The paper describes studies on the development of the new formulas of water-based drilling mud for drilling in clays and shales. The research were undertaken as a part of the OPTIDRILTEC project. First stage of the project included studies related to selection of ionic inhibitors of hydration. The tests of inorganic agents with various concentrations influence on technological parameters of the developed drilling muds was undertaken. The disintegration and linear swelling tests under influence of developed muds with different ionic inhibitors were conducted on the rock samples. Miocene shale was used as the model rocks. Within a framework of the project, it was conducted selection of the polymeric inhibitors of hydration. Subsequently, different polymers were tested for the influence on technological parameters of drilling muds as well as on disintegration and linear swelling of model rocks. Studies also consists of synthesis of short-chained cationic polymers (with primary amine groups in the side chains) and cationic-anionic polymers (with, apart amine groups, sulfonic amine groups). Synthesized polymers are characterized by low molecular masses (about 10.000 - 20.000 atomic mass unit) and small steric hindrance of side chains. The studies allowed development of new water-based mud formulas for drilling in clay rocks. Developed drilling muds are characterized by good technological parameters, resistance to temperature and to salts along with effective preservation against disintegration and swelling of clay rocks. Moreover, based on the research results it can be observed that synthesized cationic polymers are efficient inhibitors of clay rocks hydration. Newly developed drilling muds could be successfully applied in the oil and gas industry causing improved drilling conditions and decreased drilling costs.
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