Gas holdup tool applications in production logging

Document Type

Conference Proceeding

Publication Date



SPWLA 39th Annual Logging Symposium 1998


© 1998 Society of Petrophysicists and Well-Log Analysts (SPWLA). All rights reserved. Horizontal and multilateral wells are being drilled as a cost-effective approach to increasing production and adding reservoir value. Conventional center-sample production logging tools have proven to be inadequate in horizontal and highly deviated wells. A new quick well analysis has been developed, along with a new generation of tools used for production logging and reservoir monitoring. This suite of tools is used to improve understanding of downhole flowing conditions and to expedite the evaluation of the reservoir. The Gas Holdup Tool (GHT™) has proved to be a major component of this new approach. Less than 3 feet in length, the GHT is a 1-11/16-inch-OD through-tubing production logging tool, which directly and accurately determines the volumetric fraction of gas over a cross-sectional volume element of the wellbore. This sensitive downhole tool operates in horizontal, highly deviated, and vertical cased wells. It uses real-time downhole pressure and temperature, casing inside diameter, and gas gravity measurements to generate a 0% to 100% gas holdup log in stratified or homogenized flows. The GHT uses a low-energy cobalt-57 source and a sodium iodide detector located a short distance from the source and separated by a tungsten shield. The detector counts gamma rays that are scattered back from the production fluid to the detector; the magnitude of the count rate is directly related to the gas holdup. The measurement is not affected by the composition and density of materials outside the casing. Log examples illustrate a variety of applications of the fullbore gas holdup tool measurements. Guidelines are provided for running production logs for evaluating horizontal completions and improving reservoir production and value. The examples demonstrate the new wellsite production analysis program, which incorporates new interpretation algorithms, and features fast automatic processing capability to permit the user to quickly determine the type and rate of produced fluids while the logging unit is still on location.

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