Soil conductivity is responsible for its aggressive behavior to metallic objects either in contact or buried in the ground. Rapid deterioration and eventual rupture of pipelines leading ultimately to crude oil spillag...Soil conductivity is responsible for its aggressive behavior to metallic objects either in contact or buried in the ground. Rapid deterioration and eventual rupture of pipelines leading ultimately to crude oil spillages have been of economic as well as environmental concern. Although many factors contribute to soil resistivity, these relationships have hardly been quantitatively expressed. This paper explores the factors affecting soil resistivity firstly by matching the spatial regional distribution with each of the identified factors of influence, including ground elevation soil type, depth to water table and undrained strength. 183 Vertical Electrical Sounding VES with the ABEM SAS 1000, using Schlumberger electrode configuration were carried out along a pipeline route to generate resistivity distribution across a linear alignment that traverses three geomorphic sub-environments in the Niger Delta Region. The apparent resistivity values averaged over depths of 3 m and 10 m were plotted against the co-ordinates using Surfer-16 and overlaid on Google earth Pro to produce a spatial distribution with enhanced location visibility. The results show that apparent resistivity is influenced by depth to water table with lower values in areas of shallow water table occurrence. Furthermore, it is shown that changes in resistivity below the water table are more due to variation in soil type. Within a soil type above the water table, soil resistivity increases monotonically with depth until the depth of probe extends to a different soil horizon. Results of this study provide guidance as to what ground resistivity to expect in different part of the delta as well as provide valuable information to assess the risks to assets either as a means of prioritizing maintenance or of improving design for new installations in the Niger Delta Region.展开更多
The inhabitants of this area depend solely on contact springs as supply source of potable water. However, provision of potable water to meet the needs of the people still remains an unsolved problem. Therefore, this p...The inhabitants of this area depend solely on contact springs as supply source of potable water. However, provision of potable water to meet the needs of the people still remains an unsolved problem. Therefore, this paper attempts to solve this problem by using Dar Zarrouk (D-Z) Parameters;Total Transverse Unit Resistance, T (Ωm<sup>2</sup>) and Total Longitudinal Unit Conductance, S (Ω<sup>-1</sup>) to suggest optimal locations for drilling of boreholes in the study area. To attain this purpose, 50 Schlumberger Vertical Electrical Sounding (VES) curves with maximum current electrode spacing of AB/2 = 681 m were interpreted. Thus, the aquifer parameters information estimated from the (VES) curves were used to prepare contour maps of T (Ωm<sup>2</sup>), S (Ω<sup>-1</sup>), aquifer thickness h (m), aquifer resistivity ρ (Ωm), and Water Table Depth (WTD). For effective use of these parameters, iso-thickness and iso-resistivity maps were compared with contour map of transverse resistance. The good agreement between these parameters provided the basis for identification of prolific aquiferous zones. It was observed that the Southern part of the study area majorly underlain by the Afikpo Sandstone of Nkporo Formation (Campanian-Maastrichtian), relatively showed higher T (Ωm<sup>2</sup>), h (m), and ρ (Ωm) values, which implies high yield aquiferous zones. The relatively loose structure of this sandstone unit, coarse grains, and sorting enables it to be porous and permeable. The Northern part of the region which shows low values for T (Ωm<sup>2</sup>), h (m), and ρ (Ωm) suggests low productivity for the aquiferous zones. The paucity of water in this parts of the study area can be explained to be as a result of the dominant geology. The high S, values at the Uburu and Okposi locations in this region suggests the presence of saline aquifer. This study would be relevant to the development of effective ground water scheme and for future hydrogeological investigations in the area.展开更多
文摘Soil conductivity is responsible for its aggressive behavior to metallic objects either in contact or buried in the ground. Rapid deterioration and eventual rupture of pipelines leading ultimately to crude oil spillages have been of economic as well as environmental concern. Although many factors contribute to soil resistivity, these relationships have hardly been quantitatively expressed. This paper explores the factors affecting soil resistivity firstly by matching the spatial regional distribution with each of the identified factors of influence, including ground elevation soil type, depth to water table and undrained strength. 183 Vertical Electrical Sounding VES with the ABEM SAS 1000, using Schlumberger electrode configuration were carried out along a pipeline route to generate resistivity distribution across a linear alignment that traverses three geomorphic sub-environments in the Niger Delta Region. The apparent resistivity values averaged over depths of 3 m and 10 m were plotted against the co-ordinates using Surfer-16 and overlaid on Google earth Pro to produce a spatial distribution with enhanced location visibility. The results show that apparent resistivity is influenced by depth to water table with lower values in areas of shallow water table occurrence. Furthermore, it is shown that changes in resistivity below the water table are more due to variation in soil type. Within a soil type above the water table, soil resistivity increases monotonically with depth until the depth of probe extends to a different soil horizon. Results of this study provide guidance as to what ground resistivity to expect in different part of the delta as well as provide valuable information to assess the risks to assets either as a means of prioritizing maintenance or of improving design for new installations in the Niger Delta Region.
文摘The inhabitants of this area depend solely on contact springs as supply source of potable water. However, provision of potable water to meet the needs of the people still remains an unsolved problem. Therefore, this paper attempts to solve this problem by using Dar Zarrouk (D-Z) Parameters;Total Transverse Unit Resistance, T (Ωm<sup>2</sup>) and Total Longitudinal Unit Conductance, S (Ω<sup>-1</sup>) to suggest optimal locations for drilling of boreholes in the study area. To attain this purpose, 50 Schlumberger Vertical Electrical Sounding (VES) curves with maximum current electrode spacing of AB/2 = 681 m were interpreted. Thus, the aquifer parameters information estimated from the (VES) curves were used to prepare contour maps of T (Ωm<sup>2</sup>), S (Ω<sup>-1</sup>), aquifer thickness h (m), aquifer resistivity ρ (Ωm), and Water Table Depth (WTD). For effective use of these parameters, iso-thickness and iso-resistivity maps were compared with contour map of transverse resistance. The good agreement between these parameters provided the basis for identification of prolific aquiferous zones. It was observed that the Southern part of the study area majorly underlain by the Afikpo Sandstone of Nkporo Formation (Campanian-Maastrichtian), relatively showed higher T (Ωm<sup>2</sup>), h (m), and ρ (Ωm) values, which implies high yield aquiferous zones. The relatively loose structure of this sandstone unit, coarse grains, and sorting enables it to be porous and permeable. The Northern part of the region which shows low values for T (Ωm<sup>2</sup>), h (m), and ρ (Ωm) suggests low productivity for the aquiferous zones. The paucity of water in this parts of the study area can be explained to be as a result of the dominant geology. The high S, values at the Uburu and Okposi locations in this region suggests the presence of saline aquifer. This study would be relevant to the development of effective ground water scheme and for future hydrogeological investigations in the area.
