Methodological Approach for Analyzing the Impact of Chemical EOR on Surface Processes

Abstract

Abstract One important aspect that is generally neglected in chemically-based enhanced recovery technology concerns the impact of the EOR chemicals on the produced water cycle. After the chemical breakthrough, part of the EOR chemicals will be recovered in the produced fluids and may strongly impact oil/water separation and water treatment surface processes. This paper describes a specific laboratory methodology designed to study the impact of ASP-type chemicals on produced fluids treatment efficiency and will highlight the impact of polymers and sulfonated EOR surfactants on oil/water separation and water treatment efficiency. The methodology consists in a first step in evaluating the risk of stable emulsion formation and assessing the impact of chemical EOR on separation efficiency. Produced fluids are formulated and characterized (different water cuts, type of agitation, EOR chemicals,…). The stability of the different emulsified systems is analyzed over time. Then the efficiency of separation of water-in-oil (w/o) emulsions is determined for the three main types of dehydration processes: gravity separation, chemical demulsification, electrical dehydration. The quality of the separated water is systematically reported. In a second step, impact of chemical EOR on produced water treatment efficiency is studied. Produced waters are formulated and characterized (different oil concentrations, simulated back produced EOR chemicals,…). Behavior of theses systems are then studied using here an induced gas flotation lab column and membrane filtration. Turbidity of the water and concentration of oil in water is monitored as a function of time to quantify the impact of the EOR chemicals on treatment efficiency. This methodology will be illustrated on a heavy oil in presence of EOR chemicals (HPAM, sulfonated surfactants). The results show that these chemicals can have a strong impact on surface processes. This work emphasises that water management is an important challenge for chemical EOR that needs an integrated approach and should be studied upfront.