地震找气技术在台南气田勘探中的应用

Application of gas seismic technique in Tainan gas field exploration,

柴达木盆地东部地区的第四系浅湖相沉积最大厚度达3200m,生气面积达15000km^2,是寻找天然气最有利地区。本区第四系地层的速度较低,一般为1700～2500m/s。在这样的低速背景下,地层含气后在地震时间剖面上出现如下特征:低速异常现象更加明显,在隆起部位出现隆中之凹;含气层的反射能量较弱;频率变低。依据这些基本特征,并利用地震模型正演、合成声波测井、AVO、岩性模拟及地震压力预测等技术,对本区的天然气进行了地震检测。经钻探证实,这项研究天然气的方法是成功的。

The maximum thickness of Quaternary shallow lake facies sediments in the East Chaidamu basin is 3200m.Gas source rock covers an area of 15 000km^2,which is the most favourable area where we can dis- cover gas resources.Seismic velocity in the Quaternary formation is quite low,generally ranging from 1700m/s to 2500m/S.with such low velocity,gas-bearing horizons in seismic time section show the features:obvious low velocity anomaly—depression that occurs in a dome,weak energy and low frequency.In the light of these features, gas resources in this area were predicted using seismic methods,such as forward seismic modeling,synthetic sonic logging,AVO,lithology modeling,seismic pressure prediction and so on,Drilling proved suc- cessful the technique by which we search for gas resources.