METODOLOGÍA PARA EL DISEÑO DE BACHES EN UN PROCESO DE INYECCIÓN DE POLÍMEROS PARA RECOBRO MEJORADO, CONSIDERANDO FENÓMENOS DE INTERACCIÓN ROCA/FLUIDOS

Polymer Injection is an enhanced recovery process meant to improve conventional water flooding. This technique takes advantage of polymer¿s solution viscosity to control fluids formation mobility and generate an uniform reservoir coverage, resulting in a better oil displacement. Due to actual needs of increasing hydrocarbon reserves through production optimization strategies, implementing this process is attractive in water flooding fields where recovery of hydrocarbon has not met expectations. To increase the probability of success, it is critical for the process, designing the right slug to be injected, since the nature of flow through porous media is governed by fluid- rock interaction that may affect flooding efficiency. The pill has to be big enough to withstand loss or change of polymer concentration preserving physical and chemical slug properties during the process. Understanding this phenomenon during design stages is very important to ensure acceptable flow during minimum required time. This paper develops a methodology to design polymer slugs during a chemical injection process based on rockfluid interactions phenomena in porous media, starting from a computerized tool during pre-design stage, involving analytical models available through a sensitivity analysis of the design parameters and observe behaviours of the polymer concentration on the injected fluid as a function of time and length; and how interaction phenomena within reservoir affects its performance. Additionally, since analytical models do not take into account all diffusion, dispersion and adsorption phenomena on the rock, a simulation model (sector model) was developed on the STARS platform from CMG Ltd. to model chemical injection projects, where obtained results from computerized tools are processed through a sensibility analysis of operational parameters that affect the process. Considering Recovery factor analysis, production rates, water front velocity, flooding efficiency and water cut, the optimized operational conditions can be obtained. Once the best operational conditions for design concentration, injection rate and time are encountered, the next step is to include them in the simulation model for final analysis. Finally, obtained results allowed stablishing a methodology to design slugs during polymer injection using a computerized tool to pre- design the slug, that involves analytical models such as Fick law, Perkins model, Warren model, Bentsen method and El- Khatib model which are based on the rock- fluid interaction within the porous media and finalising with a reservoir numeric simulation to validate the results.