Role of Asphaltenes in Gas Flooding Processes
Nawi, Syaidatul, N
Engineering Honours Degree 2008
University of Adelaide
Asphaltenes flocculation is one of the detrimental problems in oil industry. It is commonly happen in undersaturated oil reservoir and during enhancement oil recovery involving gas flooding process. It is mostly happen in carbon dioxide injection or flooding process where huge amounts of literature found that cover this subjects.
Asphaltenes even though being recognized long ago, but their characteristics including molecular structure, components, size and shapes are still being the point of arguments. However, with the advance in technology, details of this most complex component of crude oil become gradually clear. The characteristics of asphaltenes will be presented with guidance from recent investigations presented in literature.
Besides that, the other parts of asphaltenes problems also will be presented here. Asphaltenes is everywhere in production life cycle of oil. However, it will start causing problem when certain factors disturb the natural equilibrium of suspended asphaltenes. pH, temperature drop, pressure and compositional change are just a few factors that can affect asphaltenes flocculation and depositions.
From E&P point of view, knowing the structure and characteristics of asphaltenes has no impact on the economic. However, one thing that petroleum engineers should pay attention on is the point of asphaltenes onset because this will denote the starting of asphaltenes problem in the reservoir. Few techniques are being used in industry to predict the onset of precipitation. Four techniques are being presented here and their basic principles on determining onset conditions, pro and cons will be discussed.
Lastly issues in modelling asphaltenes precipitation and depositions during simulation runs will be discussed. Two simulators which are general purpose adaptive simulator and compositional reservoir simulator will be discussed in depth in term of modelling issues.