Decoding the Impact of Injection-Induced Fractures on the Sweep Efficiency of a Mature Polymer Flood through Pressure Falloff Analysis

IF 2.1 4区 工程技术 Q3 ENERGY & FUELS
Vivek Shankar, Gaurav Sharma
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引用次数: 4

Abstract

Polymer flooding is one of the most popular chemical enhanced oil recovery processes in the world, with many large-scale commercial field implementations. It improves mobility ratio and sweep efficiency over waterflooding. However, injection of high volumes of viscous fluid at high injection pressures almost inevitably induces fractures. Induced fractures are not necessarily negative for the flood, and they are documented to improve injectivity and reduce shear degradation of polymer. The big question is on their effect on areal and vertical sweep efficiency. Mangala is one of the largest and most commercially successful polymer floods in the world. The FM-1 unit has the highest stock tank oil initially in place among all the layers of Mangala. Polymer flood sweep efficiency in FM-1 is excellent despite the presence of injection-induced fractures and geological layering. Pressure falloff (PFO) studies are an important and inexpensive source of monitoring the growth of induced fractures in mature polymer floods. Extensive work has been done in the past to derive analytical solutions and numerically assisted solutions for polymer PFOs for non-Newtonian rheology and induced fractures with variable storage. There is also extensive and sometimes contradictory literature on polymer rheology in porous media at both high and low flux rates. Most of the work on polymer PFOs have published a few field examples or synthetic examples and addressed specific issues in depth. We have interpreted 40 PFOs carried out over a period of 1 year. All relevant data sources in the field on geomechanics, polymer rheology in core and rheometers, temperature logs, and saturation logs were integrated to get a consistent estimate for fracture half-length. The results provide insight into the role of induced fractures in improving the sweep efficiency of FM-1. The arguments are backed with literature survey. The work can be used by operators around the world to manage mature polymer floods. The observations mentioned in the work can be used by researchers to fine tune their work. Secondary hypothesis on polymer rheology in porous media is also derived out of the work, which may be of academic interest and merit further work. There are other important aspects of polymer flood PFOs, such as impact of suspended solids and rock dilation near wellbore, which have not been explored in the paper.
通过压降分析解读注入裂缝对成熟聚合物驱波及效率的影响
聚合物驱是世界上最流行的化学提高采收率工艺之一,在许多大型商业油田都有应用。与水驱相比,它提高了流动性比和波及效率。然而,在高注入压力下注入大量粘性流体几乎不可避免地会导致裂缝。诱导裂缝并不一定对驱油不利,有文献表明,它们可以提高注入能力,减少聚合物的剪切降解。最大的问题是它们对面积和垂直波及效率的影响。Mangala是世界上规模最大、商业上最成功的聚合物驱之一。FM-1单元在Mangala所有层中拥有最高的初始储油量。尽管存在注入裂缝和地质分层,但FM-1油藏的聚合物驱波及效率仍然很好。压力下降(PFO)研究是监测成熟聚合物驱诱导裂缝发育的重要且廉价的方法。过去已经做了大量的工作来推导非牛顿流变性和可变存储诱导裂缝的聚合物PFOs的解析解和数值辅助解。关于聚合物在高通量和低通量下在多孔介质中的流变性,也有大量有时相互矛盾的文献。大多数关于聚合物全氟辛烷磺酸的工作都发表了一些现场实例或合成实例,并深入讨论了具体问题。我们在一年的时间里对40个pfo进行了解释。整合了地质力学、岩心聚合物流变性、流变仪、温度测井和饱和度测井等所有相关数据源,以获得一致的裂缝半长估计。该研究结果进一步揭示了诱导裂缝在提高FM-1扫描效率中的作用。这些论点得到了文献调查的支持。这项工作可以被世界各地的运营商用于管理成熟的聚合物驱。研究人员可以使用工作中提到的观察结果来微调他们的工作。本文还提出了聚合物在多孔介质中的流变性的二次假设,具有一定的学术价值,值得进一步研究。聚合物驱PFOs的其他重要方面,如悬浮固体的影响和井筒附近岩石膨胀,在本文中没有进行探讨。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
5.30
自引率
0.00%
发文量
68
审稿时长
12 months
期刊介绍: Covers the application of a wide range of topics, including reservoir characterization, geology and geophysics, core analysis, well logging, well testing, reservoir management, enhanced oil recovery, fluid mechanics, performance prediction, reservoir simulation, digital energy, uncertainty/risk assessment, information management, resource and reserve evaluation, portfolio/asset management, project valuation, and petroleum economics.
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