挥发性油藏原油采收率预测的改进方法

An improved oil recovery prediction method for volatile oil reservoirs

为描述挥发性油藏衰竭开发过程中复杂的相态转换,定义4个流体转换相并依据地面体积平衡原理计算各分相产量和分相剩余体积,进而建立考虑脱出溶解气中凝析油含量的挥发性油藏原油采收率预测方法以及多次脱气实验数据矫正方法。基于典型黑油、中—弱挥发性原油、强挥发性原油3种典型原油,结合多次脱气实验矫正数据,采用改进方法模拟等容衰竭实验,验证了改进方法的可靠性。采用"实验数据-传统方法"、"矫正数据-传统方法"、"矫正数据-改进方法"分别计算3种典型原油采收率,结果表明:参数来源和计算方法对典型黑油采收率影响不大,但随原油挥发性增强,直接采用实验数据或传统方法预测,都会严重低估原油采收率;"矫正数据-改进方法"在实验参数和计算方法中都考虑到气相中凝析油的影响,对典型黑油和挥发性原油都有很好的适用性;挥发性原油的强收缩性使得更多的液态油转为气态油采出,衰竭式开发的挥发性油藏可以达到相当高的原油采收率。图6表1参23。

To describe the complex phase transformation in the process of depletion exploitation of volatile oil reservoir, four fluid phases are defined, and production and remaining volume of these phases are calculated based on the principle of surface volume balance, then the recovery prediction method of volatile oil reservoir considering the influence of condensate content in released solution gas and the correction method of multiple degassing experiments data are established. Taking three typical kinds of crude oil(black oil, medium–weak volatile oil, strong volatile oil) as examples, the new improved method is used to simulate constant volume depletion experiments based on the corrected data of multiple degassing experiment to verify the reliability of the modified method. By using "experimental data and traditional method", "corrected data and traditional method" and "corrected data and modified method", recovery factors of these three typical kinds of oil are calculated respectively. The source of parameters and calculation methods have little effect on the recovery of typical black oil. However, with the increase of crude oil volatility, the oil recovery will be seriously underestimated by using experimental data or traditional method. The combination of "corrected data and modified method" considers the influence of condensate in gas phase in both experimental parameters and calculation method, and has good applicability to typical black oil and volatile oil. The strong shrinkage of volatile oil makes more "liquid oil" convert to "gaseous oil", so volatile oil reservoir can reach very high oil recovery by depletion drive.