This paper presents a study on the possible use of scleroglucan and guar gum mixture modified with aluminum ions as a part of a drilling mud. Currently, the most popular structure-directing agent for dispersed water-base drilling mud is the xanthan biopolymer (XCD). Scleroglucan is alternate structure-directing agent which can be used in a drilling mud, particularly in high temperature conditions. It has a completely nonionic character and creates a structure composed of polymer chains twisted

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... n the form of a triple helix. Such build is characterized by high thermal resistance, multivalent metals cations resilience and salinity. Scleroglucan shows better capability in limiting water filtration than XCD especially in high temperatures. With that in mind its use is justified in the case of deep well. Improvement of rheologically-structural parameters of drilling muds can be achieved by using guar gum modified with use of trivalent ions, e.g. aluminum. This allows to reduce polymer concentration in drilling mud, resulting from a significant increase in viscosity due to the growth in molecular weight. Using scleroglucan in drilling mud composition combined with modified guar gum assures proper rheological parameters of drilling mud in low temperature as well as in high temperature. The combination of these two polymers enable the development of a drilling mud, which is characterized by the unique stability of its parameters in a wide temperature range. It is expected to reduce the expenditure on controlling drilling mud parameters during drilling due to combination of this type of agents in the drilling mud composition. In order to ensure an appropriate level of claystone hydration inhibition the addition of polyglycol was used in the composition of drilling muds, which in the proposed compositions additionally ensures appropriate technological parameters of drilling mud in borehole conditions. The paper proposes drilling mud compositions characterized by a special stability of rheological parameters in increased temperature. The most favorable properties of the drilling mud were obtained using a combination of xanthan, scleroglucan and guar gum modified with aluminum ions in its composition. By changing the type and concentration of individual polymers, we can design rheological parameters of drilling mud in the selected temperature range.