共查询到17条相似文献，搜索用时 140 毫秒
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国外的水合物探测试验证明,可控源电磁法是探测天然气水合物的有效方法之一.开展海底可控源电磁法工作的重点之一在于研制高精度、高可靠、低功耗观测海底可控源电磁信号的设备.为可靠地观测海底可控源电磁场宽频带、大动态范围信号,设计了以Linux与ARM9相结合的测量电路,并开发了Linux2.4内核下的设备驱动程序.本文分别论述了采集硬件原理,Linux字符设备驱动模型,SSC和GPS对钟驱动实例. 相似文献
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为了测试我国自主设计与研发的海洋可控源电磁仪器性能及其在水合物探测中的适用性,本文从海洋可控源电磁法基本原理出发,首先根据试验海域水合物地质特征,建立简化地电模型开展理论研究,确定海洋可控源电磁试验的技术方案;利用研发的海洋可控源电磁仪器,在南海天然气水合物远景区开展探测试验,首次获得了我国深水海域的海洋可控源电磁数据.通过对采集数据进行处理与反演,获得了试验剖面的海底电性结构模型,揭示了4号测点下方存在一个50m厚的高阻层,其电阻率为25Ωm、顶部埋深为181m,为该区天然气水合物调查提供了有价值的电性参考资料.研究结果表明,自主研发的海洋可控源电磁仪器性能达到了预期的设计指标,这标志着我国海洋可控源电磁探测技术向实用化进程迈出了重要一步. 相似文献
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采用海洋可控源电磁方法进行海底油气和水合物的勘查,需事先在海底布放接收机阵列,而后用一艘携带深拖缆的科考船将大功率电磁发射机牵引至海底,沿预设路线慢速走航,并将大功率电磁场导入海底.海底的人工电磁场中,空气波和直达波对提取勘探目标体的异常信息不做贡献.只有当折射波经过被测目标体时,产生电磁感应,海底的接收机对此感应信号进行数据采集,经数据处理,揭示被测目标体的几何大小和物理属性.异常体的有用信息与导入海底电磁场的能流密度(坡印廷矢量)有着密切的关系,以致于后者决定了前者的有效探测范围、有效带宽以及尽可能达到的最佳测量精度.能流密度在海底的分布情况十分复杂,但在均匀全空间中可较清楚地认识其分布特征,可为复杂地质条件的情况作理论铺垫.以此推广,在水平层状介质的地电条件下,建立能流密度的数理模型,利用海洋生产作业中的典型物性与几何参数,对海底以下有覆盖层的高阻体(可模拟油气或天然气水合物)进行正演,建立电磁场能流密度分布特征与数据采集技术的有机联系,为海洋可控源电磁发射机和接收机的优化改进提供理论依据. 相似文献
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海底采集到的电磁数据按照其主要包含的信息及研究目的大致可分为海洋可控源电磁场(CSEM)信号、天然场源大地电磁场(MT)信号、海洋环境电磁场信号以及其他随机干扰信号.常常通过计算功率谱密度、时频分析和极化分析的方法研究海洋电磁场特征.本文介绍一种新方法——时频方向谱分析法及其在实测海洋电磁数据处理中的应用,该方法能够在一定的时间-频率尺度上有效分辨场源信号的运动方向.对于海洋CSEM数据,利用该方法可以估算发射源的运动方向,进而在发射源或采集站方位信息缺失情况下,实现海洋CSEM数据的旋转电性轴处理.对于海洋电磁数据,利用该方法可以详细分析海水运动感应电磁场的信号特征. 相似文献
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南海琼东南盆地是天然气水合物重要远景区之一.由于盆地大部分地区海底地形平缓、地层近于水平,增加了利用地震反射剖面识别似海底反射（BSR,bottom simulating reflector）的难度,从而影响了对水合物的评价.为了进一步开展琼东南盆地水合物调查研究,本文在研究海域进行了海洋可控源电磁探测试验,将自主研发的10台接收机以500 m的间距,投放至水深约为1360 m的海底,完成了一条4.5 km剖面的电磁数据采集.通过对采集的数据进行处理与二维（2D）反演,获得了研究剖面海底的电阻率断面图.反演结果显示,研究区海底60~330 mbsf（meter bottom of seafloor）的地层中,存在多个横向不连续分布的高阻异常体,电阻率介于2~10 Ωm之间;在海底330 mbsf之下,横向上发育了电阻率为2~4 Ωm的3个高阻体.根据研究区热力学条件,本文估算了生物成因气与热成因天然气的水合物稳定带（GHSZ,gas hydrate stability zone）厚度,结合高阻体的分布特征推断了地震剖面上BSR的位置.在此基础上,对反演的电阻率断面进行解释,推断了研究区水合物的分布及游离气运移通道.研究表明,勘探区具有形成天然气水合物矿藏的地质与地球物理条件,其成藏模式可能属于"断层、裂隙输导的下生上储型",水合物的气源为生物成因气. 相似文献
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海洋可控源电磁探测(MCSEM)是勘查天然气水合物资源的有效方法之一.海洋可控源电磁发射系统是实现MCSEM的重要硬件组成部分.本文以天然气水合物在海底的一维地电模型为例,研究电偶源发射频率、发射偶极侧向漂移、源偶极矩大小对电场响应的影响,进而指导发射系统研制.该系统包括:甲板升压控制单元,可将船载大功率电能升为高压并通过万米光电复合缆输送至海底的发射机;水下变压器,可将深拖缆中的大功率高压转换为低压;拖曳式大功率电磁发射机,其内部的控制电路硬件和嵌入式驱动软件可将水下变压器输出的电能逆变为大功率矩形脉冲,并通过发射偶极将脉冲发送至海水介质中;借助水动力学设计的发射机拖体,用于装载发射系统水下部件和保持拖曳过程中的平衡与稳定;甲板端上位机监控单元,利用万米光电复合缆中的光纤实现船上计算机与海底发射机的远程数据通信.2012年5月和2013年5月海洋试验的结果均表明,所研制的发射系统可作为天然气水合物资源勘探的有效激励场源. 相似文献
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海洋天然气水合物资源调查中,电磁法已成为地震勘探最有效的补充手段之一,而我国海洋水合物电磁探测中的拖曳式电场接收机此前是空白.本文从方法原理、仪器设备和海洋试验等方面,对海洋拖曳式水平电偶极-偶极方法进行研讨.建立三维电阻率模型,进行数值模拟,讨论收发距、发射频率、拖曳装置离海底高度等参数与电场异常响应的关系,针对特定模型给出了最佳观测参数以指导仪器硬件设计与海洋测试.在此基础上,采用高级嵌入式计算机的智能化控制、前端低噪声斩波放大、高精度同步采集等技术,研制了由拖体、承压舱、采集电路、低噪声电场传感器等组成的海洋拖曳式水平轴向电场接收机,其系统噪声达到2 nV/√HZ
@(1~100Hz).将自主研制的电场接收机用于国内首次拖曳式电偶极-偶极方法的海洋试验与评估,并对海试资料进行了处理与分析.研究结果表明,所研发的仪器达到了设计指标,能够用于海洋天然气水合物调查. 相似文献
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本文实现了2.5维电导率正交各向异性海洋可控源电磁等参有限元数值模拟.利用傅里叶变换导出了电导率正交各向异性2.5维海洋可控源电磁法波数域电磁场耦合方程,采用伽里金加权余量法推导了相应的有限元方程;采用任意四边形单元对研究区域进行剖分,在单元中进行双二次插值,将有限元方程化为线性代数方程组;最后,求解线性方程组并进行反傅里叶变换获得空间域电磁场值.这个方法可以模拟海底起伏地形条件下地下任意形状电导率正交各向异性的复杂模型.与一维模型的数值模拟结果对比表明,电磁场数值解与解析解吻合.二维模型的计算结果与二维自适应非结构有限元模拟结果也吻合.水平海底二维地电模型考察了不同各向异性系数对海洋可控源电磁响应的影响特征.海底起伏地形地电模型的数值结果表明,电导率各向异性对海洋可控源电磁响应影响明显,有可能淹没海底地形和高阻油气藏引起的异常. 相似文献
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在海洋可控源电磁法勘探中,接收站常置于海底.在进行海洋电磁场模拟时,由于海水和海底介质存在显著电性差异,这给海底接收点处场值的求取带来困难.本文提出一种新的接收点插值算法,该算法考虑到海底电场法向分量不连续性问题,用法向电流分量进行插值以准确求取海底任意接收点处电磁场值.本文利用交错网格有限差分法实现了二维介质中频率域海洋可控源法(CSEM)正演.对构造走向做傅里叶变换,将三维电磁模拟问题转换为波数域2.5维问题,即三维场源激励下针对二维地电模型的电磁模拟问题.使用交错网格有限差分法,基于一次场/二次场分离方法导出波数域二次电场离散形式,并进一步求得波数域电磁场.采用本文提出的改进的插值算法可求得海底任意接收点处波数域电磁场,采用傅里叶逆变换对波数域电磁场进行积分可得到接收点处空间域电磁场.模型算例表明,与常规的线性插值和严格插值算法相比,本文提出的改进的插值算法具有更高的精度. 相似文献
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A new marine controlled‐source electromagnetic receiver with an acoustic telemetry modem and arm‐folding mechanism 
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下载免费PDF全文 We developed a new marine controlled‐source electromagnetic receiver for detecting methane hydrate zones and oil and gas reservoirs on the seafloor, which is not imaged well by seismic reflection surveys. To determine the seafloor structure, the electromagnetic receiver should have low noise, power consumption, clock drift error, and operating costs while being highly reliable. Because no suitable receiver was available in our laboratory, we developed a new marine controlled‐source electromagnetic receiver with these characteristics; the receiver is equipped with acoustic telemetry modem and an arm‐folding mechanism to facilitate deployment and recovering operations. To demonstrate the applicability of our new receiver, we carried out a field experiment offshore of Guangzhou in the South China Sea, where methane hydrates have been discovered. We successfully obtained controlled‐source electromagnetic data along a profile about 13 km long. All six new receivers were recovered, and high‐quality electromagnetic data were obtained. Relatively high apparent resistivity values were detected. The results of the offshore field experiment support the claim that the electromagnetic data obtained using the new receiver are of sufficient quality for the survey target. 相似文献
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In order to suppress the airwave noise in marine controlled-source electromagnetic （CSEM） data, we propose a 3D deconvolution （3DD） interferometry method with a synthetic aperture source and obtain the relative anomaly coefficient （RAC） of the EM field reflection responses to show the degree for suppressing the airwave. We analyze the potential of the proposed method for suppressing the airwave, and compare the proposed method with traditional methods in their effectiveness. A method to select synthetic source length is derived and the effect of the water depth on RAC is examined via numerical simulations. The results suggest that 3DD interferometry method with a synthetic source can effectively suppress the airwave and enhance the potential of marine CSEM to hydrocarbon exploration. 相似文献
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地层宏观电性各向异性会对可控源电磁响应产生重要影响.由于海底地层电性结构常表现为电导率各向异性,若仅对海洋可控源电磁(MCSEM)数据进行常规各向同性反演,有可能无法获得准确的反演解释结果,从而削弱MCSEM技术的可靠性.本文实现了电导率垂直各向异性(VTI)条件下频率域海洋可控源电磁数据三维反演算法.其中,三维正演采用基于二次场控制方程的交错网格有限体积法,并利用直接矩阵分解技术来求解离散所得的大型线性方程组,有利于快速计算多场源的响应.反演采用具有近似二次收敛性的高斯牛顿算法对目标函数进行最优化.最后,对具有VTI电性各向异性特征的盐丘构造模型的MCSEM合成数据分别进行了电导率各向同性和垂直各向异性三维反演,结果表明:各向同性三维反演算法无法对受VTI介质影响的MCSEM数据进行正确的反演解释,而垂直各向异性三维反演能够获得更为可靠的地下电阻率结构和异常体分布,展现出对海底电性各向异性结构更为优良的反演解释能力. 相似文献
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The marine controlled source electromagnetic (CSEM) technique has been adopted by the hydrocarbon industry to characterize the resistivity of targets identified from seismic data prior to drilling. Over the years, marine controlled source electromagnetic has matured to the point that four‐dimensional or time lapse surveys and monitoring could be applied to hydrocarbon reservoirs in production, or to monitor the sequestration of carbon dioxide. Marine controlled source electromagnetic surveys have also been used to target shallow resistors such as gas hydrates. These novel uses of the technique require very well constrained transmitter and receiver geometry in order to make meaningful and accurate geologic interpretations of the data. Current navigation in marine controlled source electromagnetic surveys utilize a long base line, or a short base line, acoustic navigation system to locate the transmitter and seafloor receivers. If these systems fail, then rudimentary navigation is possible by assuming the transmitter follows in the ship's track. However, these navigational assumptions are insufficient to capture the detailed orientation and position of the transmitter required for both shallow targets and repeat surveys. In circumstances when acoustic navigation systems fail we propose the use of an inversion algorithm that solves for transmitter geometry. This algorithm utilizes the transmitter's electromagnetic dipole radiation pattern as recorded by stationary, close range (<1000 m), receivers in order to model the geometry of the transmitter. We test the code with a synthetic model and validate it with data from a well navigated controlled source electromagnetic survey over the Scarborough gas field in Australia. 相似文献
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海洋天然气水合物可控源电磁法的响应特征:一维正演模拟 总被引：1，自引：1，他引：0
We discuss the feasibility of using controlled-source electromagnetic （CSEM） in the frequency domain for prospecting marine gas hydrates. Based on the Ocean Drilling Program （ODP） Leg 164 log data, we have established several 1-D resistivity models which have different gas hydrate concentrations. Meanwhile, we analyzed the electromagnetic response of marine gas hydrates in the frequency domain based on these models. We also studied the relationship between electrical field magnitude or phase and parameters such as receiver-transmitter distance and frequency. Our numerical modeling results provide us with a quantitative reference for exploration and resource evaluation of marine gas hydrates. 相似文献
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Controlled-Source Electromagnetic Approaches for Hydrocarbon Exploration and Monitoring on Land 总被引：4，自引：1，他引：3
Rita Streich 《Surveys in Geophysics》2016,37(1):47-80
Electromagnetic methods that utilize controlled sources have been applied for natural resource exploration for more than a century. Nevertheless, concomitant with the recent adoption of marine controlled-source electromagnetics (CSEM) by the hydrocarbon industry, the overall usefulness of CSEM methods on land has been questioned within the industry. Truly, there are few published examples of land CSEM surveys carried out completely analogously to the current marine CSEM standard approach of towing a bipole source across an array of stationary receivers, continuously transmitting a low-frequency signal and interpreting the data in the frequency domain. Rather, different sensitivity properties of different exploration targets in diverse geological settings, gradual advances in theoretical understanding, acquisition and computer technology, and different schools in different parts of the world have resulted in a sometimes confusing multitude of land-based controlled-source EM surveying approaches. Here, I aim to review previous and present-day approaches, and provide reasoning for their diversity. I focus on surface-based techniques while excluding airborne EM and well logging and on applications for hydrocarbon exploration. Attempts at the very demanding task of using onshore controlled-source EM for reservoir monitoring are shown, and the possible future potential of EM monitoring is discussed. 相似文献
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为了分析海洋中含金属矿的储油气砂层的成分、结构对于海洋可控源电磁场的影响特征,引入多相微增等效介质模型,结合非结构化网格实现了海洋可控源电磁三维矢量有限元正演.首先对多相微增模型进行了介绍,并分析不同参数影响下的等效电导率变化特征.而后,详细推导了频率域可控源电磁法非结构化矢量有限元方程.接着,利用预处理的IDR （s）迭代算法求解线性方程组.最后设计典型的海洋地电模型,通过正演计算,验证了本文算法的正确性和有效性,同时研究了海洋储油砂层中的金属矿的含量、孔隙度、含水饱和度等参数对于可控源电磁场响应特征的影响. 相似文献