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The exploration and development of P oilfield in Melut basin South Sudan is early. The water-flooded layers are caused by bottom water coning, edge water propulsion and injected water. At present, the oilfield has entered the middle and high water cut stage. In order to stabilize oil and control water and enhance oil recovery, it is necessary to carry out the evaluation of water flooded layer. Based on the flow unit index theory, the reservoir is divided into three types by cumulative frequency method using experimental data of mercury injection and physical properties. Then the water flooding level is qualitatively and quantitatively evaluated by comprehensively using logging and masterlog data. According to the sensitivity optimization of logging and masterlog, the spontaneous potential curve, resistivity curve and total gas curve are selected to identify the water-flooded layers. Based on the result of petrophysical facies, the original water saturation, remaining oil saturation and irreducible water saturation of different reservoir types are finely evaluated. Then the water cut content is determined accurately. The water-flooded layers are quantitatively evaluated. The method is used in the production practice, the result shows that the accurate identification rate of water-flooded layer is 90.9%. The result of calculation match well with the core analysis data. The quantitative evaluation of water-flooded layers match well with the production. The comprehensive evaluation method of water-flooded layer meet the needs of oilfield development and production. This method organically combines the petrophysical facies with the comprehensive evaluation of water flooded layer. The water flooded layer is finely evaluated; this result provides an important basis for stabilizing oil, controlling water and improving oil recovery in old oilfields.
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