Difficulties encountered in describing fracture flow using classical fluid flow equations has led to extensive studies of the roughness effect on fracture flow over the past 70 years. Despite the significant progress made thus far, understanding the impact of roughness on fracture flow remains a complex challenge, as suggested by the discrepancies found among theoretical, numerical, and experimental observations. In this review paper, we discuss recent progress made in an effort to relate the roughness effect to various fluid flow phenomena. The term “the roughness effect” of fractures in this paper incorporates the influence of various geometrical parameters such as matedness, aperture distribution, spatial correlation, contact area, channeling, and tortuosity. As a fundamental step, we summarize and analyze the fracture roughness quantification and characterization methods which are currently applied and the future trend ahead. Then, we review and discuss the recent developments in the area of the roughness effect on various types of flow and transport such as single-phase flow (including heat transfer), multi-phase fluid flow (including both miscible and immiscible flow), and solid transport (such as proppant transport in hydraulic fracturing). Lastly, we discuss future directions for the research on the roughness effect on fracture flow and what this means for the petroleum engineering industry—especially with the rising popularity of hydraulic fracturing methods for unconventional oil and gas recovery. The overall objective of this review is to provide an overview of current research progress on the roughness effect on fracture flow and discuss the current challenges and research directions for future studies while also providing extensive background knowledge (classical studies) and relating them to the recent research advances. As a specific outcome, we finally define the limiting conditions such as the divergent claims on the predominance of single fracture effect (as opposed to that of the fracture network models) due to the lack of available experimental and analytical data. And we address the observed gap with respect the roughness effect that has been significantly overlooked in modeling studies. Thereby, providing insights in the future research outlook and the directions for more accurate fracture flow simulation studies for their application.

在过去的70年中，使用经典流体流动方程式描述裂缝流动时遇到的困难导致对粗糙度对裂缝流动的影响进行了广泛的研究。尽管迄今为止取得了重大进展，但如理论，数值和实验观察结果之间的差异所表明的那样，了解粗糙度对裂缝流动的影响仍然是一个复杂的挑战。在这篇综述文章中，我们讨论了将粗糙度效应与各种流体流动现象联系起来的最新进展。本文中的术语“粗糙度效应”包括各种几何参数的影响，例如配合度，孔径分布，空间相关性，接触面积，通道和曲折度。作为基本步骤，我们总结并分析了目前应用的裂缝粗糙度量化和表征方法以及未来的趋势。然后，我们回顾并讨论粗糙度对各种类型的流动和传输（如单相流（包括热传递），多相流体流（包括可混溶和不可混溶流））的影响的最新进展，以及固体运输（例如水力压裂中的支撑剂运输）。最后，我们讨论了对裂缝流动的粗糙度影响研究的未来方向，以及这对石油工程行业的意义，特别是随着水力压裂方法在非常规油气采收中的日益普及。综述的总体目的是概述粗糙度对裂缝流动的影响的最新研究进展，并讨论未来研究的当前挑战和研究方向，同时提供广泛的背景知识（经典研究）并将其与最新研究相关联进步。作为一个具体的结果，由于缺乏可用的实验和分析数据，我们最终定义了限制条件，例如对单一裂缝效应优势（与裂缝网络模型的优势相反）的不同主张。并且，我们针对在模型研究中已被严重忽略的粗糙度影响解决了观察到的间隙。从而，