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Mobility control by polymer under bottom-water conditions.

机译:在底水条件下通过聚合物控制流动性。

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摘要

In many light or moderately viscous oil reservoirs in Alberta and Saskatchewan, a high water saturation zone of varying thickness and extent ("bottom-water zone") occurs in communication with the oil zone above. As a result, the primary production period is short, and water coning occurs very early in the life of the reservoir. Later, during the secondary recovery stage, such a zone can have an adverse effect on the waterflood efficiency. This research addresses the problem of waterflooding such reservoirs.; The research was directed towards reducing water mobility in the bottom-water zone for more efficient oil displacement. Polymer in various concentrations was used as a blocking agent in the bottom-water zone and as a mobility control agent in the oil zone. Different strategies were investigated to reduce the water mobility in the bottom-water zone and improve the vertical sweep efficiency. The variables examined were: relative water-oil layer thickness, oil viscosity, polymer concentration, permeability contrast, injection rate and injection point, as well as the effect of vertical and horizontal injection and production wells.; An analytical model predicting fluid flow in a reservoir under bottom-water conditions considering the effects of viscous crossflow was developed. The model accounts only for crossflow due to potential gradients formed by the displacing and displaced fluids having unequal mobilities. All other forces responsible for initiating vertical and horizontal flow are considered negligible. The primary simplifying assumption requires the transfer of fluids between the oil zone and the bottom-water zone to be instantaneous; this assumption is usually referred to as vertical equilibrium. The model is restricted to two phases only and to any arbitrary initial and injection conditions. The model accounts for crossflow and predicts oil recovery, and the total volume of fluid injected.; A multiphase, three-dimensional, numerical model was developed to simulate water/polymer flooding experimental data. The model employs the implicit-pressure explicit-saturation (IMPES) formulation for solving the system of finite-difference equations. Polymer characteristics such as rheology, adsorption, inaccessible pore volume and permeability reduction are included in the model.; The results showed that oil recovery can be increased by minimizing crossflow between layers by blocking the bottom-water zone completely. It was also found that for an unfavourable mobility ratio, as the injection rate increases the ultimate oil recovery increases.; The injection of a Polymer solution had a favourable impact on the waterflood performance. Moreover, the worse the conventional waterflood performance was, the more effective the polymer was as a mobility and blocking control agent. The use of horizontal wells showed slightly better oil recovery over vertical wells in a conventional waterflood of reservoirs under bottom-water conditions. In addition, some certain well combinations (horizontal production and vertical injection) gave better oil recovery due to the increase in the swept area.
机译:在艾伯塔省和萨斯喀彻温省的许多轻度或中度粘性油藏中,与上面的油区相通的是厚度和程度各不相同的高水饱和度区(“水底区”)。结果,初级生产期短,并且在油藏寿命的很早阶段就发生了水锥进。随后,在二次采收阶段,这样的区域可能会对注水效率产生不利影响。这项研究解决了这类油藏注水的问题。该研究旨在降低底部水区的水流动性,从而提高驱油效率。各种浓度的聚合物在底水区用作封闭剂,在油区用作迁移率控制剂。研究了不同的策略来减少底部水区域的水流动性并提高垂直吹扫效率。所考察的变量为:相对水油层厚度,油粘度,聚合物浓度,渗透率对比,注入速率和注入点,以及垂直和水平注入和生产井的影响。建立了一种分析模型,该模型考虑了粘性横流的影响,预测了在底水条件下储层中的流体流动。该模型仅考虑由于由不等流动性的驱替液和驱替液形成的潜在梯度造成的横流。负责引发垂直和水平流动的所有其他力都可以忽略不计。简化的主要假设要求油区和底水区之间的流体传输是瞬时的。该假设通常称为垂直均衡。该模型仅限于两个阶段,并且限于任何初始和注入条件。该模型考虑了横流并预测了采油量和注入的流体总量。建立了多相三维数值模型来模拟水/聚合物驱油实验数据。该模型使用隐式压力显式饱和(IMPES)公式求解有限差分方程组。该模型包括聚合物特性,例如流变学,吸附,难以接近的孔体积和渗透率降低。结果表明,通过完全封堵底部水带,可最大程度地减少各层之间的错流,从而提高采收率。还发现对于不利的迁移率,随着注入速率的增加,最终的油采收率增加。注入聚合物溶液对注水性能有有利影响。此外,常规注水性能越差,聚合物作为迁移率和封闭控制剂越有效。在井底水条件下,常规油藏注水开发中,水平井的使用比垂直井的采收率略好。另外,由于扫掠面积的增加,某些井的组合(水平生产和垂直注入)可提供更好的采油率。

著录项

  • 作者

    Shirif, Ezeddin.;

  • 作者单位

    University of Alberta (Canada).;

  • 授予单位 University of Alberta (Canada).;
  • 学科 Engineering Petroleum.
  • 学位 Ph.D.
  • 年度 1998
  • 页码 242 p.
  • 总页数 242
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 石油、天然气工业;
  • 关键词

  • 入库时间 2022-08-17 11:48:37

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