At present it is revealed that microorganisms have a deleterious influence on the processes of petroleum production from well-boring to transportation of commercial oil. The vital activity of cellulose-decomposing and other bacterium species led to rapid impairment of technological properties of drilling mud based on polysaccharides (starch, xanthan gum, different kinds of cellulose), which is particularly expressed in the change of rheological properties and increase of filtration rate while drilling. Biodegradation results in the loss of technological and rheological properties of drilling mud which in turn leads to the necessity of additional treatment by expensive reagents, which increases the drilling operation cost. Therefore the prevention of polysaccharides biodegradation is an urgent problem. Under the influence of mud microflora, high biodegradation of polysaccharides gives grounds to carry out investigations to reveal the influence of bactericide additives on the stability of biopolymer muds. Phenol and formaldehyde have bactericide properties, but their application for drilling muds treatment is restricted by sanitary and ecological requirements. Therefore, the application of a dialdehyde - glyoxal - as a bactericide is perspective. Glyoxal is more than twice as active as formaldehyde and excels noticeably in ecological characteristics. One molecule of glyoxal can bind two sulfur-containing molecules, so it is possible to apply it for the prevention of hydrogen sulphide corrosion. Bactericide properties of glyoxal are widely used for prolongation of drilling muds durability and for oil disinfection, particularly, for sulfate-reducing bacterium control. We researched the rheological and technological properties of model drilling muds modified by glyoxal. Treatment of bentonite suspension with glyoxal leads to a substantial decrease of relative viscosity of drilling mud. The effect of glyoxal on the colloidal solution of clay in water can be used to decrease the swelling capacity of shale. In this research we modified polysaccharides to increase their resistance to enzymes. Glyoxal was not a part of drilling mud composition and was used for spontaneous treatment of starch reagent to impart bactericide properties. It was revealed that the population of bacterial colonies in drilling mud with modified starch is considerably smaller than that with unmodified starch. The comparative study of the yield point of xanthan gum solution with such bactericides as glyoxal and MI CIDE and without them showed that glyoxal reveals better stabilization properties, similar to starch. The stability of polymer solution increases with greater concentration of bactericide.
