气驱油藏单井动态储量与可采储量计算新方法

A New Method for Calculating Dynamic Reserves and Recoverable Reserves of Single Well in Gas Drive Reservoir

常规气驱特征曲线的推导与建立,其基础是油气两相相对渗透率比值(K_(ro) K_(rg))与含气饱和度(S_(g))在半对数坐标中的线性关系;但实际上,只有在S_(g)处于中间阶段时,两者才呈线性关系,ln(K_(ro) K_(rg))与S_(g)的二项式方程的相关系数大于其线性拟合方程。首先,采用半对数二项式拟合关系式来表征K_(ro) K_(rg)与S_(g)的关系;然后,基于物质平衡方法和油气两相渗流规律,推导并建立了气驱油藏的生产气油体积比与累计产油量的新型二项式气驱特征曲线;最后,根据ln(K_(ro) K_(rg))与S_(g)二项式方程和新型二项式气驱特征曲线方程的拟合参数,建立了单井动态储量与可采储量计算方法。应用实例表明,与常规气驱特征曲线相比,新型二项式气驱特征曲线对实际生产动态数据的拟合精确度更高。

The derivation and establishment of conventional gas drive characteristic curve is based on the linear relationship between oil-gas two-phase relative permeability ratio and gas saturation in semi logarithmic coordinates.For the actual relationship between oil-gas two-phase relative permeability ratio and gas saturation,it conforms to the linear relationship only when the gas saturation is in the middle stage.It is found that the correlation coefficient of binomial fitting equation between oil-gas relative permeability ratio and gas saturation in semi-logarithmic coordinates is greater than that of linear fitting equation.In this paper,the semi-logarithmic binomial fitting relationship is used to characterize the relationship between the relative permeability ratio of oil and gas two-phase and gas saturation.Then,based on the material balance method and the seepage law of oil and gas two-phase,a new gas drive characteristic curve between the production gas-oil ratio and the cumulative oil in the gas drive reservoir is deduced and established.The calculation method of single well dynamic reserves and recoverable reserves is established based on the fitting parameters of the binomial equation of the relative permeability ratio of oil and gas phases and gas saturation and the new binomial gas drive characteristic curve equation.The application example shows that compared with the conventional gas drive characteristic curve,the new binomial gas drive characteristic curve has higher fitting accuracy for actual production dynamic data.