基于模型的地震波阻抗反演在水平井随钻跟踪中的应用

在水平井地质导向随钻跟踪中,通常利用临井的测井资料建立地质导向前导模型指导随钻.该模型在水平井着陆阶段能相对准确地预测目的层的深度,但在水平段随钻跟踪时,要保证钻头始终控制在目的层内物性较好的部位钻进,仅靠临井的井资料插值预测储层物性,误差就比较大.为此,针对地质导向前导模型储层横向非均质预测的缺陷,把基于模型的地震波阻抗反演技术引入到地质导向模型修正中,预测目的层横向非均质性,指导水平井水平段随钻跟踪服务,以控制井轨迹始终在储层物性较好的部位钻进,提高储层钻遇率.此方法经过实钻水平井的验证,达到了良好的效果.     

随钻监测技术在气体钻井中的应用

气体钻井是近年来兴起的一种实用钻井技术,具有保护油气产层、提高钻速、缩短建井周期及处理井漏事故等优点,应用范围越来越广泛。与常规钻井液钻井相比,气体钻井是单向循环,使用气体作为循环介质来携带岩屑、清洗井眼,使得现有录井监测系统还不能满足气体钻井现场参数监测需要,易出现钻具失效、井下燃爆、地层出水及井壁坍塌等复杂钻井问题,影响气体钻井的安全性。基于井下燃爆理论和监测监控系统技术,开展了随钻监测基本原理研究,形成了UBD气体监测系统及分析技术;通过在多口井气体钻井现场服务,验证了气体监测系统及分析技术的合理性和实用性,为安全顺利实施气体钻井提供了有力的技术支持。     

东营城区高精度三维地震采集方法研究

根据东营城区内建筑物较多，环境干扰较大，地下构造复杂，断裂非常发育，目的层埋藏深，资料信噪比较低的特点，以地震老资料和钻井资料为基础，建立地震地质模型，利用射线追踪技术选取合适的观测系统参数。充分利用卫星数字地图，没计了灵活多变的观测系统，采用可控震源与炸药震源配合使用方法，及时对城区内地下面元的覆盖次数、方位角和炮检距的分布进行质量监控，利用现场处理系统对资料进行及时分析，提高了地震资料品质。所获得的东营城区高精度三维地震采集资料显示，其浅中层分辨率和中深层信噪比都有了明显改善，取得了良好的地质效果。     

南海北部揭阳凹陷天然气水合物的地震异常特征分析

大量研究表明南海北部珠江口盆地是天然气水合物发育区,但是该盆地东部揭阳凹陷水合物研究较少。本文利用揭阳凹陷新采集三维地震资料,对该三维地震资料进行成像道集优化和叠前时间偏移处理,得到针对水合物的新处理地震数据体,并通过高精度网格层析反演得到层速度数据体。利用该数据开展叠后约束稀疏脉冲反演,获得含天然气水合物地层波阻抗异常,综合分析反演与地震属性识别水合物。从新处理地震资料看,该区域似海底反射(bottom simulation reflection,BSR)反射呈连续、不连续与地层斜交等特征,BSR发育在一个继承性小型水道上,且下部断裂和气烟囱发育。通过分析BSR特征及BSR上下地层的速度、波阻抗、振幅、频率、相干等属性异常,结合水合物成藏条件,发现了南海北部新的天然气水合物有利富集区,为该区域水合物勘探提供基础。     

地震测井联合反演技术在南黄海盆地北部坳陷中生代储层预测中的应用

在构造复杂和测井资料少的海域,有效地进行地震反演和储层预测是油气前景评价的关键。针对南黄海盆地白垩系砂岩储层中岩性复杂和物性高度非均质的问题,采用了测井、地震资料联合的稀疏脉冲约束反演方法和构造形态约束下的低频模型构建技术,对二维多道地震数据进行了目标层波阻抗反演处理,并对白垩纪砂岩储层的横向分布进行了追踪预测。结果表明:地震波阻抗剖面能够刻画储层的空间展布特征,表征储层内部物性变化,预测有利储层分布范围;储层预测认为白垩系泰州组发育多层低波阻抗的泥岩生烃层,中间夹两层波阻抗较高的砂层,与钻井资料对比为物性较好的油气储集层。     

基于HHT方法的地层Q值补偿方法研究

常规的基于叠后地震资料的地层Q值补偿方法受数据平均效应的影响,Q值估算精度较低,导致保真性差,而HHT时频分析可以反映出信号的局部信息,基于以上原因,提出一种基于HHT方法的地层Q值补偿方法。首先应用HHT分频技术将浅层、中深层地震数据分成不同的频率范围,得到不同目标层频率尺度的地震数据;然后在HHT时频域内通过谱比法提取Q值;最后分别进行地层Q值振幅补偿和相位补偿。该方法针对不同的目标地层将地震数据分解成不同的频率尺度,避免了不同频率成分之间的干扰,而且可针对性处理目标层的频率信息,提高了地层Q值提取的稳定性。模型试算和实际资料应用表明,该方法能够有效地对振幅和相位进行补偿,使中深层反射波形得到恢复,主频提高,频带展宽,地震资料的品质得到提升。     

海洋多道地震拖缆数据实时传输系统的设计与实现

为满足深拖式高分辨多道地震勘探需求,设计并实现了海洋地震拖缆数据的实时传输系统。系统由数传包与地震采集站连接组成,采用推荐标准485(Recommended Standards 485,RS485)串行总线实现了采集站与数传包的物理连接,利用低电压差分信号(Low-Voltage Differential Signaling,LVDS)、预加重/均衡器、8位/10位(8 bit/10 bit)编码等技术实现了数传包之间的通信链路。设计了无等待反馈重传的差错控制方法,提高系统高效性和可靠性;在现场可编程门阵列(Field Programmable Gate Array,FPGA)内部采用先进先出(First Input First Output,FIFO)构建多优先级任务队列的多级流水线设计,解决了大容量数据并发而产生的数据漏帧问题。在实验室用已知正弦信号对系统进行了对比测试,结果表明系统能够满足海洋多道地震勘探的数据传输需求,对于海洋多道高分辨率地震资料的可靠获取具有重要的意义。     

南海西南次海盆反射莫霍面成像及其地质意义

深部地质结构是研究海盆动力成因的重要基础。南海西南次海盆以往多道地震资料中莫霍面的成像普遍不清,选取NH973-1测线长排列多道地震数据对西南次海盆的莫霍面反射成像进行研究。该地震资料中层间多次波非常发育,严重掩盖或干扰了莫霍面有效反射信号。针对地震资料特征,首先采用抛物线型Radon变换滤波对部分层间多次波进行压制以拾取一个相对准确的初始速度,在此基础上进一步采用速度滤波和内切除组合方法对层间多次波进行压制。从资料处理效果看,层间多次波得到有效压制,莫霍面成像清晰,呈现出断断续续的特征。由此解释的海盆区地壳(除沉积层外)厚度整体较薄,约为2.3~3.9km,有别于正常洋壳结构,更接近于构造拉伸主导型的地壳。     

东沙海域复杂海况下单源单缆长排列地震资料处理*

大量研究表明南海北部东沙海域的中生界地层具有很好的油气成藏条件, 是油气勘探的有利区域。但中生界地层构造成像不清晰限制了该区域油气资源的准确评价。本文利用在该海域采用单源单缆长排列采集的三维地震数据, 提出了对该类数据的优化处理技术方案, 以期获得中生界地层的清晰成像。处理过程主要包括各种噪音干扰和不同类型多次波的压制, 尤其是比较严重的海洋湍流干扰压制, 提高中深层反射信号信噪比; 通过压制气泡和压缩子波提高地震反射的分辨率; 同时利用高密度速度分析进行各向异性双谱非双曲线动校正, 提高成像质量, 使波组特征、振幅特征更为明显。针对密集二维采集数据特点, 通过合理的面元规则化处理, 使得覆盖次数均匀和横向分辨率提高, 实现高精度三维成像。本研究针对噪音干扰较严重的单源单缆长排列加密地震资料, 按照三维地震资料进行数据处理, 处理后明显突出了浅、中、深各层的有效信息, 特别是针对中生界的成像质量改善更为明显, 形成了一套行之有效的处理流程, 为今后邻近区块的勘探和资料处理提供了技术基础, 也为东沙海域的油气勘探与评价提供了科学依据。     

海洋油气勘探钻录测井数据可视化分析

海洋油气勘探是国家地质勘探的基础工作之一,与国家的发展紧密相连。通过详细分析海洋油气勘探钻录测的数据需求和业务需求,设计了基于"三层"体系结构的海洋油气勘探钻录测数据库平台,并构建了海洋油气勘探钻录测数据库。针对海洋油气勘探钻录测数据可视化分析进行了重点研究,实现了钻井柱状图的自动生成和基于测井曲线数据的自动分层分析,通过海上某井的海洋油气勘探钻录测数据的实际应用,验证了数据库平台高效性以及钻录测数据可视化分析模块的实用性,表明该模块对海洋油气勘探工作具有一定的应用价值。     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone.     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.     

Flow Cytometric Analysis of Coastal Lagoon Bacterioplankton and Picophytoplankton: Fixation and Storage Effects

The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics.     

INFORMATION FOR AUTHORS

<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology,     

Estimation of Sediment Properties during Benthic Impact Experiments

Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans. The estimates show that the weights of dry (355-1332 t) and wet sediment (1651-4888 t) recovered during the experiments, are not only a function of the total duration and distance covered during the experiment, but also depend on water content and density of the sediment. Estimation of dry sediment and its volumetric ratio in the discharge, are key parameters for calculating the discharged volume. The estimated volume of wet sediment recovered (1427-4049 m 3 ) as well as discharged (2693-6951 m 3 ) during the experiments, provide important inputs to evaluate the sediment resettlement and migration. Using these estimates, the average depth of excavation on the seafloor, can also been calculated. However, the stages of sediment recovery and discharge are expressed differently in some of the experiments. In order to standardize these, different stages have been identified, and definitions of certain terms have been suggested, for use in the future. The methods of calculating different properties, as well as weight and volume of discharged sediment are described in the paper for use in other applications concerning deep-sea discharges.