Examination of the Seismic Characteristics of Onshore Reservoirs for Dom Gas Production Potentials in the Niger Delta Region of Nigeria

The objective of this research work is to examine two prominent dom gas reservoirs H1000 and H4000 in onshore Niger Delta region of Nigeria for potential production activities using seismic wavelet and well-toseismic tie process to facilitate interpretation and evaluate dom gas (hydrocarbon) bearing formation. Well log and sidewall samples analyses show that the velocity attributes, high P-wave, S-wave and Vp/Vs ratio characterize sediments with high concentration of dom gas. The wells validated the presence of dom gas with total gas in place on the field estimated at 4.017 trillion ft3, GIIP 5,228.683 bscf, CIIP 445.136 MMstb, and STOIIP 34.647 MMstb, URg 4,120.494 bscf and URc 219.208 MMstbl, 90 % of which resides in the two reservoirs. The hydrocarbon intervals are estimated at H1000 (8864 ft, TVDSS) and H4000 (9577 ft, TVDSS). The borehole information was combined with seismic data to confirm lateral continuity of the dom gas reservoirs

Vertical Electric Sounding of Leachate Contaminant Plumes at a Dumpsite in Obigbo, Rivers State, Nigeria

The quality of underground water at a dumpsite in Obigbo, Rivers State, Nigeria, was investigated by collecting 7 vertical electrical soundings (VES) using Wenner electrode configuration with current electrode spacing (AB/2) ranging from 1.0 m to 300 m. Field data were acquired using the SAS 300C resistivity meter and accessories, coordinates and elevation were measured using the Global Positioning System (GPS) at each sounding station. The VES data showed that the area is composed of clay, sandy clay and sand. The contaminated zones have low resistivity and corresponding high conductivity. Two zones were identified, zones of low resistivity and high resistivity with values of 11.3 Ωm to 21.4 Ωm, and 357.0 Ωm to795.0 Ωm respectively. There is thus, both lateral and downward movement of the contaminant leachate plumes. The results also revealed that the  surrounding soil and groundwater around the landfill has not been contaminated to depths exceeding 15.6 m, which is shallower than the productive aquifer depth greater than 37.0 m. Judging from the age of the dumpsite, this site has a good protecting capacity, probably as a result of the presence of sufficient confined layers of clay that have impeded or slowed down the percolation of leachate into the aquifer. The aquifer is the underlying rocks of sand and gravel that are porous which constitute the water body.Keywords: Dumpsite, Resistivity, Sounding, Leachate, Aquifer

Evaluation of the layering of rock strata and basement rock depth of a university teaching hospital premises in northern Nigeria

The layering of rock strata and depth to the basement rocks of a Federal University Teaching Hospital premises in Northern Nigeria was investigated in this study with the aim of providing 2D geo-electrical resistivity images of the subsurface for geotechnical development using a modern and state-of-the-art field instrument, the ABEM Automatic LUND Imaging System (Terrameter SAS 4000 and ES 464). Three profiles were covered and the data processed to display the variations of electrical resistivity using the RES2DINV software. The results of the survey in correlation with borehole data in the area revealed three distinct layers: the overburden which is about 16 m - 26 m thick having a resistivity range of about 194 Ωm – 1759 Ωm. The weathered basement which is appreciably thick (about 5 m – 14 m),which is highly fractured and weathered, so constitutes a good aquifer having a resistivity range of about 0.687 Ωm – 678 Ωm and the fresh crystalline basement having a resistivity of about 1223 Ωm. The fresh crystalline rock is at variable depths of about 21 m - 40 m below the surface.Keywords: Rock strata, Geotechnical, Electrical resistivity, Basement, Overburde

2D geo-electrical imaging for groundwater exploration in Shika, along Zaria-Funtua Road north of Ahmadu Bello University main campus, Samaru, Zaria

A two dimensional (2D) geoelectrical tomography of Ahmadu Bello University Teaching Hospital Premises was carried out with the aim of identifying a suitable location for siting a borehole. This was sequel to the fact that a borehole drilled without proper geophysical investigation in the quarters for resident doctors did not produce water. State-of-the-art equipment was employed and 2D surveying proved a powerful geological mapping tool, for use in hydrogeological mapping including engineering and environmental applications. The 2D inversion results of the survey were correlated with the lithology information obtained from the boreholes in Jama’a village, and the hostels and the residential quarters of ABUTH. The stratigraphic structure of the study area is very complex and is a product of volcanic and magmatic activities of various ages. Based on the geo-electrical images obtained in the study area, three distinct layers were revealed, the overburden with an average thickness of about 16 m – 26 m. The overburden is immediately underlain by the weathered basement, 5 m – 14 m thick which consists of disintegrated schistose rock materials, sand and gravel. This layer has a relatively low resistivity due to the presence of water and clay, which reduces the permeability, so this layer is thus regarded as the aquifer. The fresh basement rock was encountered at a variable depth of between 21 m and >30 m with resistivity 1223 Ωm up to 11918 Ωm. These results agree with the borehole logs. The complete set of borehole logs used in this research were obtained from the original hydro-geologic assessment report of the groundwater research department of the National Water Resources Institute (NWRI), Mando, Kaduna; Kaduna State, Nigeria.Keywords: Tomography, Inversion, Lithology, Geo-electrical, Aquifer, Borehol

Lithology and Fluid discrimination of Sody field of the Nigerian Delta

The lithology and fluid discrimination of an onshore Sody field, of the Niger Delta was studied using gamma ray, resistivity and density logs from  three wells in the field in order to evaluate the field’s reservoir properties. Two reservoir sands (RES 1 and RES 2) were delineated and identified as hydrocarbon bearing reservoirs. The petrophysical parameters calculated include total porosity, water saturation and volume of shale. The results obtained revealed that the average porosity of the reservoir sands, range from 21% to 39%, which is excellent indicator of a good quality reservoir and probably reflecting well sorted coarse grain sandstone reservoirs with minimal cementation. Water saturation is low in all the reservoirs, ranging from 2% to 32%, indicating that the proportion of void spaces occupied by water is low, and implying high hydrocarbon saturation. The crossplot discriminated the reservoirs lithologies as sand, shaly sand and shale sequences, except well Sody 2 which differentiated its lithologies as sand and shale sequences and distinguished the reservoirs’ litho-fluids into three, namely; gas, oil and brine. These results suggest that the reservoirs sand units of Sody field contain significant accumulations of hydrocarbon. Keywords: Reservoir, porosity, net-to-gross, impedance, litholog

Effect of Landfill Leachate on Groundwater Contamination: A case study of Obio- Akpo Local Government Area, Rivers State, Nigeria

This research investigates the effect of landfill leachate on the groundwater in “Odum”, a community that plays host to a dumpsite along  Choba/Alakahia road in Obio/Akpor Local Government Area (L.G.A.) of Rivers State, Nigeria. Five vertical electrical soundings (VES) were conducted using the Schlumberger configuration and also five horizontal profiling were done using the Wenner configuration. The field data were acquired using ABEM tarrameter SAS 300C, and processed using the IP TWO WAY software. The results showed that the area is composed of sandstone, clay, laterite, sandy clay, and sand. Also, from careful analysis and interpretation of the processed data it was observed that contaminated zones have low resistivity (high conductivity). Strikingly, areas of low resistivity such as 11.9 Ωm and others with high resistivity up to greater than 1818 Ωm do exist. The results show that groundwater around this landfill contaminated area contains highly conductive leachates like sulphur, methane, ammonia gas at depths > 16 m. This indicates that the study area is not a good aquifer zone. Keywords: Resistivity, Landfill, Leachate, Groundwater, Dumpsite, Aquifer, Soundin

Reservoir Characterization and Volumetric Analysis of “Lee” Field, Onshore Niger Delta, Using 3D Seismic and Well Log Data

Three dimensional (3D) seismic data, and a suite of four geophysical well logs from four wells located on the Lee field, Niger Delta were analyzed  using Petrel software for the aim of reservoir characterization and  volumetric analysis of the field. The objectives among others include  identification and delineation of the reservoirs and estimating the petrophysical parameters from the well logs available, generating time and depth structure maps of horizons from the seismic section, and a volumetric analysis in order to estimate hydrocarbon in place. The method adopted involves petrophysical analysis, structural analysis, static modelling, and volumetric analysis. Detailed petrophysical analysis revealed three reservoirs. Average Reservoir parameters such as effective porosity (0.17), gross thickness (86 m), hydrocarbon saturation (0.42), permeability (1215 mD) and net-to-gross (0.79) were derived from petrophysical analysis. The three reservoirs were classified using average results of petrophysical parameters. And based on these results, Reservoir 1 is the most prolific while Reservoir 3 is the least prolific within Lee field. Fault and Horizon interpretations were done using Petrel software which culminated in delivery of 3D structural map of the reservoirs. Structural,stratigraphic and Petrophysical models were developed and then integrated to produce a high resolution static model for Reservoir 1. The hydrocarbon in place shows that reservoir 1 is of appreciable thickness and areal extent. The volume of hydrocarbon originally in place was estimated to be 367,180,095.08 barrels of oil.Keywords: volumetric, petrophysical, fault, saturation, net-to-gross, permeability, horizo

Effect of Landfill Leachate on Groundwater Contamination: A case study of Obio-Akpo Local Government Area, Rivers State, Nigeria

This research investigates the effect of landfill leachate on the groundwater in \u201cOdum\u201d, a community that plays host to a dumpsite along Choba/Alakahia road in Obio/Akpor Local Government Area (L.G.A.) of Rivers State, Nigeria. Five vertical electrical soundings (VES) were conducted using the Schlumberger configuration and also five horizontal profiling were done using the Wenner configuration. The field data were acquired using ABEM tarrameter SAS 300C, and processed using the IP TWO WAY software. The results showed that the area is composed of sandstone, clay, laterite, sandy clay, and sand. Also, from careful analysis and interpretation of the processed data it was observed that contaminated zones have low resistivity (high conductivity). Strikingly, areas of low resistivity such as 11.9 \u3a9m and others with high resistivity up to greater than 1818 \u3a9m do exist. The results show that groundwater around this landfill contaminated area contains highly conductive leachates like sulphur, methane, ammonia gas at depths > 16 m. This indicates that the study area is not a good aquifer zone

Well-to-Seismic Tie of a Field Onshore of the Nigerian Delta

This work presents a modern procedure for understanding seismic data wavelets through well-to-seismic tie on an onshore field in the Nigerian Delta using the state-of-the-art techniques. The purpose of this work is the correlation of formation tops and seismic reflectors in the field. The objectives among others include the calibration of the seismic data in terms of polarity and phase, as well as to ensure that the seismic data is descriptive to well markers and discoveries, extending knowledge from the well location to rest of the field and reducing uncertainties. Logs from the two wells on the field and also logs from three wells on neighbouring fields were used to establish lateral continuity of the reservoirs H1000 and H4000. Their results show that the top, base and thickness of both reservoirs are quite variable laterally and this posed some challenges in the correlation from well to well. The field does not have checkshot data, so checkshot data from one of the wells on the neighbouring field was borrowed. Calibrated sonic and density logs of well-01 and well-02 were used to assess the seismic ties at the well locations. Strong correlations at the wells are fundamental to the evaluation of the spatial extent of the horizons around the wells from the seismic data. Seismic-to-well ties are a very important part of the interpreter\u2019s business as they provide a means of correctly identifying horizons to pick, and estimating the wavelet for inverting seismic data to impedance and rock property indicators

Lithology and Fluid discrimination of Sody field of the Nigerian Delta

The lithology and fluid discrimination of an onshore Sody field, of the Niger Delta was studied using gamma ray, resistivity and density logs from three wells in the field in order to evaluate the field\u2019s reservoir properties. Two reservoir sands (RES 1 and RES 2) were delineated and identified as hydrocarbon bearing reservoirs. The petrophysical parameters calculated include total porosity, water saturation and volume of shale. The results obtained revealed that the average porosity of the reservoir sands, range from 21% to 39%, which is excellent indicator of a good quality reservoir and probably reflecting well sorted coarse grain sandstone reservoirs with minimal cementation. Water saturation is low in all the reservoirs, ranging from 2% to 32%, indicating that the proportion of void spaces occupied by water is low, and implying high hydrocarbon saturation. The crossplot discriminated the reservoirs lithologies as sand, shaly sand and shale sequences, except well Sody 2 which differentiated its lithologies as sand and shale sequences and distinguished the reservoirs\u2019 litho-fluids into three, namely; gas, oil and brine. These results suggest that the reservoirs sand units of Sody field contain significant accumulations of hydrocarbon