Fiber-Optic Technology Reduces Production Logging Limitations in Complex Conditions: Case Studies from Mexico

Abstract

Production logging forms an integral part of reservoir monitoring and problem diagnosis during the productive life of a hydrocarbon field. However, conditions in many wells make acquiring logs difficult, if not nearly impossible. An innovative conveyance and acquisition system applied in four nonconventional operations from Mexico has made it possible to acquire logs that would not have been attempted without this technology.The new technique uses coiled tubing equipped with optical fibers to acquire real-time measurements from the downhole logging string. The advantages of this conveyance option include a lighter, more portable coil, compared to traditional coil tubing with logging cable, the capacity to pump fluids through the coil, and no need for a logging unit. This novel technology can be used for production logging in horizontal or high angle wells, especially when a lighter coil is needed to get down, on offshore platforms when space is limited, to lift and log wells that do not flow naturally, and in wells that need cleaning out before logging because the same coil can be used for both purposes.Each of these cases from Mexico illustrates a unique application of the system. The first involves an offshore well, which was cleaned out, lifted with nitrogen and logged to obtain a production profile, with a single coil. The second is a production log for water entry diagnosis in a well with two branches, one horizontal and the other vertical. The third well, a highly deviated barefoot completion, does not flow because of water accumulation in the wellbore, but was cleaned out, lifted and logged with fiber-equipped coil. The fourth is a horizontal shale gas well for which the same coil was used to clean out and then run an advanced production logging string.These selected cases highlight the significant extension in the range of application of production logs and well diagnosis with the introduction of this new system, especially in complicated cases or in wells that need to be lifted to flow. The technology also reduces the amount of resources required on location, improving logistics, saving time, and ultimately lowering costs for operators.