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.     

浅层地震资料解释陷阱(英文)

高分辨率浅层地震方法是在近地表调查中使用最为广泛的方法。然而,在许多情况下,地震资料的解释经常会出现错误。在本文中,我们介绍了三个例子,分析了造成P波,SH波,多道的面波(MASW)地震资料解释的错误原因,大都是由于在表面或地下条件约束不确当引起的。第一个例子是P波反射剖面上的一个波的特征被解释为浅层断裂带,但后来证实它是由高水平的背景噪音引起的,因为采集测线通过了一个公路交叉口。第二个例子是SH波反射地震剖面上一个波特征被解释为是逆倾向滑断层,但有针对性的钻探表明,它是一个侵入到基岩面的一个深层局部侵蚀。最后,第三个例子,MASW调查剖面上,一个陡倾特征一开始被解释为基岩谷。然而,后来的钻探表明这是一个非常软的湖泊沉积物,后者严重损坏了应用面波频段。虽然最初的解释是不正确的,但这刺激地球物理学家和地质学家之间的讨论,并强调地球物理数据采集的时候,采集之前以及采集之后需要科学家之间有意义的合作与讨论。     

编码震源提高地震探测能力的野外实验研究

地球深部结构研究是地震预报和地球动力学研究的基础,传统人工地震受到探测深度、分辨率或震源能量的环保限制,探索利用小能量震源进行深部高分辨率探测技术具有重要意义.本文借鉴雷达探测中的编码原理,开展了震源编码探测实验,利用人工震源向地下发送具有独特特征的随机编码序列脉冲,作为一次等效激发,利用准确记录的编码震源的源函数与地震连续观测的互相关进行“解码”分析,获取地下信息,形成编码地震探测技术.实验表明编码地震能够大幅度提高地震探测能力,利用小能量震源获得远距离的探测和高分辨率,是一种具有重要发展前景的人工探测技术.     

炸药震源的地震安全性野外实验研究

选定一块场地,针对相同井深、不同药量的情况,进行炸药震源的地震安全性野外实验,用Etna数字强震动加速度仪记录每次爆破时房屋振动的加速度.在选定房屋结构的地基、窗台、屋顶等3个位置分别布设了仪器,记录结构响应的加速度波形.为了与《爆破安全规程》的参考标准对应,将加速度值转换成速度值,并对位于屋顶的结构响应速度峰值进行分析.通过对结构响应、安全距离、频率的研究,分析建筑物结构对每次爆破的响应,并对其安全性进行讨论.     

井间地震资料精细解释方法研究与应用

井间地震资料分辨率很高,但是缺乏成熟的解释方法,本文针对井间地震资料的特点,借鉴地面地震解释技术对井间地震资料开展了精细解释方法研究.首先在深度域资料特点分析的基础上,利用区域速度和层析成像速度将深度域井间地震资料转换到时间域进行研究,并通过粗化降频建立起井间地震资料与地面地震资料之间的相似性联系,得到对井间地震低频反射特征的认识,结合井旁道合成地震记录标定建立起井间地震资料的反射特征,准确的解释了井间地震的反射层位.采用地震瞬时属性分析和时频属性分析得到了对沉积环境的认识,进一步通过波阻抗反演更好的认识井间储层特征.在实际应用中综合多种方法进行解释,并结合测井资料对比落实了井间砂体展布特征,得到对井间储层的精细描述结果,解决了两口井之间储层分布范围、横向连通性及厚度变化等问题,取得了较好的应用效果.     

A physical model study of effect of fracture aperture on seismic wave

Based on Hudson’s theoretical hypothesis of equivalent fracture model,inserting aligned round chips in solid model can simulate fractured media. The effect of fractures on the propagation of P and S waves can be observed by changing the fracture thickness. The base model is made of epoxy resin,and the material of fractures is a kind of low-velocity mixture containing silicon rubber. With constant diameter and number of fractures in each model,one group of models can be formed through changing the thickness of fracture. These models have the same fracture density. By using the ultrasonic pulse transmission method,the experiment records time and waveform of P and S waves in the direction parallel and perpendicular to the fracture orientation. The result shows that,with the same fracture density,changing fracture aperture will affect both velocity and amplitude of P and S waves,and the effect on P-wave amplitude is much greater than that on the velocity. Moreover,the variation in velocity of S wave is more obvious in the slow shear wave (S2),while the variation in amplitude is more obvious in the fast shear wave (S1). These properties of wave propagation are useful for seismic data processing and interpretation.     

SMA负刚度双曲面减震装置的优化及抗震性能研究

SMA负刚度双曲面隔震装置的试验结果表明：绕支座布置的SMA索在支座转弯处不能自由滑动,导致SMA索的受力与设计目标严重不符。为解决上述问题,拟提出一种优化升级的SMA负刚度双曲面减震装置。基于某一连续梁桥,比较研究了正刚度、零刚度与该负刚度装置的抗震性能。结果表明：该优化装置具有良好的耗能能力、自恢复性能以及强震下的限位能力。与正刚度装置及零刚度装置相比,该装置具有更好的抗震性能。     

Ground viscosity and stiffness measurements for near surface seismic velocity

In land surveys, the weathering layer can often distort the seismic signal due to it passing through rapid velocity and density changes, dispersion, scattering and inelastic absorption. In a simple spring‐dashpot model for the earth response, an equivalent medium groups these complex phenomena into two parameters only; these are called ground viscosity and ground stiffness. The most recent controllers for vibrators can estimate both parameters. To validate these measurements, Saudi Aramco conducted an experiment measuring ground viscosity and stiffness from two different vibrator control systems over an area of varying terrain conditions, including unconsolidated sand and limestone outcrop. The two systems measured different values, but detected similar trends that correlated well with weathering conditions and surface geology, e.g. lower viscosity values on the outcrop than on the sand. The ratio of ground viscosity to ground stiffness can approximate the shallow S‐wave velocity, which we converted into P‐wave velocity through calibration with sparse uphole data. Static corrections incorporating this velocity information somewhat improved the focusing of seismic time sections. This new approach does not require additional acquisition efforts, and can model shallow complex formations in arid areas where classical static methods often fail.     

地震解释技术现状及发展趋势

本文以我国塔里木油田石油地球物理勘探实例为基础,概述了石油勘探过程中地震解释技术类型、特征、现状和发展趋势.本文认为,在地震勘探技术飞速发展的今天,地球物理学家及地质学家希望获得的地震信息,应当是能够直接反应地下岩石物理特性或油气水的分布,而利用常规的地震解释技术是很难做到这些;随着石油勘探的进一步深化,一些新的地震解释技术涌现出来,并在油气勘探与开发过程中发挥着巨大作用.未来的石油勘探将会面临前所未有的困难,新情况、新问题将层出不穷,地震解释技术也同样面临着考验,因此,只有立足在现有的成熟解释技术之上,并不断探索新的技术与思路,才能与未来的石油勘探步伐相一致.     

The role of visual saliency in the automation of seismic interpretation

In this paper, we propose a workflow based on SalSi for the detection and delineation of geological structures such as salt domes. SalSi is a seismic attribute designed based on the modelling of human visual system that detects the salient features and captures the spatial correlation within seismic volumes for delineating seismic structures. Using this attribute we cannot only highlight the neighbouring regions of salt domes to assist a seismic interpreter but also delineate such structures using a region growing method and post‐processing. The proposed delineation workflow detects the salt‐dome boundary with very good precision and accuracy. Experimental results show the effectiveness of the proposed workflow on a real seismic dataset acquired from the North Sea, F3 block. For the subjective evaluation of the results of different salt‐dome delineation algorithms, we have used a reference salt‐dome boundary interpreted by a geophysicist. For the objective evaluation of results, we have used five different metrics based on pixels, shape, and curvedness to establish the effectiveness of the proposed workflow. The proposed workflow is not only fast but also yields better results as compared with other salt‐dome delineation algorithms and shows a promising potential in seismic interpretation.     

渗流场参数与地震波场参数的关联关系研究综述

地球表层岩石是由不同尺度的岩石骨架、孔隙、以及孔隙中的流体物质相互作用形成的.研究含有孔隙和裂缝的复杂岩石介质中的地震波传播效应一直是石油地球物理勘探领域的热点.因此,许多学者对复杂岩石介质的渗流特征,和地震波的传播与衰减进行了大量的研究.本文在回顾孔隙介质的地震波的传播与衰减理论发展的基础上,首先介绍了孔弹介质的非局部Biot理论,并用它预测负频散现象,然后介绍了实验观测到的波的衰减与岩石物理性质(如孔隙度和渗透率)的关系,最后,给出了对渗流场和地震波的传播与衰减的认识,并对它们之间的相互关系做了一些展望.     

Towards the interpretation of Uranus's eccentric magnetic field

Abstract

Coriolis forces stimulate dynamo action in a rapidly-rotating fluid by promoting complexities in the pattern of fluid motions, notably departures from symmetry about the axis of rotation. This pattern and its time variations determine the instantaneous form and temporal behaviour of the magnetic field so produced. Instantaneous magnetic fields will usually exhibit in their broad-scale features approximate alignment with the rotation axis. This is borne out by observations of the magnetic fields of the Earth, Jupiter and Saturn, and it is likely on general grounds that Neptune will be found to have an aligned magnetic field. But, as is shown by laboratory and theoretical studies of thermal convection in rapidly-rotating fluids, for some ranges of rotation speed, rate of heating, etc. certain patterns can occur which in electrically-conducting fluids would produce magnetic fields exhibiting departures from alignment with the rotation axis, which instantaneously could be quite pronounced but would average out to very small values over sufficiently long periods of time. These findings indicate obvious strategies for theoretical studies towards the interpretation of Uranus's eccentric magnetic field (which need not invoke departures from axial symmetry in the thermal, mechanical or electrical boundary conditions of the dynamo region within the planet) and for further observational studies.     

基岩弹性刚度对土层地震反应的影响

将基岩上均匀、各向同性土层的地震反应,简化为置于弹性支座上的一维剪切梁模型进行分析。将地震激励假定为白噪声谱,在随机边界激励下,主要探讨了土层与基岩2种介质间的波阻抗比、波速比、土层厚度和阻尼特性对土层地震反应的影响。计算结果表明,对于一定的土层厚度,在一定阻尼比条件下,土层和基岩的阻抗比小到一定程度时,可以将基岩假定为刚性约束,而误差可以控制在一定的范围内。     

地震波散射理论及应用研究综述

回顾了地震波散射的概念、研究历史及分类.对散射理论及应用研究成果进行了系统评述，特别对前人关于散射波数值模拟和应用研究的不足进行了总结：(1)观测系统设计不合理；(2)对散射波的特征研究缺乏系统性；(3)对复杂散射波场的识别方法没有进行系统研究；(4)适合散射成像的处理软件还有待开发.并介绍了作者关于地震散射波场特征数值模拟研究的初步成果.     

Genetic algorithm in seismic waveform inversion and its application in deep seismic sounding data interpretation

A genetic algorithm of body waveform inversion is presented for better understanding of crustal and upper mantle structures with deep seismic sounding （DSS） waveform data. General reflection and transmission synthetic seismogram algorithm, which is capable of calculating the response of thin alternating high and low velocity layers, is applied as a solution for forward modeling, and the genetic algorithm is used to find the optimal solution of the inverse problem. Numerical tests suggest that the method has the capability of resolving low-velocity layers, thin alternating high and low velocity layers, and noise suppression. Waveform inversion using P-wave records from Zeku, Xiahe and Lintao shots in the seismic wide-angle reflection/refraction survey along northeastern Qinghai-Xizang （Tibeteau） Plateau has revealed fine structures of the bottom of the upper crust and alternating layers in the middle/lower crust and topmost upper mantle.     

协同办公系统在地震行业中的应用

协同办公系统为地震行业提供了一个基于"十五"信息网络应用的高效率沟通平台.该系统可实现强大的远程会议功能;提供高效实用的数据协作平台;具有良好的音视频效果;提供易操作的应用界面.协同办公系统改变了地震系统传统的工作模式,解决了异地办公、远程沟通的地域障碍问题,不仅大大提升了工作效率,而且节约了日常开销,也使得全国地震行业网络各节点间的联系更加紧密、快捷.     

煤田采区三维地震精细构造解释方法

虽然煤田三维地震勘探已经过了十多年的发展,但构造解释问题仍是目前需要解决的主要问题之一.随着三维地震资料解释方法的不断发展,小波分析技术、相干体技术、地震属性技术、图像处理等提高解释精度的方法相继在地震勘探领域中得到应用.另一方面,由于煤矿采区三维地震勘探资料一般具有高信噪比和高分辨率的特点,为做好三维地震资料精细构造解释提供了物质基础.本文结合小波分析技术、相干体技术、地震属性技术等多种方法,结合两个采区的实例,对小断层和小规模陷落柱做了精细构造解释.解释结果显示联合使用以上几种解释技术,能提高三维地震资料的构造解释精度和可靠信.     

The influence of lateral variations on seismic refraction interpretation

The effects of unsuspected lateral variation in seismic velocities at depth on the interpretation of a seismic refraction profile are discussed with the aid of a numerical experiment. The results show that there will be bias in any velocity depth models derived by travel time analysis based on the assumption of horizontally layered media. This bias is examined for a lithospheric profile using both extremal and linearised travel time inversion. In addition quite mild subsurvace topography can have an appreciable effect on the amplitude distribution along the profile.     

多分量地震资料处理解释技术研究

随着油田勘探开发的不断深入,多波多分量地震资料的应用也越来越广泛.本文结合实际资料,对多波多分量地震资料的处理和解释方法进行了探讨和研究,主要针对多波资料的静校正、叠加成像、转换波资料的共转换点的求取方法等技术进行了分析研究,开发了综合利用多波资料进行地震属性和各向异性研究的方法,形成了一套较完善的多分量地震资料的处理、解释技术系列.经过在胜利油田罗家地区的初步应用,表明了预测结果与钻井资料相吻合.     

Statistics of seismic events at the Groningen field

Depletion of gas fields, even in a tectonically inactive area can induce earthquakes. This is the case for the Groningen gas field, located in the north of the Netherlands. Increased seismic activity raised public concern which led to the government trying to understand the cause of the earthquakes and optimize production such as to minimize the risk of induced seismicity. The main question is how production is correlated with induced seismicity. In this paper we deal with the statistics of seismic events using Bayesian model comparison and a Bayesian change point model. We have developed a method to assess seismic event rate, its changes and tendencies. These statistical analyses are in agreement with each other and find a constant event rate up to 2003, an increasing event rate from 2003 to 2014 and a preference for a decreasing event rate from early 2014 to now. Seasonality in the production and the number of events is present. The seasonality indicates a delay ranging between 2 and 8 months between seismicity and production changes. The question of interest is whether the production reduction since January 2014 has had an effect on the seismicity occurring in the Groningen field. The number of events in the Groningen field in the area affected by the production change has been reduced significantly. We present evidence that changes in seismicity are closely related to changes in production.