The problem of reliable isolation cementing of oil wells belonging to non-operating stock is considered. It is shown that the oil and gas fields of the Carpathian region are characterized by unique mining, geological and geographical conditions, as well as a large number of old wells of complex design that require unconventional solutions when performing isolation works. The peculiarities of structure formation, technological properties of insulating materials based on oil well cement PCT I-100 and composite mixtures CREA, CREA-LF have been studied. It was found that in the first case, the hydration products are represented by ettringite, hexagonal AFm phases, calcium hydroxide and fibrous hydrosilicates. The following phenomena are characteristic for composite materials: a more uniform distribution of hydrates in the gel mass of hydrosilicates, better ordering of the contact zones of accretion, and an increase in the number of intergrown fibers in blocks of hydrosilicates. All of that ensures the formation of a stone of a denser structure, the closure of a larger number of hydrates surface active centers in contact interactions, controlled synthesis, improvement of the strength characteristics and deformation properties of the cement stone. It is shown that the improvement of the quality of composites is facilitated by the use of modern polyfunctional additives-modifiers applying the technology of manufacturing dry building mixtures. It has been found that to increase the efficiency of krents, it is advisable to use complex additives of multifunctional action, which, complementing each other, make it possible to achieve an additive and sometimes synergistic effect. A new generation plasticizer based on polycarbonates, stabilizing additives and micro-reinforcing fibers is used as a modifier of the CREA and CREA-LF composite mixtures. The ability to microplastic deformation of the composite matrix, reinforced by microreinforcement, causes higher energy consumption for the destruction of the stone. An improved technology for performing insulation works is proposed, taking into account the design features and the state of well support elements, which provides for the use of thermographenite and zeolite tuff in addition to the binder material. Key words: oil well cement, composite mixture, thermographenite, zeolite tuff