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缝洞型碳酸盐岩油藏多发育大尺度的溶洞和裂缝,非均质性极强。这类油藏不能使用常规的连续介质理论描述。根据缝洞型碳酸盐岩油藏的特征,结合地震、地质等资料,建立了井未钻遇溶洞的缝洞型碳酸盐岩油藏数值试井物理数学模型。利用有限元方法对模型进行求解并绘制了试井样版曲线,对影响井底压力动态的主要因素进行了分析。研究表明:当井打在洞外时,由于洞内的渗透性远优于洞外地层,压力导数曲线后期出现明显下掉,溶洞的尺寸主要影响压力导数曲线的下掉幅度。模型解释结果与实测数据对比分析表明,该试井模型具有较高的预测精度,能够为碳酸盐岩油藏的试井分析提供理论指导。
The fractured-hole carbonate reservoirs develop large-scale karst caves and fractures and are highly heterogeneous. Such reservoirs can not be described using conventional continuum theory. According to the characteristics of fractured carbonate reservoirs and the seismic and geological data, a numerical well test mathematical mathematical model of fractured-cavity carbonate reservoirs that have not encountered fractured caves has been established. The finite element method was used to solve the model and draw the curve of well test pattern, and the main factors influencing the dynamic of bottom hole pressure were analyzed. The results show that when the well is drilled outside the hole, the permeability derivative in the hole is much better than that in the outer layer of the cave. The pressure derivative curve obviously drops off later in the curve. The size of the cave mostly affects the fall-off amplitude of the pressure derivative curve. The comparative analysis of the model interpretation results and the measured data shows that the well test model has high prediction accuracy and can provide theoretical guidance for the well test analysis of carbonate reservoirs.