Impact of EOR Chemicals on Oil-Water Separation Processes, from Laboratory Scale to Flow Loop Scale

Abstract

Abstract With the use of chemically-based enchanced recovery methods, water management which has always been a major point in the production operation processes, needs to be considered and adapted as the whole water cycle will be impacted by the back-produced additives. The main issues encountered in oil-water separation processes are directly related to the risk of tight emulsions formation which may considerably complicate the water treatment surface processes. The objective of this paper is to underline the impact of EOR chemicals (surfactants) on the produced water cycle, when they are back produced firstly, at a laboratory scale and secondly, on a large scale separation unit using an industrial size flow loop and a well instrumented separator. At the lab scale, impact of having surfactant within produced fluids on oil/water separation (regarding the separation kinetics but also the oil and water phases qualities) will be evaluated by performing bottle tests. Those laboratory bottle tests enabled us to screen various different parameters such as the surfactant concentration, the water cut that may strongly impact the type of formed emulsion (O/W or W/O) and its stability. The oil and water phases qualities were quantified and correlations with parameters related to the large scale experiment have been drawn, helping us in defining the key parameters for this last campaign. Indeed, to get closer to a field case, a semi industrial-scale test platform (IFPEN GOwSP loop) was used. Main operating conditions are liquid flow rate set between 6 and 10 m3/h and temperature 50 °C. The influence of different parameters may be studied such as the concentration of surfactant, the mixing conditions (liquid flow rate), the residence time controlled by the height of water phase in separator, the water cut and the presence of chemicals that will help the separation process. Different types of emulsion were formed depending on the tests conditions and their stability were evaluated through the measurement of separation profiles using a SECAP probe within the separator. The presented results will show how the surfactant but also the demulsifier concentration have led to different types of emulsions and have influenced the oil-water separation processes. Laboratory workflows as well as experiments carried out at large scale using an industrial size separator could help the de-risking of operations to mitigate these challenges in terms of separation issues. This work illustrates that water management is a major challenge for produced fluids containing EOR chemicals that need an integrated approach and should be studied beforehand.