地震速度场建立与变速构造成图的一种方法

马海珍 ,雍学善 ,杨午阳 ,鲁烈琴 ,王小卫 .地震速度场建立与变速构造成图的一种方法 .石油地球物理勘探 ,2 0 0 2 ,37(1) :5 3～ 5 9本文剖析了地震速度场建立与变速构造成图传统方法中影响成图精度的主要因素 ,指出了传统方法中造成误差较大、准确性较低的原因。从解决传统方法中存在的问题入手 ,提出了相应的速度场建立与变速构造成图方法 ,指出了在浮动基准面地震工区中使用本方法的条件和要求 ,并将其扩展为适合于深度偏移的层速度建模方法。本方法采用层位反偏移技术、沿层横向叠加速度谱剖面技术、三维空间射线追踪层速度相干反演技术和图形偏移构造成图技术 ,对各反射目的层位进行单层速度场建立与构造成图 ,解决了传统方法中影响速度场和构造图精度的主要问题。实际应用表明 ,该方法提高了速度场建立与构造成图的精度 ,是一套技术先进。

地震速度场的趋势面分析及应用

建立地震速度场的数据主要来源于速度谱，速度的影响因素较复杂，而由速度谱数据过渡到地层的层速度与平均速度的各种方法都存在一定的局限性。在速度数据体中，异常数据较多。地震速度场的平均值与中值滤波趋势分析能较好地压制速度场中的异常数据和提高速度场数据的精度。用这种分析方法对某盆地Ｙ构造带Ｔ８层的平均速度数据进行了处理，效果十分显著。

三维地震速度场建立技术——以饶阳凹陷河间南地区为例

在复杂构造地区,由于受不同时期构造运动的影响,不仅存在各种各样的特殊地质体,还存在大量低幅度构造,其速度在纵向和横向上变化也很大。用传统的Dix公式变速成图方法所用的地震叠加速度不准确,不适合于高陡倾角地层的速度转换,构造图的精度也较低。模型层析法变速空校成图方法是一种解决高陡构造速度计算的方法,其能够消除地表结构复杂、地下地层倾角大、层速度纵横变化大等因素对构造形态及构造高点的影响,但是这种方法是基于解释数据来建立初始速度模型的,解释层位不足以描述全区构造变化特征时,建立初始模型的效果较差,会造成速度运算错误。因此,单一使用一种方法无法较好解决全区构造成图问题。针对饶阳凹陷河间南地区地质条件特殊的情况,采用Dix公式法和模型层析法分区建立速度场变速成图很好地解决了这一难题。实际资料应用表明,该方法提高了速度场建立和变速成图精度。

西湖凹陷M气田区块低孔渗致密砂岩储层高精度三维孔隙压力场地震预测

西湖凹陷M气田区块泥岩超压为欠压实和生烃共同作用的结果,目的层砂岩具有低孔渗特征,导致流体孔隙压力预测难度大,为此,基于测井资料分析,建立了适用区块低孔渗地层和多压力异常成因特点的纵波速度压力预测模型,基于非欠压实成因异常压力对总孔隙压力的贡献程度的参数来表征多压力异常成因的压力预测,基于层控和断控多约束层速度反演的低频地震速度建模和叠前AVO反演的精细三维地震速度场的构建策略获得用于地震压力预测所需的三维高精度速度场。实际区块三维地层孔隙压力场的预测结果表明,在工区实测点深度处的孔隙压力预测值与实测值之间的平均误差小于6%,验证了多压力异常成因情形下的压力预测的可靠性。

卡拉库里区块异常高速层对勘探的影响及解决方案

卡拉库里区块具有良好的生储盖组合,上侏罗统启莫里-齐顿阶膏盐层是良好的盖层。在该区的油气勘探中发现,膏盐层异常高速对下伏构造形态的精细落实和目的层埋深的精确预测影响很大,使得传统的构造成图方法误差较大。针对卡拉库里区块膏盐岩构造区构造成图的难点,从膏盐层的地质、地震特征对构造成图的影响入手,分析了不同岩层的层速度及其对构造成图的影响,改变以往构造成图的思想,采用平均速度场进行时空转换,再利用钻井计算硬石膏层厚度图和盐岩层厚度图,然后将三者相加进行目的层的时深转化,最后进行校正的方法。实钻效果验证该方法实用可靠,对膏盐岩高速异常层发育的类似区块油气勘探具有借鉴作用。

Micro-seismic wave's propagation law and its numerical simulation

Deduced the propagation rule of longitudinal and transverse wave. On the basis of this, propagation rules in attenuated visco-elastic media and varied Lame coefficient were put forward as well. The subsequent numerical analysis found that in a small scope longitudinal and transverse wave could be considered as homogeneously propagating when faultages and joints were not taken into account. The existence of lane hindered the wave＇s propagation, and it made the velocity gradient change in a local vicinity area. Therefore velocity varied in different direction.

The Application of GNSS to Fault Deformation Studies

Great earthquakes often occur along or near active fault belts. Thus,monitoring and research on fault deformation are quite important. Methods such as short-leveling,shortbaseline and integrated monitoring profile across fault belts have been used to monitor fault activities for many years. GNSS observations are mainly used to obtain the horizontal velocity field in large areas and to study the activities and deformation of major blocks.GNSS technology has been used to monitor and study the deformation of faults from a different aspects. In this paper,some applications and new explorations of GNSS are discussed. They are:( 1) Research and monitoring of strike-slip activities of faults with GNSS.( 2) Research and monitoring of vertical activities of faults with GNSS.( 3)Investigating the laws of deformation of blocks on the sides of fault zone and setting up strain models to deduce the activities and deformation of faults with respective models and compare the deduced results with the actual measurements across fault. It is concluded that a larger discrepancy between the deduced and the observed deformation indicates a stronger interaction between the blocks,which can be important for predicting the location of a strong earthquake and assessing seismic hazard,as well as the seismicity trend.

Intensity measures for seismic liquefaction hazard evaluation of sloping site

This work investigates the correlation between a large number of widely used ground motion intensity measures(IMs) and the corresponding liquefaction potential of a soil deposit during earthquake loading. In order to accomplish this purpose the seismic responses of 32 sloping liquefiable site models consisting of layered cohesionless soil were subjected to 139 earthquake ground motions. Two sets of ground motions, consisting of 80 ordinary records and 59 pulse-like near-fault records are used in the dynamic analyses. The liquefaction potential of the site is expressed in terms of the the mean pore pressure ratio, the maximum ground settlement, the maximum ground horizontal displacement and the maximum ground horizontal acceleration. For each individual accelerogram, the values of the aforementioned liquefaction potential measures are determined. Then, the correlation between the liquefaction potential measures and the IMs is evaluated. The results reveal that the velocity spectrum intensity(VSI) shows the strongest correlation with the liquefaction potential of sloping site. VSI is also proven to be a sufficient intensity measure with respect to earthquake magnitude and source-to-site distance, and has a good predictability, thus making it a prime candidate for the seismic liquefaction hazard evaluation.

Effects of the February 12,2014 M_S 7.3 Yutian Earthquake on Seismicity of the Northeastern Edge of Qinghai-Tibetan Block

First of all,using the GPS velocity field from campaign GPS measurements implemented by CMONC( C hina Crustal Movement Observation) a nd TEONC( C hina Tectonic Environment Observation Networks) u p to 2013, w e analyzed the background of regional crustal horizontal movement and deformation before the M S7. 3 Yutian,Xinjiang earthquake on February 12,2014. Then,by comparing this to the vertical movement from leveling measurements,we studied the crustal movement deformation and the state of strain accumulation on the northeastern edge of Qinghai-Tibetan block.Finally,we investigated the possible effects on the earthquake activity of the northeastern edge of Tibet from the M S7. 3 Yutian earthquake. The result indicates that,the M S7. 3Yutian earthquake occurred against the background of strong tectonic movement and intensive intracontinental crustal differential movement on the edges of tectonic blocks in western China,and also that it happened in the period of the strong tectonic stress field in Qinghai-Tibetan block and its edges. The sinistral strike-slip and stress transfer of the Yutian M S7. 3 earthquake may accelerate the rupture of fault segments with high strain accumulation at the northeastern edge of Qinghai-Tibetan block( especially in Qilian Mountain fault zone,and border area of Gansu,Qinghai and Sichuan provinces on the south of western Qinling).