Technology Focus: Well Integrity (January 2020)

Abstract

Technology Focus Fiber-optic technologies—distributed temperature sensing (DTS) and distributed acoustic sensing (DAS)—have been experiencing an increasing number of applications in the oil and gas industry as monitoring systems. In the area of well integrity, both technologies have been used in combination to monitor and evaluate qualitatively the cement placement and integrity in wells. An interesting technical article showing how these two technologies are used to monitor cement integrity in an actual well is selected as recommended additional reading. Ongoing research studies are also investigating casing deformation and downhole detection of hydro-carbon leakage. The use of these two technologies seems to have a very promising future when considering well-control situations. One potential application of DTS and DAS technologies is being evaluated now at Louisiana State University (LSU) as a part of a 3-year research project currently under way under the auspices of a grant by the Gulf Research Program to investigate the gas-in-riser issue. A 5,000-ft actual well at LSU was recompleted recently and instrumented with DTS and DAS for continuous monitoring information along the well and downhole gauges to record pressure and temperature at four different depths. These instruments were clamped to the outside of the production tubing installed inside the experimental well. A gas-injection line also was run into the well to displace nitrogen to simulate gas-in-riser situations. The data gathered by the downhole instruments are expected to shed light on well-control attributes such as gas velocity and distribution, two-phase-flow patterns, and gas breakout from solution in nonaqueous drilling fluid inside the marine riser. The viability of generating distributed pressure profiles from DTS and DAS data collected in the experiments also will be investigated. Undoubtedly, the research findings will help detect gas-in-riser situations earlier and monitor deepwater managed-pressure drilling operations that may allow for a controlled amount of gas inside the riser. Recommended additional reading at OnePetro: www.onepetro.org. SPE/IADC 194553 Evolving Well-Control Procedures With Managed-Pressure Drilling on Floaters by Andre Alonso Fernandes, Petrobras, et al. SPE/IADC 194145 Well-Control Incident in the North Sea as Interpreted With Advanced Gas-Influx Modeling by Jan Ole Skogestad, SINTEF, et al. SPE 195678 Real-Time Well-Integrity Monitoring Using Fiber-Optic Distributed Acoustic Sensing by T. Raab, GFZ German Research Centre for Geosciences, et al.