大庆油田聚合物驱注入工艺参数优化及驱油机理研究
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长江大学地球科学学院

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国家科技重大专项“大型油气田及煤层气开发”(2016ZX05007-002);


Study on injection parameters optimization and displacement mechanism of polymer flooding in Daqing Oilfield
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    摘要:

    大庆油田经过长年的注水注聚开发,一类油层剩余油开采潜力逐年降低,注聚主力油层正在逐步向二类油层转化,但由于大庆油田二类油层具有储层渗透率较低、平面及纵向非均质性较严重的特点,与一类储层相比聚驱的矿场应用难度更大,聚驱采油效果急需进一步提高。本文以大庆油田B区块二类油层储层和流体特征为研究对象,通过开展层内非均质岩心模型的室内驱替实验研究,优选适合目标储层的最佳注入参数及注入方式。实验结果表明:随着聚合物相对分子质量及溶液浓度的增加,聚合物分子聚集体尺寸增大,阻力系数和残余阻力系数增大,但由于受到岩心孔喉剪切作用的影响,残余阻力系数升幅逐渐变小。从驱油实验可以看出,聚合物注入粘度对开采效果影响依次为:梯度增粘>交替变粘>梯度降粘>单一高粘>单一低粘。其中梯度增粘、交替变粘与梯度降粘采收率增幅较大,增幅达到20%以上,梯度增粘提高采收率效果最优,采收率增幅为24.2%。聚合物注入速度对开采效果影响依次为:梯度增速>单一高速>变速交替>梯度降速>单一低速。其中梯度增速与交替变速采收率增幅较大,梯度增速采收率增幅为25.6%。在注入段塞尺寸一定条件下,不同组合注入方式下采收率增幅效果为:增速降粘>降速增粘,其中增速降粘组合方式采收率提高幅度为28.6%。由此可见,注入过程中同时改变注入速度和注入粘度的组合方式相比于单一改变速度或粘度的增油降水效果更好。

    Abstract:

    After years of waterflooding and polymer injection development in Daqing Oilfield, the recovery potential of the remaining oil in the first type reservoir is decreasing year by year, and the main reservoir of polymer injection is gradually transforming into the second type reservoir. However, due to the characteristics of low permeability and serious horizontal and vertical heterogeneity in the second class reservoir of Daqing Oilfield, compared with the first class reservoir, the field application of polymer flooding is more difficult, and the oil recovery effect of polymer flooding needs to be further improved. In this paper, the reservoir and fluid characteristics of the second class reservoir in Block B of Daqing Oilfield are taken as the research object, and the best injection parameters and injection methods suitable for the target reservoir are optimized by carrying out the laboratory displacement experimental study of the heterogeneous core model. The experimental results show that: with the increase of polymer molecular weight and solution concentration, the size of polymer molecular aggregates increases, the resistance coefficient and residual resistance coefficient increase, but due to the influence of core pore throat shear, the increase of residual resistance coefficient gradually decreases. It can be seen from the oil displacement experiment that the influence of polymer injection viscosity on the production effect is as follows: gradient viscosity increasing > alternating viscosity changing > Gradient viscosity decreasing > single high viscosity > single low viscosity. Among them, the oil recovery of gradient viscosity increasing, alternate viscosity changing and gradient viscosity reducing increased by more than 20%, and the oil recovery of gradient viscosity increasing was the best, with an increase of 24.2%. The influence of polymer injection rate on mining effect is as follows: gradient increase > single high speed > alternate speed change > Gradient decrease > single low speed. Among them, the gradient growth rate and alternating variable rate oil recovery increase greatly, and the gradient growth rate oil recovery increase is 25.6%. Under the condition that the injection slug size is fixed, the increasing effect of recovery under different combination injection methods is as follows: increasing speed and reducing viscosity > decreasing speed and increasing viscosity, and the increasing range of recovery under the combination of increasing speed and reducing viscosity is 28.6%. It can be seen that the combination of changing injection speed and viscosity at the same time in the process of injection is better than that of single changing speed or viscosity.

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  • 收稿日期:2021-02-23
  • 最后修改日期:2021-03-30
  • 录用日期:2021-05-12
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