Analytical solution of polymer slug injection with viscous fingering

Abstract

We present an analytical solution to estimate the minimum polymer slug size needed to ensure that viscous fingering of chase water does not cause its breakdown during secondary oil recovery. Polymer flooding is typically used to improve oil recovery from more viscous oil reservoirs. The polymer is injected as a slug followed by chase water to reduce costs; however, the water is less viscous than the oil. This can result in miscible viscous fingering of the water into the polymer, breaking down the slug and reducing recovery. The solution assumes that the average effect of fingering can be represented by the empirical Todd and Longstaff model. The analytical calculation of minimum slug size is compared against numerical solutions using the Todd and Longstaff model as well as high resolution first contact miscible simulation of the fingering. The ability to rapidly determine the minimum polymer slug size is potentially very useful during enhanced oil recovery (EOR) screening studies.

Application of Fractional Flow Theory for Analytical Modeling of Surfactant Flooding, Polymer Flooding, and Surfactant/Polymer Flooding for Chemical Enhanced Oil Recovery

“…The analytical solution for surfactant slug injection has been first proposed by Bedrikovetski [49]. In this section, we use a semi-analytical approach developed by Hamid [50]. The viscous fingering effect and adsorption effect are not considered in this example case.…”

“…The viscous fingering effect and adsorption effect are not considered in this example case. The key results are summarized as follows, and more details can be found in the reference [50]. The boundary conditions corresponding to injection of the surfactant slug and the chase water are expressed in Equation ( 24),…”

Comparative Study of Green and Synthetic Polymers for Enhanced Oil Recovery

“…Green and Willhite [ 2 ] highlighted that the relatively low density and viscosity of CO 2 as compared to reservoir oil are the major determinants of viscous fingering. However, water alternating gas (WAG) and foaming solutions have been employed to combat this challenge as regards the volumetric sweep efficiency control and the reduction in CO 2 mobility, respectively [ 91 , 92 , 93 ]. In the case of polymer flood, temperature, concentration, and viscosity are the major factors associated with viscous fingering.…”

Practical Mathematical Model for the Evaluation of Main Parameters in Polymer Flooding: Rheology, Adsorption, Permeability Reduction, and Effective Salinity

“…Afterward, with considerable simplifications, several authors introduced some analytical solutions to one-dimensional (1D) water and polymer flooding problems such as Buckley and Leverett (BL) and Welge described the classical frontal advance behavior for waterflooding, Pope presented the application of fractional flow theory to EOR, Sorbie and Lake documented the solution to the convection–dispersion equation for polymer transport, and more recent studies have presented analytical expressions − for 1D polymer injection (Table ). Although analytical methods cannot represent all the required physics of multiphase flow for EOR processes, they can draw a rough image of the flooding performance and can help build a decision framework for proceeding to support a decision …”