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排序方式: 共有617条查询结果,搜索用时 15 毫秒
1.
Derek Sears 《Meteoritics & planetary science》1996,31(5):543-544
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We present solutions for the effective stress induced by gas flow through a porous solid into a borehole resulting from sudden pressure reduction. Tensile effective stress that exceeds the strength of the solid will lead to borehole failure. This has applications to the intentional creation of cavities, relevant to the efficient recovery of coalbed methane, and the avoidance of borehole stability problems in conventional gas production. 相似文献
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Quick-look assessments to identify optimal CO2 EOR storage sites 总被引:1,自引:0,他引:1
Vanessa Núñez-López Mark H. Holtz Derek J. Wood William A. Ambrose Susan D. Hovorka 《Environmental Geology》2008,54(8):1695-1706
A newly developed, multistage quick-look methodology allows for the efficient screening of an unmanageably large number of
reservoirs to generate a workable set of sites that closely match the requirements for optimal CO2 enhanced oil recovery (EOR) storage. The objective of the study is to quickly identify miscible CO2 EOR candidates in areas that contain thousands of reservoirs and to estimate additional oil recovery and sequestration capacities
of selected top options through dimensionless modeling and reservoir characterization. Quick-look assessments indicate that
the CO2 EOR resource potential along the US Gulf Coast is 4.7 billion barrels, and CO2 sequestration capacity is 2.6 billion metric tons. In the first stage, oil reservoirs are screened and ranked in terms of
technical and practical feasibility for miscible CO2 EOR. The second stage provides quick estimates of CO2 EOR potential and sequestration capacities. In the third stage, a dimensionless group model is applied to a selected set
of sites to improve the estimates of oil recovery and storage potential using appropriate inputs for rock and fluid properties,
disregarding reservoir architecture and sweep design. The fourth stage validates and refines the results by simulating flow
in a model that describes the internal architecture and fluid distribution in the reservoir. The stated approach both saves
time and allows more resources to be applied to the best candidate sites. 相似文献
6.
Multi-AUV Control and Adaptive Sampling in Monterey Bay 总被引:3,自引:0,他引:3
Edward Fiorelli Naomi Ehrich Leonard Pradeep Bhatta Derek A. Paley Ralf Bachmayer David M. Fratantoni 《Oceanic Engineering, IEEE Journal of》2006,31(4):935-948
Operations with multiple autonomous underwater vehicles (AUVs) have a variety of underwater applications. For example, a coordinated group of vehicles with environmental sensors can perform adaptive ocean sampling at the appropriate spatial and temporal scales. We describe a methodology for cooperative control of multiple vehicles based on virtual bodies and artificial potentials (VBAP). This methodology allows for adaptable formation control and can be used for missions such as gradient climbing and feature tracking in an uncertain environment. We discuss our implementation on a fleet of autonomous underwater gliders and present results from sea trials in Monterey Bay in August, 2003. These at-sea demonstrations were performed as part of the Autonomous Ocean Sampling Network (AOSN) II project 相似文献
7.
A flare observed with the Hard X-Ray Imaging Spectrometer (HXIS) was studied during its rise to maximum temperature and X-ray emission rate. Two proximate flare loops, of lengths 2.8 × 109 cm and 1.1 × 1010 cm, rose to temperatures of 21.5 × 106 K and 30 × 106 K, respectively, in 30 s. Assuming equal heat flux F into each loop from a thermal source at the point where they met, we derive a simple relationship between temperature T and loop length
, which gives a loop temperture ratio of 0.68, in close agreement with the observed ratio of 0.72. The observations imply that heating in each loop was maintained by a thermal flux of 5 × 109 ergs cm-2 s-1. It is suggested that conductive heating adequately describes the rise and maximum phase emissions in the loops and that long flare loops reach higher temperatures than short loops during the impulsive phase because of an equipartition of energy between them at their point of interaction. 相似文献
8.
Phytolith analysis from the archaeological site of Kush, Ras al-Khaimah, United Arab Emirates 总被引:1,自引:0,他引:1
Sachiko Ishida Adrian G. Parker Derek Kennet Martin J. Hodson 《Quaternary Research》2003,59(3):310-321
Despite the wealth of archaeological sites and excellent conditions for preservation, few phytolith investigations have been undertaken from the Arabian Gulf region. The results from the Sasanian and Islamic archaeological tell of Kush, Ras al-Khaimah, United Arab Emirates, are presented. Kush is situated just inside the Gulf on an important trade route. The occupation sequence dates from the 4th century A.D. until the 13th century A.D., recording the development of the site in the Sasanian period, followed by the arrival of Islam in the 7th century A.D. and the final abandonment of the site in the late 13th century when the nearby site of al-Mataf (Julfar) began to develop closer to the present day coastline. All the samples analyzed contained abundant phytoliths (short cells, elongated cells, and groups of elongated cells) of various types. They included date palm (Phoenix dactylifera), papillae (possibly from barley (Hordeum)), and hair cells possibly from species of canary grass (Phalaris spp.). Some researchers have suggested that groups of elongated cells may indicate the presence of irrigation in semiarid environments. The present results for this class of phytoliths appeared to imply that intensive irrigation was unlikely to have taken place around Kush. 相似文献
9.
We investigate how well the variability of extreme daily precipitation events across the United Kingdom is represented in a set of regional climate models and the E-OBS gridded data set. Instead of simply evaluating the climatologies of extreme precipitation measures, we develop an approach to validate the representation of physical mechanisms controlling extreme precipitation variability. In part I of this study we applied a statistical model to investigate the influence of the synoptic scale atmospheric circulation on extreme precipitation using observational rain gauge data. More specifically, airflow strength, direction and vorticity are used as predictors for the parameters of the generalised extreme value (GEV) distribution of local precipitation extremes. Here we employ this statistical model for our validation study. In a first step, the statistical model is calibrated against a gridded precipitation data set provided by the UK Met Office. In a second step, the same statistical model is calibrated against 14 ERA40 driven 25?km resolution RCMs from the ENSEMBLES project and the E-OBS gridded data set. Validation indices describing relevant physical mechanisms are derived from the statistical models for observations and RCMs and are compared using pattern standard deviation, pattern correlation and centered pattern root mean squared error as validation measures. The results for the different RCMs and E-OBS are visualised using Taylor diagrams. We show that the RCMs adequately simulate moderately extreme precipitation and the influence of airflow strength and vorticity on precipitation extremes, but show deficits in representing the influence of airflow direction. Also very rare extremes are misrepresented, but this result is afflicted with a high uncertainty. E-OBS shows considerable biases, in particular in regions of sparse data. The proposed approach might be used to validate other physical relationships in regional as well as global climate models. 相似文献
10.
Derek Flinn 《Geological Journal》1979,14(1):87-98
The mathematics of irrotational deformation are simplified by presentation in matrix form. Matrix equations are easily programmed and are easily interpreted in geometrical terms. Graphical operations commonly carried out on orientation nets such as rotation of data can be translated into simple matrix equations for use with a computer. If the shape and orientation of the deformation ellipsoid for a pure shear are known, a matrix can be constructed for use as a deformation matrix. This can be used to deform other deformation ellipsoids to obtain a resultant ellipsoid. It can also be used to deform geological structures such as lineations and planes. The matrix equations for these operations are very simple, but their numerical solution often requires a computer. 相似文献