Lost circulation, a time-consuming issue that has long plagued the oil drilling industry, presents a number of challenges to the operator such as lost rig time, stuck pipe, increased cost from lost drilling fluids, well-control situations, and bad zonal isolation due to poor cement placement. Several methods are used to treat lost circulation, depending on the severity of the losses and the type of losses. For severe losses (100 to 500 bbls/hr), few methods are routinely successful in curing losses with a treatment that is durable and lasting until the well is cemented. The methods used to treat severe losses include pills with coarse, medium, and fine particles and crosslinked polymers or gunk/cement pills. The mixed results of such methods in attempting to treat total losses in a durable way have led to the design of a fusible-particle lost-circulation material (FPLCM). This study investigates the properties and placement techniques of FPLCM through four field studies in the Elk Hills field, Bakersfield, CA.FPLCM consists of fusing particles, along with weighting agents of optimized particle size and various additives that control leak-off rate and dispersion of the material. FPLCM can also be used with engineered fiber material (EFM). The fusing of the material depends on dehydration rate, which can be controlled depending on lithology and lost-circulation geometry (highly permeable depleted sands, impermeable shale, natural or induced fractures, etc.). FPLCM works best if placed during fracture initiation and/or propagation, when the material will dehydrate both axially and radially in the fracture, thus isolating the fracture tip and increasing the nearwellbore hoop stress.Laboratory data have shown that FPLCM can plug a variety of different fracture geometries, while at the same time passing through smaller drillbit nozzle geometries. Further, FPLCM remains stable under simulated downhole temperatures for extended periods of time without gelling, but, at the same time, set rapidly under simulated fracture closure pressure.Currently, four trials have been performed in the Elk Hills field, in which FPLCM immediately promoted returns of 80% to 90% after placement in wells that previously had varying degrees of returns (0% to 70%). All treatments have been applied during drilling operations either through the bottomhole assembly (BHA) or through a fluid diverterbypass tool.