scholarly journals Application of 3D Seismic Attribute Analyses for Hydrocarbon Prospectivity in Uzot-Field, Onshore Niger Delta Basin, Nigeria

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
U. C. Omoja ◽  
T. N. Obiekezie
Keyword(s):  
Niger Delta ◽  
Hanging Wall ◽  
Average Energy ◽  
Maximum Amplitude ◽  
Seismic Attributes ◽  
Bright Spot ◽  
Maximum Magnitude ◽  
3D Seismic ◽  
Amplitude Maximum ◽  
Niger Delta Basin

3D seismic interpretative study was carried out across the Uzot-field in the western Coastal Swamp Depobelt of the onshore Niger Delta Basin, Nigeria, with the aim to identify possible hydrocarbon leads and prospects away from the drilled zone, utilizing seismic amplitude attributes. The method employed in this study involved systematic picking of faults and mapping of horizons/reservoir tops across seismic volume and extraction of seismic attributes. Structural analysis indicates the presence of down-to-basin footwall and hanging wall faults associated with rollover anticlines and horst-block (back-to-back fault). Generated time and depth structural maps from three reservoir intervals (D3100, D5000, and D9000) revealed the presence of fault dependent closure across the field. Analyses of relevant seismic attributes such as root-mean-square (RMS) amplitude, maximum amplitude, average energy amplitude, average magnitude amplitude, maximum magnitude attribute, and standard deviation amplitude, which were applied on reservoir tops, revealed sections with bright spot anomalies. These amplitude anomalies served as direct hydrocarbon indicators (DHIs), unravelling the presence and possible hydrocarbon prospective zones. In addition, structural top maps show that booming amplitude is seen within the vicinity of fault closures, an indication that these hydrocarbon prospects are structurally controlled. Results from this study have shown that, away from currently producing zone at the central part of the field, additional leads and prospects exist, which could be further evaluated for hydrocarbon production.

scholarly journals Characterization of reservoir sands using 3D seismic attributes in the coastal swamp area of Niger Delta Basin

2021 ◽  
Author(s):  
Oluwatoyin Khadijat Olaleye ◽  
Pius Adekunle Enikanselu ◽  
Michael Ayuk Ayuk
Keyword(s):  
Seismic Data ◽  
Niger Delta ◽  
Seismic Attributes ◽  
Effective Porosity ◽  
High Porosity ◽  
Hydrocarbon Accumulation ◽  
3D Seismic ◽  
Seismic Attribute ◽  
Niger Delta Basin

AbstractHydrocarbon accumulation and production within the Niger Delta Basin are controlled by varieties of geologic features guided by the depositional environment and tectonic history across the basin. In this study, multiple seismic attribute transforms were applied to three-dimensional (3D) seismic data obtained from “Reigh” Field, Onshore Niger Delta to delineate and characterize geologic features capable of harboring hydrocarbon and identifying hydrocarbon productivity areas within the field. Two (2) sand units were delineated from borehole log data and their corresponding horizons were mapped on seismic data, using appropriate check-shot data of the boreholes. Petrophysical summary of the sand units revealed that the area is characterized by high sand/shale ratio, effective porosity ranged from 16 to 36% and hydrocarbon saturation between 72 and 92%. By extracting attribute maps of coherence, instantaneous frequency, instantaneous amplitude and RMS amplitude, characterization of the sand units in terms of reservoir geomorphological features, facies distribution and hydrocarbon potential was achieved. Seismic attribute results revealed (1) characteristic patterns of varying frequency and amplitude areas, (2) major control of hydrocarbon accumulation being structural, in terms of fault, (3) prospective stratigraphic pinch-out, lenticular thick hydrocarbon sand, mounded sand deposit and barrier bar deposit. Seismic Attributes analysis together with seismic structural interpretation revealed prospective structurally high zones with high sand percentage, moderate thickness and high porosity anomaly at the center of the field. The integration of different seismic attribute transforms and results from the study has improved our understanding of mapped sand units and enhanced the delineation of drillable locations which are not recognized on conventional seismic interpretations.

Bright spots, dim spots: Geologic controls of direct hydrocarbon indicator type, magnitude, and detectability, Niger Delta Basin

2016 ◽  
Vol 4 (3) ◽  
pp. SN45-SN69 ◽  
Author(s):  
Krzysztof M. Wojcik ◽  
Irene S. Espejo ◽  
Adebukonla M. Kalejaiye ◽  
Otuka K. Umahi
Keyword(s):  
Niger Delta ◽  
Soft Clay ◽  
Bright Spot ◽  
Systematic Analysis ◽  
Bright Spots ◽  
Key Factor ◽  
Well Data ◽  
Diagenetic Evolution ◽  
Niger Delta Basin ◽  
Fluid Signal

Bright-spot amplitude anomalies have been an attractive exploration target in the Niger Delta since the early 1970s, and the bright-spot play can now be considered mature. There is a need to extend the bright-spot exploration success to include other types of direct hydrocarbon indicators such as dim spots or polarity reversals. Several true dim spots have been identified in the basin, calibrated with well data and characterized in detail to enable a systematic analysis of the geologic factors that produce the dim-spot response. Dim spots in deeper stratigraphic intervals reflect a high degree of compaction and quartz cementation and are characterized by minimal fluid signal and commonly very low detectability. Robust and detectable dim spots have been identified in shallow marine/deltaic systems in the Niger Delta in shallower stratigraphic intervals with a relatively strong fluid signal. The key factor promoting a robust dim-spot response is the presence of acoustically soft, clay-rich shales as the bounding lithology. The variability of the bounding shales in the Niger Delta is stratigraphically constrained and, to some degree, predictable. The change from hard mudstones to soft claystones, which can be recognized in seismic data, may result in a transition from bright to dim spots, possibly taking place within the same stratigraphic interval and over short distances. Many clastic basins globally follow a similar stratigraphic and diagenetic evolution; thus, the Niger Delta example may be a good analog for dim-spot plays elsewhere.

scholarly journals Evaluation of seismic attributes for reservoir characterization over Edi field, Niger delta, Nigeria using 3d seismic data

2020 ◽  
Vol 8 (2) ◽  
pp. 168
Author(s):  
Nyeneime O. Etuk ◽  
Mfoniso U. Aka ◽  
Okechukwu A. Agbasi ◽  
Johnson C. Ibuot
Keyword(s):  
Seismic Data ◽  
Niger Delta ◽  
Reservoir Characterization ◽  
Seismic Attributes ◽  
3D Seismic ◽  
Root Mean Square Amplitude ◽  
Phase Gradient ◽  
Major Fault ◽  
Seismic Sections ◽  
3D Seismic Data

Seismic attributes were evaluated over Edi field, offshore Western Niger Delta, Nigeria, via 3D seismic data. Manual mappings of the horizons and faults on the in-lines and cross-lines of the seismic sections were done. Various attributes were calculated and out put on four horizons corresponding to the well markers at different formations within the well were identified. The four horizons identified, which includes: H1, H2, H3 and H4 were mapped and interpreted across the field. The operational agenda was thru picking given faults segments on the in–line of seismic volume. A total of five faults coded as F1, F2, F3, F4 and F5, F1 and F5 were the major fault and were observed as extending through the field. Structural and horizon mappings were used to generate time structure maps. The maps showed the various positions and orientations of the faults. Different attributes which include: root mean square amplitude, instantaneous phase, gradient magnitude and chaos were run on the 3D seismic data. The amplitude and incline magnitude maps indicate direct hydrocarbon on the horizon maps; this is very important in the drilling of wells because it shows areas where hydrocarbons are present in the subsurface. The seismic attributes revealed information, which was not readily apparent in the raw seismic data.   

scholarly journals Modelling and mapping hydrocarbon saturated sand reservoir using Poisson’s impedance (PI) inversion: a case study of Bonna field, Niger Delta swamp depobelt, Nigeria

2020 ◽  
Author(s):  
Aniefiok Sylvester Akpan ◽  
Francisca Nneka Okeke ◽  
Daniel Nnaemeka Obiora ◽  
Nyakno Jimmy George
Keyword(s):  
Niger Delta ◽  
Seismic Attributes ◽  
Well Logs ◽  
3D Seismic ◽  
Saturated Sand ◽  
Inversion Process ◽  
Data Set

Abstract 3D seismic volume and two well logs data labelled Bonna-6 and Bonna-8 were employed in the inversion process. The data set was simultaneously inverted to produce P- and S-impedances, density, VP −  VS, and PI seismic attributes. An average “c” term value of 1.37 was obtained from the inverse of the slope of the crossplot of P-impedance versus S-impedance for Bonna-6 and Bonna-8 wells. This value was employed in the inversion process to generate the PI attribute, which aided in reducing the non-uniqueness inherent in discriminating the probable reservoir sands. Five seismic attributes slices were generated to ascertain the superiority of each attribute in delineating the probable reservoir sand. These attributes were: density, S-impedance, P-impedance, VP− VS ratio and PI. These attributes reveal low value of density (1.96 − 2.14 g/cc), P-impedance (1.8 × 104 − 2.1 × 104) ft/s*g/cc, S-impedance (9.2 × 103 − 1.1 × 104) ft/s*g/cc, VP − VS (1.65 − 1.72) and PI (4.9 × 103 − 5.1 × 104) ft/s*g/cc around the area inferred to be hydrocarbon saturated reservoir. Although the attributes considered reveals the same zone suspected to be probable hydrocarbon zone, PI gives a better discrimination when compared to other attributes. A distinctive spread and demarcation of the delineated hydrocarbon sand are observed in the PI attribute slice.

Sequence Stratigraphic, Structural and Reservoir Analyses: An Integrated Approach to Exploration and Development of the Eastern Coastal Swamp Cluster, Niger Delta Basin

2016 ◽  
Author(s):  
C. I. Dim ◽  
K. Mosto Onuoha ◽  
C. Gabriel Okeugo
Keyword(s):  
Niger Delta ◽  
Evaluation Studies ◽  
Hanging Wall ◽  
Hydrocarbon Exploration ◽  
Foot Wall ◽  
Stratigraphic Correlation ◽  
Sequence Stratigraphic ◽  
Hydrocarbon Reservoir ◽  
Niger Delta Basin ◽  
System Tract

ABSTRACT Sequence stratigraphic, structural and reservoir analytical tools have been employed in interpreting the geology of the eastern Coastal Swamp Depo-belt of the Niger Delta Basin. The aim was to understand the stratigraphic framework, structural styles and hydrocarbon reservoir distribution for improved regional hydrocarbon exploration across the onshore Niger Delta basin. This interpretative study made use of well logs, biostratigraphic (biofacies and bio-zonation) and petrophysical data obtained from twenty wellbores, integrated with recently merged and reprocessed 3D Pre-Stack Time Migrated regional seismic volume spanning across eight fields (over 960 km2). Results reveal the occurrence of nine key chronostratigraphic surfaces (five maximum flooding surfaces and four sequence boundaries) that were tied to well-established pollen and foram bio-zones for high resolution sequence stratigraphic interpretation. The sediment stacking patterns recognized from gamma ray log signatures were used in delineating the lowstand system tract (LST), transgressive system tract (TST) and highstand system tract (HST) genetic units. Well log sequence stratigraphic correlation reveals that stratal packages within the area were segmented into three depositional sequences occurring from middle to late Miocene age. Furthermore, there is thickening of stratal packages with corresponding decrease in net-to-gross thickness from north to south (basinwards). This is due possibly to the influence of syn-depositional structures on stratigraphy. The combination of reservoir sands (of LST and HST), source and seal shales (of TST and HST) and fault structures allows for good hydrocarbon accumulation and should be targeted during exploration. Reservoir evaluation studies using petrophysical parameters indicates the presence of good quality reservoir intervals, which are laterally continuous and partly compartmentalized. Structural top maps of reservoirs show good amplitude response that are stratigraphically and structurally controlled. Structural analysis revealed the occurrence of back-to-back faulting, collapsed crest structures, simple/faulted rollovers, regional foot wall and hanging wall closures and sub-detachment structures. These structural styles constitute the major hydrocarbon entrapment mechanism in the area. Overall, the study has unraveled the existence of undrilled hydrocarbon leads at deeper depths that should be further revalidated for development and production.

scholarly journals THE SUBSURFACE STRUCTURES IN KOCR FIELD IN THE NIGER DELTA, NIGERIA, USING 3D SEISMIC TIMELAPSE DATA

2020 ◽  
Vol 5 (1) ◽  
pp. 07-12
Author(s):  
Igwenagu Chinyere L. ◽  
Uko Etim D ◽  
Tamunobereton -Ari I. ◽  
Amakiri Arobo R.C.
Keyword(s):  
Seismic Data ◽  
Niger Delta ◽  
3D Seismic ◽  
Hydrocarbon Production ◽  
Seismic Surveys ◽  
Subsurface Structures ◽  
Decline Rate ◽  
Good Repeatability ◽  
Niger Delta Basin ◽  
Monitor Data

The subsurface structures in KOCR Field, in the Coastal Swamp Niger Delta, Nigeria, are here presented, using seismic 3D timelapse. The KOCR Field lies on latitudes 4o50’58’’-4o55’19’’N and longitudes 6o18’41’’- 6o26’41’’E with aerial extent of 840km2. The base (1997) and the monitor (2009) seismic surveys resulted in a 4D response difference. The Base and Monitor data have a root-mean-square repeatability ratio (RRR) of 0.38 implying a very good repeatability when considering the acquisition, processing and environmental noises. Data processing and interpretation were carried out using Petrel software. The average thickness of the reservoir is about 69m at the depth of 3932m. Reservoir pressure decline rate of 0.062psi/day resulted in production decline rate of 1192.21bbl/day. Structural interpretation of seismic data reveals a highly-faulted field. Fault and horizon interpretation shows closures that are collapsed crestal structures. All the interpreted faults are normal synthetic and antithetic faults which are common in the Niger Delta basin. The lengths, dips and orientations of the faults and horizons, in the base and monitor stacks, are equal indicative of no faults reactivation that could have resulted from hydrocarbon production. The results of this work can be used in reservoir, field and environmental management in the area of study.

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