缝洞型碳酸盐岩油藏试井分析模型研究

针对缝洞型碳酸盐岩油藏经过构造及岩溶作用之后大尺度溶洞、裂缝发育比较成熟、尺度差别不大的情况,建立了溶洞及裂缝发育的双孔模型。利用裂缝及溶洞中流体的流动方程,建立了考虑井筒储集系数及表皮系数影响的封闭边界油藏双孔单渗试井分析模型;利用Laplace变换法和Stehfest数值反演法算法对数学模型进行求解,得到实空间下无因次井底压力的解析解;绘制并分析了试井典型曲线,并对试井典型曲线特征及不同参数对试井压力响应曲线的敏感性进行了分析。结果显示,所建立的试井分析模型能够反映缝洞型碳酸盐岩油藏实际储层特征和流体的流动机理。研究结果为进一步完善和发展缝洞型碳酸盐岩油藏试井模型、丰富试井解释方法提供了理论参考。

Research of the fractured vuggy type carbonate reservoirs well test analysis model

The fractured vuggy type carbonate reservoirs follow the structure and karst function processes, large scale caves and fractures are mature, and there''s little difference in scale. Therefore, the formation of caves and fractures can be regarded as a double porosity model. Considering the flow of fluid in fracture and cave, a double porosity of single permeability well test model with sealed boundary reservoir is established considering the influence of wellbore storage and skin factor. The mathematical model is solved by Laplace transform and Stehfest numerical inversion algorithm, and the solution of dimensionless well bottom pressure in real space is obtained. The typical curves of well test are plotted and analyzed. The characteristics of well test typical curves and the influence of sensitivity with different formation parameters to well test pressure response curves are analyzed. The results of well test analysis model established in this paper can reflect the characteristics of reservoir and flow mechanism of fluid in fractured vuggy carbonate reservoir. It lays a theoretical foundation for further improving and developing well test model of fractured vuggy carbonate reservoir and enriching well test interpretation method.