Reservoir characterization and seal integrity of Jemir field in Niger Delta, Nigeria
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Ignoring fault seal and depending solely on reservoir parameters and estimated hydrocarbon contacts
can lead to extremely unequal division of reserves especially in oil fields dominated by structural traps
where faults play an important role in trapping of hydrocarbons. These faults may be sealing or as
conduit to fluid flow. In this study; three-dimensional seismic and well log data has been used to
characterize the reservoirs and investigate the seal integrity of fault plane trending NW-SE and dip towards
south in Jemir field, Niger-Delta for enhanced oil recovery. The petrophysical and volumetric
analysis of the six reservoirs that were mapped as well as structural interpretation of the faults were
done both qualitatively and quantitatively. In order to know the sealing potential of individual hydrocarbon
bearing sand, horizonefault intersection was done, volume of shale was determined, thickness of
individual bed was estimated, and quality control involving throw analysis was done. Shale Gouge Ratio
(SGR) and Hydrocarbon Column Height (HCH) (supportable and structure-supported) were also determined
to assess the seal integrity of the faults in Jemir field.
The petrophysical analysis indicated the porosity of traps on Jemir field ranged from 0.20 to 0.29 and
the volumetric analyses showed that the Stock Tank Original Oil in Place varied between 5.5 and 173.4
Mbbl. The SGR ranged from leaking (<20%) to sealing (>60%) fault plane suggesting poor to moderate
sealing. The supportable HCH of Jemir field ranged from 98.3 to 446.2 m while its Structure-supported
HCH ranged from 12.1 to 101.7 m.
The porosities of Jemir field are good enough for hydrocarbon production as exemplified by its oil
reserve estimates. However, improper sealing of the fault plane might enhance hydrocarbon leakage.
Keywords
Q Science (General), QC Physics