Role of plume dynamics phase in a deepwater oil and gas release model

Offshore exploration and production of oil and gas have increased significantly in the last decade. Computer models are used in emergency response, contingency planning, and impact assessment to simulate the behavior of oil and gas if accidentally released from a well, pipeline, or ship. There are two types of models used for this purpose-models that have both plume dynamics stage and the advection diffusion stage and models that are of simplified nature that has only the advection diffusion stage. This paper compares both types of models and shows what information are similar and what are different and under what conditions. The paper also examines in detail about different criteria that can be used as the transition point (TLPD) from plume dynamics stage to advection diffusion stage. Key findings of the paper are that except for slow leaks the two types of models give different results for surfacing time and location. This is important because sometimes the two models may show profiles that correspond to different times to be similar in shape. The present parametric study suggests that the transition point for TLPD can be based on the buoyant oil droplet velocity corresponding to the median oil droplet size.     

Fate and transport of oil in sediment laden marine waters

Spilled oil when present in sediment-enriched waters, is known to interact with sediments. Oil droplets form aggregates with sediments due to collision and dissolved oil partitions (absorption and adsorption) into sediments due to capillarity and surfactant ions. This may change the fate and transport of both oil and sediments. Interaction with sediments acts as a natural oil removal process. This has been recognized as a crucial component in developing oil spill countermeasures. However, no comprehensive models are currently available to describe the process. This paper presents a novel numerical model developed to simulate oil-sediment interaction and transport in near-shore waters. The present model simulates, oil and sediment transport, oil-sediment aggregate (OSA) formation, oil partitioning into sediments, and sediment aggregation. The critical information provided by the model such as the fraction of oil removed due to sediment interaction would be useful in developing oil spill countermeasures.The model results are compared with the limited data from laboratory experiments and show a good agreement. Scenario simulations showed that up to 65% of released oil may be removed from the water column as OSAs. They further showed that when oil droplets and sediment particles are smaller (less than 0.1 mm), the amount of OSAs formed is higher. According to the scenario simulations, the amount of oil partitioned into sediments is 4–5 orders of magnitude smaller than the amount of OSAs formed.     

井筒环雾流传热模型及其在深水气井水合物生成风险分析中的应用

该文采用Hewitt流型判别法,表明深水含水气井测试时井筒内多为环雾流,考虑了气核与液膜间速度及热力学性质差异,建立了环雾流传热模型,与南海某深水气井实测数据对比,模型预测误差在5%以内。计算表明,忽略含水影响的气体单相模型在含水量大于0.1%时,泥线以上井筒压力和温度预测误差均超过10%,应用该研究建立的环雾流模型则可以得到更准确的结果。含水会使泥线以上一定范围内井段井筒温度显著降低,压力损失增大。产气量较低时,含水量对水合物生成风险基本无影响;产气量较高时,含水量会使得水合物生成区域下界下移,水合物生成区域增大,并使过冷度增大,更容易诱导水合物生成,水合物生成风险增大,需要增加水合物抑制剂用量,并加深注入位置。产水会使无水合物生成所对应的临界产气量增大,需要调整水合物抑制剂用量和注入位置。     

Additional deepwater sampling of prey fish in Lake Michigan annual bottom trawl survey reveals new insights for depth distribution dynamics

Beginning in 2013, sites at the 128-m bottom depth contour were added to the sampling design of the annual Lake Michigan bottom trawl survey for prey fish, which has been conducted by the U.S. Geological Survey Great Lakes Science Center (GLSC) each fall since 1973, to better assess fish depth distributions in a changing ecosystem. The standard sampling design included bottom depths from 9 to 110 m, although the GLSC also sporadically conducted bottom trawl tows at the 128-m bottom depth contour during 1973–1988. Enactment of this new sampling design in 2013 revealed that mean biomass density of deepwater sculpins (Myoxocephalus thompsonii) at the 128-m depth exceeded the sum of mean biomass densities at shallower depths, indicating that the bulk of the deepwater sculpin population is residing in waters deeper than 110 m. Thus, our findings supported the hypothesis that the depth distribution of the deepwater sculpin population had shifted to deeper waters beginning in 2007, thereby explaining, at least in part, the marked decline in deepwater sculpin abundance since 2006 based on the standard sampling design. In contrast, our results did not support the hypothesis that the slimy sculpin (Cottus cognatus) population had shifted to deeper waters sometime after 2000. A portion of the burbot (Lota lota) population may have also shifted in depth distribution to waters deeper than 110 m after 2007, based on our results. Our findings have served as an impetus to further expand the range of depths sampled in our bottom trawl survey.     

燃油燃气锅炉房水喷雾灭火系统设计探讨

《高层建筑设计防火规范》要求高层建筑的燃油、燃气的锅炉房应设置水喷雾灭火系统。由于这两种锅炉房火灾分别属于液体火灾和气体火灾 ,水喷雾的设计喷雾强度、喷雾时间、喷头的选用及喷头的布置方法不同。结合北京银谷大厦地下锅炉房的水喷雾设计 ,简要介绍了燃油、燃气锅炉房的水喷雾设计及水雾喷头的选用方法。     

复合气藏内凝析油气流动问题的新模型及应用

建立了凝析油-气在多孔介质中的渗流方程，针对形成不同流体区域的凝析藏、有边水的凝析气藏、岩性尖灭凝析气藏及井底存在污染和改善等多种情况，建立了复合气藏内的凝析油气渗流新模型，求出了凝析气藏油－气拟压力分布的解析解，并指出了凝析气田开发中的实际应用价值。     

Fall diet and bathymetric distribution of deepwater sculpin (Myoxocephalus thompsonii) in Lake Huron

Deepwater sculpin Myoxocephalus thompsonii are an important component of Great Lake's offshore benthic food webs. Recent declines in deepwater sculpin abundance and changes in bathymetric distribution may be associated with changes in the deepwater food web of Lake Huron, particularly, decreased abundance of benthic invertebrates such as Diporeia. To assess how deepwater sculpins have responded to recent changes, we examined a fifteen-year time series of spatial and temporal patterns in abundance as well as the diets of fish collected in bottom trawls during fall of 2003, 2004, and 2005. During 1992–2007, deepwater sculpin abundance declined on a lake-wide scale but the decline in abundance at shallower depths and in the southern portion of Lake Huron was more pronounced. Of the 534 fish examined for diet analysis, 97% had food in the stomach. Mysis, Diporeia, and Chironomidae were consumed frequently, while sphaerid clams, ostracods, fish eggs, and small fish were found in only low numbers. We found an inverse relationship between prevalence of Mysis and Diporeia in diets that reflected geographic and temporal trends in abundance of these invertebrates in Lake Huron. Because deepwater sculpins are an important trophic link in offshore benthic food webs, declines in population abundance and changes in distribution may cascade throughout the food web and impede fish community restoration goals.     

对变压器油中溶解CO和CO_2气体的分析

变压器的检查项目很多,在生产实际中需要具体检查的项目依其容量的大小而定,电力系统所用的变压器一般容量比较大.因此,对变压器油检查分析是必须检查的试验项目,而其中CO和CO2气体的检测对分析变压器内部绝缘情况是十分重要的.     

PG9171E型燃气轮机液压油系统2次泄漏的原因分析

介绍了PG9171E燃气轮机在新疆喀什应急电站调试运行中出现2次液压油系统泄漏的查找和处理过程。总结了＂在液压油系统发生泄漏时,辅助液压油泵会自启动;液压油系统的出口压力越低,辅助液压油泵电机电流就越小且泄漏点就越靠近油泵出口＂的经验,供技术人员处理同类问题时参考。     

Expansion characteristics of twin combustion gas jets with high pressure in cylindrical filling liquid chamber

To deal with the problem of how to control the interior ballistic stability in the bulk-loaded liquid propellant gun, the expansion and mixing process of the twin combustion-gas jets with high temperat...