitivity analysis of the NPV showed that for the cost structure used here, in addition to the polymer costs, the well costs are important for the economics of a full-field polymer-injection project.