NANOPARTICLES USAGE TENDENCIES IN CEMENTING SYSTEMS FOR HYDROCARBON WELLS

摘要

In oil and gas wells construction, one of the most critical processes is oil well cementing, whose function is to provide a zonal isolation between the pipe and sedimentary formation. For these reasons, one of the needs in the oil industry, specifically in cementing wells area, is the use of materials with high performance, in order to enhance the useful well's life, and reduce costs associated with their repair or losses due to failures in the cementing. Currently, the efforts in the area of high performance materials for oil wells cementing are focused on the development and use of Nanotechnology, science that study materials at nanoscale (10-9 m) and offers means to obtain substantial changes in the chemical, physical and mechanical properties, due to the increase of their surface that allows them to have a high reactivity. The cement is a complex mixture of inorganic chemical compounds, that contain mainly calcium silicates, aluminates (C3S, C2S, C3A), and gypsum. In the cementitious slurry preparation, the cement is put up in contact with water, producing the C-S-H gel as the main hydration product, with an amorphous initial structure that generate a mixture of solid final crystalline phases sometimes in the nanoscale sizes. This final structure is responsible for providing its mechanical properties. Therefore, their comprehension, modification and size control at nanoscale could enable the production of cementitious systems with improved properties. The present work shows a resume of studies done in PDVSA Intevep on the synthesis and potential use of nanoparticles in diverse faces of oil well cementing and their use as nano-additives. Those papers were focused mainly on the preparation and laboratory-scale study of colloidal solutions of silica nanoparticles (nano-SiO2), Alumina (nano-Al2O3), iron oxides (nano-Fe2O3) and ternary systems of calcium oxide-silica and aluminum (CaO-SiO2-Al2O3). Promising results were obtained on strength and cementing properties by adding nanosilica to the cement slurry formulations, and improvements on the mechanical properties, such as compressive strength at the order of 90% for 0.5% nanosilica concentrations based on weight of cement (BWOC).