Abstract
The fiber-optic distributed temperature sensor (DTS) has emerged in recent years as a valuable tool in the oil and gas industry. From intervention services, to permanent wellbore installations, steam-flood, sub-sea installation, and flow assurance, the number and diversity of DTS applications has steadily grown. Supply of DTS instruments, fibers, and services is a lively and growing market which has attracted multiple competing suppliers.
The DTS measures temperature using a length of optical fiber as the sensing element. Each measurement takes the form of a temperature trace or profile comprising samples from regular intervals – usually about 1m – along the entire fiber. Each profile is generated by averaging the weak optical signals that carry the temperature information, over a period of anywhere between a few seconds and a few hours.
While a temperature profile is similar to a temperature log, the simultaneous measurement of all data points and regular repeated measurements give new opportunities for wellbore temperature analysis. Over the last few years, existing techniques have been modified and new ones developed to capitalize on DTS temperature profile measurements. These include measurement of flow rate in producing and injecting wells, and monitoring gas lift valves, as well as monitoring steam flood and SAGD wells. (References [1], [2], [3], [4], [5], [6], [7], [8]).
