Heat generation is a well-known problem in bone drilling. Excessive heat generation during drilling operation on bone causes necrosis of the tissue. This paper presents measurements and analysis of temperatures in ultrasonically assisted drilling of bone. The main objective was to find critical drilling parameters (drill speed and feed rate) and ultrasonic parameters (frequency and amplitude) for producing higher temperatures in bone. The increase in drilling speed and feed rate were found to increase the temperatures in bone. The frequencies above 15 kHz were found to produce higher temperatures in bone. The feed rates above 30 mm/min and the amplitude of vibration up to 20 mm were found to have no significant effect on bone temperature. Ultrasonically assisted drilling may be used as an alternative to conventional drilling in orthopaedic surgical procedures to avoid death of bone cells.

Zinc oxide (ZnO) has received lot of attention as a nanostructured material because of unique properties rendering it for various applications. Severe drilling problems like pipe sticking, formation damage and high torque and drag are common in extended reach hydrocarbon wells that limit the performance of drilling operations. Bentonite (MMT) is commonly used as a rheology modifier, and attapulgite (ATP) has good Fann viscosity for use in drilling fluids, but both clays face the limitations of flocculation and instability at high temperature and pressure conditions (HTHP). ZnO–clay nanocomposites were formed by incorporating nano‐ZnO in nano‐modified MMT and ATP to maintain remarkable colloidal dispersion and superior rheology, thus enabling homogeneous drilling fluid recipes. ZnO–clay nanocomposites were characterized using scanning electron microscopy and X‐ray diffraction. After successive laboratory investigations, drilling fluid compositions of certain proportions of water and MMT in the presence of ZnO–clay nanocomposite yielded perfect stability at high temperatures and pressure, i.e. stable drilling fluid rheology at HTHP conditions. The best‐recorded results are reported in this paper, and the properties focused here are the plastic viscosity and yield point. Copyright © 2014 John Wiley & Sons, Ltd.

a This work deals with the synthesis of nano-sepiolite (NSP) and its evaluations as potential drilling fluids (DF) additive for improvement of DF rheological properties and filtration loss. Results show that addition of NSP to the base drilling fluids stabilized its rheological properties (plastic viscosity and yield point) and improved its gel strength at normal and increased temperature and pressure. The effect of NSP on fluid loss was also investigated, and results show that NSP stabilized and improved fluid loss for both normal and high pressure and temperature conditions.

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