The study investigates the structural and surface changes occurring in carbonate drilling sludge (CDS) of oil-based origin under high-temperature pyrolysis. The main focus is placed on the transformation of the organo-mineral system using IR spectroscopy, as well as on the changes in textural characteristics analyzed by adsorption–pore methods (BET and BJH). It has been established that pyrolysis ensures the complete removal of the organic fraction of the sludge, which is confi rmed by the disappearance of characteristic aliphatic hydrocarbon bands in the IR-spectra. At the same time, more thermally stable aromatic and mineral components, including carbonates, sulfates, and silicates, are preserved and undergo transformation. The processes of dehydration and dehydroxylation are accompanied by the formation of active acidic sites that enhance the reactivity of the material. Adsorption-pore analysis has revealed the development of a stable meso- and macroporous structure in the solid residue. For the sample pyrolyzed at 800°С, the specifi c surface area reached 7.3 m2 /g, with an average pore radius of about 36Å. Granulometric analysis has confi rmed that the residue is characterized by a fi ne-dispersed and homogeneous structure, with a predominance of particles in the 0.6–2,9 μm range. Such a texture, combined with high surface activity, makes the material promising for practical applications. Thus, pyrolysis of drilling sludge is not only an environmentally safe disposal method but also a way to obtain a secondary resource with valuable sorption and catalytic properties. The results obtained may serve as a basis for the development of technologies for drilling waste recycling and the creation of functional materials derived from them.