Showing papers by "Abu Dhabi Company for Onshore Oil Operations published in 2007"
TL;DR: In this article, the characteristics of mangrove communities along the Gulf Coast of the UAE were explored using high-resolution satellite data Terra ASTER imageries in the common visible and near infra-red bands.
Abstract: Characteristics of mangrove communities along the Gulf Coast of the UAE were explored using high-resolution satellite data Terra ASTER imageries in the common visible and near infra-red bands. Mangrove stands in three geographically distinctive sites, Khor Kalba, Khor Umm Al-Quwain and Al Dabbiya, were studied through spatial data and ground verification surveys. Mangroves in the UAE appear in patchy and scattered patterns, occupying about 40 km 2 of the coastal zone, half of which are located in Abu Dhabi in sheltered lagoons. The remaining areas are linear communities fringing tidal waterways distributed along intertidal zones. Their distribution is limited however, by aridity and site topography. Despite similarities in substrate conditions, differences in climatic and vegetation characteristics between the three sites indicate that growth conditions seem to be more favourable at Khor Kalba with the higher winter temperatures and higher annual rainfalls. Nine main units were recognized on the colour co...
29 citations
TL;DR: In this article, the authors proposed a turbine inlet air cooling system that utilizes the cooling tower as primary source of cooling simultaneously with the chiller which serves as a secondary source at elevated wet bulb temperature.
Abstract: Free-cooling is a well-known concept in the HVAC industry in which the cold water produced by cooling tower is used directly to satisfy the requirement of the cooling load without assistance by the chiller, this concept, however, is not reported in the turbine inlet air cooling applications. Free-cooling works well as long as the ambient wet bulb temperature WBT is sufficiently low to produce cold water at the required temperature but once WBT reaches its threshold value hence free-cooling mode is ceased and the chiller kicks off working under its normal mode of operation i.e. free-cooling is either enabled or disabled. The proposed system in this paper provides in addition to the above modes of operation a novel mode that utilizes the cooling tower as primary source of cooling simultaneously with the chiller which serves as a secondary source at elevated WBT. This new feature significantly reduces the yearly operating hours of the chiller and possibly its size depending on the desired inlet air temperature, actual weather conditions and design WBT. Chiller size can vary between 0-100 percent as compared to a similar classical chiller system with significant reduction in the operating hours. The proposed system basically consists of chiller, cooling tower, cooling coils, interconnecting piping and controls. The arrangement of the system equipments changes with the operation modes in two configurations; dual water circulation loops and single water circulation loop. In the dual loops configurations the system has two separate loops such that the evaporator and the cooling coils are tied in one loop while the cooling tower and condenser in the other loop whereas in the single loop configuration all equipments are connected in series in one water circulation loop. This paper presents the major equipments and characteristics of the novel chiller scheme. In addition, the study outlines the potential reduction in the chiller load, size and operating hours under a generalized weather envelope. The paper in general portrays the feasibility of using the proposed cooling scheme for turbine inlet air cooling.Copyright © 2007 by ASME
5 citations
TL;DR: Walkaway VSP repeatability tests with a marine air gun and land vibrator show that VSP images can be repeated with significantly lower background noise compared to surface seismic as discussed by the authors.
Abstract: VSP results successfully demonstrate that high resolution VSP data can be collected and are repeatable in the Abu Dhabi carbonate environment. Comparisons between shallow marine air gun and land vibrator VSP images show similar quality results, suggesting that land and marine surveys can potentially be combined in transition areas. Walkaway VSP repeatability tests with a marine air gun and land vibrator show that VSP images can be repeated with significantly lower background noise compared to surface seismic. Background noise is the non-repeatable signal that remains after subtracting two VSP images collected at different times, when no changes in the subsurface have occurred. With fixed geophones and an optimized 4D VSP processing flow background noise levels below 1% of the original VSP amplitudes were achieved. Both reflected p-wave signals and converted shear wave signals were found to be repeatable. The positive results from this VSP repeatability pilot and a 4D feasibility study indicate that time-lapse 3D-VSP’s could provide another means for monitoring reservoir saturation changes in Abu Dhabi Carbonate fields.
3 citations