Furthering the Capabilities of Coiled Tubing Production Logging in Horizontal and Highly Deviated Wells: The Advent of Reservoir Saturation Logging in Southern Mexico

Abstract

A new solution to reservoir saturation logging in highly deviated and horizontal wells leverages a light system using coiled tubing (CT) equipped with fiber optics to overcome reach limitations and provide real-time acquisition of downhole reservoir information. The advantages of the methodology in terms of technical capabilities and efficiency have been demonstrated in wells in Mexico where acquisition of once-inaccessible logging information opened new avenues in the production management of the area. The conveyance of logging tools via wireline cable or wired CT presents significant reach and pumping limitations in highly deviated or horizontal wells. The combination of a recent downhole module development and the use of lighter CT package equipped with fiber optics addresses these conveyance and operating challenges. The optical telemetry link supports real-time logging without the need for wireline surface equipment, and the new downhole module provides power to a wide range of logging tools, including the power-demanding reservoir saturation tools. The lighter system overcomes weight limitations, and logging can be performed in any type of well profile. The new module significantly increases the voltage output from the downhole source to the logging toolstring, thus enabling the use of power-demanding components that were previously unusable with CT systems. It also extends the downhole operating logging time for traditional production logging tools by up to six times over that of previous methods. As the production of mature fields in Southern Mexico is gradually decreasing and water has become an increasing issue, operators in the area are currently performing major workover operations to rejuvenate the fields. This novel approach enabled acquisition of reservoir saturation data in several wells in which this information could not be acquired previously because of reach limitations. The newly acquired data enabled identification of bypassed hydrocarbons in those wells. With this information, the operator could selectively shut off the water-producing zones while opening new hydrocarbon-bearing ones, thus significantly reducing water production and prolonging the life of the wells. The introduction of the innovative methodology not only significantly broadens the range of logging interventions that can be performed, it also enables accessing reservoir data that, in some cases, have been inaccessible for a long time, and which can be key to the optimization of production management of entire fields.