塔中深层稠油减氧空气驱氧化特征及机理研究

针对塔中深层稠油油藏开展静态氧化实验,通过测试分析不同氧含量与不同氧化时间下产出油气组成,研究了油藏注减氧空气过程中原油与减氧空气的氧化特征、氧化途径与氧化机理。实验结果表明,原油的耗氧速率与减氧空气的氧含量呈正相关,与氧化时间呈负相关;二氧化碳的生成量随氧化时间与减氧空气氧含量的增加而增大;原油与减氧空气的反应会一定程度上使原油黏度增加,其黏度增加的幅度随减氧空气氧含量的升高和氧化时间的增长而增大;氧化后原油饱和烃与芳香烃的含量减少,胶质与沥青质的含量增加,且沥青质增加更为明显。原油在氧化后出现了C=O的伸缩振动峰,且振动峰随着减氧空气氧含量的增加而增强,说明原油在氧化过程中发生了加氧反应生成了醛类等物质,且氧化反应随着氧含量的升高而不断加深。

一种新型油藏气驱采收率预测图版

基于童氏图版,考虑油、气、水三相的影响,提出以累计产气、产水量地下体积之和占总产出流体地下体积比例的含水气率替代含水率,将累计产气量纳入童氏水驱特征曲线图版中,推导了气驱特征曲线方程,建立了一种适用于气驱油藏采收率预测的新型图版,同时采用油田实际生产数据,结合油藏数值模拟预测数据,论证了新型图版的适用范围并用实例验证了预测结果的精度。结果表明,新型图版同时适用于水驱、气驱油藏采收率预测。当油藏不注气或未产气时,可忽略气相,仅考虑油、水两相,新型气驱特征曲线图版退化为童氏图版,可评价油藏水驱效果。当气驱油藏含水气率为60%~80%时,新型图版回归法预测采收率适用性较好。当气驱油藏含水气率大于80%时,新型图版回归法与赋值法均可较准确地预测气驱油藏最终采收率。

异常高压含水凝析气藏有效库容影响因素

有效库容是储气库的关键参数,有效库容评价影响储气库的功能定位、调峰规模、建库参数设计以及整体建库方案设计。异常高压含水凝析气藏改建储气库时,异常高压、水侵和反凝析现象影响库容。由于气藏异常高压,储气库设计上限压力为58.00 MPa,远低于原始地层压力,气体体积系数不同,储气库库容也不同;储气库注采运行过程中,水体往复运移对储集空间动用效率具有较大的影响;储气库交替注采过程中,当地层压力低于露点压力时,凝析油析出对库容有一定的影响。针对这一问题,研究建立了改进的物质平衡和数值模拟双模型,以气藏动态储量为基础,定量分析了异常高压、反凝析、水侵等因素对库容的影响,并建立了一套考虑多因素影响的储气库有效库容评价方法。该成果现场应用于轮南59石炭系气藏建库,准确评价了该储气库的有效库容,为轮南59石炭系气藏改建地下储气库建库参数研究奠定基础。

A novel type curve for estimating oil recovery factor of gas flooding

A novel type curve is presented for oil recovery factor prediction suitable for gas flooding by innovatively introducing the equivalent water-gas cut to replace the water cut,comprehensively considering the impact of three-phase flow(oil,gas,water),and deriving the theoretical equations of gas flooding type curve based on Tong’s type curve.The equivalent water-gas cut is the ratio of the cumulative underground volume of gas and water production to the total underground volume of produced fluids.Field production data and the numerical simulation results are used to demonstrate the feasibility of the new type curve and verify the accuracy of the prediction results with field cases.The new type curve is suitable for oil recovery factor prediction of both water flooding and gas flooding.When a reservoir has no gas injected or produced,the gas phase can be ignored and only the oil and water phases need to be considered,in this case,this gas flooding type curve returns to the Tong’s type curve,which can evaluate the oil recovery factor of water flooding.For reservoirs with equivalent water-gas cuts of 60%-80%,the regression method of the new type curve works well in predicting the oil recovery factor.For reservoirs with equivalent water-gas cuts higher than 80%,both the regression and assignment methods of the new type curve can accurately predict the oil recovery factor of gas flooding.