Apparatuses and methods for sensing temperature along a wellbore using temperature sensor modules connected by a matrix

A wellbore temperature sensing apparatus for use in sensing temperature along a wellbore, the apparatus comprising:

• tubing being metallic tubing, comprising a plurality of temperature sensor modules provided at locations along the inside of the tubing, having electrical properties that vary with temperature;
• and
• an electrical network comprising a plurality of wires and said plurality of temperature sensor modules, wherein the plurality of wires and plurality of temperature sensor modules are configured as a matrix by which the plurality of wires comprises a first group of wires and a second, different group of wires and each wire of the first group is electrically connected to each wire of the second group once, each electrical connection being by a respective temperature sensor module of the plurality of temperature sensor modules, such that each temperature sensor module can be individually electrically connected by a pair of wires comprising a first wire from the first group and a second wire from the second group;
• wherein the temperature sensor modules comprise temperature sensors that are configured as silicon bandgap temperature sensors each having two p-n junctions that, in use, are operated a different current densities to infer a temperature by determining a voltage difference between the two p-n junctions at the different current densities, which is proportional to absolute temperature.

A wellbore temperature sensing apparatus for use in sensing temperature along a wellbore, the apparatus comprising:

• tubing being metallic tubing, comprising a plurality of temperature sensor modules provided at locations along the inside of the tubing, having electrical properties that vary with temperature;
• and
• an electrical network comprising a plurality of wires and said plurality of temperature sensor modules, wherein the plurality of wires and plurality of temperature sensor modules are configured as a matrix by which the plurality of wires comprises a first group of wires and a second, different group of wires and each wire of the first group is electrically connected to each wire of the second group once, each electrical connection being by a respective temperature sensor module of the plurality of temperature sensor modules, such that each temperature sensor module can be individually electrically connected by a pair of wires comprising a first wire from the first group and a second wire from the second group;
• wherein the temperature sensor modules each comprise a diode arranged to block current from flowing back through the temperature sensor modules in the matrix and, optionally, wherein the blocking diode is a low reverse current leakage diode, optionally having a reverse current leakage of less than 50 nA at the operational voltage of the apparatus and at a temperature of 25 degrees Celsius.

A wellbore temperature sensing apparatus for use in sensing temperature along a wellbore, the apparatus comprising:

• tubing being metallic tubing, comprising a plurality of temperature sensor modules provided at locations along the inside of the tubing, having electrical properties that vary with temperature;
• and
• an electrical network comprising a plurality of wires and said plurality of temperature sensor modules, wherein the plurality of wires and plurality of temperature sensor modules are configured as a matrix by which the plurality of wires comprises a first group of wires and a second, different group of wires and each wire of the first group is electrically connected to each wire of the second group once, each electrical connection being by a respective temperature sensor module of the plurality of temperature sensor modules, such that each temperature sensor module can be individually electrically connected by a pair of wires comprising a first wire from the first group and a second wire from the second group;
• further comprising a control module electrically connected to multiple temperature sensor modules, via the electrical network, and configured to, in use, periodically switch through combinations of pairs of wires to electrically connect and infer a temperature at each of the temperature sensors, and wherein the control module comprises at least one relay arranged to, in use, to switch through the combinations of pairs of wires, wherein the relays are optionally one of electromechanical relays and semiconductor switches.

A well comprising a wellbore temperature sensing apparatus having apparatus for use in sensing temperature in a wellbore, the apparatus comprising:

• tubing being metallic tubing, comprising a plurality of temperature sensor modules provided at locations along the inside of the tubing, having electrical properties that vary with temperature;
• and
• an electrical network comprising a plurality of wires and said plurality of temperature sensor modules, wherein the plurality of wires and plurality of temperature sensor modules are configured as a matrix by which the plurality of wires comprises a first group of wires and a second, different group of wires and each wire of the first group is electrically connected to each wire of the second group once, each electrical connection being by a respective temperature sensor module of the plurality of temperature sensor modules, such that each temperature sensor module can be individually electrically connected by a pair of wires comprising a first wire from the first group and a second wire from the second group;
• the apparatus arranged to sense a temperature in a wellbore of the well;
• wherein the tubing is clamped to and extends across perforating guns.

A method of calibrating a wellbore temperature sensing apparatus, the method comprising:

• tubing being metallic tubing, comprising a plurality of temperature sensor modules provided at locations along the inside of the tubing, having electrical properties that vary with temperature;
• and
• an electrical network comprising a plurality of wires and said plurality of temperature sensor modules, wherein the plurality of wires and plurality of temperature sensor modules are configured as a matrix by which the plurality of wires comprises a first group of wires and a second, different group of wires and each wire of the first group is electrically connected to each wire of the second group once, each electrical connection being by a respective temperature sensor module of the plurality of temperature sensor modules, such that each temperature sensor module can be individually electrically connected by a pair of wires comprising a first wire from the first group and a second wire from the second group, the method comprising:
• determining the resistance characteristics of the individual circuits associated with each temperature sensor of the apparatus, and
• compensating for that circuit resistance to isolate the responsiveness of the electrical properties of the temperature sensors to temperature variations.