Working fluids, such as drilling fluids, may remove heat from other fluids, tools, equipments and environments and transfer it to other locations by using reversible phase change elements. The heat removal occurs through the absorption of heat by one or more phase transitions or a sequence of phase transitions in the elements of the working fluid. For instance, heat is absorbed when the phase change portions of the reversible phase change elements change phase including, but not necessarily limited to, a change from solid to smectic liquid crystal, from solid to nematic liquid crystal, from smectic liquid crystal to isotropic liquid, from nematic liquid crystal to isotropic liquid, from solid to isotropic liquid, and sequences and combinations thereof. Heat is released when the phase change reverses. These phase changes are first-order transitions and are associated with a latent heat or enthalpy.

A spallation drill head can include a drill head body having a primary face substantially oriented facing in a primary drilling direction along a longitudinal axis of the drill head body. A liquid inlet can be on the drill head body. The liquid inlet can be connected or connectable to a liquid supply line. An internal liquid connection can be oriented within the drill head body and fluidly connected to the liquid inlet. A plurality of liquid jets can be oriented on the primary face of the drill head. The liquid jets can be fed by the liquid inlet through the internal liquid connection. A mass flow controller can be associated with the liquid jets to control delivery of liquid by the liquid jet, and flowrates to at least two of the liquid jets can be independently controllable.

Systems and methods for measuring a parameter of interest in a borehole in an earth formation are provided. The systems include a downhole sensor having a first sensor component with a first temperature and a second sensor component with a second temperature, the downhole sensor disposed on a downhole component. A temperature control system is configured with a thermal control mechanism operatively connected to at least one of the first and second sensor components. The thermal control mechanism is configured to maintain a temperature difference between the first temperature and the second temperature below a pre-determined temperature difference. The downhole sensor is configured to measure the parameter of interest when the temperature difference is below the pre-determined temperature difference.

Systems and methods for cooling an electronics compartment of a downhole tool include a tool assembly. The tool assembly is an elongated member formed of axially aligned tool units. The tool units include a turbine and the electronics compartment. The electronics compartment has an interior cavity containing electronics components. The tool units further include a compressor powered by the turbine. The compressor is operable to compress a coolant fluid. The compressor has a central heat exchanger operable to cool a non-electrically conductive fluid with the coolant fluid. An impeller is rotated by the turbine. The impeller is operable to circulate the non-electrically conductive fluid past the electronics components.

Apparatus, method and wellbore installation to mitigate heat damage to well components during high temperature fluid injection operations such as steam injection from surface through a wellbore. The apparatus includes an injection tubing that conveys the high temperature fluid to an injection zone and an isolation packer through which a lower end of the injection tubing passes. A pipe extends alongside the injection tubing with an outlet end close above the packer. When the apparatus is installed in a wellbore, the pipe creates a cooling fluid circuit that flows from just above the packer up in the wellbore alongside the outer surface of the injection tubing to surface and then back into the pipe.

Systems and methods for cooling an electronics compartment of a downhole tool include a tool assembly. The tool assembly is an elongated member formed of axially aligned tool units. The tool units include a turbine and the electronics compartment. The electronics compartment has an interior cavity containing electronics components. The tool units further include a compressor powered by the turbine. The compressor is operable to compress a coolant fluid. The compressor has a central heat exchanger operable to cool a non-electrically conductive fluid with the coolant fluid. An impeller is rotated by the turbine. The impeller is operable to circulate the non-electrically conductive fluid past the electronics components.

A pressure control device can include an outer housing, a bearing assembly with bearings to rotatably support an inner barrel in the outer housing, a heat exchanger, and fluid passages that communicate between the bearings and the heat exchanger, and a latch assembly configured to releasably secure the bearing assembly in the outer housing. The latch assembly can include a heat exchanger configured to exchange heat with the bearing assembly heat exchanger. Another pressure control device can include a bearing assembly with bearings to rotatably support an inner barrel in the outer housing, fluid passages that communicate with space adjacent the bearings, a pump in communication with the fluid passages, and a gear train connected between the pump and a ring gear secured to the inner barrel.

A bell nipple assembly is attached to an upper end of a blowout preventer stack and has a central passageway fluidically connected to a central bore of the blowout preventer stack. The bell nipple assembly includes upper and lower nipple annular preventers. Closure of the nipple annular preventers forms a closed volume within the central passageway between the upper and lower nipple annular preventers. A coolant injection system selectively injects coolant through a coolant conduit positioned within the closed volume.

Methods and apparatus for simultaneous operation of a variable-frequency drive (VFD) and a controller. The VFD drives an electric motor of a drilling rig machine. The controller controls temperature of an insulated-gate bipolar transistor device (IGBT) of the VFD by controlling an air mover in response to real-time temperature data. The air mover generates airflow into a passage, the airflow thereby interacting with radiating members extending into the passage from a heat sink thermally coupled with the IGBT in the inner housing outside the passage.

A method of increasing hydrocarbon recovery from a wellbore in a tight formation with greater breakdown pressures, the method including using hydro-jetting to effect a plurality of oriented cavities or discoidal grooves in the horizontal portion of the wellbore to overcome near-wellbore stresses, injecting a thermally controlled fluid into the wellbore to alter the temperature of the formation and lower stresses, and then fracturing the formation to generate a series of fractures that can be formed in a planar formation.