WELL LOG ANALYSIS AND CLUSTER ANALYSIS FOR LITHOLOGY AND FLUID IDENTIFICATION IN WABI FIELD, NIGER DELTA, NIGERIA

Formation evaluation analysis and log-facies classification are powerful tools for identification and assessment of hydrocarbon - bearing zones. In this paper, petrophysical evaluation of well logs data from a suite of four wells (WABI 05, 06, 07 and 11) in the study area was carried out by integrating conventional log analysis and cluster analysis of some reservoirs in WABI field located in the Niger Delta Basin of Nigeria. The methods employed are based on conventional formation evaluation models and cluster analysis techniques. Cluster analysis of different log properties was generated to recognize the lithologic variability and pore-fluid type. The final output is the set of petrophysical curves, fluid type and fluid contacts and neutron–density cluster analysis. Eight reservoirs were delineated and established to be mainly sandstone with intercalation shale. Neutron–Density crossplot analyses revealed the presence of oil, gas or brine in all wells. Gas intervals showed very big cross over on neutron-density curves and are also supported by very high resistivity readings. The Neutron log versus Density cross-plot is colour-coded with gamma ray in WABI 07. It discriminates the reservoirs into shale, brine sands, oil sands and gas sands. Some reservoirs are made up basically of gas or gas and brine. From the results, the reservoirs are prolific and feasible for hydrocarbon production. This study has shown that the integration of conventional log analysis and cluster analysis are robust methods in the determination of the production potentials of hydrocarbon reservoirs.