Fiber-optic systems are able to generate a temperature log along an optical fiber using a laser source and analysis of the backscattered light. This paper details a novel application of this technology using an optic fiber embedded in a 1/8 th inch slickline cable to calculate the inflow distribution of multi-zone gas wells with velocity strings.EnCana's multi-zone gas wells in the Deep Basin of Western Canada are often completed with production tubing landed near the lowest perforated interval to act as a velocity string and lift produced water to surface. This completion technique makes spinner production logs impossible to run without initially performing a wellsite operation to lift the tubing shoe above the reservoir, requiring either a workover rig or a snubbing unit. Running a slickline containing an optical fiber to the bottom of the tubing and producing the well up the annulus for a short period allows the temperature profile of the well to be measured and therefore, the inflow distribution of the well can be calculated.Determining the inflow distribution of multi-zone gas wells now becomes a simple slickline operation with no tubing shift required. Additional benefits are the detection of crossflow on shut-in and the measurement of flowing bottomhole pressure when a gauge is run at the end of the slickline. The process is cost effective, less risky than conventional production logging, and the slickline can be safely employed where there is significant surface pressure.The paper uses case studies validated by spinner log comparisons to demonstrate that slickline fiber optic distributed temperature sensor measurements are a viable method for performing reservoir surveillance in multi-zone gas wells with velocity strings in Western Canada. Utilizing fiber optic measurements in these wells reduces operating costs and should ultimately lead to increased efficiency of reservoir stimulation practices.
Over the past 3 years fiber optic slickline distributed temperature measurements (DTS) have become a commonplace method of monitoring Canada’s Deep Basin commingled gas wells produced through velocity string completions. The use of velocity string completions prohibits conventional production logging, so the wells are flowed up their annulus for a short period of time and a DTS slickline is used to monitor the flowing temperature profile. This temperature profile is then interpreted to give the flow from each reservoir zone. DTS is a much more cost effective solution than having to pull the tubing in order to run a conventional production log and allows testing of lower rate wells that would otherwise liquid load. The analysis technique conventionally assumes that during the annular flow period, where the DTS is used to acquire the flowing temperature, all the thermal effects of the previous counter-flow production period have dissipated and the problem can be solved by an upward flow thermal model only. This paper evaluates the magnitude of the residual thermal effect of a period of counter-flow on the annular flow response over the timescales typical for DTS monitoring. A counter-flow thermal model has been developed for typical well scenarios and the shut-in decay of the thermal response of this model is superposed on the conventional annular flow model to highlight the magnitude of influence of previous counter-flow production. The model is used to interpret the counter-flow response of annular flowing gas wells using real well DTS data and demonstrates the magnitude of the effect and how to use this method to improve the accuracy of the resulting flow analysis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.