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Main Article Content
Sediment Characteristics and Hydrocarbon Composition of Makukwa Seep in Southern Tanzania: Potential Implications for Subterranean Hydrocarbon Accumulation
Abstract
Exploring the interplay between natural seeps and nearby sediment and
hydrocarbon properties is key to unlocking subsurface hydrocarbon
potential. This study presents findings on the hydrocarbon composition
and sediment characteristics of the Makukwa seep in southern
Tanzania, providing insight into subterranean hydrocarbon
accumulation. Sediment analysis across areas A and B, located
approximately 20 m apart, showed a decrease in porosity with depth,
indicative of typical sandstone formations. Area A, near the seeps,
exhibited porosity ranging from 23% to 36%, whereas Area B, further
away, showed porosity ranging from 22% to 38%. This suggests that a
lower cretaceous sandstone layer may have overlain the hydrocarbon
seep. XRD analysis confirmed quartz as the dominant mineral, with
concentrations of 46.1% in area A and 50.1% in area B, underscoring
the sediment's sandstone-like nature. Additionally, graphite was higher
in area A (29.5%) than in area B, indicating a varying degree of
hydrocarbon influence across the sampled locations. ICP-OES analysis
revealed elevated trace metal concentrations, particularly iron, which
varied from 27.47 ppm to 471.47 ppm in area A, significantly higher
than in area B, indicating the geochemical influence of hydrocarbon
seepage on sediment composition. GC-MS analysis showed a range of
heavy aliphatic hydrocarbons (n-alkanes) from n-C14 to n-C38 within
the sediments, indicating a dormant state. Notably, the concentrations
in area A were higher, with specific hydrocarbons such as octadecane
and eicosane measured at 0.330 µg/mL and 0.789 µg/mL, respectively,
compared with the lower concentrations in area B (octadecane at 0.105
µg/mL and eicosane at 0.089 µg/mL). This highlights the impact of
proximity to the seep on hydrocarbon distribution. This study offers
crucial insights into hydrocarbon dynamics at the Makukwa seep,
Tanzania, highlighting the relationship between sediment properties
and hydrocarbon accumulation. These findings enhance our
understanding of hydrocarbon seepage, guiding future exploration and
environmental monitoring efforts.
