油气层录井的精细解释方法 ——以吉林探区为例

采用“四大参数法” (峰值、峰基比、甲烷和重烃) 、全烃曲线形态法和全烃储层灌满系数法, 解决了吉林探区油气层气测低异常和组分发育不全等问题。进一步以地化录井为核心, 结合核磁孔隙度和色谱油性, 建立了地化含油饱和度储层评价体系, 解决了油气层荧光、气测显示异常和电测低电阻的油层评价难题。     

水泥粉煤灰碎石桩工程实例

通过某高层住宅地基处理的设计实例,分析了水泥粉煤灰碎石桩（CFG桩）的特性,指出了水泥粉煤灰碎石桩使用时须注意的要点。     

GPS载波定位中双差观测值权的合理确定

在GPS载波定位中双差观测值权的确定较为重要,本文在简要介绍了两种常规定权方法之后首次提出了“高度角定权法”,并以某大型水电站的实测数据分析了三种定权方法对基线坐标解算结果精度的影响,数据结果清楚地表明本文提出的“高度角定权”能有效地提高基线坐标解算结果的精度。     

柴达木盆地石炭系地球物理特征及解释

柴达木盆地具有丰富的油气资源,柴北缘、柴西、粜东三湖地区分别以侏罗系、古近系、新近系和第四系为主要勘探目的层.随着北疆石炭系研究的进展和钻探的成功,石炭系已经成为中国西部地区重要的勘探层系,柴达木盆地的石炭系也引起了勘探家的注意,地面地质调查表明石炭系为柴达木盆地一套潜在烃源岩.为了落实石炭系在柴达木盆地内的分布,笔者充分利用近10年来在柴达木盆地及周缘完成的重、磁、电等资料进行了针对石炭系的资料解释、剥层反演和综合研究,明确了石炭系的分布特征,为柴达木盆地石炭系油气勘探指明了方向.     

Condensed hyperelements method of non-vertical consistent boundaries for wave propagation analysis in irregular media

The study of wave propagation in finite/infinite media has many applications in geotechnical and structural earthquake engineering and has been a focus of research for the past few decades. This paper presents an analysis of 2D anti- plane problems （Love waves） and 2D in-plane problems （Rayleigh waves） in the frequency domain in media consisting of a near-field irregular and a far-field regular part. The near field part may contain structures and its boundaries with the far-field can be of any shape. In this study, the irregular boundaries of the near-field are treated as consistent boundaries, extending the concept of Lysmer＇s vertical consistent boundaries. The presented technique is called the Condensed Hyperelements Method （CHM）. In this method, the irregular boundary is limited to a vertical boundary at each end that is a consistent boundary at the far-field side. Between the two ends, the medium is discretized with hyperelements. Using static condensation, the stiffness matrix of the far-field is derived for the nodes on the irregular boundary. Examples of the application of the CHM illustrate its excellent accuracy and efficiency.     

Perfectly matched layer-absorbing boundary condition for finite-element time-domain modeling of elastic wave equations

The perfectly matched layer (PML) is a highly efficient absorbing boundary condition used for the numerical modeling of seismic wave equation. The article focuses on the application of this technique to finite-element time-domain numerical modeling of elastic wave equation. However, the finite-element time-domain scheme is based on the second-order wave equation in displacement formulation. Thus, the first-order PML in velocity-stress formulation cannot be directly applied to this scheme. In this article, we derive the finite-element matrix equations of second-order PML in displacement formulation, and accomplish the implementation of PML in finite-element time-domain modeling of elastic wave equation. The PML has an approximate zero reflection coefficients for bulk and surface waves in the finite-element modeling of P-SV and SH wave propagation in the 2D homogeneous elastic media. The numerical experiments using a two-layer model with irregular topography validate the efficiency of PML in the modeling of seismic wave propagation in geological models with complex structures and heterogeneous media.     

On the impossibility of mean-field dynamos with some spherical symmetry of the motions

Abstract

A spherical mean-field dynamo model is considered in which both the mean motion and the mean electro-motive force due to fluctuating motions show some spherical symmetry. It is shown that under some reasonable assumptions the magnetic field is bound to decay to zero.     

Residual vorticity induced by the action of tidal currents in combination with bottom topography in the Southern Bight of the North Sea

Abstract

Results are presented of calculations on the generation of residual vorticity by tidal currents over the bottom topography of the Southern Bight of the North Sea. A typical order of magnitude is 10^?6 to 10^?7 s ^?1. This is compared with current measurements on calm days, when similar magnitudes are found. At windspeeds less than about 5 m/s tidal generation of residual vorticity is important; at higher windspeeds wind effects begin to dominate. Our results are relevant in understanding the spatial variability of residual currents, because a non-zero vorticity implies the existence of horizontal gradients in the residual current field.     

基于单差搜索的格拉纳斯双差模糊度固定方法

格拉纳斯(GLONASS)系统采用频分多址技术,差分技术处理双差载波相位观测值时为保持模糊度参数的整数特性,需要加入伪距计算单差模糊度进行辅助求解。为了降低伪距观测误差对双差模糊度快速固定的影响,本文给出了一种GLONASS双差模糊度解算方法:建立检验搜索出最佳的单差模糊度,再固定双差模糊度;并利用实测数据对该方法进行验证,结果证明可以有效地减少伪距误差对双差模糊度解算的影响。     

一种改进的GPS短基线直接解算方法

本文通过推导基线偏差与波长之间的数学关系,在DC算法的基础之上,考虑双频相位双差数学模型本身存在的相等关系,并结合宽巷模糊度组合,提出一种求解整周模糊度的改进直接计算法。在求取模糊度之后,分别采用单历元最小二乘和序贯平差两种解算方案求解基线,以基线长约6.3km、9.1km的两组数据为实例进行求解,并与TGO软件求取的基线向量作比较,试验结果表明了本文方法的正确性和可靠性。