Application of cashew nut shell liquid as a green oilfield chemical: A state-of-the-art review

The oilfield industry faces significant challenges, such as high raw material costs and negative environmental impacts due to the widespread use of synthetic oilfield chemicals sourced from petrochemicals. The reliance on environmentally hazardous synthetic oilfield chemicals contributes to severe global issues, including carbon emissions, global warming, and climate change, posing potential threats. Therefore, ongoing research is increasingly directed toward the development of oilfield chemicals derived from natural sources, particularly plant-based extracts—an approach commonly known as "green oilfield chemicals." Among these, cashew nut shell liquid (CNSL), a key plant-derived material and low-cost byproduct of the cashew industry, has emerged as a promising and economically viable alternative to conventional feedstocks. So far, numerous chemicals and value-added products have been generated from CNSL, establishing its applications across various industries. This review provides a comprehensive overview of recent advancements in CNSL-based oilfield applications, including fuel, crude oil-water emulsions, emulsifiers and demulsifiers, flow improvers for waxy crude oil, corrosion inhibitors, lubricants, enhanced oil recovery (EOR), surfactants and foaming agents, with an emphasis on chemical structure–function relationships. We further present a comparative life-cycle assessment (LCA) of CNSL-based versus conventional oilfield chemicals, highlighting their potential environmental and sustainability benefits. Finally, we discuss market trends in green energy, technological opportunities, challenges, and future research directions aimed at improving reproducibility, scalability, and industrial adoption of CNSL-based additives. By integrating chemical, environmental, and economic perspectives, this review offers a forward-looking roadmap for the advancement of bio-based materials in the oilfield industry. The oilfield industry is shifting from petrochemical-based to eco-friendly "green oilfield chemicals" to reduce environmental impact. Cashew nut shell liquid (CNSL), a plant-derived byproduct, offers a sustainable and cost-effective alternative feedstock. Recent advances highlight CNSL's role in synthesizing oilfield chemicals with broad industrial applications. This review also examines market trends, compares CNSL-based green chemicals with conventional oilfield formulations, and explores the future outlook for green technologies in oilfield applications.