双渗油藏产量递减分析模型及应用研究

Production Decline Model and Its Application in Dual Permeability Reservoirs

针对层状油气藏生产问题,建立了考虑表皮系数的双渗油藏单井产量递减数学模型,并对其进行了求解,运用Stefest数值反演方法绘制了Blasingame产量递减特征曲线,最后对产量递减曲线形态及影响因素进行了分析。结果表明,其产量递减曲线介于均质油藏与双重介质油藏之间,且产量递减特征曲线分为4个阶段;产量曲线出现相对平缓的递减段;产量积分导数曲线出现类似双重介质油藏试井曲线特征的凹子,凹子出现早晚受窜流系数影响,深浅受储容比影响;产量递减晚期,无因次递减产量积分与积分导数曲线晚期为一条斜率为-1的直线,表现为调和递减。最后用实例验证了该方法的正确性。

To solve the production problem in producing reservoirs,a mathematical model considering skin factor was developed and it was solved.Production decline type curves of single well in dual permeability reservoirs were drawn by using Stefest numerical inversion method.Their shapes and influencing factors were analyzed.The result indicates that the production decline curves are between homogeneous and double porosity reservoir curves and could be divided into four periods.The production decline curves are relative smooth periods and there was a concave,which could be seen on type curves of dual-porosity reservoirs.The concave occurrence time is determined by interporosity flow coefficient and concave extent is determined by storage ratio.A unity slop line is emerged in both integral and integral derivative curves at the late period of production decline curves,which is the indication of harmonic decline.The correctness of the method is demonstrated by an example.