Reservoir characterization and seal integrity of Jemir field in Niger Delta, Nigeria

• Published in: Journal of African earth sciences (1994) 2017-05, Vol.129, p.779-791
• Main Authors: Adagunodo, Theophilus Aanuoluwa, Sunmonu, Lukman Ayobami, Adabanija, Moruffdeen Adedapo
• Format: Article
• Language: English
• Subjects: Faults; Hydrocarbons; Niger delta; Reservoir characterization; Seal integrity; Structural traps
• ISSN: 1464-343X; 1879-1956
• DOI: 10.1016/j.jafrearsci.2017.02.015

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, horizon–fault 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 (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. •Jemir field traps have good pore spaces to hold large hydrocarbons.•Leaking and sealing parts of the fault planes were identified.•The estimated SGR ranged from leaking (60%) fault.•The traps might have been hindered by fault against appropriate charge.