PETROPHYSICAL PROPERTIES AND 3D GEOLOGIC MODELLING OF THE RESERVOIR SANDS OF JIO FIELD, NIGER DELTA, NIGERIA

Abstract

Reservoir modelling of JIO field was carried out to do a detailed evaluation of the petrophysical properties and
to estimate the reserves of the identified reservoirs in the field. Methodology employed includes well log
interpretation and delineation of the reservoir sands, 3-D seismic analysis and a 3D static modelling of the
identified reservoir sands (D3A, D4, D5 and D6). These were achieved by integrating all the available data
provided for the field. Fault and Horizon interpretations were carried out in Petrel software while well log
interpretation, correlation and estimation of petrophysical parameters were done using Geographix software.
Petrel software was also employed in facies modelling. Structural, stratigraphic and petrophysical models
produced were integrated to generate a high resolution geological model (3D static model). The model was
used to re-assess the reserves of the identified reservoirs (D3A, D4, D5 and D6). Volume (bulk volume, net
volume, hydrocarbon pore volume, STOIIP, and recoverable reserves) calculation was also achieved using the
Petrel software. Across the four reservoir sands, average value ranges for petrophysical properties are porosity
21.64- 24.23%, permeability 5.33 to 6796 md, water and hydrocarbon saturation 40.03 to 53.38% and 46.62 to
59.98% respectively, net- to- gross thickness 0.72 to 0.98 and shale volume 0.07 to 0.187%. Structural and
stratigraphic analyses revealed that the field consists of rollover anticlinal structures with dip fault bounded
closures as well as lateral continuity of the reservoir sands with pinch out in the southern and eastern parts.
Depositional environment is interpreted as predominantly deltaic. The estimated recoverable reserve include
D3A = 37049mbbl, D4= 658650mbbl, D5= 4979308mbl and D6= 1117080mbbl. D5 has the highest
permeability as well as computed STOIIP. The field is characterized by quality reservoirs, large hydrocarbon
zone and good deliverability. The 3D static model developed can serve as an input into reservoir simulation
model which will help in proper well planning and management.