Lost circulation in drilling: Mechanisms, materials, and future directions for HPHT and energy-transition wells

Lost circulation is one of the most persistent and costly challenges in drilling operations, particularly under high-pressure and high-temperature conditions and in fractured carbonate reservoirs. Despite decades of research, no universal solution exists, and severe fluid losses continue to jeopardize well construction, increase non-productive time, and compromise safety. This review delivers a comprehensive synthesis of mechanisms, materials, experimental evaluations, and field practices, spanning petroleum, geothermal, and emerging energy-transition wells. Mechanistic pathways of loss initiation are critically examined across porous, fractured, and cavernous formations, as well as severe lost circulation scenarios, highlighting the limitations of existing predictive models. Lost circulation materials, ranging from conventional particulates and fibers to advanced nano-enabled and biodegradable systems, are assessed in terms of bridging efficiency, survivability under high-pressure and high-temperature conditions, and sustainability. Experimental and modeling approaches, including fracture-slot tests, dynamic high-pressure and high-temperature flow loops, and computational tools such as computational fluid dynamics, discrete element modeling, and artificial intelligence and machine learning, are evaluated to expose the gap between laboratory results and field reliability. Field strategies, including wellbore strengthening, cement squeezes, and managed pressure drilling, are reviewed to underline their largely reactive nature. Finally, a forward-looking roadmap is presented, identifying research needs such as standardized high-pressure and high-temperature validation protocols, chemically compatible and durable materials for carbon dioxide and hydrogen wells, and the integration of digital twins with artificial intelligence-driven predictive diagnostics.