A system for and method of use with a downhole tool that includes a tubular with a fluid flow path therethrough for flowing a fluid and a housing coupleable to a downhole portion of the tubular. A fluid-driven motor assembly is included and has a drive shaft rotatable to output rotational drive forces. An electric generator is coupled to the drive shaft to convert the rotational drive forces into electrical power. There is also an electric motor electrically coupled to the electric generator to convert electrical output of the electric generator into a rotational drive force to control the downhole tool. A controller is electrically coupled to the electric motor and the electric generator to conduct electrical power output from the electric motor to the electric generator and dissipate excess energy produced by the electric motor to the fluid-driven motor assembly as hydraulic energy.

A mill including a housing having a fluid bypass pathway, a milling feature at a longitudinal end of the housing, a chamber defined by the housing, and a piston disposed in communication with the chamber, the piston defining a fluid passageway initially aligned with the fluid bypass pathway, the piston responsive to pump pressure to move toward the milling feature, the movement misaligning the fluid passageway with the fluid bypass pathway.

A drill bit for drilling a bore, the drill bit comprising: an outer housing; a primary cutting structure defining a cutting plane of a first diameter; a flow path arranged to let drilling fluid flow through the drill bit; and a deployable blade assembly at least partially located within the outer housing, the deployable blade assembly comprising a cutting structure and being arranged to be axially movable from a first position, in which the deployable cutting structure is recessed with respect to the primary cutting structure, towards the cutting plane, to a second position; wherein when the deployable blade assembly is in the second position, the deployable cutting structure defines a cutting diameter which is less than or equal to the first diameter.

A system for real-time steering of a drill bit includes a drilling arrangement and a computing device in communication with the drilling arrangement. The system iteratively, or repeatedly, receives new data associated the wellbore. At each iteration, a model, for example an engineering model, is applied to the new data to produce an objective function defining the selected drilling parameter. The objective function is modified at each iteration to provide an updated value for the selected drilling parameter and an updated value for at least one controllable parameter. In one example, the function is modified using Bayesian optimization The system iteratively steers the drill bit to obtain the updated value for the selected drilling parameter by applying the updated value for at least one controllable parameter over the period of time that the wellbore is being formed.

Aspects of the disclosed technology provide techniques for determining frictional forces bearing on a downhole drill string. In some implementations, a method of the disclosed technology can include steps for segmenting a plurality of continuous nodes of the drilling string into a first segment and a second segment, computing a first set of values corresponding with one or more nodes in the first segment using a first model, computing a second set of values corresponding with one or more nodes in the second segment using a second model, and determining a torque of the drill string based on the first set of values and the second set of values. In some aspects, the method can further include steps for determining a drag force on the drill string based on the first set of values and the second set of values. Systems and machine-readable media are also provided.

Aspects of the disclosed technology provide techniques for determining frictional forces bearing on a downhole drill string. In some implementations, a method of the disclosed technology can include steps for segmenting a plurality of continuous nodes of the drilling string into a first segment and a second segment, computing a first set of values corresponding with one or more nodes in the first segment using a first model, computing a second set of values corresponding with one or more nodes in the second segment using a second model, and determining a torque of the drill string based on the first set of values and the second set of values. In some aspects, the method can further include steps for determining a drag force on the drill string based on the first set of values and the second set of values. Systems and machine-readable media are also provided.

A tunable wellbore pulsation valve reduces drillstring friction in a wellbore. An upper valve plate and a lower valve plate, and upper valve plate orifice and lower valve plate orifice enabling throughflow. A Moineau motor rotates the upper valve plate while the lower valve plate remains stationary. Fluid flow causes a first fluid state of fluid passing through both the upper valve plate and the lower valve plate when the fluid passing causes rotation of the upper valve plate to align the upper valve plate orifice with the lower valve plate orifice. Increased flow efficiency produces more powerful fluid pressure pulsations and axial vibrations without increasing pump pressure at the surface of the wellbore, yielding increased wellbore friction reduction while expending the same or less energy at the surface pump than would be expended in the absence of the reduced turbulent and shear conditions and increased laminar conditions.

A bottom hole assembly for use in a subterranean well can include a whipstock, a mill releasably secured to the whipstock, an antenna, and a release mechanism configured to release the mill from the whipstock in response to a predetermined radio frequency signal received by the antenna. A method can include positioning a bottom hole assembly in a well, the bottom hole assembly including a mill and a whipstock releasably secured to the mill, and then releasing the mill from the whipstock by displacing a radio frequency identification tag into the bottom hole assembly. A well system can include a bottom hole assembly comprising an anchor, a whipstock and a mill, and a radio frequency identification tag displaceable with fluid flow into the bottom hole assembly.

A collapsible bullnose assembly may include a mandrel, a bullnose secured to a distal end of the mandrel, a lower ramp disposed about the mandrel adjacent the bullnose and having a first ramped surface, and an upper ramp slidably disposed around and releasably secured to the mandrel. The upper ramp may have a second ramped surface axially offset from the first ramped surface. The collapsible bullnose assembly may further include a collapsible guide member having opposing ends initially supported on the first and second ramped surfaces and protruding radially outwardly of the bullnose. The collapsible guide member may be actuatable to a radially collapsed orientation in response to axially shifting the upper ramp along the mandrel to a released position away from the lower ramp.

The invention concerns compounds of Formula (I)

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or pharmaceutically-acceptable salts thereof, wherein R.sup.1, R.sup.2 and n have any of the meanings defined hereinbefore in the description; processes for their preparation, pharmaceutical compositions containing them and their use as anti-proliferative and/or cell-killing agents.