Managed pressure drilling is a sophisticated pressure control method which is intended to meet increasingly high demands in drilling operations in the oil and gas industry. With this method, the well is pressurized and the drilling mud is released through a control choke which can be used to actively control/reject pressure variations. Such a control system needs to handle several disturbances,...

A genetic algorithm assisted minimum mean-square error (MMSE) multi-user detector (MUD) is proposed for a turbo-trellis-coded modulation-based space division multiple access aided orthogonal frequency division multiplexing system. The simulation results show that the system employing the concatenated MMSE-GA MUD was capable of achieving a similar performance to that attained by its optimum coun...

It is very important to reduce drilling costs because the cost of drilling the wells is approximately 50% in geothermal energy development for electric power generation. Lost Circulation (LC) is serious problem that contributes greatly to the cost of drilling and completion of the geothermal wells. LC also can be the cause of formation collapse and/or stuck drill strings as well as failure in c...

Due to temperature increase during bone drilling, bone necrosis is likely to occur. To minimize bone tissue damage during drilling, a detailed in vitro experimental study by using fresh calf cortical bones has been performed with various combined drilling parameters, such as: drilling environment, drill diameter, drill speed, drill force, feed-rate and drill coating. Bone temperatures at the dr...

Acoustical data transmission through the wall of drill pipes is considered. Drill pipes are known to behave like bandpass filters; the position of the pass bands can be determined analytically. This work extends the frequency domain drill pipe models presented by Barnes and Kirkwood J. Acoust. Soc. Am. 51, 1606–1608 1972 , and more recently by Drumheller J. Acoust. Soc. Am. 85, 1048–1064 1989 ....

Cutting tools are widely used in manufacturing processes and drilling is the most commonly used machining process. Although drill-bits used in drilling may not be expensive, their breakage can cause damage to expensive work piece being drilled and at the same time has major impact on productivity. Predicting drill-bit breakage, therefore, is important in reducing cost and improving productivity...

Breakage of the drill bit is common in orthopaedic procedures, but migration of the broken drill bit is rarely reported. We report a case of migration of a broken drill bit five years after acetabular fracture fixation. The drill bit migrated to the subcutaneous layer of the anterior aspect of the right hip following total hip replacement. We highlight this case as it could be encountered in an...

To meet the great needs for MFL (magnetic flux leakage) inspection of drill pipes at wellheads, a lift-off-tolerant MFL testing method is proposed and investigated in this paper. Firstly, a Helmholtz coil magnetization method and the whole MFL testing scheme are proposed. Then, based on the magnetic field focusing effect of ferrite cores, a lift-off-tolerant MFL sensor is developed and tested. ...

Pedicle screw insertion technique has made revolution in the surgical treatment of spinal fractures and spinal disorders. Although Xray fluoroscopy based navigation is popular, there is risk of prolonged exposure to Xray radiation. Systems that have lower radiation risk are generally quite expensive. The position and orientation of the drill is clinically very important in pedicle screw fixatio...

The Drill for the Mars Science Laboratory mission is a rotary-percussive sample acquisition device with an emphasis on toughness and robustness to handle the harsh environment on Mars. The unique challenges associated with autonomous drilling from a mobile robot are addressed. A highly compressed development schedule dictated a modular design architecture that satisfies the functional and load ...