| dc.description.abstract | In this research project an assessment of source rock maturity in the Lamu Basin based on well distribution, hydrocarbon shows, total organic carbon (T.O.C) levels, kerogen type using hydrogen-oxygen indices and Vitrinite Reflectance (Ro) has facilitated modeling of the hydrocarbon prospectivity in the Lamu Basin. The Lamu Basin, also known as the Lamu Embayment, is the largest sedimentary basin in Kenya and covers an area of approximately 259,782 square kilometers. The Lamu Basin covers both onshore and offshore geologic settings. The Basin contains sediments thickness of up to thirteen thousand (13,000) meters of sediments in the offshore parts of the Basin. Over eighteen (18) exploratory wells have been sunk in Lamu Basin. Seven (7) wells had with gas shows, two (2) had oil shows and two (2) had both oil and gas shows. Most of the wells drilled on the onshore portion of the Lamu Basin so far have targeted trapping mechanisms identified on a north-south axial trend thought to be an extension of the Davie Fracture Zone (DFZ).
There has not been any commercial discovery so far in the Lamu Basin but most of the wells drilled in this basin have yielded hydrocarbon shows of oil and or gas. Average (TOC) for horizons ~ 0.5% within the Lamu Basin sediments measured 1.17% in Simba-I Well, 0.59% in Maridadi-1 Well, 1.53% in Kipini-I Well and 0.56% in Walu-1 Well. Highest TOC level of up to 11.36% in the Kipini Formation of Middle Eocene age which is enough to yield commercial accumulations of hydrocarbons on maturation. Type III kerogen is the most dominant Kerogen Type and gas occurrences are the most frequent type of hydrocarbon encountered in the Lamu Basin. In Simba-I Well, gas shows were encountered at 1389m-3080m.
In Maridadi-1 Well, gas shows were encountered at the depth of 3320m-3600m, and oil shows at the depth of 3660m, while in Kipini-l Welt gas shows were encountered at 1110m- 3360m. Vitrinite Reflectance values indicate deeper source rocks to have attained thresh hold values of more than 0.6%. These sediments are therefore mature with a threshold maturity depth of 3183m in Simba-I Well, 3583m in Maridadi-l Well, 2609m in Kipini-1 Well and 2000m in Walu-l Well. These observations are consistent with the interpretations arrived at in this research. This research has indicated that the wells drilled so far are terminated just as the sedimentary column is entering oil window therefore deeper drilling is required to intercept hydrocarbon bearing sediments. | en_US |
