GEOPHYSICAL ASSESSMENT FOR CARBON DIOXIDE (CO2) SEQUESTRATION IN “IT” FIELD, NIGER DELTA, NIGERIA
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Date
2022
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Department Of Physics And Engineering Physics, Faculty Of Sciences, Obafemi Awolowo University Ile-Ife.
Abstract
This study established the fault framework of theThis study established the fault framework of the reservoir environment, identified suitable
reservoirs, determined petrophysical parameters of the identified reservoirs, estimated the storage
capacity of the reservoirs and determined the sealing efficiency within IT field Niger Delta,
Nigeria. These were with a view to assessing the suitability and utilization of IT field for
implementation of geological CO2 sequestration.
High resolution aeromagnetic, 3D seismic and well log data were used. The magnetic data were gridded, reduced to equator and upward continued to produce residual magnetic intensity (RMI) map. Quantitative processes were applied on the RMI to estimate the sedimentary thickness and delineate lineaments on a regional scale. Hydrocarbon reservoirs were mapped and their petrophysical parameters computed from well log data. Fault and horizon mapping were carried
out on the vertical seismic sections to produce structural maps. The structural maps and petrophysical parameters obtained were used to determine the storage capacities of the identified
hydrocarbon reservoirs. The calculated volume of shale (Vshale) was used to generate fault
models which were used to evaluate the sealing efficiency of the mapped faults. Compressional
wave velocity (Vp) and shear wave velocity (Vs) obtained from identified reservoirs and shales
(caprocks) were used to compute, model and analyze geomechanical parameters to deduce the
sealing efficiency of the identified reservoirs and caprocks.
The results showed that the sedimentary thickness ranged from 2.5 km to 21.5 km with a mean of 10
km. The basement structures delineated trended majorly in the NE-SW direction and were deep
seated structures which may not influence the overburden. Three sand reservoirs; RES-1, RES-2 and
RES-3, were identified and mapped across six wells (IT-01 to IT-06). Results of petrophysical
analysis revealed gross thickness values of 145.25, 98.86 and 474.94 ft; porosity values of 0.29,
0.22 and 0.27; hydrocarbon saturation values of 0.29, 0.45 and 0.64; permeability values of
3890, 243.24 and 2401.95 mD; and Net-to-Gross values of 0.90, 0.36 and 0.69 for RES-1, RES-2
and RES-3 respectively. The storage capacity computed from the petrophysical and volumetric
analyses, and storage efficiency factors for RES-1, RES-2 and RES-3 using DOE model (1% and
4%) revealed 49.42 Mtons and 197.77 Mtons; 16.00 Mtons and 64.02 Mtons, and 1.35 Gtons and
5.67 Gtons; respectively. According to Goodman’s model (10% and 15%), RES-1, RES-2 and
RES-3 were estimated to have storage capacity of 494.30 Mtons and 741.45 Mtons; 160.00
Mtons and 240.07 Mtons, and 13.52 Gtons and 20.29 Gtons; respectively. RES-3 was adjudged
the reservoir with the largest storage capacity. Fault seal analyses revealed that fault sealing
percentages ranged from 20 – 60 %, indicating that the reservoirs are assisted by moderately
sealing faults which are capable of sealing the reservoir for a longer period. Geomechanical
analyses revealed that the identified reservoirs and caprocks are ductile and possess sufficient
strength to withstand external pressure.
The study concluded that IT field contain reservoirs which have moderate fault seal capacity,
appreciably thick caprocks with very good storage capacity thereby indicating that the field is
capable of hosting CO2 sequestration.
xviii identified suitable
reservoirs, determined petrophysical parameters of the identified reservoirs, estimated the storage
capacity of the reservoirs and determined the sealing efficiency within IT field Niger Delta,
Nigeria. These were with a view to assessing the suitability and utilization of IT field for
implementation of geological CO2 sequestration.
High resolution aeromagnetic, 3D seismic and well log data were used. The magnetic data were
gridded, reduced to equator and upward continued to produce residual magnetic intensity (RMI)
map. Quantitative processes were applied on the RMI to estimate the sedimentary thickness and
delineate lineaments on a regional scale. Hydrocarbon reservoirs were mapped and their
petrophysical parameters computed from well log data. Fault and horizon mapping were carried
out on the vertical seismic sections to produce structural maps. The structural maps and
petrophysical parameters obtained were used to determine the storage capacities of the identified
hydrocarbon reservoirs. The calculated volume of shale (Vshale) was used to generate fault
models which were used to evaluate the sealing efficiency of the mapped faults. Compressional
wave velocity (Vp) and shear wave velocity (Vs) obtained from identified reservoirs and shales
(caprocks) were used to compute, model and analyze geomechanical parameters to deduce the
sealing efficiency of the identified reservoirs and caprocks.
The results showed that the sedimentary thickness ranged from 2.5 km to 21.5 km with a mean of 10
km. The basement structures delineated trended majorly in the NE-SW direction and were deep
seated structures which may not influence the overburden. Three sand reservoirs; RES-1, RES-2 and
RES-3, were identified and mapped across six wells (IT-01 to IT-06). Results of petrophysical
analysis revealed gross thickness values of 145.25, 98.86 and 474.94 ft; porosity values of 0.29,
0.22 and 0.27; hydrocarbon saturation values of 0.29, 0.45 and 0.64; permeability values of
3890, 243.24 and 2401.95 mD; and Net-to-Gross values of 0.90, 0.36 and 0.69 for RES-1, RES-2
and RES-3 respectively. The storage capacity computed from the petrophysical and volumetric
analyses, and storage efficiency factors for RES-1, RES-2 and RES-3 using DOE model (1% and
4%) revealed 49.42 Mtons and 197.77 Mtons; 16.00 Mtons and 64.02 Mtons, and 1.35 Gtons and
5.67 Gtons; respectively. According to Goodman’s model (10% and 15%), RES-1, RES-2 and
RES-3 were estimated to have storage capacity of 494.30 Mtons and 741.45 Mtons; 160.00
Mtons and 240.07 Mtons, and 13.52 Gtons and 20.29 Gtons; respectively. RES-3 was adjudged
the reservoir with the largest storage capacity. Fault seal analyses revealed that fault sealing
percentages ranged from 20 – 60 %, indicating that the reservoirs are assisted by moderately
sealing faults which are capable of sealing the reservoir for a longer period. Geomechanical
analyses revealed that the identified reservoirs and caprocks are ductile and possess sufficient
strength to withstand external pressure.
The study concluded that IT field contain reservoirs which have moderate fault seal capacity,
appreciably thick caprocks with very good storage capacity thereby indicating that the field is
capable of hosting CO2 sequestration.
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xviii, 217p
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Citation
ADENIKA,C.I(2022),Geophysical assessment for carbon dioxide(CO2) sequestration in "it", Niger Delta, Nigeria., Department Of Physics And Engineering Physics,Faculty Of Sciences, Obafemi Awolowo University