Basement structural architecture and hydrocarbon conduit potential of polygonal faults in the Cooper‐Eromanga Basin,Australia

A thorough and complete understanding of the structural geology and evolution of the Cooper‐Eromanga Basin has been hampered by low‐resolution seismic data that becomes particularly difficult to interpret below the thick Permian coal measures. As a result, researchers are tentative to interpret the basement fault architecture within the basin, which is largely undefined. To provide a better understanding of the basement fault geometry, all available two‐dimensional seismic lines together with 12 three‐dimensional seismic surveys were structurally interpreted with assistance from seismic attribute analysis. The Upper Cretaceous Cadna‐owie Formation and top Permian reflectors were analysed using a common seismic attribute technique (incoherency) that was used to infer the presence of faults that may have otherwise been overlooked. Detailed basement fault maps for each seismic survey were constructed and used in conjunction with two‐dimensional seismic data interpretation to produce a regional basement fault map. Large north‐northeast–south‐southwest‐striking sinistral strike–slip faults were identified within the Patchawarra Trough appearing to splay from the main northeast–southwest‐striking ridge. These sinistral north‐northeast–south‐southwest‐striking faults, together with field‐scale southeast–northwest‐striking dextral strike–slip faults, are optimally oriented to have potentially developed as a conjugated fault set under a south‐southeast–north‐northwest‐oriented strike–slip stress regime. Geomechanical modelling for a regionally extensive system of Cretaceous polygonal faults was performed to calculate the Leakage Factor and Dilation Tendency of individual faults. Faults that extend into Lower Cretaceous oil‐rich reservoirs with strikes of between 060°N and 140°N and a high to near‐vertical dip angle were identified to most likely be acting as conduits for the tertiary migration of hydrocarbons from known Lower Cretaceous hydrocarbon reservoirs into shallow Cretaceous sediments. This research provides valuable information on the regional basement fault architecture and a more detailed exploration target for the Cooper‐Eromanga Basin, which were previously not available in literature.     

基于交错网格有限差分法的断面波叠前时间偏移成像影响因素正演分析

断层和断裂带的有效识别是地震资料解释中的重要环节,断层在地震信号响应中以断面波的形式体现,因此断面波成像的质量关系到断层的精细识别与刻画.本文利用精度较高的交错网格有限差分正演模拟方法对断面波成像的影响因素进行了正演研究,主要正演分析的参数包括采集因素中的电缆长度和采集方向,地质因素中的断层倾角、断距、反射系数,以及处理因素中的偏移方法等几个方面.通过正演论证得出：采用合理的采集参数能够提高断面波的照明度;有效结合地质因素能够提高断面波的解释精度;利用合理的偏移方法能够使断层归位更加准确,断面波有效成像.基于以上结论,对于断面波的精确识别与刻画,应综合采集因素,处理因素及地质因素,只有这样才能提高断层的解释精度,有效减小解释误差.     

基于地震多属性融合的断层识别与评价——以塔里木盆地SHB地区碳酸盐岩缝洞型储层为例

塔里木盆地SHB地区的深部碳酸盐岩缝洞型储层主要发育于断裂破碎带,大多表现为断裂破碎形成的裂缝和后期溶蚀形成相互连通的断溶体.因此,断层的识别与精细评价成为该区缝洞型储层识别评价的基础.考虑到研究区处于沙漠腹部,深部地层的地震反射能量相对较弱,用单一地震属性难以实现断裂带的识别.本文针对研究区地震资料的地质-地球物理特...     

Semi-automatic fault/fracture interpretation based on seismic geometry analysis

Fault and fracture interpretation is a fundamental but essential tool for subsurface structure mapping and modelling from 3D seismic data. The existing methods for semi-automatic/automatic fault picking are primarily based on seismic discontinuity analysis that evaluates the lateral changes in seismic waveform and/or amplitude, which is limited by its low resolution on subtle faults and fractures without apparent vertical displacements in seismic images. This study presents an innovative workflow for computer-aided fault/fracture interpretation based on seismic geometry analysis. First, the seismic curvature and flexure attributes are estimated for highlighting both the major faults and the subtle fractures in a seismic volume. Then, fault probability is estimated from the curvature and flexure volumes for differentiation between the potential faults and non-faulting features in the geometric attributes. Finally, the seeded fault picking is implemented for interpreting the target faults and fractures guided by the knowledge of interpreters to avoid misinterpretation and artefacts in the presence of faulting complexities as well as coherent seismic noises. Applications to two 3D seismic volumes from the Netherlands North Sea and the offshore New Zealand demonstrate the added values of the proposed method in imaging and picking the subtle faults and fractures that are often overlooked in the conventional seismic discontinuity analysis and the following fault-interpretation procedures.     

双井Walkaway VSP技术在辽河坳陷曙光高陡构造地区的应用研究

针对辽河坳陷西部凹陷曙光潜山高陡构造带顶界面断裂成像精度差、内幕地层识别难的问题,开展双井Walkaway VSP应用研究.利用大阵列检波器接收、炸药与震源联合采集方法,获得了高品质采集数据,是高陡构造成像的基础;子波一致性校正、基于射线追踪的矢量波场分离、VSP数据与地面地震数据联合各向异性速度建模、双井Walkaway VSP成像方法对比等针对性处理技术和波阻抗反演、地震属性提取等综合研究方法的应用,精细刻画了潜山顶界面,新识别出井旁小断层,落实了大倾角潜山构造形态,分析了内幕地层的接触关系,对板岩隔夹层及储层分布有进一步认识,展现了Walkaway VSP技术在高陡构造地区的应用前景.研究得到以下认识:(1)逆时偏移成像方法对高陡潜山成像更具适用性;(2)增加检波器进入潜山内幕的深度,避开潜山高速顶界面的能量屏蔽及滑行波、转换波等干扰,对潜山勘探具有重要意义;(3)双井Walkaway VSP联采时,两井距离要控制在一定范围内,防止两井间距离过大对深层偏移成像造成影响.     

保幅Kirchhoff弯曲射线叠前时间偏移技术在天然气水合物三维地震资料处理中的应用

天然气水合物的富集往往与断裂、底辟及泥火山等构造有关,这就要求地震成像要精确,而针对水合物的地震处理又要以保真保幅为前提,因此快速高效而又有较高成像质量的的保幅Kirchhoff弯曲射线叠前时间偏移技术被广泛应用于三维水合物资料处理中。与直射线Kirchhoff叠前时间偏移技术相比,弯曲射线Kirchhoff叠前时间偏移同样具有快速高效的特点,同时成像精度在一定程度上可媲美叠前深度偏移。在实际资料的应用中可发现,基于保幅Kirchhoff弯曲射线叠前时间偏移技术处理的地震剖面可精确地刻画气体通道,有利于天然气水合物富集区的识别。     

Seismic measurements of the internal properties of fault zones

The internal properties within and adjacent to fault zones are reviewed, principally on the basis of laboratory, borehole, and seismic refraction and reflection data. The deformation of rocks by faulting ranges from intragrain microcracking to severe alteration. Saturated microcracked and mildly fractured rocks do not exhibit a significant reduction in velocity, but, from borehole measurements, densely fractured rocks do show significantly reduced velocities, the amount of reduction generally proportional to the fracture density. Highly fractured rock and thick fault gouge along the creeping portion of the San Andreas fault are evidenced by a pronounced seismic low-velocity zone (LVZ), which is either very thin or absent along locked portions of the fault. Thus there is a correlation between fault slip behavior and seismic velocity structure within the fault zone; high pore pressure within the pronounced LVZ may be conductive to fault creep. Deep seismic reflection data indicate that crustal faults sometimes extend through the entire crust. Models of these data and geologic evidence are consistent with a composition of deep faults consisting of highly foliated, seismically anisotropic mylonites.     

Velocity anisotropy characteristics and pre-stack time migration imaging of the marine sedimentary strata in the South Yellow Sea Basin

The South Yellow Sea is a superimposed basin overlying Mesozoic-Cenozoic continental sediments, which in turn overlie Paleozoic-Mesozoic marine deposits that are now the target of hydrocarbon exploration. Strongly modified by multiple tectonic events, the marine sediments feature a large tectonic relief, with obvious horizontal anisotropy in seismic velocity, which significantly affects the seismic image quality. In this study, the sedimentary velocity anisotropy and its influence on image quality were analyzed using an analytical theory method, assuming transversely isotropic medium with vertical axis of symmetry (VTI), and using seismic and well-log data. Additionally, an anisotropic prestack time migration was used for the imaging of the field data. The results showed that the anisotropic pre-stack time migration processing could be used to significantly improve the accuracy of the seismic images in areas with distinct faults, offering clear images of accurately located fault planes and fault edges, thereby improving the lateral resolution of the seismic data and its signal-to-noise ratio.     

Diffraction imaging of sub‐vertical fractures and karst with full‐resolution 3D Ground‐Penetrating Radar

Vertical fractures with openings of less than one centimetre and irregular karst cause abundant diffractions in Ground‐Penetrating Radar (GPR) records. GPR data acquired with half‐wavelength trace spacing are uninterpretable as they are dominated by spatially undersampled scattered energy. To evaluate the potential of high‐density 3D GPR diffraction imaging a 200 MHz survey with less than a quarter wavelength grid spacing (0.05 m × 0.1 m) was acquired at a fractured and karstified limestone quarry near the village of Cassis in Southern France. After 3D migration processing, diffraction apices line up in sub‐vertical fracture planes and cluster in locations of karstic dissolution features. The majority of karst is developed at intersections of two or more fractures and is limited in depth by a stratigraphic boundary. Such high‐resolution 3D GPR imaging offers an unprecedented internal view of a complex fractured carbonate reservoir model analogue. As seismic and GPR wave kinematics are similar, improvements in the imaging of steep fractures and irregular voids at the resolution limit can also be expected from high‐density seismic diffraction imaging.     

Steered migration in hard rock environments

Hard rock seismic exploration normally has to deal with rather complex geological environments. These types of environments are usually characterized by a large number of local heterogeneity (e.g., faults, fracture zones, and steeply dipping interfaces). The seismic data from such environments often have a poor signal‐to‐noise ratio because of the complexity of hard rock geology. To be able to obtain reliable images of subsurface structures in such geological conditions, processing algorithms that are capable of handling seismic data with a low signal‐to‐noise ratio are required for a reflection seismic exploration. In this paper, we describe a modification of the 3D Kirchhoff post‐stack migration algorithm that utilizes coherency attributes obtained by the diffraction imaging algorithm in 3D to steer the main Kirchhoff summation. The application to a 3D synthetic model shows the stability of the presented steered migration to the presence of high level of the random noise. A test on the 3D seismic volume, acquired on a mine site located in Western Australia, reveals the capability of the approach to image steep and sharp objects such as fracture and fault zones and lateral heterogeneity.     

琼西北地区的基底速度图象

利用人工地震测深纵剖面和非纵剖面的资料,对琼西北地区P_g波的走时进行了层析反演,对比了代数重建法和同时迭代重建法的效果.综合了纵剖面的模型后,在三维弯曲界面上重建了基底速度图象,探讨了用射线椭圆评价分辨的途径. 层析成象结果给出了许多有价值的信息,揭示琼西北的结晶基底存在三条北东向断裂和两条北西向断裂,后者是继承性的活动断裂,控制着新生代次级断块的发展与火山活动.地表所推断的东西向王五-文教深大断裂,在该处只呈断续隐伏状显示.该区的基底存在儋县、临高和光村三个高速区,主要反映着基性岩体或花岗侵入体.基底整体性最好的是在儋县-王五地区,破碎程度最严重的是在王五-中和-光村以西的地区.     

三维地震资料叠前时间偏移应用研究

本文通过选取合适的叠前时间偏移软件,对两块三维地震资料进行偏移成像试验,验证叠前时间偏移中影响偏移成像效果的几个主要因素.该软件偏移算法的核心技术是弯曲射线偏移处理,这不同于工业界常用的直射线假设.偏移速度是偏移成像好坏的主要因素,通过迭代进行偏移、速度分析,使共成像点道集拉平,从而实现构造的准确成像;偏移孔径也是影响偏移成像的一个关键参数,其选取与成像目标层的倾斜角、深度、速度等有关;反假频参数对偏移成像效果有一定影响,是偏移中需要考虑的因素之一.     

Semi-automatic detection of faults in 3D seismic data

The semi‐automated detection of objects has been quite successful in detecting various types of seismic object, such as chimneys. The same technique can be applied successfully to detect faults in 3D seismic data. We show that several different attributes – among others, similarity, frequency and curvature, all of which potentially enhance the visibility of faults – can be combined successfully by an artificial neural network. This results in a fault ‘probability’ cube in which faults are more continuous and noise is suppressed compared with single‐attribute cubes. It is believed that the fault‐cube can be improved further by applying image‐processing techniques to enhance the fault prediction.     

衰减干涉假象的海洋一次波与多次波同时成像方法

海水与空气间的强波阻抗差使得海洋地震资料普遍发育自由表面相关多次波,如何利用好多次波所携带的有效信息已成为提高海洋地震资料成像品质的新突破点.基于面炮偏移的一次波与多次波同时成像方法能够避免多次波预测精度的影响,但是,正向传播的震源子波与反向延拓的自由表面相关多次波所产生的干涉假象严重制约了该技术的应用,本文提出了一种基于单程波偏移算子,可在成像域压制干涉假象的一次波与多次波同时成像方法.其中包含了三个步骤:第一,传统单程波偏移成像方法中的震源子波替换为一次波、多次波与震源子波,初始上行延拓波场为一次波与多次波,基于单程波算子的波场延拓与互相关成像条件的应用得到包含干涉假象的一次波与多次波同时成像;第二,以子波为震源,自由表面相关多次波为记录,按照传统单程波偏移成像方法得到干涉假象;第三,基于最小二乘匹配滤波算法,将第一步的成像结果与第二步的干涉假象进行匹配相减,得到干涉假象衰减后的一次波与多次波同时成像,避开了由于实际资料子波无法准确提取而造成一次波与多次波对成像能量级的不一致性.Sigsbee2B模型测试验证了本方法的有效性,并在我国某探区深海实际资料处理中得到了成功应用,深层基底得到了清晰刻画,并且照明均衡度明显改善.     

Study and application of PS-wave pre-stack migration in HTI media and an anisotropic correction method

Anisotropy correction is necessary during the processing of converted PSwave seismic data to achieve accurate structural imaging, reservoir prediction, and fracture detection. To effectively eliminate the adverse effects of S-wave splitting and to improve PSwave imaging quality, we tested methods for pre-stack migration imaging and anisotropic correction of PS-wave data. We based this on the propagation rules of seismic waves in a horizontal transverse isotropy medium, which is a fractured medium model that reflects likely subsurface conditions in the field. We used the radial (R) and transverse (T) components of PS-wave data to separate the fast and slow S-wave components, after which their propagation moveout was effectively extracted. Meanwhile, corrections for the energies and propagation moveouts of the R and T components were implemented using mathematical rotation. The PS-wave imaging quality was distinctly improved, and we demonstrated the reliability of our methods through numerical simulations. Applying our methods to three-dimensional and three-component seismic field data from the Xinchang-Hexingchang region of the Western Sichuan Depression in China, we obtained high-quality seismic imaging with continuous reflection wave groups, distinct structural features, and specific stratigraphic contact relationships. This study provides an effective and reliable approach for data processing that will improve the exploration of complex, hidden lithologic gas reservoirs.     

银川盆地深地震断层的三维透射成像

为了获得三维地震透射成像技术在活断层探测中的有效性和应用价值的评价,在银川盆地中北部布设了一个三维地震透射台阵,利用该台阵获得的基底初至折射波和莫霍界面反射波资料,采用有限差分反演、时间项反演和连续速度模型反演方法,对台阵区域基底及上地壳结构进行了分析.结果表明：研究区基底呈东西浅、中部深的界面形态,且西陡东缓,最深处大致位于芦花台至西大滩一带,埋深达7 km.芦花台断层、银川—平罗断层、黄河断层在研究区内均表现为北北东走向的速度差异条带,且断层两侧基底及沉积界面埋深存在显著变化.芦花台断层东倾,倾角较陡,延伸至研究区基底之下;银川—平罗断层倾向西,是一条超基底的隐伏断层;黄河断层西倾,延伸深度超过研究区基底.本探测结果证明,初至折射波与莫霍面反射波探测相结合的三维地震透射台阵技术能够给出研究区上地壳三维细结构图像,不仅可以揭示主要断裂的展布位置、浅部空间形态和特征,而且可以揭示断裂向基底之下的延伸状况.     

成像测井解释模式在基岩油气藏裂缝性储层的应用研究

基岩油气藏裂缝性储层具有复杂的储集空间和储层非均质性,为了实现对基岩油气藏储层的精细评价,以地层微电阻率扫描成像测井和井周声波成像测井资料为核心,通过岩心资料标定,结合录井、常规测井、试油、地质等实际资料,系统建立了基岩油气藏变质岩储层的成像测井解释模式.根据成像测井模式的识别实现了对基岩油气藏特征的认识、准确的裂缝分析和现今地应力场分析.分析结果表明,研究区基底变质岩地层中基本以基岩内幕油气藏为主;裂缝以中高角度缝、网状裂缝为主,其主要走向与井旁断层走向大致平行,属纵裂缝;裂缝主要发育在东西两侧靠近断层、近源的构造陡坡上;现今最大水平主应力方向主要呈NE-SW和NEE-SWW.成像测井解释结果与地质情况吻合较好.     

委内瑞拉奥里诺科重油带J区块新老二维地震资料精细匹配处理及构造特征分析

针对委内瑞拉奥里诺科重油带J区块新老二维地震资料存在的问题,应用精细匹配处理方法,即以精细频率匹配和精细振幅匹配和相位校正为主要手段,结合时间偏移处理以及去噪、混波处理等手段,普遍突出了有效反射信息,提高了不同年度地震剖面之间的闭合精度,大大提高了构造解释的准确性,虽然地震资料很少,但仍解释出了J区块的三层构造图,构造解释结果表明,J区块地层总体是一个北倾单斜,其上发育一些北东和近东西向的断层,油藏类型以岩性油藏为主,断层对油藏主要起复杂化作用,J区块这一构造特征与其所处的构造背景、基底形态和构造应力作用有关.     

地震折射和反射方法研究郯庐断裂带宿迁段的浅部构造特征

郯庐断裂带是中国东部最大的一个活动构造带,其内部结构非常复杂,不同区段表现出不同特征的构造样式.本文采用浅层地震反射波成像技术对郯庐断裂带宿迁段的近地表结构进行了高分辨率成像,利用该区已有的深地震反射剖面数据,采用初至波层析成像方法获得了郯庐断裂带的浅层P波速度结构.结果表明,郯庐断裂带宿迁段是一个由多条断裂以及凹陷和隆起构成的复杂构造带,且新生代地层厚度和地震波速分布明显受到断裂的影响与控制.郯庐断裂带的东、西两侧为基底隆起区,近地表速度结构呈现为明显的高速特征,新生代地层厚度小于200m.郯庐断裂带总体显示为低速凹陷结构,新生代地层厚度在300～600m之间变化,最厚处位于宿迁市的陵城镇附近.郯庐断裂带宿迁段主要由5条断裂构成,从这些断裂的上断点埋深和第四纪活动特征来看,郯庐断裂带的东边界断裂F_1和西边界断裂F_4的活动性相对较弱,为第四纪早期活动断裂.断裂F_2和F_3控制了郯庐断裂带内部的新生代凹陷,两者的活动时代分别为中更新世和晚更新世.安丘—莒县断裂F_5位于断裂F_1和F_2之间,由2条相向而倾的分支断层F_5和F_(5-1)构成,其活动时代分别为全新世和晚更新世.研究结果为进一步认识郯庐断裂带宿迁段的近地表特征及其活动性提供了新证据.