Asphaltene zones affecting reservoir properties & oil production at Johan Sverdrup

How did they form & what are the controlling factors?

Wells drilled into the Johan Sverdrup/Luno oil field have demonstrated the existence of biodegraded residual oil (ROS) zones in deep reservoir sections, on a hitherto unprecedented scale.

As oil production from a field hinges on well placement and the right perforation intervals in relation to injector wells, all knowledge about the distribution of normal oil, with normal API gravity and viscosity  -  as well as heavy oil which is largely immobile during production is essential.

Thus, knowing how oil is occurring in a field is a great help in producing the field as it helps to maximize production output.

Asphaltene formation in oil fields is normally related to biodegradation, blending oil of different chemical composition, injection of gas, depressurizing, water washing or thermal alteration, and may result in core extracts containing bitumen with often up to 40 to 50% asphaltens, which restrict oil movement.

Such precipitation of the large asphaltene molecules may result from transformation of a normal virgin oil which entered the trap, and which at that time only contained 1-3% asphaltenes. Thus, a massive process was necessary to get the asphaltene percentage up to the observed levels.

 

Learning outcome:
Mapping out reservoir heterogeneity using organic geochemical methods and high density sampling schemes. Process understanding – how and when did the asphaltene precipitation zones form. Understanding the “oil-filed-filling-process” and learning about standard organic geochemical techniques, working methods and interpretation schemes.


Methods:
The student will learn all contemporary standard organic  geochemical tools. Work involves sampling at NPD, core processing at UiO, and analytical work in the chemical laboratory environment at our department.

The project is aiming at presentations at the associated oil company and at a national meeting.

Published Nov. 17, 2016 12:48 PM - Last modified Nov. 17, 2016 2:04 PM

Supervisor(s)

Scope (credits)

60