Niger Delta Province Research Articles

GEOLOGICAL AGE EVALUATION OF SAPELE DEEP FIELD, DELTA STATE, SOUTH-SOUTH NIGERIA

One of the most productive fields in the Niger Delta is the Sapele Deep field, an onshore field of OML 41 that is situated in the Northwestern region (Greater Ughelli depobelt) of the oil province. The Niger Delta chronostratigraphic map from SPDC (2010) and well-log, seismic, and biostratigraphic data from six wells within the Niger Delta Province were used to conduct the age assessment of the field. Petrel®2016 (Schlumberger software) was used in the interpretation of seismic and well log data used in this research. Age of rocks within the depositional basins of the study area ranges from early Miocene to late Miocene and this was established through the delineated maximum flooding surface and marker fauna from the regional seal of marine transgression which are Me-2-Bolivina-48, Me-1-Haplophragmoides-24, Tor-2-Uvigerina-8, Tor-1-Nonion-4, Ser-3-Dodo Shale, Ser-2-Cassidulina-7, Ser-1-Bolivina-25, Lang-1-Bur-5-Chiloguembelina-3, and Bur-3-Ogara Shale. The specified reference fossils from depths of 6814.5 ft to 12573 ft include Globorotalia plesiotumida, Globigerinoides extremus, Neogloboquadrina acostaensis, Globorotalia lenguaensis, Globoturborotalita nepenthes, Orbulina suturalis, Fohsella robusta, Fohsella fohsi, Fohsella peripheroacuta, Fohsella praefohsi, Praeorbulina glomerosa, Fohsella birnageae, Globigerinatella insueta, Praeorbulina sicana, and Catapstdrax dissimilis. The depth range for these markers spans from 6814.5 ft to 12573 ft.

Blood Plasma Concentration of Polycyclic Aromatic Hydrocarbons in Under Five Children in Niger Delta, Nigeria

PAHs are known carcinogens associated with immune system suppression, skin irritation, allergic reactions, respiratory problems, mutagenic issues and are generally toxic to humans. In this study, we assessed the presence and proportions of PAHs in the blood plasma of under-five children living in crude oil-polluted environment in Ogoniland, Niger Delta region of Nigeria. Communities resident in close proximity to crude oil exploration sites are constantly faced with environmental, socio-economic and health consequences of crude oil pollution. People can be exposed to PAHs through multiple routes including inhalation, ingestion and dermal contact. Ethical clearance for this study was obtained from the Ethics Committee, University of Port Harcourt. A total of 78 children were recruited from Gokana (male =17, female= 22) and Ideato (Male=15, female=24) using multi-clustered sampling method. Standard procedures were observed in this study. Results obtained were compared with under five children living in non-oil polluted environments within the Niger Delta province. The overall average PAHs was 0.331±0.383 mg/kg for Gokana males and 0.058±0.057mg/kg for Ideato males; overall average PAHs was 0.514±0.373 mg/kg for Gokana females and 0.100±0.049 mg/kg for Ideato female; overall average PAHs was 0.423±0.383 mg/kg Gokana and 0.081±0.057 mg/kg for Ideato. Under-five children in Ogoniland showed positive blood plasma PAHs higher than the comparison group in Ideato. However, carcinogenic PAHs were below levels of concern in the study population. The male gender showed higher positive PAHs than the female gender. Further studies on inflammation, stress factors and overall health status are recommended considering the vulnerability of the study population.

Effects and Causes of Illegal Crude Oil Bunkering in Nigeria: Case Study Niger Delta

Illegal bunkering of crude oil includes stealing crude oil as well as its derivatives through diverse mechanism without the permission of the Federal government. Crude oil blasts and spillages are common occurrences in Niger Delta area, due to illegal bunkering of crude oil. This paper investigates the causes and effects of illegal bunkering of crude oil in Niger Delta area, which has become a major threat in the environment and the Nigerian economy in recent time. Opuama, Igbomotoru, and Diebu Communities are all in Southern Ijaw Local Government Area (SILGA), Bayelsa State, Niger Delta province. Over 90 people (both men and women), ranging in age from 18 to 90, were interviewed to gather the primary data. About 30 persons from each community of the age groups of 18 - 30, 31 - 50, and 51 - 90 years were interviewed, which focused mainly on effects of unauthorized bunkering of crude oil on human health, and its environment. Every investigation and data that were gotten from the three communities has negative health impact on people and the environment. These illegal bunkering of crude oil activities has caused poverty to many people in these communities with health, environmental, and economic challenges. The study also discovered that Nigeria has loss revenues that is valued to ₦2.184 trillion per annum, because of illegal bunkering of crude oil. There is poverty in the environment of Niger Delta, high growth of criminal activities with acquiring of weapons, and increase in dropouts from schools, especially students and pupils from secondary and primary school. Possible solutions have been suggested to the issue of crude oil being illegally bunkered. Therefore, each person should work together with government authorities and the operating companies that is responsible for petroleum products in Nigeria in controlling it. Stealing is bad, and let it stop.

Paleoenvironmental and paleodepositional architecture of SAMO field in Niger-Delta Basin of Nigeria using seismic and well log data

The use of Seismic data and well log data within the context of sequence stratigraphy is a valuable tool for the recognition of ancient cycles and sequences because they reflect information on the different processes that deposit sediments in different palaeoenvironment. An integrated geophysical well log data and seismic data from our wells within the SAMO field have been utilized to delineate the upper Miocene-Pliocene depositional environment parts of the Niger-Delta Basin. Identification of the different lithologies and depositional environment present in the penetrated borehole was achieved using gamma ray log. This enables the establishment of different rock units in the well from the gamma ray log values and signatures. Three succession signatures which include; the bell, cylindrical and the funnel being more prominent were identified from the log motifs in the different sand bodies attenuated in the wells from the field. The mapped sequences generated Low stand System Tracts (LST) progradational, Trangressive System Tracts (TST) retrogradational and High stand System Tract (HST) aggradational packages. All these reflect the depositional systems that dominated the different phases as a result of base level changes. Furthermore, values quantified from the logs revealed that porosity and permeability are more prominent in places where sand bodies accumulated in the slope channel setting indicative of slope-fills and turbidity fans. This deep-sea channels and switch complex fault system suggest good hydrocarbon bearing potential associated with the distal Niger-Delta province. Also a good quality reservoir was inferred from the sands of both LST and HST while the shale of the TST could serve as a good reservoir.

English

Accurate quantification of heavy metals is essential for optimizing remedial efforts at polluted waterfronts. Although surface water quality models can be helpful tools for rapid quantification of heavy metals in streams, they cannot be extrapolated to other water bodies. This study estimated Mg, Cd, and Ni levels in one of the polluted urban waterfronts in the Niger Delta Province, Nigeria (5.317°N, 6.467°E) using one-dimensional transport model. To do this, water samples were collected along the waterfront in both dry and rainy seasons and analyzed for the selected heavy metals using a SHIMADZU® AA6800 Atomic Absorption Spectrophotometer according to international standards. Model parameters were determined by simple linear regression using the experimental dataset. Results showed that the average concentrations of Mg (5.964 mg/L), Cd (0.088 mg/L), and Ni (0.071 mg/L) in the waterfront in both dry and rainy seasons exceeded both local and international regulatory values. The seasonal variation of the heavy metals in the waterfront showed that the concentrations of Mg and Cd were higher during the dry season. Model validation of experimental data showed reasonable prediction precision with root mean square error (RMSE) of 0.0016-0.2254 mg/L in the dry season, RMSE of 0.0026-0.3259 mg/L in the rainy season, and corresponding average validation r2 of 0.985 in both seasons. These results suggest that the waterfront is laden with heavy metals and the one-dimensional transport model is a useful tool to rapidly estimate the levels of Mg, Cd, and Ni in the waterfront for pollution control. Key words: Environmental monitoring, heavy metals, water pollution, water quality modelling. &nbsp

Diagnostic screening of organic contaminant level in solidified/stabilized pre-treated oil-based drill cuttings

The reuse of solidified/stabilized low-temperature thermally desorbed (pre-treated) oil-based drill cuttings for construction purposes is becoming increasingly attractive in recent times; though, without screening a priori the levels of target residual organic contaminants against environmental guidelines to ensure compliance. In this study, pre-treated oil-based drill cuttings were collected from a waste treatment facility in the Niger Delta Province (5.317oN; 6.467oE), Nigeria and subjected to cement-based solidification/stabilization (S/S) followed by chemical leaching and screening of the data against local environmental guidelines. S/S was done with drill cuttings contents of 0 (control), 2, 4, 6, 8, and 10 % as part replacement for fine aggregate at 0.6:1, 0.65:1, 0.7:1, 0.75:1, and 0.8:1 water-to-cement ratios using 1:2:4 mix design for a grade-20 concrete. Afterwards, the surface microstructure, elemental composition, and unconfined compressive strength (UCS) of the solidified/stabilized matrix were determined. Amounts of heavy metals and total petroleum hydrocarbons (TPH) leached were also assessed. Results showed that the 2 % drill cuttings addition yielded the highest UCS (22.22–26.22 N/mm2) at water-to-cement ratio of 0.6:1, which were well above the recommended minimum UCS of 20 N/mm2 for a grade-20 concrete. The average amount of residual TPH in the solidified/stabilized matrix (62.41 mg/kg) was slightly higher than the local regulatory target value of 50 mg/kg; suggesting that the cement-based S/S failed to immobilize completely all the hydrocarbons in the pre-treated oil-based drill cuttings. This shows that the solidified/stabilized matrix is not in compliance with environmental guidelines on TPH for sustainable reuse as construction materials.

Bright Spot Validation from 3-D Seismic Data: A Study of Naso-Field, Niger Delta Province, Nigeria

The validation of identified bright-spots A, B and C on 3D seismic data as Direct Hydrocarbon Indicator (DHI) in Naso field, Niger Delta was achieved through the integration of four surface attributes. These attributes include root mean square, average reflection strength, total energy, and total amplitude which are all amplitude dependent, where region of high value in every attribute indicated possible hydrocarbon prospects. Seismic data and check-shot data were used, which provided positive input for velocity extraction and structural mapping interpretation. A series of NW-SE trending normal growth faults A, B & C were interpreted defining the reservoir structural framework while fault D, E, F & G are post-depositional minor faults which also supported the trapping mechanism. Bright-spot A was mapped between 2,400-2550 milliseconds, while bright-spot B was mapped between 2,600-2,720 milliseconds and bright-spot C between 2,750-3,050 milliseconds. Two hydrocarbon prospects were identified. Prospect-1 was estimated to cover about 907.17, 1323.59 and 1075.44 acres, with subsurface total vertical depth of 9514.3ft, 10499.6ft, 10963ft in BS_A, B & C respectively. Prospect-2 covered about 653.49, 1080.33 and 493.77 acres with subsurface total vertical depth of 8650ft, 9525ft, and 10120ft, respectively. Hence, prospect-1 is considerably more prolific in hydrocarbon yield than prospect-2. The total area of the hydrocarbon prospects in-place has been estimated to about 5,533.79 acres which is likely to yield a prolific reserve for commercial purpose. The gas Chimney and push down highlight the subsurface leakage of gas from a poorly sealed cap rock and show a deep petroleum migration process. The study has been able to validate bright spot during exploration studies in effect to evaluate hydrocarbon reservoir, prospect identification and reservoir prediction.

Oil Well Fordacos – Nigeria

In this article we will touch upon one of the most important oil region in Africa, the Niger Delta, it is located in southern Nigeria, with an area of about 292,407.m2 Niger Delta knows how geological feature, offer huge reserves of hydrocarbons. The stratigraphic sequence of the Niger Delta consists of three broad lithostratigraphically. Units and its geochemical analyses of rocks have shown that clays from the lower coastal plain, marine Delta sediments (prodelta) and completely marine areas can be enriched with both terrestrial plant material and non-structural organic matter. That is an indicator of wealth.Forcados (forcados) in the Niger Delta province and follow plays a crucial role in the Nigerian economy and the world oil exchange. Forkados field, its physical and geographical location, Characteristics, molar and mass content of oil composition

English

This study examined the application of the Analytic Network Process (ANP), a multi-criteria decision analysis tool, in the selection of the best bioremediation technique for the remediation of a hydrocarbon-polluted site at Kwawa (4°36'29.26''N, 7°28'55.70''E) in Ogoniland, Niger Delta province, Nigeria. The decision-making problem involved four bioremediation techniques (that is, landfarming, field biopiles, thermal desorption, and phytoremediation) as well as four selection criteria (that is, health and safety, technical feasibility, regulatory requirements, and site-specific characteristics) and their twelve selection sub-criteria. The ANP evaluation involved pairwise comparisons of the remediation alternatives, selection criteria, and selection sub-criteria. Judgement matrices including unweighted supermatrix, weighted supermatrix, and a limit matrix were developed. The alternative with the highest priority vector at convergence was selected as the best. Result showed that phytoremediation with the highest priority vector of 0.1054 was the most appropriate remediation alternative for the study site. Additionally, site-specific characteristics with highest priority vector of 0.1636 was the most important selection criteria while type of soil with highest priority vector of 0.0625 was the most influential selection sub-criterion for the study site. This suggests that the ANP promises to be a veritable decision-support tool for the selection of the most appropriate bioremediation method for petroleum-contaminated sites in the Niger Delta province, Nigeria. Key words: Multi-criteria decision analysis, land contamination, bioremediation.

Reservoir characterization and volumetric estimation of Orok Field, Niger Delta hydrocarbon province

Geophysical analysis was undertaken on the available suit of well logs, 3D seismic and checkshot data from the field in a view to carrying out reservoir characterization and volumetric estimation of Orok Field Niger Delta Province. Lithology delineation and Petrophysical evaluation including porosity, water saturation and net-to-gross were undertaken. Well to seismic tie, structural interpretation and horizon mapping were carried out. Time and depth maps were generated and volumetric estimation of the reservoirs were carried out. Four gas-bearing reservoir (A001, B001, C001 and D001) of variable thickness and depth from the subsurface were identified. Their effective porosity ranges from 19% for A001, 20% for B001, 20% for C002 and 18% for the basal D001 respectively. Water saturation estimated from the reservoir sands ranges from 23% for A001, B001 20%, C001 12% and 10% for D001. The hydrocarbon saturation of the reservoirs stood at 77%, 80%, 82%, 90% for A001, B001, C001 and D001 respectively. Only sand A001 and sand B001 had good seismic tie and were able to be mapped through the seismic. Three synthetic structural building listric faults were interpreted across the inlines intercepting the top of reservoir Sand A001 and B001. The volumetric estimation reveals that A001 and B001 have an area of 813.708 acres and 813.693 acres and volume of 151 billion cu.ft and 286 billion cu.ft of gas respectively. Three synthetic structural building listric faults (F1, F2 and F3) intercept the top of sandstones A001 and B001. The structural trapping mechanism in both sandstones resulted from synthetic fault assisting structures i.e rollover anticlines. The modeled faults trends approximately northwest to southeast direction and dip in the southwest direction.

Curie Point Depth (CPD) Investigation Of Offshore Niger Delta Using High Resolution Aeromagnetic Data

Offshore Niger Delta, Nigeria, is known to be a hub for hydrocarbon exploration within the West Africa region and the world in general. The geologic settings within the Niger Delta province have a proven potential to assist in oil and gas exploration. However, much of the offshore provinces potential remains unknown with respect to the temperature differences using aeromagnetic data. In the present research, high resolution aeromagnetic data covering longitude 4°30i E - 5° E and latitude 3°30iN - 4°30N with an approximate area of about 6050 km2 was used to estimate the Curie Point Depth (CPD) of the study area. For this aim to be realizable, regional-residual was undertaken on the Total Magnetic Intensity (TMI) data. This art gave rise to the regional and the residual maps. The residual map was then after divided into thirty five overlapping spectral grids. Spectral analysis was performed on each of the grids and this decomposed each grid into its energy and frequency segments. The results show three depth models, namely the depth due to the deeply seated sources or the centroid depth, Dc, depth due to the shallow magnetic sources, Dt and the depth at which minerals lose their ferromagnetic properties or the basal depth, Db. However, Dc varies from - 9950 m to - 35294.12 m but with a true or average depth value of - 9751.75 m while Dt lies between -1250 m and -3684.21 but with a true depth of - 2000 m. Similarly, the basal depth ranges from -9950 m to -35294.12 m. This study therefore suggests that at a depth of - 9950 m and beyond ferromagnetic minerals turn into a paramagnetic one within the area of study.

Assessment of the effectiveness of onsite exsitu remediation by enhanced natural attenuation in the Niger Delta region, Nigeria

This study was conducted to quantify and rank the effectiveness of onsite exsitu remediation by enhanced natural attenuation using soil quality index. The investigation was conducted at three oil spill sites in the Niger Delta (5.317°N, 6.467°E), Nigeria with a predominance of Oxisols. Baseline assessment and a two-step post-remediation monitoring of the sites were conducted. Target contaminants including total petroleum hydrocarbon (TPH) and BTEX (benzene, toluene, ethylbenzene, and xylene) were analyzed by gas chromatography-mass spectrometry. Results of the baseline assessment showed that TPH concentrations across the study sites averaged between 5113 and 7640 mg/kg at 0- to 1-m depth, which was higher than the local regulatory value of 5000 mg/kg. The soil quality index across the sites ranged between 68 and 45, suggesting medium to high potential ecological health risks with medium to high priority for remediation. BTEX concentrations followed a similar trend. However, after remediation TPH degraded rapidly initially and then slowly but asymptotically during the post-remediation monitoring period. Then, soil quality index across the study sites ranged between 100 and 58, indicating very low to medium potential ecological health risks. This demonstrates the effectiveness of onsite exsitu remediation by enhanced natural attenuation as a remediation strategy for petroleum-contaminated soils, which holds great promise for the Niger Delta province.

Sedimentologic and sequence-stratigraphic characteristics of wave-dominated deltas

Wave-dominated deltaic strata form prolific hydrocarbon plays in many mature basins across the world. Examples include the Jurassic Brent Group play in the North Sea, offshore United Kingdom and Norway (e.g., Husmo et al., 2003); Eocene Jackson Group and Oligocene Frio Formation plays, Texas, onshore United States (e.g., Fisher et al., 1970; Galloway and Morton, 1989); and Tertiary plays in the Niger Delta province, offshore Nigeria (e.g., Evamy et al., 1978), the Baram Delta province, offshore Brunei (e.g., Rijks, 1981), and the Columbus Basin, offshore Trinidad and Tobago (e.g., Sydow et al., 2003). Wave-dominated deltas also form key exploration targets in frontier basins (e.g., Triassic Snadd Formation, Barents Sea, offshore Norway; Klausen et al., 2014, 2016). The overall architecture of many wave-dominated deltaic reservoirs is determined by their sequence-stratigraphic framework together with their structural configuration. Sequence-stratigraphic frameworks contain elements such as shoreface–shelf parasequences bounded by flooding surfaces and fluvio-estuarine complexes that fill incised coastal valleys developed at sequence boundaries. The internal facies distributions and stacking patterns of such elements are ordered, which aids prediction of reservoir character and behavior. Outcrop analogs of wave-dominated deltaic reservoirs display aspects of ordered stratigraphic architecture across a range of spatial scales that are equivalent to those observed in core, well-log, and seismic data and can therefore be used to support interpretation of their subsurface counterparts. The Cretaceous Blackhawk Formation contains wave-dominated deltaic strata that are superbly exposed in the Book Cliffs of eastcentral Utah (Figure 1A). The extensive, continuous exposures of the Book Cliffs outcrop belt have allowed the wave-dominated deltas and related deposits to be mapped for tens of kilometers (e.g., Young, 1955; Balsley, 1980), and, consequently, these strata were the “birthplace” of high-resolution sequence stratigraphy using outcrop data (Van Wagoner et al., 1990). The Blackhawk Formation and related …

Determination of Reservoir Sand Body Using Well-C in Niger Delta

There are several techniques which can be used to determine the depositional environment of a sedimentary rock. the technique include the determination of sedimentary structures, fossil records, logging etc. This work was carried out on Well-C located in the Niger Delta region of Nigeria. The Niger Delta basin is the most prolific and economic sedimentary basin in Nigeria. The depositional environment has been described by many workers which lay emphasis on sedimentary environment as having certain processes operating within discernible spatial framework. The Niger Delta basin, also referred to as the Niger Delta Province, is an external rift basin located in the Niger Delta and Gulf of Guinea on the passive continental margin near the western coast of Nigeria with suspected or proven access to Cameroon, Equatorial Guinea and Sao Tome and Principe. The Niger Delta has been pro-grading since the Eocene with truncation at intervals by marine transgressions on either local or regional scales. The three major sedimentary environments are the continental, transitional and the marine environments which are represented by Benin, Agbada and Akata formations respectively. Petroleum in the Niger Delta is produced from the sandstone and unconsolidated sands predominantly in the Agbada formation. in order of standard of the standard of geological approach required for the interpretation of portable depositional environments and research qualities of the C-Well reservoir sand bodies, analysis and interpretation (Gamma Ray Logs) gotten from the Well-C was done. the gamma ray is used to measure the radioactivity of the formation. In sedimentary formations, the log normally reflects the shale content of the formation. The results of the well log readings in the figures provided. A total of nine sand bodies were recognized and their thickness and log shapes delineated. The C-Well reservoir is interpreted as deposits associated with a coastal barrier island system formed in a progradational wave dominated coastline environment with tidal current influence. The sand occurs with laminated silts and clay towards the base and become clay/silt free sand upwards. They show funnel shaped log signatures that are serrated at the bottom, which could be attributed to sedimentation rate exceeding the rate subsidence. It is recommended that further work should be done in the study area using different dada such as seismic data, core log to further prove adequate properties of the well.

English

This study was conducted to investigate the combined effects of municipal and industrial waste discharges on the quality of the new northern Calabar River in the Niger Delta province (5.317°N, 6.467°E) of Nigeria. Water samples were collected in June 2015 from five regions along the stretch of the river. The five regions comprised three observed pollution sources (abattoir, open market, and noodle factory) and two non-pollution sources at the downstream and upstream sections of the river. Using standard analytical protocols, results showed that the current pollution loads of the river varied significantly (p < 0.05) across the three pollution sources. Over 33% of studied quality indicators of the river including total hardness (1526.19±154 mg/l), biochemical oxygen demand (10.14±4 mg/l), and chemical oxygen demand (57.62±13 mg/l) over time increased beyond their permissible limits due to the disposal of municipal and industrial wastes into the river. The present quality of the river was only fair with a Water Quality Index of 64.71. This result suggests that the water quality is usually protected but occasionally impaired by the wastes discharged into the river, leading to conditions that often depart from permissible levels. Key words: Pollution loads, water quality index, river, Niger Delta

Mapping polycyclic aromatic hydrocarbon and total toxicity equivalent soil concentrations by visible and near-infrared spectroscopy

In this study, we used data from spectroscopic models based on visible and near-infrared (vis-NIR; 350–2500 nm) diffuse reflectance spectroscopy to develop soil maps of polycyclic aromatic hydrocarbons (PAHs) and total toxicity equivalent concentrations (TTEC) of the PAH mixture. The TTEC maps were then used for hazard assessment of three petroleum release sites in the Niger Delta province of Nigeria (5.317°N, 6.467°E). As the paired t-test revealed, there were non-significant (p > 0.05) differences between soil maps of PAH and TTEC developed with chemically measured and vis-NIR-predicted data. Comparison maps of PAH showed a slight to moderate agreement between measured and predicted data (Kappa coefficient = 0.19–0.56). Using proposed generic assessment criteria, hazard assessment showed that the degree of action for site-specific risk assessment and/or remediation is similar for both measurement methods. This demonstrates that the vis-NIR method may be useful for monitoring hydrocarbon contamination in a petroleum release site.

Static Reservoir Modeling Using Well Log and 3-D Seismic Data in a KN Field, Offshore Niger Delta, Nigeria

This study focuses on the application of 3D static model using 3-D seismic and well log data for proper optimization and development of hydrocarbon potential in KN field of Niger Delta Province. 3D Seismic data were used to generate the input interpreted horizon grids and fault polygons. The horizon which cut across the six wells was used for the analysis and detailed petrophysical analysis was carried out. Structural and property modeling (net to gross, porosity, permeability, water saturation and facies) were distributed stochastically within the constructed 3D grid using Sequential Gaussian Simulation and Sequential Indicator Simulation algorithms. The reservoir structural model show system of different oriented growth faults F1 to F6. Faults 1 and Fault 4 are the major growth faults, dipping towards south-west and are quite extensive. A rollover anticline formed as a result of deformation of the sediments deposited on the downthrown block of fault F1. The other faults (2, 3, 5 and 6) are minor fault (synthetic and antithetic). The trapping mechanism is a fault assisted anticlinal closure. Results from well log analysis and petrophysical models classified sand 9 reservoir as a moderate to good reservoir in terms of facies, with good porosity, permeability, moderate net to gross and low water saturation. The volumetric calculation of modeled sand 9 horizon reveals that the (STOIIP) value at the Downthrown and Ramp segment are 15.7 MMbbl and 3.8 MMbbl respectively. This implies that the mapped horizon indicates hydrocarbon accumulation in economic quantity. This study has also demonstrated the effectiveness of 3-D static modeling technique as a tool for better understanding of spatial distribution of discrete and continuous reservoir properties, hence, has provided a framework for future prediction of reservoir performance and production behavior of sand 9 reservoir. However, more horizontal wells should be drilled to enhance optimization of the reservoir.

Analysis of petroleum-contaminated soils by diffuse reflectance spectroscopy and sequential ultrasonic solvent extraction–gas chromatography

In this study, we demonstrate that partial least-squares regression analysis with full cross-validation of spectral reflectance data estimates the amount of polycyclic aromatic hydrocarbons in petroleum-contaminated tropical rainforest soils. We applied the approach to 137 field-moist intact soil samples collected from three oil spill sites in Ogoniland in the Niger Delta province (5.317°N, 6.467°E), Nigeria. We used sequential ultrasonic solvent extraction–gas chromatography as the reference chemical method. We took soil diffuse reflectance spectra with a mobile fibre-optic visible and near-infrared spectrophotometer (350–2500 nm). Independent validation of combined data from studied sites showed reasonable prediction precision (root-mean-square error of prediction = 1.16–1.95 mg kg−1, ratio of prediction deviation = 1.86–3.12, and validation r2 = 0.77–0.89). This suggests that the methodology may be useful for rapid assessment of the spatial variability of polycyclic aromatic hydrocarbons in petroleum-contaminated soils in the Niger Delta to inform risk assessment and remediation.