Distributed Temperature Sensors (DTS)

Boston Instruments distributed temperature sensor (DTS) is based on Raman distributed temperature sensing systems that are designed for large-scale thermal profile mapping from oil field, downhole, reservoir, dam, tunnel, power transmission, to subsea asset management where the thermal profile is slow-varying measurand. For downhole and subsea applicaition, it can be used to monitor hydrocarbon flow contribution and delcine by thermal profile variation to provide flow assurance. It also can monitor production rate and tubing integrity that definitely benefit to asset management and produciton efficiency control.

A DTS can measure axial thermal profile with 1-2 meter sensing spacing or spatial resolution. To measure a surface thermal profile one can wrap a fiber sensing cable surrounding a structure surface, such as an oil/gas tank or vessel. Meanwhile, multiple fiber sensing cables can be simultaneously interrogated by an optical switch of 16 to 32 channels for one DTS system to monitor multiple oil wells or reservoirs. The normal length of a fiber sensing cable ranges from 1km to 20km.

Boston Instruments provided DTS sensing instruments have single-end system with single fiber sensing cable for 1-20km range thermal profile measurement, which is more suitable for Oil/Gas, Petrochemical, Refinery, and Energy industrial assets management. The double-end DTS system is specifically preferred for downhole and oil reservoir thermal and flow measurement due mainly to the potential hydrogen effect induced temperature accuracy issue. For wellhead and subsea deployment, these DTS instruments can be customized to meet required compliances.

Boston Instruments has a fiber sensing cable supplier chain that could provide specific fiber cable for a specific application where both cost and performance are critical. The normal used fiber sensing cable is based on 50/125 gradient index multi-mode fiber. A standard fiber cable consist of a 1/4" stainless steel tube or Inconel 625 tube, with a 1/8" aluminum tube for anti-hydrogen protection. Two multi-mode fibers inside the aluminum tube are for single-end DTS system. Additional single-mode fiber will be used for DTS+PT gas configuration. For mitigating hydrogen-darkness effect the pure silicon dioxide core fiber cable is also available. The fiber sensing cable length ranges from 2km to 20km. The fast data rate of thermal profile measurement is from 10sec to 1min. For high-temperature resolution and accuracy, multiple data traces average will be preferred. The data transmission can be directly connected to customer's intranet for oil & gas production process monitoring and diagnostics.


DTS System Specifications


High-pressure and High-temperature PT Gage

Pressure and Temperature (PT) gage is normally used for downhole drilling, artificial lift, completion, process monitoring, and production optimization. It can be simply installed in the distal end of the Raman DTS fiber sensing cable to provide baseline data for temperature correction. The PT gage is based on Fabry-Perot interference principle for temperature-compensated pressure measurement. The Measuring range can be customized to 5kpsi, 10kpsi, 15kpsi, and 25kpsi for maximum operation temperature up to 175°C with existing products. New engineering prototype, up to 400°C, is in prototyping & evaluation phase.

Boston Instrument offered Single-end DTS can attach a single-point or dual-point PT gage at the distal end of the fiber cable. In PT gage and fiber cable are mounted at the bottom of the well with a protected case. The 1/4" fiber cable will secured along the well to the upground. At the wellhead location, a seal gland will pass fiber cable from potential high-pressure environment to ambient. For dual-end DTS fiber sensing cable, a turnaround sub will be sealed at the distal end for looped signal detection.


A typical PT gage can be installed at different oil/gas zones. For single zone, a PT gage will be sufficient. Otherwise, multiple PT gages are required for multi-zone well installation. In some case, a differential pressure measurement is also possible with two PT gages that can be used for evaluate 3-phase hydrocarbon fluid density.



PT Gage Specifications


To meet different customer needs, we can customize the fiber sensing cable, DTS instrument configuration, and installation package designs. Please specify your specific requirements to our sales department at: sales@bostoninstruments.com