天然气水合物样品保压转移及处理技术系统设计

天然气水合物样品保压取样技术已经成熟,但保压样品只能进行压降处理成为常压样品,这种方法很大程度上影响了水合物在沉积物中的存在初始状况,压力的急骤变化以及温度的变化都会引起沉积物中水合物成分析出,影响后处理的判别。样品保压转移及处理技术不仅是未来天然气水合物资源勘探技术的发展趋势,也是重要技术手段之一。天然气水合物保压样品的获取、检测、处理是天然气水合物取样技术从初级走向成熟阶段的重要标志。介绍了天然气水合物沉积物样品保压转移及处理技术的设计思路及系统各组成单元。该系统主要由天然气水合物样品保压转移系统、天然气水合物保压样品在线探测及岩心分析系统等2部分组成。该系统的设计为今后天然气水合物资源的勘探和开发提供了很好的技术支撑。     

天然气水合物保压子取样装置压力特性研究

从海底采集的长柱状保压天然气水合物一般不能被直接分析,需要被切割成小段再转移。保压子取样装置是在天然气水合物保压转移系统的基础上研发的,该装置能够获取任意小尺寸的带压岩心,并将其转移到测试装置中进行原位检测。介绍保压子取样的总体结构和工作原理,并分析系统压力变化的趋势,然后利用AMESim软件对压力维持部分进行仿真,最后通过水合物转移实验,验证保压子取样技术的可行性。重点讨论了蓄能器对于系统压力维持能力的影响,得出预充压力越大蓄能器保压效果越好的结论。     

区别于DSDP-ODP的深海保压保温天然气水合物钻探取心技术

到目前为止，任何深海天然气水合物原位岩心样品的钻探、取心技术都离不开ODP(大洋钻探计划)或DSDP(深海钻探计划)专用船舶钻探技术，该技术主要通过从工作母船上连接几百到几千米钻杆到海底，实现500—1000m的钻探，再通过不同类型PCS(保压取心器)与PTCS(保压保温取心器)取心工具实现样品采集。重要特点是投入经费巨大。新型保压保温取心钻具是将钻具直接固定在深海海底，实现样品的原位保真采集，针对国内外两类着底式天然气水合物钻探、取心技术进行了分析，对于深海浅表层天然气水合物原位样品采集作业反映了创新的思维、技术模式、设计方案与科学方法     

非保温保压采集深海天然气水合物原位样品的外观与保存状况研究

因为取样时未使用保温保压工具，所以通常情况下采集到的天然气水合物样品在被放入液氮罐冷藏之前，必定已经发生了部分分解；具有代表性意义的ODP 204取得的样品85％分解了，且转变成六方晶体冰。因此，分析描述天然气水合物分解的状况、外观和特征十分必要。综述了利用可确定天然气水合物中冰、水合物和其他矿物相对数量以阐明其保存程度的同步加速X光衍射（XRD）技术和可在低至几十纳米分辨率条件下对样品进行详细观测的低温扫描电镜技术进行非保真采取水合物样品外观和保存状况研究的概况，包括Ⅰ型结构水合物及孔隙横截面均为六边形和亚微米级孔隙区域到密集孔隙区域特征等成果，指出取心时水合物分解耗热，是吸热反应并导致分解释放水同步冻结；同时气体膨胀和气体脱溶也形成冰；这类样品中天然气水合物周围小区域内温度很低并在局部成冰，水合物实现自我保存，这一特性允许天然气水合物在稳定正常的温压条件以外存在一段时间，对于天然气水合物商业储运具有重要意义，但是，多数情况下水合物还是分解了。在“水合物海脊”，样品含天然气水合物量仅少数超过15％，极少数达到70％，只有在原位状态为大块状的天然气水合物中，才可以用肉眼观察到高含量的天然气水合物组分。     

新型深水天然气水合物保真筒保压特性研究

为解决国内现有天然气水合物采样器无法实现大深度保真取样的问题,提出一种配套气垫式保真筒的深海天然气水合物采样器,并以气垫式保真筒的保压特性作为研究重点。在考虑采样过程中样品自身体积膨胀因素的基础上,建立了不含气垫保真筒和气垫式保真筒的数学模型,并通过仿真计算,对不含气垫保真筒和气垫式保真筒的保压特性进行了分析。实验结果表明基于样品自身体积膨胀的不含气垫的保真筒和气垫式保真筒保压特性理论研究是正确的,同时,也表明气垫式保真筒具有良好的保压性能,极具开发价值。     

深海热液样品保温保压储存装置系统设计

设计了一套深海热液样品保温保压储存装置,该装置由结构系统和控制系统两部分组成,可实现热液样品的长时间自动保真储存,并可完成样品由该储存装置到后续培养分析设备的分时、分批转移。结构系统由支撑架、筒体、自动保压系统组成,筒体保温储存样品,自动保压系统对样品长时间自动保压。控制系统由PLC控制加热,并能实现样品状态参数的自动采集和全程记录。整个装置结构简单紧凑、功能完备,为深海热液样品的长时间保真储存以及转移提供了一套安全可靠的装置。     

南海北部天然气水合物研究进展

天然气水合物是一种新型的储量巨大的绿色能源,是目前世界各国研究界的研究热点之一。我国以及美国、日本、印度、韩国等国家都采集到了天然气水合物的实物样品。虽然我国对天然气水合物的研究起步较晚,但近年来的研究已经取得了飞速的进步,而且也于2007年5月在南海北部陆坡的神狐海域成功采集到天然气水合物的实物样品,这是在南海海域首次获取天然气水合物实物样品,证实了南海北部蕴藏着丰富的天然气水合物资源,标志着我国天然气水合物调查研究水平又上了一个新的台阶。目前,南海北部陆坡已经作为我国天然气水合物未来开发的战略选区之一。在总结我国天然气水合物以往十几年研究工作的基础上,综述了我国天然气水合物近年来在南海北部的地质、地球物理、地球化学3个方面的研究进展,提出了未来天然气水合物勘探和研究的方向和建议。     

天然气水合物分解对海底斜坡稳定性影响研究进展

天然气水合物作为一种新型能源,已经逐渐引起人们的重视。赋存于海底沉积物中的天然气水合物虽然本身作为亚稳定胶结物对海底有建造作用,但是由于其对特定温度和压力条件的严格依赖,海底温压条件的改变会引起其分解,从而使海底沉积物失稳甚至导致海底滑坡。本研究系统介绍了近年来国内外针对天然气水合物合成、物理性质及对海底稳定性影响进行...     

流体剖面上溶解硫酸盐的含量能否反映原地甲烷通量

在天然气水合物稳定带中，受生物地球化学因素制约的甲烷通量是控制天然气水合物分布和含量的关键。我们将通过非保压岩心和保压岩心数据进行说明，这些数据分别来自孟加拉海两个海盆：克里希纳河－哥达瓦里河盆地（K—G）和印度东南部近海的Mahanadi盆地（水深9001170m），以及位于安达曼海（水深1600m）的1个站位和卡斯卡底古陆（水深890m）的水合物脊上的2个站位。以上所有站位都发现了天然气水合物存在的证据，但每个站位水合物的含量、分布和含水合物沉积物的结构各不相同。     

气垫式保真筒保压特性的参数影响分析

介绍配套了气垫式保真筒的深海天然气水合物采样器的结构及其工作原理,同时为提升气垫式保真筒的保压性能,基于压降模型仿真分析了关键参数(预充压力、气腔长度、筒体长度、筒体内径和筒体壁厚)对采样终了筒内压降的影响。仿真研究结果表明:预充压力、气腔长度和筒体壁厚对气垫式保真筒的保压性能影响较大,且取值越大保压效果越好;筒体长度、筒体内径与筒内压降正相关且对其影响较小;同时综合保真筒的整体性能来讲,提高预充压力和增加气腔长度是提高气垫式保真筒的保压性能可选的有效方式。     

压力传感器的自动标定技术

针对压力测量设备生产和维护过程中,对关键部件压力传感器标定处于手工操作状态、效率低、操作人员不易掌控、标定结果处置复杂的现状,开发了针对压力传感器的自动标定技术。该技术将计算机控制、智能化、曲线拟合和误差分析引入到压力传感器的标定过程中,大幅度提高了标定的效率和可靠性。经此技术标定过的压力探头,在使用中具有互换性,减轻了数据后处理工作的难度。     

Calculation of Wave Pressure and Pressure Spectrum for Perforate-Pipe Breakwater

Standing waves are formed due to the reflection when waves meet vertical wall,thereforestrong structures are needed to keep the wall stability under the serious wave attack.For the improvementof the working condition and increase of the stability of the wall,the lower reflecting breakwaters have at-tracted close attention Reports mostly from Japanese researchers are often concerned with the wall ofcaisson equipped with open windows.In this paper a kind of hollow-pipe perforated breakwater is exam-ined which waves may partially perforate into the harbour basin.The wave in front of the wall can onlyform partial standing wave and wave force is reduced obviously.And the theoretical calculation of waveforce and analysis of wave force spectrum are all derived.Comparison between the results from theoreticalcalculation and hydraulic modeling shows reasonable agreement.     

Argo剖面浮标压力测量误差问题剖析

部分配置Druck压力传感器的APEX型Argo剖面浮标所观测的压力值存在明显偏差.尽管压力传感器故障的原因已经查明,但目前还没有寻找到一种比较理想的解决方法.文章扼要介绍了压力传感器故障产生的原因.探讨了压力误差校正的办法,以及目前可供选择的措施等.供国内浮标技术研制人员和Argo、CTD用户参考.     

Buckling Properties of Water-Drop-Shaped Pressure Hulls with Various Shape Indices Under Hydrostatic External Pressure

The water-drop-shaped pressure hull has a good streamline, which has good application prospect in the underwater observatory. Therefore, this study conducted analytical, experimental and numerical investigation of the buckling properties of water-drop-shaped pressure hulls under hydrostatic pressure. A water-drop experiment was conducted to design water-drop-shaped pressure hulls with various shape indices. The critical loads for the water-drop-shaped pressure hulls were resolved by using Mushta...     

Pressure Dependence of Cymbal Transducers

The hydrostatic pressure limit that a receiver can withstand without failure is of major importance in underwater sonar systems. In this paper, the hydrostatic pressure tolerance and sensitivity of cymbal receivers were investigated. The failure mode in cymbal transducers under hydrostatic pressure is described. Effects of cavity geometry and material selection on hydrostatic piezoelectric coefficients and pressure limits were evaluated using both experimental data and finite-element analysis (FEA). It was found that cavity depth has a very strong effect on the stability of underwater sensitivity and pressure tolerance of these devices. Cymbals made with soft piezoelectric transducers (PZTs) possess higher figures of merit and better pressure tolerance than those made with hard PZTs. Alternatively, the cymbal sensitivity and pressure tolerance can be improved by changing the cap material.     

Pressure significance of gas chimneys

Analysis was carried out of part of the northern North Sea to test what the presence and style of gas chimneys indicate about fluid pressure (P_f) within hydrocarbon reservoirs. Previous results suggest that broad chimneys above a trap and thin chimneys on the flanks indicate the presence of hydrocarbons, whilst thin chimneys in the crest suggest the hydrocarbons have escaped. Each type of gas chimney is usually associated with overpressure within Mesozoic reservoirs, but the water leg is hydrostatically-pressured in most Cenozoic reservoirs. This indicates: (a) gas leaking from a trap does not necessarily cause P_f to become hydrostatic; (b) overpressure may not be necessary for the expulsion of gasses through seal units to create the chimneys; (c) although gas chimneys indicate the existence of an active hydrocarbon system, their presence does not appear to indicate anything significant about present-day P_f.     

Pressure cells and pressure seals in the UK Central Graben

The Central Graben of the North Sea is characterised by high levels of overpressure (up to 40 MPa overpressure at 4500 m depth). We present pressure data for Cenozoic and Mesozoic reservoirs. Palaeocene sandstones control pressures in Tertiary mudstones and Cretaceous Chalk by acting as a regional ‘drain’. We divide the Jurassic into 18 pressure cells. The rift structure of the Graben controls the magnitude of pressure in each cell. Lateral hydraulic communication exists over 10 km distance between deeply-buried terraces (> 5000 m depth) and shallow structural highs (< 4500 m depth). Lateral communication increases pressure in the structurally-elevated sandstones to the minimum stress. This dynamic process produces zones of vertical fluid flow on the Forties-Montrose High, termed Leak Points. Vertical flow at Leak Points produces a 20 MWm⁻² heat flow anomaly and controls hydrocarbon retention. Leak Points are water-wet, while deep terraces in hydraulic communication with Leak Points are condensate-bearing. The Kimmeridge Clay Fm. forms the pressure seal in deep terraces.     

OWC装置空气透平压降作用试验研究

空气透平的压降作用及由其带来的空气流速变化,是串联2次能量转换过程、实现两转换过程耦合的核心要素.试验主要是在物理模型的基础上,对带有冲击式透平的OWC装置能量转换影响因素进行研究.试验主要考察2次能量转换耦合作用下,气室内自由水面变换、气室内压强变化、输气管内空气流速变换及三者耦合与相互作用.     

Pressure resistance of the corrugated stainless steel membranes of LNG carriers

Corrugated stainless steel membranes have been used as the primary barriers for LNG carriers to reduce thermal stresses at cryogenic temperatures. As the capacity of the LNG cargo is increased, however, the corrugated stainless steel membranes suffer from buckling and collapse due to increased sloshing loads in large-capacity LNG cargo carriers. In this study, the pressure resistance of the corrugated part of the stainless steel membrane was evaluated using a finite element method for better design of the LNG containment system, and an experimental equipment was developed and the pressure resistance of the stainless steel corrugations was measured and compared with the calculated results. In addition, a new membrane with high-pressure resistance and its reinforcing method were developed and evaluated experimentally.     

Behavior of Vertical Pressure Imposed on the Bottom of a Trench

A series of model tests were performed to investigate the behavior of vertical pressure imposed on the bottom of a trench. The tests were conducted in two phases to generate soil arching due to soil deformation: (1) the backfilling phase and (2) the lowering-bottom phase. First, the backfilling phase was performed by filling sand into the trench, in which soil deformation was developed due to selfcompaction by the weight of the sand. The lowering-bottom phase was then conducted by lowering the bottom plate of the trench to induce additional soil deformation. The behavior of the vertical pressure acting on the bottom of the trench during the backfilling phase can simulate that of the vertical pressure imposed on the bottom of buried rigid pipes. The behaviors of buried flexible pipes could be observed during the lowering-bottom phase, in which both the minimum and the maximum vertical pressures could be obtained according to the induced soil deformation. A novel method for predicting the vertical pressures in each phase was proposed. The agreements between the predictions by the proposed method and the experimental results were demonstrated.