Investigation of Corrosion of Buried Oil Pipeline by the Electrical Geophysical Methods

The delineation of possible areas of corrosion along an underground oil pipeline in Ubeji, Delta State, Nigeria was investigated using the horizontal electrical resistivity profiling technique and the Spontaneous Potential geophysical method. The resistivity and self potential values of the soil along the pipeline were obtained using the R-plus resistivity meter. The results show that areas of low resistivity, having values between 98.0 and 116.0 Ohm-m, coincide with areas of high negative spontaneous potential values, in the range -31.0 to -52 mV. The low apparent resistivity and high negative spontaneous potential values are indications that the soil is very corrosive and there is the possibility of the pipeline failure and oil spillage around these hot spots in the future. These methods applied in the study are quick, economic and efficient for detecting likely anodic hot spots along buried pipelines which need to be protected. Routine electrical geophysical investigations along buried oil pipelines should be undertaken for the early detection and prevention of pipeline failure with its attendant environmental, human and economic consequences. @ JASE

Determination of Rocks Elastic constants from Compressional and Shear Waves Velocities for Western Niger Delta, Nigeria.

The elastic properties of sedimentary rocks in the western Niger delta, Nigeria, have been computed for five oil exploratory wells. The elastic properties were obtained from the continuous borehole seismic (compressional and shear waves) velocities and density logs. The computed Lame\u2019s constants, \ub5 and \u3bb range from 0.02 x1010 to 1.0 x1010 Pa and 0.26 x1010 to 1.3 x1010 Pa respectively. The computed values of the Young\u2019s modulus, E, range between 0.56 x1010 and 2.53 x1010 Pa. The values of the bulk modulus, K, and compressibility, \u3b2, vary from 0.64 x1010 to 2.16 x1010 Pa and from 0.11 x 10-11 to 9.4 x10-11 Pa-1 respectively. The values of the bulk modulus are the largest for all the wells. The calculated values of the Poisson\u2019s ratio, \u3c3, are between 0.2 and 0.41. The computed values of the elastic properties show that the rocks encountered in the wells are soft and poorly sorted. This is a confirmation of the fact that the wells encountered two major formations (Benin and Agbada Formations). The Benin Formation is made up of sands with high porosity while the Agbada Formation is made up of alternations of sands and shale lithologies. @ JASE

Evaluation of the Hydrocarbon Maturity Level of Oil Well in Sedimentary Basin of the Northern Niger Delta, Nigeria

The hydrocarbon maturation level of Oben-1 well in the northern Niger Delta sedimentary basin was evaluated using the Lopatin "Time-Temperature Index (TTI). The result shows that sediments in the basin are both oil and gas producing with the oil window lying between the depths of 2.5 to 3.5km. Time of hydrocarbon generation varies from 36 Ma upwards. The hydrocarbon maturation level was estimated for seven horizons (A, B, C, D, E, F and G), and the results show that horizons A, B, C and D which are less than 36Ma are non oil and gas producing (i.e. TTI < 15) while horizons E, F and G which are more than 36Ma old are both oil and gas producing. This result is in agreement with the values of Vitrinite reflectance obtained for the well. This study shows that exploratory wells in the area should be extended beyond the depth of 3.5kilometres and that the hydrocarbon prospects of the northern Niger Delta is high. @ JASE

Determination of Rocks Elastic constants from Compressional and Shear Waves Velocities for Western Niger Delta, Nigeria.

The elastic properties of sedimentary rocks in the western Niger delta, Nigeria, have been computed for five oil exploratory wells. The elastic properties were obtained from the continuous borehole seismic (compressional and shear waves) velocities and density logs. The computed Lame’s constants, µ and λ range from 0.02 x1010 to 1.0 x1010 Pa and 0.26 x1010 to 1.3 x1010 Pa respectively. The computed values of the Young’s modulus, E, range between 0.56 x1010 and 2.53 x1010 Pa. The values of the bulk modulus, K, and compressibility, β, vary from 0.64 x1010 to 2.16 x1010 Pa and from 0.11 x 10-11 to 9.4 x10-11 Pa-1 respectively. The values of the bulk modulus are the largest for all the wells. The calculated values of the Poisson’s ratio, σ, are between 0.2 and 0.41. The computed values of the elastic properties show that the rocks encountered in the wells are soft and poorly sorted. This is a confirmation of the fact that the wells encountered two major formations (Benin and Agbada Formations). The Benin Formation is made up of sands with high porosity while the Agbada Formation is made up of alternations of sands and shale lithologies. @ JASE

Investigation of Corrosion of Buried Oil Pipeline by the Electrical Geophysical Methods

The delineation of possible areas of corrosion along an underground oil pipeline in Ubeji, Delta State, Nigeria was investigated using the horizontal electrical resistivity profiling technique and the Spontaneous Potential geophysical method. The resistivity and self potential values of the soil along the pipeline were obtained using the R-plus resistivity meter. The results show that areas of low resistivity, having values between 98.0 and 116.0 Ohm-m, coincide with areas of high negative spontaneous potential values, in the range -31.0 to -52 mV. The low apparent resistivity and high negative spontaneous potential values are indications that the soil is very corrosive and there is the possibility of the pipeline failure and oil spillage around these hot spots in the future. These methods applied in the study are quick, economic and efficient for detecting likely anodic hot spots along buried pipelines which need to be protected. Routine electrical geophysical investigations along buried oil pipelines should be undertaken for the early detection and prevention of pipeline failure with its attendant environmental, human and economic consequences. @ JASE

Structural and seismic sequence stratigraphy analysis of seismic and biostratigraphy data from an onshore field, Niger Delta, Nigeria

The structural and sequence stratigraphy of a Niger Delta onshore field has been analysed from seismic and biostratigraphy data in order to assess the hydrocarbon potential of the area. Seven faults F1, F2, F3, F4, F5, F6 and F7 were delineated in the seismic sections. The faults, F1, F4, F6 and F7 are synthetic faults, while F2, F3 and F5 are antithetic. Two horizons H1 and H2 were identified in the seismic sections within the time window of 2200-2600 ms. The seismic sequence stratigraphy analysis revealed five sequence boundaries S1, S2, S3, S4 and S5, which represent four depositional sequences. Four maximum flooding surfaces (MFS) were also delineated in the seismic data. The analysis of the biostratigraphy data thus revealed four sequence boundaries (S1, S2, S3, S4) and three maximum surfaces (MFS1, MFS2 and MF3). The age of the sequence boundary ranges from 13.1Ma to 8.3 Ma. The age of the observed maximum flooding surfaces ranges from 12.8 Ma to 9.4 Ma. In vertical succession, the depositional sequences were identified by the order; sequence boundary, lowstand system tract (LST), Transgressive system tract (TST), Maximum flooding surface (MFS), and Highstand system tract (HST). The lowstand system tract is made up of stacking pattern of sand, while the transgressive system tract thinned into the condense section

Evaluation of the Hydrocarbon Maturity Level of Oil Well in Sedimentary Basin of the Northern Niger Delta, Nigeria

The hydrocarbon maturation level of Oben-1 well in the northern Niger Delta sedimentary basin was evaluated using the Lopatin "Time-Temperature Index (TTI). The result shows that sediments in the basin are both oil and gas producing with the oil window lying between the depths of 2.5 to 3.5km. Time of hydrocarbon generation varies from 36 Ma upwards. The hydrocarbon maturation level was estimated for seven horizons (A, B, C, D, E, F and G), and the results show that horizons A, B, C and D which are less than 36Ma are non oil and gas producing (i.e. TTI < 15) while horizons E, F and G which are more than 36Ma old are both oil and gas producing. This result is in agreement with the values of Vitrinite reflectance obtained for the well. This study shows that exploratory wells in the area should be extended beyond the depth of 3.5kilometres and that the hydrocarbon prospects of the northern Niger Delta is high. @ JASE