As a result of the recent increases in crude oil prices, a number of chemically-based enhanced recovery methods are being reconsidered by companies around the globe. But 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. This includes the compatibility of EOR chemicals with the additives used to pre-treat the injected water and to process the produced oil/water mixture after EOR chemical breakthrough. Some chemicals themselves, like surfactants and mechanically degraded polymers, may as well produce stable W/O or O/W emulsions and induce strong impact of produced water treatments, that ask for specific additives and equipment in order to keep the topside processing efficient. All these problems may seriously impact the forecast economical performance of EOR projects.
In this paper we will describe in more detail some specific constraints in terms of water management linked to chemical EOR and what are the challenges associated with backproduced chemicals (polymers & surfactants) on topside surface processes. Results will be described using a specific laboratory methodology designed to study the impact of ASP-type chemicals on water treatment efficiency, mimiking actual surface processes, that includes bottle test, gas flotation using an induced gas flotation lab column and membrane filtration. Influence of back produced polymer and surfactants is evaluated by monitoring the turbidity of the water and concentration of oil in water as a function of time.
As the present trend is to increase the use of enhanced recovery methods, among them the chemically-based ones, the industry urges for viable solutions to implement those methods while accomplishing the strict process and environmental constraints that nowadays exist. Water management is an important challenge for chemical EOR that needs an integrated approach and should be studied upfront.