This paper characterizes the aquifer system of the Niger Delta for sustainable development of the groundwater resource. The heavy-dependence on groundwater in the region and the fears of its unsustainability triggered...This paper characterizes the aquifer system of the Niger Delta for sustainable development of the groundwater resource. The heavy-dependence on groundwater in the region and the fears of its unsustainability triggered by the weak regulations, pollution, increasing user population and industrialization coupled with the present limited knowledge of the true geological condition prevailing within the groundwater domain of the Niger Delta are the considerations that compelled this review study. The hydraulic properties of the region’s aquifers are discussed. The Niger Delta is characterized by a complex multilayered aquifer system hosted in the Benin Formation with the main body of fresh water, with increasing occurrence of intercalating clay units towards the coast. Lithological analysis indicates the prevalence of unconsolidated sand and sandy gravels in the aquiferous horizons, presenting them as pervious and prolific aquifers. Reported hydrochemical data gathered from wells drilled suggest that the quality of groundwater in the Niger Delta is considered generally very good and compares favorably with WHO standards for drinking water. However, relatively high iron/manganese and chloride values are localized in time and space. In the coastal areas however, seawater intrusion has been identified as one of the major influences on hydrochemistry of groundwater in the shallow unconfined aquifers. Regional groundwater flow direction is from north to south. Changes in groundwater flow directions which occur at some places generally serve localized discharge areas. The resultant flow path eventually joins and feeds the major regional north-south flow direction. The increasing pressure on groundwater, the need for urgent attention and the absence of strong institutions and regulations have made the management of groundwater resources in the region a difficult task. Therefore, future ground water resources development in the Niger Delta requires adequate observational data, investments in infrastructure and an integrated management approach to ensure optimal basin-wide benefits.展开更多
A wildcat may not result in a petroleum prospect; however, it may indicate potential need for frontier explo- ration, since petroleum could leak into economic accumu- lations. Carbazoles and benzocarbazoles are nitrog...A wildcat may not result in a petroleum prospect; however, it may indicate potential need for frontier explo- ration, since petroleum could leak into economic accumu- lations. Carbazoles and benzocarbazoles are nitrogen compounds in petroleum and can be employed to explicitly explain migration direction and distance of leaking petro- leum. The hypothesis of this study is that the mechanism of the reaction involving the attraction of carbazoles to clay minerals on the matrix of the walls along their migration pathways determines the isomer that is preferentially attached to the mineral matrix. The objectives of this study are （a） to produce a profile for carbazoles and benzocar- bazoles ratios in the cap rock overlying the reservoir, （b） to compare carbazole and benzocarbazole ratios to 20S/ （20S ＋ 20R） （^（^C29 Sterane maturity ratios （c） to infer migration direction from the carbazoles and benzocar- bazoles ratio. Samples used were side wall cores and drill cuttings of water-based mud drilling. The EOM （ex- tractable organic matter） from various formations overlying the reservoir was obtained using Soxtherm Automatic Equipment. The TPH （total petroleum hydrocarbon） was obtained from the EOM by using a precleaned isolute C18 500 mg / 3 mL column, eluted with hexane, while the polars were eluted with dichloromethane. Fractionation into satu- rates and aromatics was done using a silver nitrate-silica gel column. The profiles of 1,8/1,3 and 1,8/2,4 dimethyl car- bazoles and the benzocarbazoles ratios show a vertical gra- dient of decreasing ratio with increasing vertical distance from the reservoir. This corroborates the %VRo equivalent of 20S/（20S ＋ 20R） αααC29 Sterane and the carbazole ratios infer vertical migration of leaked petroleum.展开更多
文摘This paper characterizes the aquifer system of the Niger Delta for sustainable development of the groundwater resource. The heavy-dependence on groundwater in the region and the fears of its unsustainability triggered by the weak regulations, pollution, increasing user population and industrialization coupled with the present limited knowledge of the true geological condition prevailing within the groundwater domain of the Niger Delta are the considerations that compelled this review study. The hydraulic properties of the region’s aquifers are discussed. The Niger Delta is characterized by a complex multilayered aquifer system hosted in the Benin Formation with the main body of fresh water, with increasing occurrence of intercalating clay units towards the coast. Lithological analysis indicates the prevalence of unconsolidated sand and sandy gravels in the aquiferous horizons, presenting them as pervious and prolific aquifers. Reported hydrochemical data gathered from wells drilled suggest that the quality of groundwater in the Niger Delta is considered generally very good and compares favorably with WHO standards for drinking water. However, relatively high iron/manganese and chloride values are localized in time and space. In the coastal areas however, seawater intrusion has been identified as one of the major influences on hydrochemistry of groundwater in the shallow unconfined aquifers. Regional groundwater flow direction is from north to south. Changes in groundwater flow directions which occur at some places generally serve localized discharge areas. The resultant flow path eventually joins and feeds the major regional north-south flow direction. The increasing pressure on groundwater, the need for urgent attention and the absence of strong institutions and regulations have made the management of groundwater resources in the region a difficult task. Therefore, future ground water resources development in the Niger Delta requires adequate observational data, investments in infrastructure and an integrated management approach to ensure optimal basin-wide benefits.
文摘A wildcat may not result in a petroleum prospect; however, it may indicate potential need for frontier explo- ration, since petroleum could leak into economic accumu- lations. Carbazoles and benzocarbazoles are nitrogen compounds in petroleum and can be employed to explicitly explain migration direction and distance of leaking petro- leum. The hypothesis of this study is that the mechanism of the reaction involving the attraction of carbazoles to clay minerals on the matrix of the walls along their migration pathways determines the isomer that is preferentially attached to the mineral matrix. The objectives of this study are （a） to produce a profile for carbazoles and benzocar- bazoles ratios in the cap rock overlying the reservoir, （b） to compare carbazole and benzocarbazole ratios to 20S/ （20S ＋ 20R） （^（^C29 Sterane maturity ratios （c） to infer migration direction from the carbazoles and benzocar- bazoles ratio. Samples used were side wall cores and drill cuttings of water-based mud drilling. The EOM （ex- tractable organic matter） from various formations overlying the reservoir was obtained using Soxtherm Automatic Equipment. The TPH （total petroleum hydrocarbon） was obtained from the EOM by using a precleaned isolute C18 500 mg / 3 mL column, eluted with hexane, while the polars were eluted with dichloromethane. Fractionation into satu- rates and aromatics was done using a silver nitrate-silica gel column. The profiles of 1,8/1,3 and 1,8/2,4 dimethyl car- bazoles and the benzocarbazoles ratios show a vertical gra- dient of decreasing ratio with increasing vertical distance from the reservoir. This corroborates the %VRo equivalent of 20S/（20S ＋ 20R） αααC29 Sterane and the carbazole ratios infer vertical migration of leaked petroleum.
