| dc.description.abstract | In life of the oil field, reservoir pressure tends to decrease with the development of the production.
The use of primary and secondary recovery techniques enables recovery of only 35-50% of the oil
in the reservoir. That means a significant amount oil is left in the reservoir untapped. The remaining
oil can either be residual oil to the water flooding or oil by passed by water flooding. Residual oil
mainly contains capillary trapped oil. The injection of chemicals such as Surfactant, Alkaline and
Polymers or their combinations is one of the potential techniques that can influence the recovery of
the oil remaining in the reservoir after water flooding.
For the Norne field, the situation is not far from this reality. The use of water flooding alone has
recovered about 60% of the oil reservoir. Although this recovery rate is high compared to the rest of
the sub sea fields, the use of water flooding alone will not be able to recover the remaining amount
of oil as now the production is declining sharply and the rate of increase in water cut is high. The
use of appropriate EOR process will help to produce the remaining amount of the oil. Basing on
the screening done on different EOR methods using EORgui software in the first part of the study,
Norne E-segment was found to be a good candidate of chemical EOR technique.
The aim of this study was to confirm the suitability of different chemical methods on Norne Esegment
by doing comparative simulation study compared to water flooding basing on incremental
oil production that was used to find the most promising method with high incremental Net Present
Value. A number of different simulation plans were run, where Alkaline, surfactant, polymer as
well as their mixtures were tested in various ways including different concentrations, injection time
as well as injection duration.
From simulation results and economic analysis, Polymer flooding was confirmed to be the best
chemical method for Norne E-segment having an incremental NPV of +68.7 million USD in 2020.
This was obtained when polymer flooding at concentration of 1.5 kg/m3 was run for five years
from 2006. Polymer flooding reduces the effect of viscous fingering for heavy oil and also perform
better for heterogeneous reservoir with light oil. Alkaline and surfactant flooding were found to be
poor candidates for this field as their incremental oil production could not cover the operational
cost including chemical cost. The combination of Polymer with alkaline and surfactant (ASP and
SP flooding) had higher incremental oil production compared to polymer alone. However, the
incremental NPV for ASP and SP flooding was low compared for Polymer flooding along.
Nevertheless, the NPV calculation did not include all the costs including pumping cost as well
as extra operational expenditures for all chemical flooding. On the other hand these costs can be
compensated by using the most compatible chemicals after doing a laboratory evaluation and find
the accurate chemicals properties that will comply with fluid and rock properties of the Norne
E-segment. | |
