天然气驱油藏开发动态评价及可采储量预测新方法

天然气驱油藏在中国油气藏开发类型中占有重要比例。目前针对气驱油藏的研究多集中于气窜规律分析,矿场缺乏针对性的生产动态监测与评价方法。从油-气两相渗流规律和物质平衡方程出发,推导了适用于气驱油藏开发指标评价及预测的气驱特征曲线。同时,通过引入经济极限气/油比及初始与边界条件,推导并绘制了无因次气体分流量与采出程度之间的理论图版,利用该图版可以快速、直观地评价油田开发效果。应用数值模拟方法,分析讨论了井网加密、工作制度调整及油井措施对气驱特征曲线形态的影响,论证了新型气驱特征曲线的适用性。实际应用结果表明,新方法预测气驱油藏开发动态与数值模拟法及产量衰减法计算结果吻合较好,对气驱油藏开发指标预测具有一定的实用性。

A new method for evaluation of development performance and recoverable reserves estimation in natural gas flooding reservoirs

Natural gas flooding reservoirs are the dominant development type of hydrocarbon reservoirs in China. At present, researches on gas flooding reservoirs mainly focus on the gas channeling laws, but lack of targeted production performance monitoring and assessment method. According to oil-gas phase percolation laws and material equilibrium equation, the gas flooding characteristic curve was derived, and applicable for assessment of development index and prediction of gas flooding oil reservoirs. Meanwhile, the economic-limit gas-oil ratio and initial boundary conditions were introduced to derive and prepare the theoretical chart of dimensionless gas fractional flow and recovery degree. This chart can be used to assess oilfield development effect rapidly and intuitively. Moreover, the numerical simulation method was applied to analyze and discuss the influences of well pattern infilling, working system adjustment and oil well measures on the morphology of gas flooding characteristic curve, so as to demonstrate the applicability of such new gas flooding characteristic curve. It is proven by actual applications that the new method for predicting gas flooding development dynamics is not only better consistent with the results calculated by numerical simulation method and production attenuation method, but also has certain practical significance in predicting the development index of gas flooding oil reservoirs.