Possibility of increasing the thermal stability of drilling muds through the use of chemicals agents

Abstract

Drilling deep holes or drilling to provide access to thermal waters places increasingly high demands on the properties of the drilling muds. Due to the very high temperature, it may be difficult to maintain the appropriate rheology of the drilling fluid during drilling, especially when an inflow of highly mineralized brines occurs. High temperatures significantly reduce the effectiveness of most of the polymeric agents currently used in the drilling muds technology, in extreme cases causing complete and irreversible damage to their structure. Polymers with ether bonds, which include starches and cellulose, are the most vulnerable. Based on the literature data, it can be concluded that the disadvantages of these polymers can be effectively compensated by the addition of synthetic polymers, e.g. sulfonated polymers. Another direction in improving the thermal resistance of drilling muds indicated in the literature is the use of carbon nanoparticles: graphene flakes and nanotubes. The article presents an analysis of the possibilities of improving thermal stability of drilling muds by using chemical agents that allow to maintain appropriate rheological and structural parameters and filtration at temperatures up to 130°C. During the tests, three types of chemicals were added to the polymer-potassium drilling mud at different concentrations. The impact of these modifications on technological parameters of the drilling mud was tested. Then, samples modified by the addition of selected agents were exposed to the temperature of 130°C for a period of 24 hours. After this time, the samples were cooled to 20°C, then their technological parameters were measured and compared with the results obtained before aging at high temperature, and based on the obtained results, the effectiveness of individual agents was assessed. Among the agents tested to protect drilling mud against the adverse effects of high temperature, the most beneficial effect was shown by potassium formate in combination with PoliAMPS.