海上多次波的联合衰减法   总被引：1，自引：0，他引：1       下载免费PDF全文

王建立  王真理  张洪宙  方正茂  李学良  杨长春 《地球物理学进展》2009,24(6):2070-2078

地震勘探尤其是海上地震勘探中存在着各类多次波,由于多次波的存在严重影响了速度分析、叠加、偏移成像等地震资料处理,海上多次波主要有全程多次波和层间多次两大类,为了压制海上不同类型的多次波,本文首先分析波场外推、预测反褶积和拉东变换衰减不同多次波的理论基础,然后联合采用这些方法,分别衰减全程多次波和层间多次波;即：首先对炮记录或者接收点记录进行波场外推,建立海底多次波模型,预测并减去全程多次波,然后利用预测反褶积衰减掉周期性明显的多次波,最后将数据转换到τ-p域,用拉冬变换根据同一时间多次波和有效波在速度等方面的差异,进一步分离层间多次波和剩余的全程多次波,并在该域中切除分离出的多次波,从而实现联合多次波衰减处理.通过对悉尼海区和里海等实际地震资料的处理证明,文提出的联合多次波衰减方法在海洋地震资料的处理中有着广泛的应用,联合衰减多次波处理流程具有快速、简洁、易于实现的特点,经处理后的地震资料有效信号损失小、保福性好的特点,有利于速度分析、叠加、叠前偏移等的后续处理工作.  相似文献   

Constraining the anisotropy structure of the crust by joint inversion of seismic reflection travel times and wave polarizations   总被引：2，自引：0，他引：2  

Jingyi Chen  Jiwen Teng  José Badal 《Journal of Seismology》2009,13(2):219-240

In the context of wide-angle seismic profiling, the determination of the physical properties of the Earth crust, such as the elastic layer depth and seismic velocity, is often performed by inversion of P- and/or S-phases propagation data supplying the geometry of the medium (reflector depths) or any other structural parameter (P- or S-wave velocity, density...). Moreover, the inversion for velocity structure and interfaces is commonly performed using only seismic reflection travel times and/or crustal phase amplitudes in isotropic media. But it is very important to utilize more available information to constrain the non-uniqueness of the solution. In this paper, we present a simultaneous inversion method of seismic reflection travel times and polarizations data of transient elastic waves in stratified media to reconstruct not only layer depth and vertical P-wave velocity but also the anisotropy feature of the crust based on the estimation of the Thomsen’s parameters. We carry out a checking with synthetic data, comparing the inversion results obtained by anisotropic travel-time inversion to the results derived by joint inversion of seismic reflection travel times and polarizations data. The comparison proves that the first procedure leads to biased anisotropic models, while the second one fits nearly the real model. This makes the joint inversion method feasible. Finally, we investigate the geometry, P-wave velocity structure and anisotropy of the crust beneath Southeastern China by applying the proposed inversion method to previously acquired wide-angle seismic data. In this case, the anisotropy signature provides clear evidence that the Jiangshan-Shaoxing fault is the natural boundary between the Yangtze and Cathaysia blocks.  相似文献   

新疆柯坪块体震源参数的初步研究与应用   总被引：1，自引：0，他引：1       下载免费PDF全文

潘振生  刘辉  谷美菊  李晓东  沈琦 《地震工程学报》2010,32(4):357-362,410

采用多台多地震联合反演的方法得到了新疆柯坪块体2006-2008年53次MS≥3.0中小地震的震源谱,进而计算了103次MS≥2.5地震的应力降、地震矩、震源破裂半径、视应力等震源参数,并讨论了它们与震级之间的关系。在此基础上分析了2006年以来柯坪块体上普昌断裂两侧区域及整个块体上应力降和地震视应力空间演化特征,并结合柯坪5.2级地震对研究结果应用于地震趋势预测和短临跟踪的可行性进行了探讨。  相似文献   

Mapping the resistivity structure of Walker Ridge 313 in the Gulf of Mexico using the marine CSEM method     

《Marine and Petroleum Geology》2017

A marine controlled source electromagnetic (CSEM) campaign was carried out in the Gulf of Mexico to further develop marine electromagnetic techniques in order to aid the detection and mapping of gas hydrate deposits. Marine CSEM methods are used to obtain an electrical resistivity structure of the subsurface which can indicate the type of substance filling the pore space, such as gas hydrates which are more resistive. Results from the Walker Ridge 313 study (WR 313) are presented in this paper and compared with the Gulf of Mexico Gas Hydrate Joint Industry Project II (JIP2) logging while drilling (LWD) results and available seismic data. The hydrate, known to exist within sheeted sand deposits, is mapped as a resistive region in the two dimensional (2D) CSEM inversion models. This is consistent with the JIP2 LWD resistivity results. CSEM inversions that use seismic horizons provide more realistic results compared to the unconstrained inversions by providing sharp boundaries and architectural control on the location of the resistive and conductive regions in the CSEM model. The seismic horizons include: 1) the base of the gas hydrate stability zone (BGHSZ), 2) the top of salt, and 3) the top and bottom of a fine grained marine mud interval with near vertical hydrate filled fractures, to constrain the CSEM inversion model. The top of salt provides improved location for brines, water saturated salt, and resistive salt. Inversions of the CSEM data map the occurrence of a ‘halo’ of conductive brines above salt. The use of the BGHSZ as a constraint on the inversion helps distinguish between free gas and gas hydrate as well as gas hydrate and water saturated sediments.  相似文献   

Improvements for the smooth joint contact model of the particle flow code and its applications     

《Computers and Geotechnics》2017

This paper deals with two shortcomings of the smooth-joint contact model (SJCM) used in the particle flow code (PFC). The first shortcoming is the increase of the shear strength of the joint when the shear displacement of the joint exceeds a specific value that is related to the particle size. This problem is named as the interlocking problem, which is caused by the interlocking particles. It occurs due to a shortcoming of the updating procedure in the PFC software related to the contact conditions of the particles that lie around the intended joint plane during high shear displacements. This problem also increases the dilation angle and creates unwanted fractures around the intended joint plane. To solve this problem two new approaches are proposed in this paper: (1) joint plane checking (JPC) approach and (2) joint sides checking (JSC) approach. These approaches and the regular approach are used to model: (a) the direct shear test using the PFC^2D and PFC^3D, (b) the biaxial test on a sample having a persistent joint with a dip angle varying from 0° to 90° at an interval of 15° using the PFC^2D and (c) the polyaxial test on two samples, one of them having a joint with a dip direction of 0° and the dip angle varying from 0° to 90° at an interval of 15°, and the other sample having a joint with a dip angle of 60° and the dip direction varying from 0° to 90° at an interval of 15° using the PFC^3D. All numerical results show that the JPC and JSC approaches can solve the interlocking problem. Also, they proved to be more consistent with the theory compared to the regular approach. However, the JPC approach leads to a slightly softer joint. Therefore, the JSC approach is suggested for jointed rock modeling using the PFC. The other shortcoming of the SJCM dealt within this paper is its inability to capture the non-linear behavior of the joint closure varying with the joint normal stress. This problem is solved in this paper by proposing a new modified smooth-joint contact model (MSJCM). MSJCM uses a linear relation between the joint normal stiffness and the normal contact stress to model the non-linear relation between the joint normal deformation and the joint normal stress observed in the compression joint normal stiffness test. A good agreement obtained between the results from the experimental test and the numerical modeling of the compression joint normal test shows the accuracy of this new model.  相似文献   

GIS在水量调度决策支持系统中的应用   总被引：7，自引：1，他引：6       下载免费PDF全文

王煜  王道席  王军良  王彤  杨立彬  侯传河 《水科学进展》2003,14(1):114-117

黄河三门峡以下非汛期水量调度是一个涉及众多部门和地区的半结构化的多目标决策问题,具有很强的空间分布特征。建立了基于地理信息系统(GIS)的空间分析子系统,实现了系统空间分析和空间表达功能,弥补了传统决策支持系统数据分析和表达的局限性,大大增强了决策支持系统的功能。从空间数据模型建立、空间子系统组成和功能及在决策支持系统中的作用等说明地理信息系统在水量调度决策支持系统中的应用。  相似文献   

Stress indicators adjacent to buried channels of Elsterian age in North Germany     

Johannes Bruns 《第四纪科学杂志》1989,4(3):267-272

Tectonic and soil mechanics investigations of a strongly plastic clay (Miocene ‘Mica Clay’) led to the detection of strain phenomena induced in connection with the formation of Elsterian buried channels. A microjoint system with randomly distributed fissures is thought to result from early Elsterian dessiccation and frost crack formation. It occurs frequently in the upper part of the clay horizon. A younger joint system, which is encountered throughout the entire clay body, comprises macrojoints arranged in three joint sets. The evidence strongly suggests that they were formed by gravitational and kinematic loading of the clay body by overriding ice. The macrojoints display various secondary alterations such as slickensides, escarpments, shear zones, erosive and pressure zones, the formation of which is seen in context with the channel incision. Investigations into the genesis of these alterations indicate a strong horizontally-orientated stress induction lateral to the channels, which resulted in stiffness modulus anisotropy. It has also caused a horizontal compression of the clay body, which at that time was already consolidated through ice overburdening. Horizontal compression of the clay led to evorsion of pore water eroding clay particles from the joint walls. Lower water content of the clay, in combination with increased dry unit weights, are found adjacent to the channels today.  相似文献   

Joint ventures as an export market: US groundfish     

Vladimir M. Kaczynski 《Marine Policy》1984,8(1):16-29

This article examines the growth of joint venture operations in the US Fishery Conservation Zone in the North Pacific since 1977. Joint ventures currently in operation are outlined and the foreign and domestic partners described. The most common joint ventures in the area are contractual joint ventures, which include over-the-side sales of fish, joint lease of processing ships and marketing, seafood trade agreements and joint ventures through US subsidiaries of foreign companies. Supply and demand factors in the joint venture market are analysed and it is pointed out that the joint ventures market does not satisfy the main principles of perfect competition. The author concludes that, because it is an imperfect market, US fishermen receive less for their fish than they would under pure competition conditions.  相似文献   

The formation and viability of a non-basin water management: The US–Canada case     

Itay Fischhendler  Eran Feitelson 《Geoforum》2005,36(6):1-804

Despite the much-vaunted advantages of basin-wide management many transboundary water regimes do not conform in practice to the basin-wide scale. This study examines whether a spatial alternative that includes only parts of the basin is indeed viable. To this end the US–Canada case is examined. Two questions are asked: why has a non-basin scale been adopted? And whether this option is indeed viable. The review of the negotiations leading up to the US–Canada 1909 Boundary Treaty, and to the establishment of the International Joint Commission (IJC) to control the boundary water (i.e., only the water that crosses the boundary at the point of crossing), shows that the choice of this scale was an outcome of a deadlock in negotiations at the basin scale. The boundary scale was chosen as it reduced the number of players involved in the decision-making process and, consequently, the political costs of a basin-wide agreement. Inevitably, in the subsequent decades the regime faced challenges due to the discrepancy between its jurisdiction and basins. Perhaps the most severe challenge was posed by the Chicago Diversion that was excluded from the regime jurisdiction. Therefore, the paper focuses on how the boundary scale addressed the Chicago diversion externalities. The discussion of this case suggests that the combination of the flexibility of the regime and its interpretations, the nature of the resource (inter-connected lakes) and the two-way upstream–downstream relations along the borders allowed this challenge to be contained. It seems, thus, that a regime can indeed be set at a different scale than the basin-wide one and still be viable.  相似文献   

Can tensile stress develop in fractured multilayers under compressive strain conditions?     

Ghislain de Joussineau  Jean-Pierre Petit 《Tectonophysics》2007,432(1-4):51-62

To contribute to the understanding of how opening-mode fractures (joints) form and open or close at depth in layered rocks, we present a 2D numerical study aiming to determine whether tensile stress can develop in pre-fractured elastic multilayers submitted to biaxial compressive strain conditions.First, we investigate the role of the elastic and geometrical properties of the layers on the development of tensile stress in models with five bonded layers and containing one open fracture in the central layer. Our results indicate that, in absence of elastic contrast (in Young's modulus) between the layers, no tensile stress develops in the models. However, when the fractured layer is stiffer than the two adjacent layers directly above and below, a lobe of horizontal tensile stress develops centered on the pre-existing fracture. The creation of this tensile stress is contingent upon the partial closing of the fracture. The levels of tensile stress and the thickness of the lobe of tensile stress increase logarithmically with an increase in the elastic contrast and are systematically larger for a larger Soft/Stiff ratio (ratio of the total thickness of the soft layers with the total thickness of the stiff layers).Second, we investigate the role of fracture interaction in the development of tensile stress in models containing a pair of open fractures. We observe that the levels of tensile stress in the region between the fractures are systematically higher than those observed in identical models containing a single fracture. This increase in tensile stress is very large for small elastic contrasts between the layers but diminishes when the elastic contrast increases. Furthermore, the spacing between the pre-existing fractures plays an important role in the stress distribution in the region between them. When the fracture spacing is equal to or lower than 1.15 times the height of the fractured layer for the experimental conditions chosen, the lobes of tensile stress centered on the fractures coalesce. This results in the formation of vast areas of tensile stress in models under remote compressive loading conditions. Such tensile areas are likely to allow the initiation and propagation of subsequent opening-mode fractures.The results obtained provide new insights into the formation of joints in layered rocks in compressive environments, with important consequences on fluid flow.  相似文献