Investigation of the effects of downhole conditions on DTS performance

Abstract

Being widely used in different surveillant and assessment jobs in different industries, DTS technologies have proved the abilities to provide high measurements accuracy that meet the requirements of those critical industries, such as firefighting, oil and gas industries and pipelines monitoring.

DTS accuracy has different spatial resolution and temporal measurements. Different industries require different accuracy levels. Nevertheless, being immersed in a medium of high pressure and temperature with multi-phase fluids, all that factors could affect the accuracy of measurements as well.

In this report, the ambient conditions that can affect the DTS accuracy are identified from different field studies. Such as high rich hydrogen environment and its effect on the fiber coating, problem of calibrations and references, deviated wells and completion design and signal to noise ratio. In addition, the problems associated with temperature perturbation and heat transfer are also covered.

Many field cases and lab studies provide good steps to improve DTS accuracy. Such as using special materials that can stand with harsh downhole environment. Using three sections as reference is better as well. Noising, as a common problem, can be mitigated by using more filters and denoising and reducing Rayleigh effects since it will not be used. The studies show the importance of simulation models for complicated jobs to understand temperature outputs, as well as knowing historical production status and well completion details. The report uses such ideas to give the user of DTS a clear idea about downhole conditions effects on DTS, further than the ones provided by DTS manufacturers, who usually assume the ideal conditions, which is not necessarily the case.