考虑纵向非均质性的底水气藏临界产量计算方法

底水锥进是底水气藏开发的重要问题。国内外学者开展过大量关于临界产量计算模型的研究;但是物理模型中一般假设为均质地层,未考虑实际储层中普遍存在的纵向非均质性对底水锥进的影响。对比分析了目前常用临界产量计算模型的优缺点,指出Dupuit公式计算结果普遍偏小,Schols公式具有更强的应用性;同时在考虑纵向非均质性基础上,对传统计算模型进行修正。实例计算表明,考虑纵向非均质性的临界产量计算结果比传统模型计算结果高12~20倍,说明纵向非均质性对底水锥进存在明显的抑制作用,新方法更加适用于实际底水气藏临界产量的计算。

Calculation of Critical Production Rate with Consideration of Vertical Heterogeneity in Bottom Water Driven Gas Reservoirs

Water coning is an important factor in the development of bottom water driven gas reservoirs. Many studies have been conducted on the calculation of critical production rate. The hypothesis of previous studies, however, is homogeneous reservoir, ignoring the vertical heterogeneity that is ubiquitous in actual gas reservoirs. The advantages and disadvantages of traditional calculation models were analyzed in this study and the conclusion was reached that the result of Dupuit model is always in a low level, while Schols model is more applicable. Besides, the traditional calculation models were modified with consideration of vertical heterogeneity. Case study indicates that the critical production rate considering vertical heterogeneity are 12-20 times as much as that of traditional calculation models, which confirms that vertical heterogeneity is playing an important role as a barrier to resist water coning. The new mathematical model has more flexibility for the calculation of critical production rate in the actual bottom water driven gas reservoir.