Application of semi-permeable membrane gas extraction to surface logging formation evaluation

by Douglas Law, Product Line Manager, Weatherford

Abstract

The advanced gas detection technology from Weatherford Surface Logging System relies on three principal technologies: an innovative extraction method, an advanced gas chromatograph, and proprietary software. While formation gas analysis has been used as an evaluation technique for more than eight decades, traditional gas-agitator-based extraction systems have limited its applicability. They permit multiple variables to affect the accuracy of samples, undermining reliable correlation of sample data between wells. The GC-TRACER™ surface gas detector leverages a unique membrane-based extraction method to deliver more accurate results. It couples this extraction method with a high-speed gas chromatograph, which enables real-time analysis of the samples. The tool’s chromatograph is configured to analyse hydrocarbon gases ranging from methane (C1) to octane (C8) in 55 seconds, and methane to decane (C10) in approximately 135 seconds; competing systems can take up to five minutes just to analyse methane to pentane (C5). Customized software enables derivation and comparison of gas ratios in the samples. Accurate, real-time gas ratio analysis permits operators to characterize reservoirs with an unprecedented degree of precision, thereby positioning them to make more informed drilling, evaluation and completion decisions.

The system will be briefly presented, but the presentation will mainly focus on case histories where the system has been used to evaluate reservoir contents and quality based on accurate gas measurements.

Douglas Law, CV

After graduating in Geology & Physics, Douglas went onto research in the area of Marine Science, obtaining a PhD from University of Wales. He joined Datalog in 1997 as a Geologist before taking a role as Operations Manager. In 2004 he became involved in the commercialisation of the GC-TRACER product line as Product Line Manager. He has continued in this role with involvement in R&D and commercialisation, following the acquisition of Datalog by International Logging and subsequently Weatherford.