Niger Delta Basin Research Articles

Seismic analysis of growth faults to predict sequence stratigraphic reservoir properties: A case study of the middle to late Miocene Coastal Swamp strata, Niger Delta Basin, Nigeria

This paper presents a graphic relationship between the throw of depositional units across a growth fault and their corresponding depth in the hanging wall on a 2-D seismic profile in predicting lithological variations. A mechanism that elucidates differential stress creating subsidence rate, on account of growth-faulting: topographic creation unthickened-shale and topographic filling thickened-sandstone sedimentation intervals in the hanging wall. The graphic relationship plot was used to analyze a seismic stratigraphic series between 1500 and 2800 ms two-way traveltime. The aim is to test the rare advantage of the method as a stratigraphic predicting tool. In addition, to use the approach to predict sequence stratigraphic reservoir properties of depositional cycles in the subsurface from a seismic profile. In particular, well data have been compared with a synthetically derived lithological column obtained with the plot. The result affirms that the technique is a satisfactory and reliable tool to predict stratigraphic surfaces, lithologies, and the net-to-gross ratio of alternating sand-shale facies sequences from 2-D seismic data. Furthermore, the study documented a relationship between lithologies and the throw-depth plot slope values in relation to sediments compaction to predict potential reservoirs and seals. The prediction technique may be employed to depict syndepositional fault-generated topographic information. Moreover, it can be a predrilled field interpretation tool for petroleum exploration in siliciclastic extensional settings.

Geological and Seismic Delineation of D2000 and D4000 Petroleum Reservoirs Within Afenmai Field, Niger Delta Basin, Nigeria

Afenmai Field is an old petroleum discovery within Central Swamp Depobelt on the eastern part of the Nigerian Niger Delta basin. Eight wells were drilled within the field, and Wells 006 and 008 respectively encountered petroleum in the D2000 Sand and D4000 Sands. This study was conducted to firm up the reservoirs’ spatial extent as well as their pore fluid distribution, which has hitherto been unattended to. To achieve this, the reservoirs were correlated within a framework of parasequence sets that was created from sequence stratigraphic interpretation of combined lithologic, geophysical and foraminiferal data. The reservoir tops were then tied at Well 008 to seismic reflections within a 3D seismic volume, and mapped through the volume. Root mean square (RMS) amplitude was extracted from the seismic volume along mapped reservoir surface. The depth maps produced reveal a southward concave, major synthetic structure building fault across the entire field. A series of en echelon synthetic faults are revealed on the NW and SE of the upthrown block of the major synthetic structure building fault. The D2000 Sand constitutes a rollover anticline with entrapped saturated petroleum in a four-way anticlinal closure that lacks fault support. The western, eastern and northern parts of the reservoir are yet to be penetrated by a well. Petroleum is entrapped in a three-way closure within the D4000 Sand in the western part of the upthrown block of the major synthetic structure building fault. Average RMS amplitude characterise the petroleum reservoir at Well 008 location and immediate vicinity. The values become low westward within the delineated reservoir. Opportunity for productive drilling exists within the undrilled part of the delineated reservoir, westward of Well 008. Opportunities for productive drilling also exist within the undrilled western, eastern and northern parts of the delineated D2000 reservoir sand.

Geochemical Assessment of some water Resources in Obio Akpor and Port Harcourt, Niger Delta Basin, Nigeria

Assessment of heavy metal concentrations in water resources within Obio-Akpor and Port Harcourt local government area of Rivers State in Niger Delta, Nigeria was carried out. Five water samples were obtained from Station 1 surface water, four water samples were acquired from Station 2 surface water and three groundwater samples were obtained from Station 3. The physiochemical parameters analyzed were pH, Temperature, Electrical conductivity, Total dissolved solids and Turbidity while the heavy metals analyzed were Total Iron, Lead, Copper, Nickel, Manganese, Zinc, Chromium, Cadmium and Cobalt. The analysis shows that the pH value for Station 1 ranges from 4.73 - 6.25, Station 2 pH value ranges from 5.72- 6.27 and Station 3 pH value ranges from 4.55 - 5.55. The mean concentration of heavy metals in Station 1 shows an increasing order of Cd>Cr>Co>Cu>Fe>Pb>Mn>Zn>Ni. The mean concentration of heavy metals for Station 1 shows that Lead (0.771mg/l) and Nickel (0.2522mg/l) are above the WHO and SON standards. The mean concentration of heavy metals in Station 2 shows an increasing order of Cd>Cr>Pb>Cu>Ni≥Co>Fe>Zn>Mn. The mean concentration of heavy metals for Station 2 shows that Lead (0.02325mg/l) and Nickel (0.035mg/l) are above the WHO and SON standard. The mean concentration of heavy metals obtained in the Station 3 shows an increasing order of Cd≥Cr>Ni≥Co>Fe>Mn>Zn>Pb>Cu. The mean concentration of heavy metals for Station 3 shows that Lead (0.044333mg/l) is above the WHO and SON standard. Water quality and pollution index shows that the water quality in all the Station is not suitable for consumption. Pollution index indicates that in station 1 and 2, Nickel and lead are the major pollutants in the water while in station 3, lead is the only major pollutant in the water. In as much as these heavy metals are accumulating, over time they become highly toxic to health.

A transform margin: Review of genetic types of the Niger Delta Basin.

A transform margin: Review of genetic types of the Niger Delta Basin.

A transform margin: Review of genetic types of the Niger Delta Basin

尼日尔三角洲盆地是世界上规模最大、油气最为富集的陆缘三角洲盆地之一,过去普遍被认为是起源于白垩纪三叉裂谷的伸展型被动大陆边缘盆地。本文综合前人研究,剖析贝努埃槽和非洲陆上断裂体系及其相关盆地构造-地层结构,认为冈瓦纳大陆裂解前(侏罗纪-早白垩世)陆内存在巨型走滑断裂系,先期裂开的南大西洋和中大西洋沿该断裂系贯通形成赤道大西洋;提出了尼日尔三角洲盆地为受先存大型走滑断裂体系影响的转换型陆缘盆地,具有明显的窄洋陆过渡带特征,致使现今三角洲主体沉积于新生洋壳之上;重建了尼日尔三角洲盆地裂陷期、过渡期和陆缘期的形成演化历程,提出因边缘脊和洋底转换脊的遮挡作用,在过渡期转换型陆缘更有利于形成局限的海洋环境,为形成大面积优质烃源岩创造了良好条件,大幅度地提升了转换型陆缘盆地的油气勘探前景。

Sedimentologic and Palynostratigraphical Modelling of Sediments Penetrated by KW Field, Onshore Western Niger Delta Basin, Nigeria

Sedimentologic and Palynostratigraphical Modelling of Sediments Penetrated by KW Field, Onshore Western Niger Delta Basin, Nigeria

Geophysical Investigation of Groundwater Potentials of the Nanka Sand in Obosi and Its Environs, Anambra State Nigeria

Geophysical investigation for Groundwater which entails the use of vertical electrical sounding (VES) methods was carried out in parts of the Idemili area of Anambra State, Nigeria. Geologically the study area falls within the Nanka Sand, belonging to the Ameki Group in the Tertiary Niger Delta Basin. The investigation intends amongst others to assess the groundwater potential of the area, find out the existence of possible aquifer(s) within the area, and estimate the possible depth of a borehole. 15 VES stations were established at the site using Ohmega System Tetrameter and Schlumberger electrode configuration with current electrode spacing (AB/2) of 350 meters. The geologic parameters, such as the number of geo-electric layers, the thickness of the geo-electric units, and their resistivities were interpreted from the VES curves. A qualitative assessment of the curves shows that a model with 5 layers would sufficiently model the field curves. The thickness value ranged from 0.1 to 86 m, the resistivity ranged from 258 to 13,258 Ωm, and the depth ranged between 1.2 and 109 m. Quantitative interpretation of field curves involved inversion with appropriate parameters using Zond Res1D software.

Source of organic matter and paleoenvironment of deposition of crude oils from the Niger Delta Basin

The study employed thirteen (13) crude oil samples from thirteen (13) producing wells, with the aim of examining the source of organic matter and the paleoenvironment of deposition. The crude oils were deasphaltened and the maltene fraction fractionated to obtain the saturates. The saturates were subjected to gas chromatography mass spectrometer (GCMS) analysis for the steranes, Isoprenoids and n-alkanes, and triterpanes and hopanes biomarker chromatograms. The biomarker composition of the studied oils indicates weakly oxic and reducing environmental conditions for the studied samples, consistent with marine deltaic environment of deposition. The study shows that the oils are associated with a mix of terrestrial and marine organic matter with a comparatively higher terrestrial and lower marine algae organic matter input. The oleanane index of 1.8 and the presence of oleanane in the studied samples denote higher terrigenous plant input into the source rock the generated the crude oils.

Depositional Environments and Reservoir Evaluation of Otuma Oil Field, Niger - Delta basin, Nigeria

This study was carried out by using well logs to evaluate the depositional environments and hydrocarbon reservoirs in the Otuma oil field, Niger Delta basin. The gamma motif/model within- study interval in the drilled well shows blocky, symmetrical, and serrated shapes which suggest a deltaic front with mouth bar to a regressive - transgressive shoreface delta respectively. A correlation was done on the well logs across the wells and the ten well logs were used to evaluate the petrophysical characteristics of the reservoirs. The reservoirs showed highly porous and permeable channels where the wells were used for the characterization. The ten reservoirs were mapped at a depth range of 2395 m to 2919 m with thicknesses varying from 4m to 135m. The petrophysical results of the field showed that the porosity of the reservoirs ranges between 0.10 to 0.30, and permeability from 48 md to 290 md; the water saturation ranges from 0.39 to 0.52, and hydrocarbon saturation from the field 0.48 to 0.61. The By-passed hydrocarbons identified in low resistivity pay sands D4 and D3 at depth 2649 m to 2919 m, respectively were also evaluated and will be put to production in the field.

Geotechnical Characteristics of Benin Formation, Owerri Imo State, Nigeria

A good road network consists of a constant stretch of asphalt laid down for a smooth ride. The spot in the smooth ride on the pavement is commonly referred to as "pavement failure." Soil type, load bearing capacity of materials, zone of vulnerability, resistance to permeation, compressibility, shrinkage limit, and other details are frequently required in order to construct a very good and solid foundation for the planned bridge site. In Nigeria, numerous factors contribute to the failure of road construction projects. They are primarily insufficient research on subgrade and other pavement materials (sub-base and base courses) prior to the start of road projects; flawed engineering, including a poor drainage system and supervision throughout road construction; and shoddy workmanship that was superimposed with asphaltic concrete to improve strength. Within the Niger Delta basin, the study area is located between latitude 5.485°N and longitude 7.035°E. The Benin Formation underpins the study area. It is composed primarily of friable sands, conglomerates, very coarse sandstone, and isolated gravel units, as well as intercalation of Pliocene to Miocene shale/clay lenses. Natural Moisture Content (NMC), Linear Shrinkage (LS), Particle Size Distribution, and California Bearing Ratio were among the laboratory tests performed on samples collected at failed and stable sections of some selected road segments (CBR). When compared to the stable sections, the NMC along the failed sections was on the high side (ranging from 13.11 percent to 26.89 percent) (ranging from 11.11 percent to 16.40 percent). The majority of the tested soils passed the 0.075mm sieve with a percentage greater than the Federal Ministry of Works and Housing's maximum of 35% for subgrade materials. The maximum dry density (MDD) for the samples at failed and stable sections was 1550 kg/m3 to 1860 kg/m3; 1650 kg/m3 to 1980 kg/m3; and the Optimum Moisture Content (OMC) was 8.30% to 20.30%. The soaked CBR values ranged from 2 to 17 percent, while the unsoaked values ranged from 4 to 25 percent.

Characterization of reservoirs and depositional study of J-P Field, shallow offshore of Niger Delta Basin, Nigeria

Well log data interpretation was carried out over J-P Field in the Niger Delta, Nigeria. This was done with a view to characterizing the reservoirs based on the estimation of petrophysical parameters and to assessing the environment of deposition in J-P Field. Seven reservoirs were mapped and correlated across the four drilled wells in J-P Field. Petrophysical parameters such as porosity, volume of shale, water saturation and hydrocarbon saturation were estimated. In addition, depositional environments of each reservoir in J-P Field were determined based on the gamma ray responses. This study reveals that the range of petrophysical parameters across the delineated reservoirs; for porosity varies from 19 to 21%, thickness varies from 24 to 122 m, volume of shale varies from 15 to 29%, water saturation varies from 22 to 60% and hydrocarbon saturation varies from 40 to 78%. The depositional environment was interpreted as comprised of prograding deltas, transgressive marine sands, fluvial channels and deltaic settings. It is concluded that J-P Field has a porosity range varying from good to very good in quality and high hydrocarbon saturation of oil. Furthermore, the study revealed that J-P Field falls within the marginal marine depositional environment.

Paleodepositional Environment and Sequence Stratigraphy of Miocene Sediments in Well TN-1, Coastal Swamp Depobelt, Niger Delta Basin, Nigeria

This research focused on the interpretation of paleodepositional environment and development of a sequence stratigraphic framework for the well TN-1 section, located in the coastal swamp depositional belt of the Niger Delta Basin. Integration of interpreted litho- and biofacies data sets that facilitated the interpretation of the paleodepositional environment enabled the erection of a sequence-stratigraphic framework. Three lithotypes (sand, clay, and shale) distributed within fourteen facies variants were integrated with palynomorph components to delineate five paleodepositional cycles ranging from distal delta plain to bathyal. Eight systems tracts (closely related to depositional cycles, but transcended depositional boundaries in some intervals) that hosted three maximum flooding surfaces (MFS), three sequence boundaries (SBs), distributed within four third-order and three second-order sequences, were defined. Age-significant palynomorphs recovered indicated an Aquitanian to Messinian age range (with non-deposition or erosion of Burdigalian, Langhian, Serravallian Stages sediments), distributed within five pollen zones (P628–P840) that correlated with published global cycles. This study demonstrates the significance of integrated studies to erect a sequence-stratigraphic framework applicable for field and basin-scale exploration and exploitation purposes.
 Keywords: Sequence stratigraphy, paleodepositional cycles, systems tract, cyclic sedimentation,lithofacies analysis, integrated studies.

3-D Seismic Structural Interpretation of High Field Offshore Western Niger Delta

Seismic Structural interpretation of subsurface system is a vital tool in mapping source rocks and good trapping system which enhances good understanding of the subsurface system for productive drilling operation. This study is geared towards mapping the structural traps available within the hydrocarbon bearing zones of the “High field” with the use of well log and 3D seismic data. Seven horizons (H1, H2, H3, H4, H5, H6 and H7) were identified on well logs using gamma ray log and resistivity logs. Nine (9) faults were mapped on seismic sections across the field, two (2) of which are major growth faults (F1 and F2), two (2) synthetic faults (F3 and F7) and five (5) antithetic faults (F4, F5, F6, F8 and F9). Rollover anticlines which are structural closure and displayed on the depth structural maps suggest probable hydrocarbon accumulation at the down throw side of the fault F1. Structural interpretation of high field has revealed a highly fault assisted reservoir which depicts the tectonic setting of Niger Delta basin.

Chemical Classification of Sediments in JVX -Well, Greater Ughelli Depobelt Niger Delta Basin, Nigeria

This study evaluate the Chemical classification of sediments in JVX well, Greater Ughelli Depo belt Niger Delta Basin. Samples collected from different intervals were analyzed using geochemical proxies. Agbada Formation was suggested for the sampled intervals due to the presence of shaleand sand intercalations. lithofacies units gotten from sampled intervals are Sand, Shale and Shaly sand facies . The sands are milky in colour, translucent to opaque, medium to coarse grain, subangular to subrounded and are moderately sorted while the shales are Grey in colour,fissile with the presence of lignite streak and calcareous materials.The geochemical studies of the sediments revealed that SiO2 is the dominant oxide followed by Al2O3 and Fe2O3 which constitutes over 90% while others like CaO, K2O, TiO2, Na2O and MgO constitute 10%. The sediments were classified as Fe-shale, Fe-sand and Quartz arenite. Samples that plotted in the quartz arenites region suggests an intense degree of weathering and reworking. The SiO2/Al2O3 ratios for the sediments in the well are appreciably high indicating that the samples have been heavily weathered, evidenced from the enrichment of quartz and depletion of feldspars. Also, the relatively high concentrations of Fe2O3 and TiO2 is an indication of iron-titanium minerals such as haematite and anatase retiles.

Geochemical Maturity and Paleo-Weathering Indices of Sedimentary Succession in JV Field Greater Ughelli Depo-Belt Niger Delta Basin

This study evaluates the geochemical maturity and paleo weathering indices of X well JV-Field, Greater UghelliDepo belt Niger Delta Basin, using reflected light microscope and geochemical proxies. The data obtained identified three lithofacies units as Sand, Shale, and Shaly sand facies .The application of source area weathering using Chemical index of alteration (CIA) and Chemical index of weathering (CIW) values for the sampled intervals ranges from (48.6-94.9%) and (60.6-96.7%), and have median values of (83.2 and 90.3) % respectively which is an indication of high weathering at the source. The values are variable and it may be as a result of multiple provenances of the sediments which have variable proportions of source area weathering and related processes or may be due to low concentrations of the alkalis and alkaline earth elements. However, all the samples excluding one with depth (12430ft) show CIA and CIW values greater than 70% indicating high (intensive) weathering either at the source or during transportation before deposition .From the high alteration indices value recorded from the sampled intervals, it can be inferred that the sediments are geochemically and texturally mature.

Detailed hydrogeological and hydrochemical reassessment of the Niger Delta Basin, South-south Nigeria

This review presents a detailed analysis of hydrogeological and hydrochemical conditions of the Niger Delta Basin. Hydrogeologically, the specific capacities recorded from different areas within this Basin vary from 6700 lit/hr/m to 13,500 lit/ hr/m. The water table is very close to the ground surface and varies from 0 to 4 meters. Unconfined groundwater aquifers occur in shallow unconfined aquifers, sands of the coastal beach ridges and river point bars, and sandy islands within the mangrove belt. There is a stable water table fluctuation which characterised the high precipitation zone. The shallow aquifers of Benin Formation are more porous than those in the Deltaic areas. In the southern areas, along the coastal zone, an artesian condition occurs. However, the aquifers are less transmissible with increased depth of the confined aquifer, owing to its more delicate texture. Therefore, more compact, and less permeable, or that there is not enough water in storage. More than half of groundwater sources in the Basin are acidic. Based on mean TDS concentration groundwater, fall in an excellent class for drinking. Groundwater classification based on conductivity showed all the reported findings indicate conductivity ranging from 250-750 μS/cm. Based on cation and anion chemistry, the Niger Delta Basin holds water of relatively acceptable drinking quality. However, the uncontrolled groundwater development, land-use changes, pollution from industrial, municipal, and agricultural effluents pose a threat to groundwater quality protection. Thus, a policy guideline is required to protect groundwater from pollution.

Detailed hydrogeological and hydro chemical reassessment of the Niger Delta Basin, South-south Nigeria

Detailed hydrogeological and hydro chemical reassessment of the Niger Delta Basin, South-south Nigeria

Sedimentary facies and petrographic analyses of Miocene nearshore deposits, Central Swamp Depobelt, onshore Niger Delta Basin: implications for reservoir quality

Sedimentary facies and petrographic analyses of Miocene nearshore deposits, Central Swamp Depobelt, onshore Niger Delta Basin: implications for reservoir quality

Modeling the Chance of Commerciality of Petroleum Assets for Economic Development

The chance to discover hydrocarbon volumes of economic quantity diminishes with progressive discovery in explored basins. Given the preponderance of smaller deposits in extensively explored basins and the cost implications of discovering deposits less than the required Minimum Economic Reserves (MER), explorationists and investors in exploration activities need a framework to evaluate the chance of a successful petroleum resources discovery to minimize the risk of unsuccessful exploration. This study develops a new framework to evaluate the chance of discovery of at least a minimum economic reserves volume in an extensively explored basin. It leverages on the postulation for the determination of probability of hydrocarbon economic success as a building block for the new framework. The model combines the concepts of Minimum Economic Reserves, Discovery Efficiency and Probability to derive an explicit analytical function for discovery efficiency and hydrocarbon probability for a commercial discovery. It digitalizes existing Risk Table to ease the complexity to obtain geological chance of success and hydrocarbon asset evaluation for commerciality. Nine Case studies from the prolific Niger Delta basin of Nigeria are used to validate the model. The result of the semi-digital solution of the model shows that three of the studied cases are commercial whereas the remaining six cases are sub-commercial. The study recommends the application of the new framework for hydrocarbon asset evaluation for chance of commerciality to complement models like the cream off curve to predict chance of commercial discovery of hydrocarbon assets.

Deep crustal network of the Equatorial Atlantic Fracture Zones in southern Nigeria

This study mapped deep crustal network of the Equatorial Atlantic Fracture Zones in southern Nigeria using regional scale magnetic and gravity data in an attempt to link the Equatorial Atlantic Fracture Zones to structures of similar trend in the continental margin of southern Nigeria. The data were analysed by removing the regional trend of the data and isolating deep-seated anomalies of interest. Thereafter, the theta potential gradient tensor method was applied to delineate the network of the Equatorial Atlantic Fracture Zones and their linkage to other associated deep-seated lineaments in southern Nigeria. Within the limit of the study area, the results obtained revealed the network of the Romanche, Chain and Charcot Fractures Zones, and their extent, several hundreds of kilometers within the landmass of southern Nigeria. The build-up and transformation of the mapped lineaments further supported evidence of extensional crustal deformation within the Niger Delta Basin and Benue Trough axis which may have influenced rifting in the early Cretaceous.