Open Access Case Study

Geophysical and Geotechnical Investigation of Road Pavement Failure in Part of Ibadan Metropolis Southwestern Nigeria

Solomon M. Jekayinfa, Olawale O. Osinowo

Asian Journal of Geological Research, Page 17-31

Road pavement failure observed along a section of Apete-Akufo Major Road in Ibadan metropolis southwestern Nigeria, necessitates the need to ascertain whether the failure results from poor construction practices or poor engineering properties of subgrade materials. Geophysical and geotechnical survey results were compared to investigate the cause of the road pavement failure. Vertical Electrical Sounding (VES) with geotechnical study which include; grain size analysis, Atterberg limits and California Bearing Ratio (CBR) tests, were carried out on disturbed subgrade samples obtained between 0 – 1 m depth from VES Stations 1, 2 and 5, corresponding to unstable, stable and highly unstable sections of the road respectively. The quality of the subgrade was evaluated based on Atterberg limits, layer resistivity and CBR values. Eight (8) VES stations established 100m apart along the road section delineated 5 lithology; topsoil, clayey sand/lateritic clay, weathered bedrock and fresh bedrock with resistivity range of 68-238Ωm, 72-236Ωm, 224-859Ωm and 6720-15351Ωm respectively. Low overburden resistivity characterized failed sections. Sample from VES Station 5 has very low wet or dry bearing capacity responsible for observable failure of the road section. Sample from VES Station 1 presents high dry bearing capacity (70%) but low wet bearing capacity (11%), suggesting poor drainage may be responsible for pavement failure at the section. Sample from VES Stations 2 presents similar wet and dry bearing capacity resulting in stable road pavement.

The study indicates poor construction practices, lack of proper drainage and poor engineering properties of subgrade materials as the causes of road pavement failure along the observed section of Apete-Akufo Major Road.

Open Access Short Research Article

New Insights on Stratigraphic Level and Record of the Nummulites Postfossulatus Sirel and Deveciler (Foraminiferida) in Safranbolu (NW Turkey) and Malatya Basins (E Turkey)

Meral Kaya Sarı

Asian Journal of Geological Research, Page 32-39

A new species, postfossulatus, was originally described by Sirel and Deveciler in the middle Lutetian sediments in the Haymana region (Central Anatolia, Central Turkey).

The main purpose of this research is to reveal the new locations and new stratigraphic level of the new species. In this study, Nummulites postfossulatus was also reported for the first time in the early-middle Eocene sediments of the Safranbolu and Malatya Basins.

Safranbolu Basin is located on the Anatolian Plate, and Malatya Basin is located in the                southern branch of Neo-Tethys. Safranbolu (Western Black Sea Region) and Malatya basins                (SW Malatya, eastern Anatolia), which are important basins of Turkey in biostratigraphic research, have rich fossil content, especially benthic foraminifera, during the Eocene period.

The early-middle Eocene units of the Safranbolu Formation is widely exposed in the Safranbolu Basin-Karabuk (northwestern Turkey). This formation is composed of abundant macro-micro fossiliferous limestone.

The Yıldıztepe Formation outcropping in the Malatya Basin, represented by reefal limestones containing abundant foraminifera, algae, and coralline, is of middle-late Lutetian age.

This study determined that the stratigraphic level of N. postfossulatus went up to the Upper Lutetian because it was seen in the Nummulites aturicus zone representing late Lutetian in the Yıldıztepe Formation.

Open Access Original Research Article

Assessing the Ecological Health of a River in North-West Nigeria using Macroinvertebrates Structural Assemblage and Environmental Factors

A. O. Edegbene, G. O. Omovoh, E. C. Osimen, E. Ogidiaka, L. O. Jegbefume, E. O. Olatunji, K.H. Nwaka

Asian Journal of Geological Research, Page 1-16

The ecological health of River Kafin Hausa was assessed in three well marked out stations for a period of four (4) months, spanning from January to April, 2018. Water samples were collected at each sampling site and analysed according to approved standard. The habitat quality evaluation index (QHEI) was used to assess the habitat quality of the riparian zone of the river. A modified kick net with 4.4 square feet (1.36m2) squared frame net was used to sample macroinvertebrates. Water quality variables were not significantly different among the months and stations sampled. Electrical conductivity, pH and TDS were higher in station 2 with mean value of 327+34µS/cm, 11 and 200.05+20.95mg/l respectively. Station 1 had the highest QHEI value of 49%. A total of 11 classes/orders, 23 families and 24 taxa of macroinvertebrates were recorded. Gastropoda was the most represented order of macroinvertebrates. Diversity indices showed significant differences (p<0.05) in the means of Taxa, Evenness and Margalef Index in station 2. The canonical correspondence analysis revealed a very weak relationship between the species composition and abundance with the selected environmental variables in the river. Flow velocity was found to influence the composition of Corbiculidae, Hydrobiidae and Potadoma sp. Chironomus sp., Viviparidae and Gyrinus sp. were associated with station 2. Bray-curtis similarity clearly showed no pattern of clustering between the months and stations. The study shows that the river has been subjected to disturbance in the river channels and catchments which was hinged on incessant anthropogenic activities.

Open Access Original Research Article

Thermal Maturation and Subsidence History Studies in Some Parts of the Eastern Niger Delta Basin, Southern Nigeria Using Well-logs

E. D. Uko, M. A. Alabraba, I. Tamunoberetonari, A. O. Oki

Asian Journal of Geological Research, Page 40-52

Subsidence history and hydrocarbon maturation studies was analysed using well log data from four adjacent fields from the eastern part of Niger Delta basin. Three major tectonic phases of the basin evolution were identified as, firstly, a phase of subsidence from the mid to early Miocene, a second phase of uplift from the early Miocene to the mid Pliocene then lastly a period of subsidence from the mid Pliocene to the early Pliestocene. Results from Vitrinite Reflectance models of the wells showed sediments of Belema, Inda and Idama wells were thermally immature for hydrocarbon generation with values less than 6.5%R0, whereas Robertkiri-14 well showed sediments were thermally mature source rock sediments with a modelled %Ro value of 6.5, this showed the well and by extension the field had great mature hydrocarbon potential.

Open Access Original Research Article

Assessment of Thermal Maturity of Crude Oils Using Biomarker Fingerprinting

Botwe Takyi, Selegha Abrakassa, G. J. Udom, Koffi Eugene Kouadio, Frederick K. Bempong

Asian Journal of Geological Research, Page 53-61

The study assesses the thermal maturity levels of crude oils from the Niger Delta Basin of Nigeria using biomarker fingerprinting technique. Thirteen (13) crude oil samples were deasphaltened by the addition of n-heptane. The maltene fractions were analysed using the Gas Chromatography-Mass Spectrometer (GCMS) in Selected Ion Mode (SIM) to obtain the biomarker chromatograms. The respective biomarker thermal maturation peaks were extracted and their ratios computed. The odd to even predominance (OEP) and carbon preference index (CPI) values vary from 0.94 to1.08, with an average value of 1.02 and 1.01 to 1.12, with a mean value of 1.07 respectively. The ratios of Pr/n-C17 and Ph/n-C18 for the samples vary from 0.44 to 1.04, with a mean value of 0.73 and 0.53 to 0.77 with a mean value of 0.63, respectively. The Ts/Tm ratio ranges between 0.56 to 1.25. The Ts/(Ts+Tm) ratio ranges from 0.36 to 0.56. The C32 22S/(22S + 22R) hopane ratios for the samples range between 0.53 to 0.58. The C29 sterane maturity ratios 20S/(20S + 20R) and ββ/(ββ+αα), vary from 0.33 to 0.56 and 0.34 to 0.67, respectively. The estimated biomarker maturation parameters suggest the analysed samples reached and or exceeded the peak of the oil generation window, with high levels of thermal maturity.

Open Access Original Research Article

Geophysical and Borehole Log Evaluation of Groundwater Prospect in Parts of Lagos State, Southwestern Nigeria

O. M. Ogunsanya, D. V. Ogunsanya

Asian Journal of Geological Research, Page 62-77

Twelve (12) vertical electrical sounding were obtained in parts of Lagos State. Nineteen (19) deep boreholes within the Dahomey basin using resistivity and natural gamma ray wirelogs data were obtained. The vertical electrical sounding obtained were interpreted by WIN resist software. Four layers were obtained from the correlated geo-electric section which are topsoil, sand, clay and sandy clay. The obtained borehole data were interpreted using the surfer 2012 software program. Lithological units and saturation fluids were delineated. The lithological logs showed the fluid contents have various aquifers. The results of the subsurface geophysical investigation carried out within the study area show geo-electric layers characterized by low to moderately high resistivity materials (7-1314) Ωm indicative of sand top soil with thickness ranging from (1.0-2.6) m. The second layer is characterized by low resistivity materials (1.0-34) Ωm, indicative of clay materials with thickness ranging from (5.1-191) m. The last layer is characterized by low to moderately high resistivity (0.4-900) Ωm, indicative of sand materials. The borehole data interpretation result shows that the study area is underlain by clays, sandy clays, clayey sand and sand. The clay occurs as lenses within the clay formation. Based on this, five (5) aquifers were delineated in the study area along traverse AB, five (5) aquifers delineated along CD, Six (6) aquifers along EF. One parametric VES and borehole were correlated and it shows the increment of the lithologic units almost at the same depth which allows for the correct interpretation of the subsurface. The sand layer constitutes the major units in the study area while sandy clay and clayey sand constitute the minor aquifer units. This research work revealed that fresh water can be tapped from the entire well in the study area at various depths depending on the area where the well is located.

Open Access Original Research Article

3D Modeling Approach of Fault Seal Integrity Analysis in Sonia Field Onshore Niger Delta

Oshodi D. Raymond, John O. Amigun

Asian Journal of Geological Research, Page 78-98

Geologic structures that aids the accumulation of hydrocarbon in reservoirs could be fault assisted or fault dependent, these faults can be described as sealing or leaking in nature. In this study, well logs and 3D seismic data were utilized for the seal integrity analysis in Sonia Field onshore Niger Delta.

The methods employed include reservoir evaluation (i.e. Determining the volume of shale), and the generation of 3D models by computing the fault seal algorithms  such as the shale gouge ratio, which was used to access the sealing capacity of the fault planes trending NW-SE in the study area.  In order to ascertain the sealing integrity of the identified hydrocarbon bearing sand, the following were done: horizon to fault intersection on the shale gouge ratio model, the 3D models of the fault attributes i.e. Fault-throw. Hydrocarbon column height (HCH and fault flow properties specifically, fault transmissibility and fault permeablillity using ‘Manzocchi’ equation.

The shale gouge ratio ranged from  (leaking zones) to sealing Zones) across the fault plane. The hydrocarbon column height at which the faults In the study area can support ranges between 26.6 m to 28.0 m. The predicted permeability model of the faults is less than 1mD in some regions along the fault plane with corresponding transmissibility values between 0 and 0.20. Based on these results, it was observed that none of the hydrocarbon reservoirs in the study area falls within in the leaking category. The fault permeability and transmissibility models which indicate that regions along the faults planes are sealed and might prevent migration of fluid out of these reservoirs.

Open Access Original Research Article

Rock-Eval Pyrolysis Analysis of Agbada and Akata Shale from Niger Delta Basin, Nigeria

Koffi Eugene Kouadio, Selegha Abrakasa, Sunday S. Ikiensikimama, Botwe Takyi

Asian Journal of Geological Research, Page 99-111

Thirty (30) shale core samples from the Agbada and Akata formations in the Niger Delta, Nigeria were evaluated using a Rock-Eval pyrolysis to determine their richness, type, thermal maturity and hydrocarbon potential. Agbada and Akata formation samples show fair to Excellent content of total organic carbon (TOC > 0.5 wt.%) for oil generation. The S2 yield values for Agbada and Akata samples ranging between 0.1 and 10 mgHC/g rock and genetic potential (0.1 mgHC/grock<PG<20 mgHC/grock), indicating that organic matter generated fair to very good significant hydrocarbon. The results acquired from Rock-Eval analysis of Agbada and Akata Formation show low to medium hydrogen index (IH) values (32 to 216 mgHC/g TOC) which indicate gas prone kerogen Type III to minor mixed kerogen Type II/III. The Tmax values for the most of studied samples range from 410°C to 444°C. In Agbada formation, Tmax values varie between 414°C and 438°C, indicating an Immature to early mature organic matter. Tmax values for Akata formation range from 410°C to 444°C, suggesting immature to mature source rocks. This study concluded that Agbada formation has organic matter for world class oil generation but the limitation of the thickness of the formation gives Akata formation a better stand, with a fair generation capacity but an ocean of thick source rock, the thickness compensates for the fair generation capacity.

Open Access Original Research Article

Rock Physics and Geo-Mechanical Analysis to Enhance Sanding Prediction in Oil Wells in “Chi Field” Offshore Niger Delta

Adejo Monday Attai, Abiola Olubola

Asian Journal of Geological Research, Page 112-121

An integrated approach of rock physics and Geomechanical analyses was adopted in this study to enhance the prediction of sanding in oil wells within ‘CHI’ field offshore Niger Delta.

The data used for this study include suite of wireline logs from three wells, base map and checkshot. concept of geomechanics was used in evaluating and understanding the rock mechanical properties of the reservoirs. Two reservoirs namely (RES1 and RES2) were mapped and interpreted. Elastic and geomechanical parameters were evaluated within the field, the parameters include; Poisson ratio, Young modulus, Bulk modulus, Shear modulus, and Unconfined compressive strength (UCS). The elastic properties of rocks are affected by geological factors which include: Lithology, Depth and Anisotropy. In addition, rock physics analysis was carried out using the friable, constant and contact cement model to quantitatively characterize the lithology and also investigate the degree of cementation, compaction trend and environment of deposition with emphasis on the reservoir. The geomechanical parameters reveal that the reservoirs within the study area is predominantly unconsolidated sandstone and friable shale which serves as reservoir seal. The result shows that the reservoir sand units have low Poisson ratio, Young modulus, Bulk modulus, Shear modulus and high UCS (0.31Gpa, 11.5GPa, 0.06GPa, 4.3GPa, 337.5psi respectively), with high compressibility value of 0.08GPa  at reservoirs intervals. This suggest that the reservoir rocks are brittle with high potential to tensile failure.

Open Access Original Research Article

Lithological Characterization Using Parasequence Set for Depositional Environment of KD Field Shallow Offshore Niger Delta Basin

Ndukwe Otobong Sunday, Godwin Jeremiah Udom, Charles Ugwu Ugwueze

Asian Journal of Geological Research, Page 122-133

Aims: The purpose of this study is to delineate the environment of deposition from gamma ray log using parasequence set, for the well 01,02 and 03 within KD field for hyrdrocarbon prospect.

Study Design: The result of the lithostratigraphic analysis carried out on three wells from the KB field are presented and discussed.

Place: The study was carried out in the shallow offshore Southern Niger Delta, Nigeria from wells 01, 02 and 03 of KD Field.

Methodology: Gamma ray logs were subjected to para sequence set before using and log motif Interpretation were referred to know the depositional environment of the KD field shallow offshore Niger Delta. The lithologic descriptions were complemented using logs analyses.

Results: Based on their lithologic properties, investigation of the three wells were based on reservoir A, B, and C in the study area. The depositional environment falls within the nearshore face to intermediate offshore part of the Delta. The Unit is estimated to be 176m thick and is characterized by sands and a sand-shale layer alternation. In this investigation, only the Agbada Formation were encountered, it is characterized by Aggrading, Prograding and Retrogradational parasequence set.

Open Access Original Research Article

Petrology and Hydrogeochemistry within the Lateritic Profiles Over the Biotite Granites and Pegmatized Granite Schists of Ogbe and Environs, South-South Nigeria

Izeze Elijah Ovie, Okumoku Dokumo

Asian Journal of Geological Research, Page 134-149

This research work was aimed at studying the petrology of the different rock types and evaluating the quality of groundwater from streams, ponds and bored holes in Ogbe and its environ. Ogbe lies within latitude N 07 19’ 15.00’’ and longitude E 006 05’ 31.5’’ and is part of Igarra schist belt, southwestern Nigeria. The study area forms part of the Mesozoic Older Granite Complex, which intruded the Pre-Cambrian Crystalline Basement. The study area is composed of biotite granite, quartz-biotite granite, granitic schist and pegmatite occurring as dykes. Groundwater samples collected from boreholes and ponds were subjected to physical and chemical analysis. Physical parameters (pH, Ec, TDS and temperature) were measured insitu using standard equipment. Chemical analysis like Anions (NO3-, Cl-) and cations (Mg2+, Ca2+, K+, Na+) were measured in the laboratory using ion chromatography and heavy metals (Cu, Zn, Pb, Mn) were analysed using voltammetric stripping analysis. The mean concentration of the element measured were temp (30.6500˚C), T.D.S (144 ppm), E.C (µs), Ph (7.0250 mg/l), Na (24.7950 mg/l), K (10.3700 mg/l), Ca (23.9400 mg/l), Mg (7.3600 mg/l), Cl (51.7700 mg/l), Fe (.0155 mg/l), Zn (.0050 mg/l), Pb (.0010 mg/l) and Mn (.0010 mg/l) the results were compared with WHO and EPA standards to determine the quality of the groundwater and it was found that the percentage of alkali earth metals and alkali metals were dominant in borehole and pond respectively which was the main source of water in the community.