深水多功能管道维修机具防腐涂层磨削装置研制

针对深水管道椭圆度大、水下去除管道防腐涂层作业时机具易损伤管道的问题,设计一种自适应管道表面形态变化的的磨削装置。基于边界层理论,建立磨削工具水下作业力学模型;通过机床磨削实验,研究刷盘结构参数对防腐层去除效果的影响,结果表明中密度碗形钢丝刷磨削效果最好;完成了样机的研制与陆上试验,结果验证了磨削装置设计的正确性。     

深海油气管道连接器密封机理与多目标优化研究

深海油气管道连接器的结构参数直接影响其密封性能,因而对连接器进行密封机理分析与结构参数优化研究具有重要的意义。为此,首先分析了金属接触静密封的形成机理,建立了连接器形成可靠密封的临界条件;基于接触力学推导出临界弹塑性接触压力均值的计算公式,并计算出219 mm连接器的临界值为370 MPa;应用ANSYS参数化设计语言(ANSYS Parametric Design Language,APDL),对连接器的结构参数进行了灵敏度分析,确定了影响密封性能的5个关键结构参数。进而以主、次密封面上的接触压力方差为2个目标,以主、次密封面上的接触压力均值和最大塑性应变为约束变量,运用多目标遗传算法(Multi-Objective Genetic Algorithm,MOGA)对连接器进行了优化设计,结果表明:接触压力方差显著减小,接触压力均值大于370 MPa,塑性应变较小。最后对优化前后的深海管道连接器进行了水压和拉伸试验,结果表明:优化之后的连接器承受水压能力大于设计极限压力18 MPa,承受轴向拉力大于7.0×10~5 N。该方法对于其他尺寸深海管道连接器的设计具有参考价值。     

Nonlinear dynamic analysis and fatigue damage assessment for a deepwater test string subjected to random loads

The deepwater test string is an important but vulnerable component in offshore petroleum exploration, and its durability significantly affects the success of deepwater test operations. Considering the influence of random waves and the interaction between the test string and the riser, a time-domain nonlinear dynamic model of a deepwater test string is developed. The stress-time history of the test string is obtained to study vibration mechanisms and fatigue development in the test string. Several recommendations for reducing damage are proposed. The results indicate that the amplitude of dynamic response when the string is subjected to random loads gradually decreases along the test string, and that the von Mises stress is higher in the string sections near the top of the test string and the flex joints. In addition, the fatigue damage fluctuates with the water depth, and the maximum damage occurs in string sections adjacent to the lower flex joint and in the splash zone. Several measures are proposed to improve the operational safety of deepwater test strings: applying greater top tension, operating in a favorable marine environment, managing the order of the test string joints, and performing nondestructive testing of components at vulnerable positions.     

深海立管的断裂与可靠性评估进展

针对海洋立管的疲劳、断裂及可靠性问题,详细评述近十年国内外这方面的研究成果.立管系统是近海勘探和开采工程中一个非常关键的组成部分,对于负载中的深水立管,结构失效控制和可靠性是设计中需要考虑的一个重要因素.对深水立管系统的可靠性断裂评估,应根据结构和环境情况,选取适当的评估方法.涡激振动是引起海洋深水管疲劳失效的主要因素,论述深水管的涡激振动和抑制方法,涡激振动分析结果可用于评定立管的强度和疲劳积累.最后,给出一些用于深水立管的疲劳寿命预测以及可靠性评估的实用理论和计算方法.     

南海北部神狐海域浅层深水沉积体对天然气水合物成藏的控制

南海北部神狐海域是我国海域天然气水合物（以下简称水合物）研究的热点区域,但该区域水合物储集体类型及特征尚未得到充分的认识。为此,在对不断积累的资料进行分析总结的基础上,基于高分辨率三维地震资料精细解释、岩心沉积物粒度参数描述和粒度C—M模式分析,系统探讨了该海域含水合物层与上覆不含水合物层沉积物的成因机制,分析了含水合物层沉积物粒度参数与水合物饱和度的关系,并初步揭示了深水沉积与水合物藏分布的耦合关系。研究结果表明：①该区水合物赋存在南海北部陆坡峡谷脊部和下游段—嘴部的细粒浊积体中,含水合物细粒浊积体和上覆不含水合物层的沉积物具有不同的粒度参数特征和显著的沉积成因差异;②与峡谷脊部细粒浊积体相比,峡谷下游段—嘴部的细粒浊积体中可能存在着不同成因类型的沉积物夹层,其沉积过程具有复杂性和多期性;③含水合物层的粒度分选系数与水合物饱和度关联性最大,其次为偏度,粒度参数可能通过影响储层物性进而控制水合物饱和度;④气烟囱、断层等流体运移通道和细粒浊积体共同构成水合物的“运聚体系”。结论认为,细粒浊积体和气烟囱构造的空间匹配是神狐海域水合物不均匀性分布的关键控制因素,“水合物运聚体系”控制水合物成藏的模式将有助于进一步理解深水沉积与水合物成藏的关联性。     

深水大型半潜式天然气生产平台风险管理

位于南海北部的陵水17-2气田半潜式天然气生产平台是国内首个1 500 m水深、立柱内大容量储存凝析油的半潜式生产平台,为了识别其各系统的潜在风险并进行风险管理,利用HAZOP、SIL和基于熵权的贝叶斯网络方法,结合专家的经验,对该平台的常规和特有风险进行了分析评价。研究方法和步骤包括：①确定事件与事故的因果关系,建立贝叶斯网络;②进行事故致因分析,确定最大事故致因链;③开展敏感性分析,找出对事故发生概率影响最大的事件,为风险防控提供重要依据;④依据风险识别与分析结果,针对平台各子系统提出相应的风险防控建议。由此建立了该半潜式平台的风险管理流程,将平台划分为系泊、立管、平台上部（气体接收和分离、气体压缩、气体脱水和燃气、生产水、凝析油处理、排水管和火焰）、船体设施、生活区以及货物装卸区等11个区域,针对每一个区域进行HAZID分析,识别出平台火灾爆炸、烟气扩散、船舶碰撞、落物、逃生撤离救生、化学品泄漏以及凝析油储存和外输等风险源,并给出了主要风险的应对措施。结论认为,该项研究成果对于我国未来深水油气项目的风险管理具有重要的参考价值。     

Characterisation and tissue distribution of polyphenol oxidase of deepwater pink shrimp (Parapenaeus longirostris)

Characterisation and tissue distribution of polyphenol oxidase (PPO) was studied in deepwater pink shrimp (Parapenaeus longirostris) post mortem. PPO activity was the highest in the carapace, followed by that in the abdomen exoskeleton, cephalotorax, pleopods and telson. No PPO activity was found in the abdomen muscle and in the pereopods and maxillipeds using the enzymatic assay. Storage of whole shrimps and of the different organs showed that melanosis (blackening) required the presence of the cephalotorax to be initiated, indicating that its development depends on other factors in addition to the PPO levels. Further characterisation was carried out in extracts partly purified using 40–70% ammonium sulfate fractionation. The enzyme had the highest activity at pH 4.5 and was most stable at pH 4.5 and 9.0. No clear maximum was observed in the 15–60 °C range but the higher stability was achieved at 30–35 °C. Apparent kinetic constants in the partly purified PPO from carapace were K_M = 1.85 mM and V_max = 38.5 U/mg of protein, pointing to a high affinity and reactivity of the enzyme when assayed with DOPA. Electrophoretic mobility was studied in native PAGE and non-reducing SDS–PAGE followed by staining with DOPA. Approximate MW of 500 kDa and 200 kDa were observed, respectively. These two forms could correspond to aggregates of minor PPO subunits that could not be resolved in these electrophoretic systems. The peptide mass fingerprinting obtained by MALDI-TOF analysis showed some peptides whose homology with hemocyanins and different PPO subunit precursors has already been demonstrated in the same species.     

深水盆地高温高压环境下的地层压力预测方法

目前,应用于南海琼东南盆地深水高温高压地区地层压力预测的方法主要为测井法、经验公式法、地震法等,由于其局限性及该区勘探对象的复杂性,致使应用效果不佳。为了提高该区地层压力预测的精度,在分析常规经验公式法原理和考虑区域压实背景多样性的基础上,结合已有的钻井资料,建立了不同区域、不同构造的正常压实速度趋势线,拟合速度与深度的关系,计算孔隙压力,形成了新的常规经验公式法(以下简称新方法);在Stephen公式的基础上,通过引入地层抗张强度、分段选择泊松比取值,计算了地层破裂压力。研究结果表明:(1)所建立的正常压实速度趋势线不需要对目标区内的岩性做出判断,可直接对目标区地层正常压实范围内的压实速度进行拟合;(2)当达到一定的地层深度后,纵波、横波速度比和泊松比基本上不受深度的影响,泊松比的这一特性可被用于分段计算破裂压力;(3)新方法预测的地层压力系数绝对误差小于0.07、相对误差小于5%。结论认为,基于新方法开发的压力预测平台可用于南海相关深水盆地高温高压环境下的地层压力预测,预测结果误差范围小、精度高,满足了设计要求、提高了工作效率,具有良好的应用前景。     

Model test investigation on an innovative lifting system for deepwater riser installation

An S-lay crane barge, named CNOOC 201, has been built for pipe laying in deepwater oil/gas fields in the South China Sea. It is due to be commissioned by the end of the year 2010. A special lifting system is developed to meet the challenge that installing deepwater risers from an S-lay barge is difficult and has not been achieved. The purpose of this paper was to investigate the model test on such an innovative system, which has to be done before field application. By applying the similarity theory, the movement of the S-lay barge is simulated through a six degrees-of-freedom motion platform, and a truncated model riser is utilized for the model testing. The displacement and force boundary conditions at the truncated position of the riser are obtained from the catenary governing equation and become realized by a slideway cart and a loading system designed to control the configuration of the model riser, which presents a similar configuration to a real riser in deepwater. The test results are in very good agreement with theoretical calculations, showing that the active truncated test is applicable for controlling the configuration of the deepwater riser in model testing investigation.     

Expansion of Dreissena into offshore waters of Lake Michigan and potential impacts on fish populations

Lake Michigan was invaded by zebra mussels (Dreissena polymorpha) in the late 1980s and then followed by quagga mussels (D. bugensis) around 1997. Through 2000, both species (herein Dreissena) were largely restricted to depths less than 50 m. Herein, we provide results of an annual lake-wide bottom trawl survey in Lake Michigan that reveal the relative biomass and depth distribution of Dreissena between 1999 and 2007 (although biomass estimates from a bottom trawl are biased low). Lake-wide mean biomass density (g/m²) and mean depth of collection revealed no trend between 1999 and 2003 (mean = 0.7 g/m² and 37 m, respectively). Between 2004 and 2007, however, mean lake-wide biomass density increased from 0.8 g/m² to 7.0 g/m², because of increased density at depths between 30 and 110 m, and mean depth of collection increased from 42 to 77 m. This pattern was confirmed by a generalized additive model. Coincident with the Dreissena expansion that occurred beginning in 2004, fish biomass density (generally planktivores) declined 71% between 2003 and 2007. Current understanding of fish population dynamics, however, indicates that Dreissena expansion is not the primary explanation for the decline of fish, and we provide a species-specific account for more likely underlying factors. Nonetheless, future sampling and research may reveal a better understanding of the potential negative interactions between Dreissena and fish in Lake Michigan and elsewhere.