DRILLING FLUSHING FLUIDS During rotary drilling, the well constantly circulates the flow of a liquid that was previously considered only as a means for removal of destruction products (cuttings). Nowadays it is perceived as one of the main factors that ensure efficiency of the entire drilling process. Drilling mud, besides cuttings removal, should perform other equally important functions, aimed at efficient, economical and safe performance and completion of drilling process. For this reason, the composition of drilling mud and evaluation of its properties has become the subject of a wide range of scientific and practical research and analysis. Today in the world practice there is a tendency of growth of drilling depths, and as a result, the danger of various drilling problems increases. Besides, the requirements to more complete exploitation of productive formations are constantly increasing. In this regard drilling mud should have composition and properties, which would provide an opportunity to fight most of possible drilling problems and would not have a negative impact on reservoir properties of productive horizons. Functions of drilling mud: - to remove the products of drilling from the wellbore; - prevent formation fluids from cross flowing; - maintain stability of the wellbore walls; - to cool and lubricate the drilling bit; - transfer hydraulic force to the drilling bit.
