Application of Injection Fall-off Analysis in Polymer Flooding (SPE 154376)

DESCRIPTION Polymers exhibit non-Newtonian rheological behavior, such as in-situ shear-thinning and shear-thickening effects. This has a significant impact on pressure decline signature as exhibited during Pressure Fall-Off (PFO) tests. Therefore, applying a different PFO interpretation method, compared to conventional approaches for Newtonian fluids is required. RESULTS, OBSERVATIONS, CONCLUSIONS This paper presents a novel, simple and practical methodology to infer the in-situ polymer rheology from PFO tests performed during polymer injection. This is based on a combination of numerical flow simulations and analytical pressure transient calculations, resulting in generic type curves that are used to compute consistency index and flow behavior index, in addition to the usual reservoir parameters (kh, faulting, etc.) and parameters relating to (possible) induced fracturing during injection (fracture length and height). The tools and workflows are illustrated by a number of field examples of polymer PFO, which will also demonstrate how the polymer bank can be located from the data. APPLICATION This methodology can be used for interpretation of PFO tests on EOR polymer flooding projects, where monitoring of injection performance and of in-situ effective polymer rheology are key in the success of a project. SIGNIFICANCE OF SUBJECT MATTER The novelty of this study is that it presents a simple, straightforward methodology for analysis of polymer properties and polymer bank location from PFO tests which can be easily implemented into any software package. The methodology has a general applicability in that it also covers cases in which radial flow symmetry has been lost owing to induced fracturing during injection.