薄油层SAGD开发蒸汽腔发育和生产指标预测

Prediction of Steam Chamber Development and Production Performance for SAGD in Thin Heavy Oil Reservoirs

通过分析现场生产数据和数值模拟结果,将薄层稠油油藏蒸汽辅助重力驱油(SAGD)生产中蒸汽腔发育分为横向扩展和向下运移两个过程,并进行简化处理预测SAGD生产指标.联合质量守恒方程、能量守恒方程和周围地层散热模型得到一个描述蒸汽腔发育的综合表达式,该方程属于典型的第二类Volterra积分函数.通过拉普拉斯变换对Volterra积分函数进行半解析求解,最终得到不同时刻蒸汽腔发育状态.为验证模型的正确性,将模型的计算结果与CMG Stars的计算结果对比,整体误差小于5%.新模型可以方便简单地预测SAGD生产中蒸汽腔发育过程和生产动态指标,从而确定SAGD生产的极限油藏参数和合理的注采参数.

Based on analyses of SAGD field production data and numerical simulations, SAGD production process in thin heavy oil reservoirs was divided into periods: steam chamber horizontal expansion period and steam chamber downwards migration period. A model was built, which includes mass conservation equation, energy conservation equation and heat loss equation. A comprehensive mathematical expression was obtained to describe steam chamber development process. The expression is a typical Volterra integral function of the second kind, which could be solved by Laplace transformation. Comparisons were made between the model and CMG Stars’ . A small relative error, less than 5% for the whole SAGD production process, was found. The model provides an accurate and quick method for determination of limited reservoir properties and proper production parameters for SAGD production.