High Speed Chromatography Utilizing Semi-Permeable Membrane Technology for Direct Analysis of Hydrocarbon Gasses in the Drilling Fluid—Applications for Geo-Steering and Reservoir Characterization

Law, Douglas J.¹, David Hawker², Aurel Brumboi², Darrell Norquay² (1) Datalog Technology Ltd, Plymouth, United Kingdom (2) Datalog Technology Inc, Calgary, AB

The role of gas chromatography in providing data for real-time formation evaluation and reservoir characterisation has long been hampered by its reliance upon the mechanical agi­tator as a method of gas extraction. Along with the inherently poor temporal and spectral resolution of most Chromatographs, the potential for using real-time gas analysis to geo­steer wells has been limited.

The technique of gas extraction via a semi-permeable membrane has been allied to the latest in TCD gas chromatograph technology to provide direct gas in mud analysis at the point of extraction. This technique avoids the problems associated with mechanical agita­tion, such as the retention of heavy hydrocarbons, and gas trap loading. Significant improve­ments in spectral resolution coupled with faster cycle times will provide benefits in terms of geological & geochemical evaluation. This is demonstrated in the real-time determination of fluid contacts and extended heavy gas component characterisation.

It has been shown that the system provides an accurate and high-speed chromatograph­ic breakdown of mud gases from Methane (C1) to Octane (C8), along with aromatics (Benzene & Toluene), sour gases (H₂S & CO₂) and Nitrogen. Data is presented from a series of tests incorporating a mudflow loop to simulate the interaction of the mud system and gas components. Field data presented also demonstrates that the system provides excellent sep­aration of all component peaks and elution times. With analysis, incorporating C1-C8, aro­matics and non-hydrocarbon gases, within 50seconds, this represents a significant advance in the characterisation of hydrocarbon bearing zones.