Slickline DTS Measurements Provide Useful Information for Well Integrity Diagnostic, Stimulation Treatments, and Water Injector Wells Performance: North America Land Case Studies

Abstract

Distributed Temperature Measurements (DTS) have been used in the oilfield now for over 10 years, with the majority of applications requiring the fiber to be installed permanently in the well, either inside a 1/4-in control line or as part of an electrical gauge cable. A slickline 1/8-in diameter wire has now been developed with an optical fiber embedded inside it so that DTS measurements can be performed during a conventional slickline operation. This new approach to temperature monitoring means that the optical fiber can now be deployed temporarily in a producer or injector well only when needed, using a conventional slickline unit which can also run a bottomhole pressure gauge or a production log at the same time. The ability to monitor the whole well with DTS using a slickline intervention installation allows the operator to use this technology to resolve a range of well integrity, production and stimulation problems. This paper highlights the use of fiber-optic slickline monitoring in Texas and New Mexico over the past two years by discussing a number of field cases that show the application of this technology for monitoring well integrity and diagnosing well problems, how the DTS can be used to evaluate the fracture height created by a fracture job, determining the effectiveness of the stimulation in acid stimulation operations and also how the data can be used to monitor water injection in low rate injector wells. Because the fiber is deployed and data is acquired on a "when needed" basis, it is proving much more economical than a permanently installed optical fiber, and can bring the benefits of this monitoring technology to a greater number of wells.

Monitoring Acid Stimulation Treatments in Naturally Fractured Reservoirs with Slickline Distributed Temperature Sensing

“…During this injection period, the temperature measured in the borehole will be the injection temperature of the acid without exothermal effects. When the acid injection is stopped, the live acid remaining in the wormhole system surrounding the borehole will react with the carbonate rock to create a heated "donut" around the wellbore, and this will then heat the liquid in the wellbore, which can be observed using SL-DTS (Gonzalez et al 2012). Fig.…”

“…Note how the top zone (orange) takes longer to warm up, and that it stays warmer much longer than the lower pink and green zones. The rapid heating and quicker cool-off of the lower zones is likely indicative of a less well-developed set of wormholes and/or less carbonate-containing minerals than in the upper (orange) zone (Gonzalez et al 2012). Understanding the effect of temperature transients during acid spending provides important insights on the stimulation effectiveness during pumping or post-treatment.…”