Oil companies commonly use hundreds of different methods to enhance production, to improve oil recovery, and to control water production, hence, it is critical to have a reliable means to evaluate the effectiveness of various IOR/EOR and bottomhole treatment technologies and to select the most effective ones that will meet the specific reservoir conditions. For evaluation, different techniques can be used: production analysis and analysis of reservoir properties in the near-wellbore zone and in the reservoir before and after treatment/stimulation, analysis of displacement characteristics. However, all these techniques have certain drawbacks. Thus, comparison of production performance ignores bottomhole pressure changes before and after treatment, pressure buildup curves are not infrequently of rather low quality to provide somewhat reliable data, while displacement analysis is based on empirical relationships, which have to be selected each time anew and, besides, are liable to misinterpretation. Devoid of these drawbacks is the rate transient analysis (RTA) offered by the Kappa Topaze software. The advantage of this method is that it makes allowance for change of production always occurring following treatment. This is achieved through use of diffusion equations. RTA allows comparative analysis of production history and cumulative oil production, porosity and permeability before and after EOR/well stimulation, being, thus, a comprehensive tool to evaluate effectiveness. Variation in oil production is the most reliable parameter, because it accounts for changes in bottomhole pressure and water cut before and after treatment. To determine this parameter, Topaze uses an algorithm based on the pressure drop change. Pressure drop is skin-dependent in well stimulation technologies aimed at productivity restoration in the bottomhole zone, while in EOR technologies we are calculating an auxiliary pressure drop to take into account change of reservoir properties. Topaze allows easy production forecasting by two scenarios, the scenario involving production enhancement operations, and the scenario without any production enhancement operations, with a view to assess cumulative incremental production. So, rate transient analysis and pressure transient analysis can be safely used to evaluate effectiveness of a large variety of IOR/EOR and well stimulation technologies and may serve a good alternative to the currently used methods.
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