挥发性油藏PVT数据矫正新方法对动态预测的影响

Influences of the New Method of PVT Data Correction on Dynamic Prediction in Volatile Oil Reservoirs

针对挥发油多次脱气实验过程中存在大量储罐油损失而导致实验数据不能直接用于油藏工程计算的问题,提出采用等容衰竭实验数据逐级压力矫正多次脱气实验数据的新方法。新方法不同于已有的采用单次脱气实验数据矫正多次脱气实验数据的Terry⁃Rogers方法。两种方法实例矫正对比表明,Terry⁃Rogers方法仅适用于传统黑油,对挥发油会出现不符合物理的矫正结果;新方法考虑排出气中储罐油含量随压力的变化规律,适用于传统黑油和挥发油,且在饱和压力下的矫正结果接近Terry⁃Rogers方法。最终,以物质平衡和油气两相渗流为原理,建立快速预测溶解气驱油藏动态的简易迭代方法,并对不同类型原油的实验数据以及Terry⁃Rogers方法和新方法矫正得到的数据对开发动态的影响进行计算对比。结果表明,典型黑油实验数据可直接用于油藏工程计算;原油的挥发性越强,新方法矫正数据计算原油采收率较实验数据计算原油采出程度更高,实例中强挥发性原油实验数据计算原油采出程度相对于新方法误差高达-13.82%.

In view of the problem that the experimental data can’t be directly used in reservoir engineering calculation due to the large amount of stock tank oil loss in the process of multiple degasification of volatile oil,this paper proposes a new method to correct the experi⁃mental data of multiple degasification by means of constant⁃volume depletion experimental data step by step.The new method is different from the traditional method presented by Terry and Rogers(2017)that the experimental data of single degasification are used to correct the experimental data of multiple degasification.The comparison of the two methods shows that the traditional correction method is only suit⁃able for conventional black oil,and may produce the non⁃physical correction results for volatile oil.The new method considers the variation of oil content in oil tanks with pressure in the exhaust gas under the standard condition,so it is applicable to both conventional black oil and volatile oil,and the correction result of the new method is close to that from the traditional Terry and Rogers method under the condi⁃tion of saturated pressure.Finally,a simple iterative method is established based on the principles of material balance and oil&gas two⁃phase percolation,and the influences of various experimental data on development performance are calculated and compared.The results indicate that the typical black oil experimental data can be directly used for reservoir engineering calculation;the stronger the oil volatility is,the higher the recovery factor calculated from the new method will be;for the high volatility oil in the case,the error of the crude oil re⁃covery percent of reserves calculated from the experimental data obtained with the traditional method is as high as⁃13.82%when compared with the new method.