The presence of tectonic fractures in rocks can have a significant impact on the absorption of drilling mud during well drilling. Prediction of mud losses in zones of natural fracturing formed by tectonic activity is based on careful study of geophmorphology and tectonogenesis of fracturing, lithology, pore pressure, rock strength and many other geological features of the fields. The information obtained is used in the design of drilling technology, well casing design, selection of fillers, characteristics and formulation of drilling mud necessary for the successful drilling. The most difficult conditions for drilling are fractured rocks in the zone of stretching of tectonic blocks of the sedimentary cover. The mud losses under these conditions are often disastrous, accompanied by decrease in the level of mud in the well. The well normalization works have a protracted nature, which sharply reduces the efficiency of well construction and incurs financial costs. The risk of mud loss while drilling into fault zones in other cases is manageable. To prevent mud loss during drilling a careful geological analysis, a corresponding drilling technology and provision of loss circulation materials are required. The integrated application of these measures helps to identify faults, prevent mud losses and even exclude them fully, as well as minimize the consequences of their occurrence. An approach is proposed to assess the degree of influence of rock fracture zones on well drilling to minimize the risks of complications using generalization of experience of drilling wells at the fields of the Vietsovpetro JV.
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