考虑相态变化的缝洞型碳酸盐岩凝析气藏生产特征分析新方法

随着对缝洞型碳酸盐岩气藏的开发,分析与预测缝洞型碳酸盐岩气藏生产动态特征变得至关重要。由于缝洞型碳酸盐岩凝析气藏储层结构、流体性质复杂,其生产动态特征变化与井打缝洞储集体位置有关,同时又与凝析气藏不同温度压力下的相态变化特征有关,现有的动态分析方法已不能满足缝洞型气藏动态分析的要求。目前缝洞型碳酸盐岩的动态分析方法主要有物质平衡法、物理模拟实验、现代产量递减法、试井和数值模拟法等,但以上所有方法都忽略了井钻遇缝洞体的位置,而其位置关系在缝洞型碳酸盐岩动态分析中起决定性因素。针对塔中地区缝洞型碳酸盐岩凝析气藏,建立了考虑相态变化的凝析气藏物质平衡方程,构建了井筒位置、裂缝和缝洞体依次连通的缝洞型碳酸盐岩凝析气藏物理和数学模型,通过推导得到分析缝洞型凝析气藏动态分析简化模型,并对气油比、产气、水和凝析油量的变化特征进行了分析和讨论。基于该简化模型对塔中某典型凝析气井开展了生产动态特征分析;其预测缝洞型碳酸盐岩凝析气藏开发过程中缝洞与油、水界面的关系和气藏相态变化分析结果与生产特征完全一致,进一步验证了模型的准确性。该方法将对缝洞型凝析气藏后期挖潜增产有重要的指导意义。

A New Method for Analyzing Production Characteristics of Fractured-vuggy Carbonate Condensate Gas Reservoirs Considered Phase Behavior Changes

With the deepening of the development of carbonate gas reservoirs, it is important to clarify the production perfomance of fractured-vuggy carbonate condensate gas reservirs. The reservoir structure and fluid properties of fractured-vuggy carbonate condensate gas reservirs are complex, and the dynamic characteristics of production are related to the drilling penetration location of the fractured-vuggy and the PVT phase-state variation characteristics of the condensate gas reservoir, which lead to the significantly different Dynamic analysis bettween carbonate and sandstone condensate gas reservoirs. The existing performance analysis methods of fractured-vuggy carbonate mainly include material balance method, physical simulation experiment, production decline analysis method, well test and numerical simulation method. However, all the above methods ignore the drilling penetration location of the fractured-vuggy, and its positional relationship plays a decisive factor in the dynamic analysis of fracture-cavity carbonate rocks. Based on the work done in the ractured-vuggy carbonate condensate gas reservirs of Tazhong II, this paper establishes the material balance equation of condensate gas reservoir considering the phase change.Constructing the conceptual physics and mathematical model of connected wellbore, fracture and cave-cleft body. Moreover, analyzes the production perfomance characteristics by calculating of one of the simplified model, and the changes in gas-oil ratio, gas production, water and condensate Features are discussed. Based on the physical and mathematical models, a dynamic analysis of the production characteristics of a typical condensate gas well in Tazhong II was carried out. The analysis results are consistent with the simplified model, which further verifies the accuracy of the model in production practice, which indicates that the model can effectively analyze and predict the relationship between the cave-cleft body and the oil and water interface and the phase behavior change during the development of gas reservoir. Finally, it has important guiding significance for EOR of single-well development anaphase.