Surveying and Geoinformatics - Scholarly Publications

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Browsing Surveying and Geoinformatics - Scholarly Publications by Author "Badejo, O.T."

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    Open Access
    Harmonic Analysis of Tides at Bonga Oil Field, Nigeria
    (2016-12) Badejo, O.T.; Evarie, P.; Anorue, N.; Alademomi, S.
    Oil exploration and exploitation activities are being moved from swamp and shallow waters to deep offshore locations in Nigeria, and therefore, there is a need to provide predicted tides to support oil and gas operations in deep offshore environment. In this work, 51 days' water level observations derived from water pressure data recorded by AANDERAA Water Level Recorder WLR 7 at a depth of 1,000 m at Bonga field were analysed and used to carry out tidal harmonic analysis. Eleven tidal constituents were used for the harmonic analysis. Astronomical arguments (v + u) and the nodal factor (f) were computed for each tidal constituent with a programme written in Matlab environment. The amplitudes and the phase lags for each constituent were calculated and tidal predictions beginning from the initial time of tidal observation in September 11, 2010 to January 2019 were done at 10 minutes' intervals. Statistical analysis of predicted tides and observed tidal data was done. The highest deviation of the predicted tides from the observed tidal data is 0.0008 m, while the Root Mean Square Error is 0.0003 m. Autocorrelation at lags 1 to 30 for the residuals of observed and predicted tidal data shows that there is no significant correlation in the series of the 30 lags. The series of residuals of observed and predicted data is white noise. The accuracy of this work is high enough for offshore operations in Bonga Field.
  • Item
    Open Access
    Tidal Charateristics and Sounding Datum Variation in Lagos State
    (2014-07) Badejo, O.T.; Olaleye, J.B.; Alademomi, A.S.
    The need for water level monitoring has increased over the years. Water level monitoring is among other things useful for oil and gas exploration and exploitation activities, and construction of ports and harbour works. The mean sea level for Lagos, Nigeria is referenced to the Lagos datum situated at the Office of the Surveyor General of the Federation at Lagos Island. This paper examines correlation and variation in the mean water levels and sounding datums for twelve water bodies in Lagos State. Water level observations were taken with the aid of tide gauges for twenty nine days at 12 tidal stations strategically situated within Lagos State. The mean water levels and other tidal characteristics for the various water bodies were calculated from the observed tidal observations from the twelve tide gauge stations. The tide gauge station at the Lagos Harbour has a known chart datum. Sounding datums were therefore determined for the eleven tide gauge locations by sounding datum transfer technique using the Chart datum at the Lagos harbor. The result from our study shows that there are variations in the tidal characteristics of the various water bodies in Lagos State. There is also a need for the harmonization of the various tidal datum in Lagos State.