LITHOLOGY IDENTIFICATION OF A PETROLEUM RESERVIOR USING WELL LOG DATA: A CASE STUDY OF JAKOMA WELL-5

Lithology and pore fluid determination was effectively carried out using well logs from Well-5, JAKOMA’s field, onshore Niger Delta. A suite of geophysical logs comprising gamma ray, resistivity, neutron and density logs from a well in the field was used in the analysis. Analysis of well logs reveals that Well-5 consists of two types of lithology: sand and shale. The thick shale bed occurs below and above the sand bodies (reservoirs) which act as potential source rock or as a seal rock. Three reservoir windows (Reservoir A, B and C) were defined from the well. The top and base of each reservoir window was delineated. The obtained results show that there are two viable hydrocarbon-bearing (gas) zones named (Reservoir B and C). Results of petrophysical evaluation reveal that region A, B, C have an average porosity of 26,22,22%, Net to Gross of 98,51,89%, permeability of 3707,2276,1150mD, water saturation of 51,44,22%, shale volume of 0.026,0.0220.011 for Reservoir A, B and C respectively. The porosity values correspond with the already established porosity range of 28 – 32% within the Agbada Formation of Niger Delta. Permeability obtained for the reservoir is rated excellent. Hydrocarbon saturation is high in two of the three reservoir sands discovered which indicates that the proportion of void spaces occupied by water is relatively low. Porosity, permeability and net to gross values reduce as the depth of penetration increases resulting to decrease in reservoir quality. The overall results indicated that the sandy reservoir units of Well-5 in JAKOMA’s field have the potential to contain significant accumulations of hydrocarbon, essential gas. It is recommended to integrate more wells, seismic data and core data to better evaluate the reservoirs.