New Paleomagnetic Study on Early Triassic Liujiagou Formation of North China Block *

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张北地震前地壳形变异常及力学分析

1998年 1月河北省张北 6 .2级地震前 ,在震中区西部存在一个幅度为 2 0mm的隆起异常区 ,震后异常恢复。根据张北地区 1984～ 1991年的水准测量资料 ,反演地震孕育期间的力学参数 ,结果显示震源区受力增加了32× 10 14 N ;力系中心位置为 4 0 .99°N ,113.99°E ,力系的方位角α =2 8.6 5°,力系的倾角 β =- 17.19° ,与后来实际发生地震的震中及震源机制十分接近 ,与华北地区区域应力场也基本一致。理论形变图与实测图大体相似。     

山东渤南油田古近系沙河街组沙二段及沙三段低渗透储层成岩储集相

渤南油田位于济阳坳陷的渤南洼陷内,是山东省胜利油田储量最大的亿吨级深层低渗透断块岩性油藏,主要含油层系为古近系沙河街组沙二段和沙三段,属中孔低渗透砂岩储层。低渗透砂岩储层的成因机理十分复杂,为了更精确地预测有效储层的分布及其内部储集性能的差异,应用成岩储集相的概念在渤南油田三区古近系沙河街组开展了低渗透储层质量评价的研究。该项研究是建立在储层沉积相、成岩作用研究的基础上,通过分析低渗透储层成岩作用对储集物性的影响及成岩作用阶段划分,认为造成本区储层砂岩渗透率较低的主要原因是成岩期各种自生矿物的充填和胶结作用。选用流动层带指标、孔隙度、渗透率、粒度中值、泥质含量、孔喉半径均值和变异系数等七项参数,采用聚类分析和判别分析方法,将渤南油田三区古近系沙河街组划分为四类成岩储集相,阐述了各类成岩储集相的特征,并结合沉积相,实现了成岩储集相的时空展布。研究成果将对低渗透砂岩储层的开发起到指导作用。     

地电阻率的年变畸变异常分析

讨论分析了3种地电阻率年变畸变异常,即年变幅度增大型、年变幅度减小型、年变畸变混合型。并针对不同的异常给出了相关分析方法,为识别和使用这类异常提供了一定的思路和科学依据。     

Synthetic Model for Prediction Seismic Risk in About 10 Years

In this paper, the relation that strong earthquakes and seismo-geological conditions bear with precursory phenomena has been analyzed. The information content concerning the long-term (i.e., a decade) seismic risk that various precursors can provide has been estimated by using the quantitative judgment method. On such a basis, a synthetic probability model for predicting the strong earthquake risk in about 10 years has been suggested. With the northern part of North China used as the test region, the feasibility of the model which is used for medium-term to long-term prediction has been proved.     

滇中鱼坝村组的建立及陆相侏罗系底界

滇中及相邻地区上三叠统舍资组含煤层与下侏罗统冯家河组红层之间，连续沉积了一套杂色细碎屑岩过渡层。其分布稳定，该层所含化石及磁性地层特征表明其时代属早侏罗世。因此建立下侏罗统鱼坝村组，并确定该组底界为陆相侏罗系的底界。     

A NUMERICAL EXPERIMENT WITH THE EFFECT OF A COMPLICATED TERRAIN ON THE MESOSCALE SYSTEMS

Improvement in two aspects is done of the one-level mesoscale numerical model of Mass et al.(1985)and the re-vised model is used to make a simulation of a severe convective weather process in North China,with the result showingthe pronounced effects of the topography upon the mesoscale systems.     

山西省部分台站下方S波速度结构研究及与地震关系探讨a

收集山西省数字台网记录的深源远震S波，采用S波理论波形拟合的方法，获得了山西省境内共6个台站下方的剪切波速度结构． 结果显示， 该省区域内地壳厚度普遍较厚，其中4个台站地壳厚度均在40 km以上；同时地壳均为高低速层相间结构，且不同地区的台站呈现不同的速度结构特征，同一构造区域周围的台站显示了区域相似的特点．最后，结合多次中小地震的优势深度层位，讨论了多震层与高低速层结构的相关性．      

NMR技术评价油田高温堵剂调剖效果

开采稠油的主要方式是注蒸汽，其中包括蒸汽驱和蒸汽吞吐，随着蒸汽吞吐的次数增加，稠油的采出量依次递减。由于油层的非均质性严重，蒸汽首先进入高渗层，高渗透地层的稠油首先被采出，低渗透率地层采出很少，之后的蒸汽都进入高渗低层，即产生汽窜，所谓的低效蒸汽，蒸汽冷凝后形成热水，受到重力作用进入底部油层，降低了蒸汽的利用率；同时，由于蒸汽的重力履和沿高渗透地层窜流，使蒸汽在地层中的波及系数降低。为了克服蒸汽驱中的问题，国内外学者进行了大量的研究。通过注入一种流体－调剖剂，由于它的高粘度高渗透层后，将减少高渗通道的渗透率，消除“汽窜”，封堵高渗透地层，提高中低渗透油层的动用程度，提高原油产量和采收率。本文利用核磁共振成像（NMR）无损检测技术，对蒸汽驱SAD－□型高温调剖剂进行岩心动态评价实验，考察该调剖剂的热稳定性以及堵剂的封堵效果。     

Post-collisional Adakitic Porphyries in Tibet: Geochemical and Sr-Nd-Pb Isotopic Constraints on Partial Melting of Oceanic Lithosphere and Crust-Mantle Interaction

The distribution of Neogene felsic porphyries intruding in earlier granitic batholiths was mainly controlled by north-south-tending rifting zones and normal faults. The main rock types of the felsic porphyries include granodiorite-porphyry, monzonitic granite-porphyry and quartz monzonitic porphyry. The porphyries are characterized by high SiO2 ((?)64.26%) and Al2O3 (>15% at 70% SiO2), low Y and HREE (Yb) contents, strong enrichment of LILE and LERR, especially K and ST. Geochemical features of the porphyries show distinct adakitic magma affinity. Nd, Sr and Pb isotopic compositions of the porphyries form a linear alignment from MORB to EM2, suggesting a mixing of the MORB reservoir with the metasomatized mantle reservoir. Considering also the geochemical characteristics of the porphyries and the sequence of observable structural-thermal-magmatic events at Gangdise, it is thought that the Neogene porphyries were formed by partial melting of dead subducted oceanic crust in a post-collision setting. K-enr