渭河盆地地温场分布规律及其控制因素     

任战利  刘润川  任文波  祁凯  杨桂林  崔军平  杨鹏  张园园 《地质学报》2020,94(7):1938-1949

本文以渭河盆地地温场为研究对象,在收集补充新地热井资料及分析测试样品的基础上,通过盆地深部结构、构造特征、地温场特征、热储层特征、地热资源量等分析,建立了盆地不同岩性岩石热导率与深度关系图版,确定了盆地地温场变化规律及地热田控制因素,提出了渭河盆地地热田形成模式。评价了盆地地热资源有利区,为盆地后续的开发利用提供了理论支持。研究认为渭河盆地热地温梯度分布在2.34～5.85℃/100m之间,平均地温梯度为3.50℃/100m,代表性大地热流68.33mw/m~2,地温梯度及不同深度地层温度具有东高西低、南高北低的特点。热导率总体上具有随深度的增加,逐渐增大的规律,热导率随深度增加主要受压实程度增强控制。相同深度条件下泥岩热导率最低,砂岩热导率居中、白云岩热导率最高。渭河盆地主要为层状地热田,盆地内地热通过热传导及热对流两种方式进行传递,以热传导为主。渭河盆地地热资源丰富,热储层可分为三种类型:①新生界砂岩孔隙型;②下古生界碳酸盐岩岩溶型;③断裂型。渭河盆地地热资源有利区主要分布于西安凹陷、固市凹陷。盆地地温场及地热田分布与莫霍面、软流圈上隆、岩石圈厚度减薄的深部背景密切相关,主要受地热传导和深大断裂热对流控制,是岩石圈深部结构、盆地构造、基底岩性、储盖组合等多因素共同作用下形成的。最后结合当前渭河盆地地热资源开发利用现状及存在问题,提出了地热开发利用建议。  相似文献   

潮页1井钻探施工技术          下载免费PDF全文

王世炬  刘昕伟  王烁  徐明曙  纪卫军 《探矿工程》2020,47(10):33-37

潮页1井是在潮水盆地布置的第一口页岩气资源调查井，取心质量要求较高，地层有大段泥页岩层段，易水化剥落，施工难度大。本文着重介绍了潮页1井取心工艺、钻头选型、冲洗液技术及井斜控制技术等相关的施工经验。潮页1井采用大口径绳索取心技术，第四系地层以深全井取心，该技术在甘肃地区鲜有可供参考的施工案例，而该井岩心采取率接近90%。钻进过程中通过选用合理的钻进参数和护壁性能较强的冲洗液体系，解决了施工中遇到的地层“打滑”、井壁稳定性差等技术难点，保障了潮页1井的顺利完工。  相似文献   

五圆柱体结构群绕流特性及互扰效应研究     

涂佳黄  张志豪  曹波  肖毅凡  梁经群 《海洋工程》2020,38(1):101-110

基于Fluent流体计算平台,运用大涡模拟方法对亚临界雷诺数Re=3900下“X”形排列五圆柱体结构群三维绕流特性进行研究,主要分析来流攻角α与间距比L/D两个关键参数对五圆柱体结构群的尾流区三维涡结构演化与流体力系数的影响,并揭示其内在流动互扰机理。研究表明:来流攻角和间距比的变化对五圆柱体结构群流动控制及互扰效应的影响显著。在小间距比工况下,观察到柱体群间隙区域内流体高速流动的现象,导致五圆柱体之间的互扰作用十分强烈。间隙流对中间圆柱体和下游圆柱体有较强的冲击作用,对其表面的流体力分布特性有显著的影响。另外,大间距比工况下,当α=0°与L/D≥5.0工况时,柱体群尾流效应强于其间隙流效应。当α=22.5°与L/D=7.0时,位于下游与中间处的圆柱体流体绕流特性存在较大差异。而当α=45°与L/D≥6.0时,位于上游与中间处的圆柱体尾流区均会产生正负交替的漩涡结构。  相似文献   

Impacts of confining pressure and safety thickness on water and mud inrush in weathered granite     

Jinquan Liu  Weizhong Chen  Zhiping Deng  Taogen Liu 《Marine Georesources & Geotechnology》2020,38(2):144-153

Abstract

Due to the strong disintegration and water erosion of completely weathered granite, water and mud inrush disasters are apt to take place in this zone during underwater tunnel construction. The pore, compactness, seepage path length, fracture geometries and their interconnections for water and mud transfer are strongly influenced by confining pressure and waterproof-resistant slab safety thickness. In order to inspect the influence, a series of experiments based on a self-designed testing system and non-Darcy testing method were performed. The results indicated that the water and mud inrush evolution increased with the increase of confining pressure and decreased with the increase of safety thickness. In particular, the confining pressure mainly influences the initial evolution stage, and a critical safety thickness to prevent water and mud inrush is obtained. Besides, the non-Darcy testing method results shows that the water and mud inrush evolution affects the influence of non-Darcy flow. For example, while the safety thickness was smaller than the critical value, the evolution was large and unstable and its behavior transferred into nonlinear. In this case, the flow changed to non-Darcy flow.  相似文献   

Analysis of resistance factors for LRFD of soil nail pullout limit state using default FHWA load and resistance models     

Hui Hu 《Marine Georesources & Geotechnology》2020,38(3):332-348

Abstract

Resistance factors for load and resistance factor design (LRFD) of pullout limit state of both permanent and temporary soil nails are calibrated against a wide design space using the current Federal Highway Administration (FHWA) nail load and resistance models. The calculated resistance factors were shown to scatter broadly among design scenarios that differ in wall face batter, soil friction angle, nail ultimate bond strength, and surcharge live load. An important lesson learned from the analysis results is that the current practice of using a single resistance factor for LRFD of nail pullout limit state could not result in uniform reliabilities across different design scenarios. Simple artificial neural network (ANN) models were developed for computation of resistance factors. Design examples demonstrated the ability of the ANN models in providing resistance factors that yield satisfactory and consistent reliabilities in different nail pullout designs.  相似文献   

春季西沙永乐龙洞浮游植物的昼夜垂直分布特征     

葛汝平  傅亮  毕乃双  陈畅  刘光兴  庄昀筠  杨作升  范德江  姚鹏  陈洪举 《中国海洋大学学报(自然科学版)》2020,(1):65-73

南海永乐龙洞位于西沙群岛永乐环礁,是迄今为止发现的最深的海洋蓝洞,水文环境及理化因素特殊,90 m以下水体为无氧环境。为研究永乐龙洞浮游植物的群落组成及其昼夜变化,于2017年3月在龙洞、潟湖及外礁坡进行浮游植物样品采集。研究结果表明:龙洞内叶绿素a浓度呈现随深度先增大后减小的趋势,日间浓度最大值层出现在40 m层(0.42μg/L),夜间则出现在20 m层(0.59μg/L)。永乐龙洞微微型浮游植物丰度介于1.1×10^3~5.1×10^4 cells/mL。聚球藻在上层水体占优势(0~20 m),40 m以下水层原绿球藻丰度对微微型浮游植物丰度贡献率最大(90%以上),微微型真核浮游植物丰度在整个水体都较低(除20 m层)。微微型浮游植物昼夜存在明显差异,夜间其丰度最大值层为20 m层,日间则上移至表层。本研究共记录微型和小型浮游植物5门41属55种(含未定种)。其中,硅藻门25属34种、甲藻门12属15种、金藻门1属1种、蓝藻3属、隐藻1属。微型和小型浮游植物丰度介于3.3×10^2~9.8×10^4 cells/L。甲藻丰度对浮游植物总丰度贡献率最大,其次是硅藻,隐藻和蓝藻丰度仅在少数水层占优势。微型和小型浮游植物昼夜变化明显,夜间丰度最大值层为20 m层,日间则出现在40 m层。微微型、微型和小型浮游植物垂直分布与叶绿素a浓度垂直分布一致性高。龙洞浮游植物的种类数和丰度高于潟湖和外礁坡。  相似文献   

准噶尔盆地西北缘及玛湖凹陷沉积储集层研究进展^*          下载免费PDF全文

张昌民  尹太举  唐勇  郭旭光  赵康  潘进  陈美玲 《古地理学报》2020,22(1):129-146

准噶尔盆地西北缘玛湖凹陷中心区10×10⁸ t级砾岩大油区的发现,带动了该区沉积储集层研究的不断深入。作者梳理了准噶尔盆地西北缘及玛湖凹陷的沉积储集层研究现状和进展,认为准噶尔盆地西北缘及玛湖凹陷的沉积储集层研究的进展主要表现为: (1)提出了新的砂砾岩储集层岩石相和岩石学分析方法;(2)探索形成了新的沉积储集层地球物理测井和地震描述技术;(3)针对不同层系,在沉积物源、沉积相、沉积环境、沉积体系和沉积模式等方面取得大量新认识,建立了大型退覆式浅水缓坡扇三角洲沉积模式,指导油气勘探不断获得新突破;(4)在成岩作用理论指导下,所发现的储集层埋藏深度不断增加。研究表明,玛湖凹陷的沉积体系具有继承性: 从二叠纪到新近纪,发育了火山—碎屑岩沉积体系、细粒—蒸发盐沉积体系以及粗粒冲积扇、扇三角洲、辫状河三角洲等沉积体系,气候、构造和湖平面变化控制了沉积体系的形成和演化。沉积储集层研究为玛湖砾岩大油田的发现提供了有力的理论支持。未来应当加强针对古老层系和深部地层的沉积储集层研究工作,重视新理论新技术在西北缘和玛湖沉积储集层研究中的应用,已经形成的理论技术需要在勘探实践中接受进一步检验和完善。  相似文献   

Wedge impact with the influence of ice     

《Applied Ocean Research》2019

This work presents a canonical study on a wedge entering water near a single piece of ice using computational-fluid-dynamics (CFD) and a Wagner-type theoretical model with corrections for non-linear effects. Calculations for a series of conditions with ice of different sizes and locations relative to the wedge are conducted. The hydrodynamic force due to impact, the pressure distribution on the wedge surface, and the pile-up phenomenon are examined to study the role of ice in the impact process. The theoretical model is shown to be accurate and can serve as a useful method to assess slamming loads under the influence of ice. It is shown that even for the case of a small piece of ice, the slamming force on the wedge can increase by 30%.  相似文献   

A method for evaluating the longitudinal functional connectivity of a river–lake–marsh system and its application in China     

Yeling Liu  Baoshan Cui  Jizeng Du  Qing Wang  Shuling Yu  Wei Yang 《水文研究》2020,34(26):5278-5297

The longitudinal functional connectivity of a river–lake–marsh system (RLMS) refers to the actual water-mediated transport of material from upstream to downstream areas along a spatial gradient and is fundamental to understand hydrological and biogeochemical cycles. However, due to a lack of consensus on appropriate data and methods, the quantification of connectivity is still a challenge, especially at the catchment scale. We developed a new method to evaluate longitudinal functional connectivity based on fluxes of materials (water, sediment, and chemicals) along a RLMS. The calculation of fluxes is based on the longitudinal pattern of terrain gradient, which influences transport efficiency, and on contributions from hillslopes, which set the initial spatial template of material loading to the RLMS. We evaluate the contributions from hillslopes to RLMS based on a new modified version of the index of sediment connectivity (IC) proposed by Borselli et al. (2008) and revised by Chartin et al. (2017).We applied this method to the Baiyangdian Basin covering an area of 3.4 × 10⁴ km² in China and quantified longitudinal functional connectivity during normal, wet, and dry periods(April, July and December) in year 2016. We found that areas with good structural connectivity exhibited poor functional connectivity during the normal and dry periods. Modelling testing with discharge data from hydrological stations and measured chemicals from Baiyangdian Lake was satisfactory in test periods. We conclude that public data and Digital Elevation Model-derived information can be used to reliably map the longitudinal functional connectivity of RLMSs. The proposed method provides a useful tool for monitoring and restoring the longitudinal functional connectivity of RLMSs and our results indicate that efforts aimed at restoring functional connectivity in RLMSs should take into account landscape patterns that can greatly influence fluxes in the watershed.  相似文献   

数字正射影像结合LiDAR数据在山区测绘中的应用     

严慧敏 《测绘通报》2020,(1):115-119

随着信息化社会的到来，现代水利测绘已经由传统测绘向信息化测绘发展，无人机技术应用于测绘行业推进了信息化测绘进程。本文探讨了如何有效利用无人机技术解决测绘领域在山区遇到的问题。固定翼无人机能及时获取地面数字正射影像数据，捕获裸露地面的平面和高程，但是无法获取植被覆盖下的地表高程信息，因此，本文通过机载激光雷达获取植被覆盖下的LiDAR点云数据；将二者数据相结合，再通过EPS软件生成三维地表模型，可以快速获取任何测区地物和地形数据，不仅提高了工作效率，还降低了外业劳动强度。  相似文献