A multiple sensor temperature measuring device for measuring temperatures at a predetermined number of points along a line of investigation within a body is described. The device has a plurality of temperature sensors mounted on a corresponding plurality of expandable mounting members, each sensor being surrounded by electrical insulation and being contained within a protective sheath. The mounting members are expanded by suitable spacers to dispose the sheath in an abutting and temperature sensing relationship with the body at each predetermined point of interest therein.

An apparatus is disclosed for developing a temperature profile of a well. That apparatus has a spring bow centralizer, wherein the bow of the centralizer contacts the sidewall of the well, and it has a temperature probe attached to the underside of the bow opposite to a point of contact with the sidewall. In one embodiment, the temperature probe is attached to the underside of the bow with studs and a shim steel backing. That temperature probe is a platinum resistance thermometer surface sensor less than 0.05 inches thick coated with a polyimide insulator.

A method and apparatus for determining the temperature in a wellbore is disclosed. The apparatus is lowered into a wellbore to a desired depth and logged over a selected interval. At least one first heat flux and temperature sensor contacts the wellbore wall. At least one second heat flux and temperature sensor is maintained in contact with the drilling fluid. Comparison of sensor responses provides an accurate determination of the wellbore wall temperature, and a determination of the quality of sensor-wellbore wall contact.

A convective heat flow probe device is provided which measures heat flow and fluid flow magnitude in the formation surrounding a borehole. The probe comprises an elongate housing adapted to be lowered down into the borehole; a plurality of heaters extending along the probe for heating the formation surrounding the borehole; a plurality of temperature sensors arranged around the periphery of the probe for measuring the temperature of the surrounding formation after heating thereof by the heater elements. The temperature sensors and heater elements are mounted in a plurality of separate heater pads which are supported by the housing and which are adapted to be radially expanded into firm engagement with the walls of the borehole. The heat supplied by the heater elements and the temperatures measured by the temperature sensors are monitored and used in providing the desired measurements. The outer peripheral surfaces of the heater pads are configured as segments of a cylinder and form a full cylinder when taken together. A plurality of temperature sensors are located on each pad so as to extend along the length and across the width thereof, with a heating element being located in each pad beneath the temperature sensors. An expansion mechanism driven by a clamping motor provides expansion and retraction of the heater pads and expandable packer-type seals are provided along the probe above and below the heater pads.

A multipoint thermocouple assembly for monitoring temperatures at various locations, for example, at different depths in a process vessel, includes a plurality of thermocouples, a protective tube well having a hollow interior, elongate guides in the protective well for guiding respective thermocouples along the interior of the protective well, and wedges in the guides at respective axial locations along the protective well for urging the measuring junctions of respective thermocouples into thermal transfer contact with the wall of the well. In one form of the invention, the guides may comprise plural channels on the exterior surface of an elongated support member, formed as by attaching fins or dividers to such exterior surface, or by providing a plurality of splines on such exterior surface. In another form of the invention, a plurality of elongated thin walled guide tubes are brazed or welded to the exterior surface of a plurality of longitudinally spaced support rings. The guide tubes have openings in the outer walls thereof at the respective points of thermocouple measuring junction locations, and wedges in the tubes at such points for urging the measuring junctions out through the openings at such points. The well when inserted in a process vessel protects the thermocouple measuring junctions while positioning them simultaneously to sense temperature at different respective locations or depths in the vessel. The invention also relates to methods for making a multipoint thermocouple assembly and for replacing a thermocouple therein.