Improvement of rock-cutting tool efficiency in drilling with air purging using vortex tube

Abstract

The practice of drilling has proven that the use of compressed air as a cleaning agent provides a significant increase in ROP (rate of penetration) and reduces the time spent on eliminating geological complications, which sharply increases the productivity and economy of drilling operations. However, air has a low heat capacity compared to liquid flushing solutions. This affects the operation of rock cutting tools through high contact temperatures with irreversible consequences such as deformation of matrices, destruction of diamonds, grinding, reduction of diamond hardness and tool burns. The current geological conditions of drilling require improvement of the technology and enhancement of drilling performance via engineering of new and highly effective drilling tools. The introduction of new drilling tolls having high durability and increased penetration rate improves performance of drilling rigs. The best results are obtained with a vortex tube placed directly at the well bottom. This article discusses the possibility of normalizing and regulating the temperature regime of the rockcutting tool due to forced cooling of the cleaning air to negative temperatures at the bottom hole. A new design of the drilling assembly with air purging is developed. The pilot tests of the designed drilling assembly are carried out. The tests proved efficiency and serviceability of the drilling assembly design with vortex cooler. The rock-drilling tool temperature is decreased by 50–60 °C and the drilling penetration rate is increased.