Proppants have evolved from their primary role of preventing fracture closure to performing technically functional roles within reservoirs. This paper presents an extensive review of recent advances in functional proppant technology. Multifunctional proppant roles, such as the enhancement of multiphase flow of reservoir fluids, delivery of CO₂ for enhanced gas recovery, detection of fracture geometry, removal of contaminants, fracture moderation, treatment of flowback water, as well as proppant flow back retardation are presented. Advances in proppants with good transport and placement properties, such as, self suspended proppants and in-situ generated proppants were further addressed. Recent field and laboratory works suggested that conventionally sized proppants (<149 μm) leave the majority of stimulated reservoir unpropped. The role of micro and nano proppants in recovering these untapped areas are critically reviewed. The optimum size of micro and nanoproppant for effective propping of induced unpropped fractures were discussed. Due to the increasing proppants pumped per lateral foot, cheap sources of regional industrial waste materials such as granitic waste powder, used foundry sand, and blast furnace slag are recommended as potential sources of micro and nano proppants. These cost-effective materials could complement the conventional sand proppants, and their application for averting the closure of micro-fissures could help in sustaining the environment from excessive regional sand mining.

支撑剂已从其防止裂缝闭合的主要作用演变为在储层内发挥技术功能的作用。本文对功能支撑剂技术的最新进展进行了广泛的综述。多功能支撑剂作用，例如增强储层流体的多相流动，CO _2的输送为了提高气体采收率，提出了裂缝几何形状的检测，污染物的去除，裂缝的缓和，返排水的处理以及支撑剂的返流延迟。具有良好运输和放置性能的支撑剂，例如自悬浮支撑剂和原位生成支撑剂的进展得到了进一步解决。最近的现场和实验室工作表明，常规尺寸的支撑剂（<149μm）使大部分受激储层没有支撑。严格审查了微米和纳米支撑剂在回收这些未开发区域中的作用。讨论了有效支撑诱发的未支撑裂缝的最佳微米和纳米支撑剂尺寸。由于每侧脚泵送的支撑剂增加，区域性工业废料的廉价来源，例如花岗石废粉，建议将用过的铸造砂和高炉矿渣作为微量和纳米支撑剂的潜在来源。这些具有成本效益的材料可以补充传统的砂支撑剂，并且它们用于避免微裂缝闭合的应用可以帮助维持区域免受过度区域性采砂的影响。