被动源反射地震方法在四川拉拉矿田海林铜矿勘查中的应用试验

在四川拉拉铜矿田海林铜矿区的勘查工作中,采用被动源地震方法进行勘查应用试验,将获得的成果与AMT(音频大地电磁)成果进行对比,发现吻合程度较高,并且在深部的分辨率要优于AMT。通过试验证明被动源地震方法可以有效识别出层控型矿床的含矿地层和围岩,为丰富矿产勘查的物探手段提供了有益的应用实例。     

Structural information derived from ambient noise tomography over a hydrocarbon-producing region in the Cachar fold belt,lower Assam,northeast India

Ambient noise tomography is a powerful tool that has found increasing application in reservoir analysis and imaging. The Cachar fold belt in lower Assam, northeast India encompasses several wells under active hydrocarbon production, along with several dry wells. To overcome the lack of active seismic data over the entire fold belt, a passive seismic study was carried out to image the concealed three-dimensional sub-surface structures. The data were recorded from February to November 2011 by a network of 65 wideband seismometers spanning an area of about 40 × 60 km². The data are crosscorrelated in the 2–5 s band, followed by phase-weighted stacking to estimate noise correlation functions with surface wave signatures. The traveltimes picked from the frequency-time analysis are utilized in a tomographic inversion for Rayleigh wave group velocities. The group velocity anomalies have a lateral resolution of ~ 3.5 × 5.5 km² and variations of up to $\pm 20\%$ for each period. The group velocities are in turn inverted for S-wave velocity distribution as a function of depth. The three-dimensional S-wave velocity tomograms reveal the tight anticlines and broad synclines, with high- and low-velocity zones corresponding to structural highs and lows, respectively. The structural interpretation is supported for the part of the region with producing wells and covered by active seismic data, wherein the post-stack time migrated seismic section shows anticlinal and synclinal features similar to those obtained from ambient noise tomography. The structures revealed by ambient noise tomography can help identify zones of interest to be targeted by active seismic surveys in the Cachar fold belt.     

被动微波辐射特征地形效应模拟与实验

基于地形对被动微波辐射的影响机理研究, 利用AIEM 模型模拟微波辐射的地形效应, 建立实验地貌微 缩景观, 由车载微波辐射计进行观测, 探索影响被动微波辐射特征的地形因子。地基实验表明, 在低频波段本地入 射角对山地倾斜表面的微波辐射有10 K—15 K 的影响, 小于10GHz 的观测频率可以消除地形高度对微波辐射的影响。 同时, 实验验证微波极化受地表形态属性——山体坡向和山体形状的影响显著, 地形坡度对极化信息影响不明显。