Abstract: Drill bits and methods of drilling curved boreholes comprising a drill bit including a bit body and one or more cutting blades positioned within the bit body, the one or more blades individually actuatable to a plurality of cut depths. Another aspect of the invention provides a method for drilling a curved borehole. The method includes: providing a drill string including a drill bit including a bit body and one or more blades positioned within the bit body, the one or more blades individually actuatable to a plurality of cut depths; rotating the drill string; and selectively actuating the one or more blades to a plurality of cut depths; thereby drilling a curved borehole.

Abstract: The invention provides drill bits and methods of drilling curved boreholes. One aspect of the invention provides a drill bit including a bit body and one or more blades positioned within the bit body, the one or more blades individually actuatable to a plurality of cut depths. Another aspect of the invention provides a method for drilling a curved borehole. The method includes: providing a drill string including a drill bit including a bit body and one or more blades positioned within the bit body, the one or more blades individually actuatable to a plurality of cut depths; rotating the drill string; and selectively actuating the one or more blades to a plurality of cut depths; thereby drilling a curved borehole.

Abstract: Apparatus and methods are described for highly attenuating vibrations of a drillstring assembly while drilling. In one embodiment, vibrations are attenuated by introducing one or more vibration attenuation modules at appropriate assembly locations. For example, vibration attenuation modules may be inserted at locations where vibration energy is expected to be maximal. In one embodiment the vibration attenuation modules include cavities loosely packed with particles of solid material such as sand or metallic powder. In one embodiment, the cavity walls are rough and/or include geometric features that enhance vibration energy transfer to the loosely packed particles in the cavity(ies). The vibration energy is dissipated via friction and inelastic particle-particle and particle-wall collisions that occur as a result of drillstring motion.

Abstract: A method and system is provided for determining the value of an attribute of ambient energy at a drilling assembly at the bottom of a borehole. Ambient energy includes kinetic energy, hydraulic energy and thermal energy. Attributes include vibration frequency spectrum, pressure difference, and temperature difference. The method uses energy harvested by at least one energy-harvesting sensor to power the system. The system generates data signals from at least one energy-harvesting sensor at one or more locations along a downhole drilling assembly, and transmits data up the borehole.

Abstract: An abrasion resistant coating and method are provided wherein the abrasion resistant coating contains both ductile and brittle components having a bimodal size distribution. The abrasion resistant coating is initially applied to a substrate in contact with an abrasive environment. The abrasive resistant coating having a bimodal size distribution results in the minimized exposure of the ductile components of the wear surface to the abrasive environment such that the life of the abrasive resistant coating is extended.

Abstract: A method and system is provided for determining the value of an attribute of ambient energy at a drilling assembly at the bottom of a borehole. Ambient energy includes kinetic energy, hydraulic energy and thermal energy. Attributes include vibration frequency spectrum, pressure difference, and temperature difference. The method uses energy harvested by at least one energy-harvesting sensor to power the system. The system generates data signals from at least one energy-harvesting sensor at one or more locations along a downhole drilling assembly, and transmits data up the borehole.

Abstract: An abrasion resistant coating and method are provided wherein the abrasion resistant coating contains both ductile and brittle components having a bimodal size distribution. The abrasion resistant coating is initially applied to a substrate in contact with an abrasive environment. The abrasive resistant coating having a bimodal size distribution results in the minimized exposure of the ductile components of the wear surface to the abrasive environment such that the life of the abrasive resistant coating is extended.

Abstract: A procedure is described for determining the power output of a downhole drilling motor, when the motor is inside the wellbore. The technique uses stand-pipe pressure and fluid flow rate as the main inputs. The power output of the motor is calculated by carrying out two low flow stall tests at flow rates lower than the drilling flow rate. These tests result in "off-bottom" and stall pressures at the two flow rates. Another off-bottom pressure is taken at the actual flow rate that will be used during drilling operations. From the use of the off-bottom and stall pressure measurements, a determination is made of the differential pressure across the motor and the stall pressure at the actual drilling fluid flow rate. A full power curve and a predicted operating stand-pipe pressure for optimal power generation are provided based on an experimentally verified assumption regarding the change in rotation rate of the motor versus the differential pressure across the motor power section.