Bitumen was observed in Upper Zakum Field since long time and found to be restricted mainly at the Northeastern margin of the field.
Bitumen occurrence at the Northeastern flank of Upper Zakum Field is originated from bacterial biodegradation and/or water washing of lighter molecular hydrocarbons.
Bitumen definition and recognition can be made by wireline logs as well as by core observation, thin sections, SEM study, polished rock sections under reflected light, and production/injection data aid.
By utilizing the above facilities, the Bitumen distribution in Upper Zakum reservoirs is defined laterally and vertically. As a result, the Bitumen occurrence is increased downwards as well as the Bitumen area which allows to delineate the Bitumen area for each reservoir.
Bitumen as a heavy molecular hydrocarbon is distinguished into two aspects, greasy and dry. In both cases, Bitumen tends to coat and/or fill the pores, hampering the fluid pathway. This consequently, resulted in a low production/injection performance.
Finally, the Bitumen in place has been calculated in the main reservoirs of Thamama 1, 2 & upper part of Thamama 3.
This amount of Bitumen is hardly to be produced, thus, has to be considered separately during any future/injection scheme.