舟曲泥石流桩林拦挡结构抗冲压极限分析   总被引：1，自引：0，他引：1  

李瑞冬  马宗源  胡向德 《甘肃地质》2011,(2):60-65

以舟曲泥石流灾害防治工程为背景,基于弹塑性有限差分方法计算分析了舟曲泥石流桩林拦挡结构的极限抗冲压能力。针对两种桩林拦挡结构设计方案,采用增量加载的数值计算方法确定了拦挡结构的侧向极限抗冲压力,并与规范建议的泥石流冲击力经验公式计算结果进行了校核。计算结果显示,舟曲泥石流桩林拦挡结构的侧向极限抗冲压力均大于经验公式计算...  相似文献   

莺歌海盆地莺歌海组二段泥岩盖层封闭性综合评价   总被引：2，自引：0，他引：2  

冯冲  黄志龙  童传新  朱建成  范泓澈  刘江涛 《地球科学与环境学报》2011,33(4):373-377

通过实测莺歌海盆地莺歌海组二段泥岩盖层的排替压力,建立了盖层排替压力与声波时差的线性关系,进而提出了利用声波时差及地震速度资料求取排替压力的方法.接着,利用测井声波时差和地震速度资料,按等效深度法确定莺歌海组二段下部泥岩盖层的超压分布.综合考虑盖层累计厚度、排替压力、剩余压力、气藏内部压力、断裂对盖层破坏程度和天然气本...  相似文献   

真空预压法在连云港潮间带软基加固工程中的应用     

刘华强  周金山  陆明志 《岩土工程技术》2011,25(3):158-160

以实际工程为例,论述了真空预压排水固结法加固连云港沿海地区潮间带软土地基的原理和施工要点,对工程实际的观测结果进行了深入分析。实践证明,使用真空预压法,对地基施加相当于80kPa荷载的真空压力,100d后地基的总沉降量可达到1m,地基土的平均固结度超过80％,经过加固的地基土抗剪强度明显增加,地基承载力基本满足后续施工要求。表明真空预压法适用连云港沿海潮间带软基加固,效果明显。  相似文献   

“Basin scale” versus “localized” pore pressure/stress coupling - Implications for trap integrity evaluation     

R. Mourgues  J.B. GressierL. Bodet  D. BureauA. Gay 《Marine and Petroleum Geology》2011,28(5):1111-1121

In petroleum industry, the difference between pore pressure (P_p) and minimum horizontal stress S_h (termed the seal or retention capacity) is of major consideration because it is often assumed to represent how close a system is to hydraulic failure and thus the maximum hydrocarbon column height that can be maintained. While S_h and P_p are often considered to be independent parameters, several studies in the last decade have demonstrated that S_h and P_p are in fact coupled. However, the nature of this coupling relationship remains poorly understood. In this paper, we explore the influences of the spatial pore pressure distribution on S_h/P_p coupling and then on failure pressure predictions and trap integrity evaluation. With analytical models, we predict the fluid pressure sustainable within a reservoir before failure of its overpressured shale cover. We verify our analytical predictions with experiments involving analogue materials and fluids. We show that hydraulic fracturing and seal breach occur for fluid pressure greater than it would be expected from conventional retention capacity. This can be explained by the impact of the fluid overpressure field in the overburden and the pressure diffusion around the reservoir on the principal stresses. We calculate that supralithostatic pressure could locally be reached in overpressured covers. We also define the retention capacity of a cover (RC) surrounding a fluid source or reservoir as the difference between the failure pressure and the fluid overpressure prevailing in shale at the same depth. In response to a localized fluid pressure rise, we show that the retention capacity does not only depend on the pore fluid overpressure of the overburden but also on the tensile strength of the cover, its Poisson’s ratio, and the depth and width of the fluid source.  相似文献   

影响XX带水凝析气田气油比变化因素分析     

王继立 《海洋地质译丛》2011,(2):72-74

气油比是已投入开发凝析气藏的一项重要开发指标。气油比的变化可反应气井、气藏生产状态,凝析气藏压力变化以及带水气藏边底水的推进程度。油藏工程研究人员还可据气油比变化对气井、气藏将来的生产形势做初步分析。因此,分析带水凝析气藏气油比变化规律以及对其影响因素进行深入剖析,对于凝析气藏生产具有重要的指导意义。  相似文献   

深水压力舱密封技术研究     

余建星  王保建  马骏  林镇诗  梁静  郝晓楠  林晓龙  张英 《海洋技术学报》2011,30(3):97-99

管道屈曲技术试验过程当中,发现深水压力舱的出厂自带密封工艺耗时过长、密封效果不好、安全性不佳、返工现象普遍.针对这一现象,采用全新的密封工艺流程与方法:在前期处理中对螺柱编号与清理以防止螺母安装过程中的卡死现象;采用自创的精度控制方法防止漏水以及返工;根据不同的工作压力对密封技术进行梯度划分,选取不同的密封方案.经过实...  相似文献   

TesTrack随钻测压工具在XX油田K14井的应用     

杨虎  罗鹏  王健  孔令强  李战奎 《海洋地质译丛》2011,(4):80-83

地层压力测试是测井作业非常重要的环节,在研究地层压力剖面、判断流体性质、划分气、油、水流体界面、估算地层渗透率、预测地层产能等方面发挥着举足轻重的作用。BakerHughes公司的TesTrack随钻测压工具在XX油田首次应用,分析了该工具的特点及其应用效果,对该工具的推广应用具有重要的参考和借鉴意义。  相似文献   

氧分压对Ni-Cr-Fe合金氧化成膜特性影响的研究     

李厚敏  初蕾  刘英才  梁丹维 《中国海洋大学学报(自然科学版)》2011,(Z1):267-271

以铸态Ni-Cr-Fe合金为试样,于1 050℃湿氢气氛下恒温氧化20 h。通过氧化增重、SEM/EDS以及薄膜X-射线衍射等方法研究了氧分压对该合金在弱氧化性气氛下氧化成膜特性的影响。结果表明:表面氧化膜从外到内氧化物组成依次为:MnCr2O4、Cr2O3以及SiO2。氧化膜的厚度、组成及形貌与体系的氧分压密切相关,中等氧分压(15.9×10-18atm)有利于表面尖晶石的形成;较低氧分压有利于形成厚而多孔的氧化膜,而高氧分压则趋向于形成薄而致密的氧化膜。  相似文献   

Reproductive biology of Spondias tuberosa Arruda (Anacardiaceae), an endemic fructiferous species of the caatinga (dry forest), under different management conditions in northeastern Brazil     

A.L.S. Almeida  C.C. Castro 《Journal of Arid Environments》2011,75(4):330-337

In areas under different management conditions (management units, MUs) located either on a slope or at the base of a slope and either in a plantation or in a pasture, we compared the flower and fruit production, floral visitors, visitation rates and pre-emergent reproductive success (PERS) of Spondias tuberosa (Anacardiaceae) in an area of dry forest in NE Brazil. Individuals in the plantation MU produced more flowers per inflorescence than those in other MUs, but there were no statistical differences in mean fruit set among MUs. The only difference in mean visitation rates was between the plantation (65.83 ± 38.49) and the slope sites (11.5 ± 12.8). We observed visits by 19 insect species, including bees (31.6%), butterflies (31.6%), wasps (26.3%) and flies (10.5%). A clustering analysis based on the number of visits showed that a) the plantation site is most different from the other MUs, b) the pasture and the site at the base of the slope are similar to the slope site, and c) the higher frequency of visits of pollinators in the plantation MU was responsible for these differences. Of the 19 species of insects visiting the flowers, 12 were considered pollinators. The pollinator similarity analysis indicated a clear separation between areas and suggested that human activity has resulted in the replacement of native pollinators by exotic species. However, these changes apparently have not affected the pre-emergent reproductive success of S. tuberosa. Our results show that plant reproductive biology in semi-arid ecosystems may be modified by human action and that changes in floral production and pollinator guilds are the most conspicuous effects. However, the traditional management performed by local people may not affect the reproductive success of plant species.  相似文献   

Particle-size distributions of low-angle normal fault breccias: Implications for slip mechanisms on weak faults     

《Journal of Structural Geology》2013

Slip on low-angle normal faults is not well understood because they slip at high angles to the maximum principal stress directions. These faults are considered weak and their motion cannot be explained using standard Byerlee friction and Andersonian fault mechanics. One proposed mechanism for weak fault slip is reduction of effective normal stress induced by high pore-fluid pressure. This mechanism is likely to allow dilation of the fault zone and, therefore, affect the particle-size distribution of fault breccia, which has been shown to differ for unconstrained versus constrained comminution. High pore-fluid pressure can cause dilation which leads to unconstrained comminution. We analyze samples from the footwalls of two low-angle normal faults in southern California (West Salton and Whipple detachment faults) to determine the fault-rock textures and grain-size distributions (GSDs). The GSDs are fractal with fractal dimensions ranging from ∼2.6 to 3.4. The lower end of this range is thought to reflect constrained comminution and only occurs in samples from the footwall of a small-offset “minidetachment” fault about 100 m below the Whipple detachment. The higher fractal dimensions are common in cataclasites related to the main faults and also reflect constrained comminution but are overprinted by shear localization. Our GSDs are similar to those from natural and laboratory-deformed fault rocks from strong faults. We conclude that if high pore-fluid pressure aided slip on these faults, it did not strongly affect mechanisms by which brecciation occurs, implying that fluid pressure generally was sublithostatic. Independent evidence exists for lithostatic fluid pressure that having dropped or cycled to hydrostatic levelsin the minidetachment, but our GSD results suggest that periods of high fluid pressure were too short or infrequent for unconstrained comminution to have been the dominant cataclastic mechanism. Fractal dimensions of ∼2.6 for these samples suggest that little subsequent abrasion occurred due to shear localization, consistent with minor offset on the minidetachment. Main detachment footwall samples with fractal dimensions ≥3 reflect constrained comminution followed by shear-related abrasion, and suggest that seismic cycling was important in formation of main detachment cataclasites.  相似文献