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AbstractCarbon dioxide (CO 2 ) occurrence in hydrocarbon bearing formations presents a challenge to the valuation and subsequent prospect development of the hydrocarbons. Corrosion is a major concern effecting capital and operational expenditures since the presence of CO 2 can cause corrosion failures. Carbon dioxide also denotes an issue for health, safety and the environment (HSE) and is readily absorbed by elastomer seals, weakening the resistance of those seals and compromising the integrity of the fluid samples and the safety of equipment and personnel. The conventional procedure to evaluate the CO 2 content in a hydrocarbon bearing formation is to take fluid samples downhole or on surface during a well test and send the fluids to the laboratory for analysis. Both methods are compromised by the reactive nature of CO 2 , whose concentration can change significantly by reaction with formation waters, mud filtrates, etc. before reaching an analysis facility. Optimizing the fluid sample acquisition program to match existing fluid complexities is impossible without real-time analysis. Recently, NIR (near-infrared) spectroscopy has enabled the real time analysis of the CO 2 content in downhole fluid samples. This paper describes a new method for using DFA * (Downhole Fluid Analysis) in the real-time determination of the CO 2 amount in the MDT * (Modular Dynamic Formation Tester) flow line. Extensive laboratory data from a research grade spectrometer and shop data with the downhole tool support the new methodology. Multiple interpretation algorithms have been developed for CO 2 quantification and verified in the laboratory. Several log examples are given * Mark of Schlumberger demonstrating successful CO 2 detection and subsequent confirmation of the measured concentrations by the laboratory data.
The State of Louisiana is leading an integrated wetland restoration and flood risk reduction program in the Mississippi River Delta. East of New Orleans, Biloxi Marsh, a ~1700 km2 peninsula jutting 60 km north toward the State of Mississippi is one of few Delta wetland tracts well positioned to dissipate hurricane surge and waves threatening the city’s newly rebuilt hurricane flood defenses. Both its location on the eastern margin of the Delta, and its genesis as the geologic core of the shallow water St. Bernard/Terre aux Boeuf sub-delta, which was the primary Mississippi outlet for almost 2000 years, make Biloxi Marsh attractive for restoration, now that the Mississippi River Gulf Outlet deep-draft ship channel has been dammed, and 50 years of impacts from construction and operation have abated. Now, the cascade of ecosystem damage it caused can be reversed or offset by restoration projects that leverage natural recovery and increased access to suspended sediment from the Mississippi River. Biloxi Marsh is (1) geologically stable, (2) benefiting from increased input of river sediment, and (3) could be restored to sustainability earlier and for a longer period than most of the rest of the submerging Mississippi Delta. The focus of this review is on the Biloxi Marsh, but it also provides a template for regional studies, including analysis of 2D and 3D seismic and other energy industry data to explore why existing marshes that look similar on the ground or from the air may respond to restoration measures with different levels of success. Properties of inherent durability and resilience can be exploited in restoration project selection, sequencing and expenditure. Issues encountered and investigative methods applied in the Biloxi Marsh are likely to resonate across initiatives now contemplated to sustain valuable river deltas worldwide.
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