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In hydrocarbon reservoirs, fluid types can often vary from dry gas tovolatile oil in the same column. Because of varying and unknown invasionpatterns and inexact clay-volume estimations, fluid-types differentiation onthe basis of conventional logs is not always conclusive. A case study ispresented by use of advanced nuclear-magnetic-resonance (NMR) techniques inconjunction with advanced downhole-fluid-analysis (DFA) measurements andfocused sampling from wireline formation testers (WFTs) to accurately assessthe hydrocarbon-type variations. The saturation-profiling data from an NMRdiffusion-based tool provides fluid-typing information in a continuous depthlog. This approach can be limited by invasion. On the other hand, formationtesters allow taking in-situ measurements of the virgin fluids beyond theinvaded zone, but at discrete depths only. Thus, the two measurements ideallycomplement each other. In this case study, NMR saturation profiling wasacquired over a series of channelized reservoirs. There is a transition from awater zone to an oil zone, and then to a rich-gas reservoir, indicated by boththe DFA and the NMR measurements. Above the rich gas, is a dry-gas intervalthat is conclusively in a separate compartment. Diffusion-based NMR identifiesthe fluid type in a series of thin reservoirs above this main section, in whichno samples were taken. NMR and DFA both detect compositional gradients,invisible to conventional logs. The work presented in this paper demonstrateshow the integration of measurements from various tools can lead to a betterunderstanding of fluid types and distribution.
Copyright 2012, Society of Petroleum Engineers This paper was prepared for presentation at the SPE North Africa Technical Conference and Exhibition held in Cairo, Egypt, 14-17 February 2012. This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright. Abstract In hydrocarbon reservoirs, fluid types can often vary from dry gas to volatile oil in the same column. Because of varying and unknown invasion patterns and inexact clay volume estimations, fluid types differentiation based on conventional logs is not always conclusive. A case study is presented utilizing advanced nuclear magnetic resonance (NMR) techniques in conjunction with the latest downhole fluid analysis (DFA) measurements from wireline formation testers to accurately assess the hydrocarbon type variations. The saturation profiling data from an NMR diffusion-based tool provides fluid typing information in a continuous depth log. This approach can be limited by invasion.
Kelleher, Hollie A. (ExxonMobil Upstream Research Company) | Braun, Edward M. (ExxonMobil Upstream Research Company) | Milligan, Bradley E. (ExxonMobil Upstream Research Company) | Glotzbach, Rodney C. (ExxonMobil Upstream Research Company) | Haugen3, Einar (StatoilHydro GoM LLC) | Haugen, Einar (PT Schlumberger Geophysics Nusantara) | Guru, U. (Services Technique Schlumberger) | Heaton, N. (Schlumberger Oilfield Service) | Bachman, H.N. (Schlumberger Oilfield Service) | LaVigne, J. (Shell Egypt) | Hamed, Walid A. (BP Egypt) | Nelson, Richard