歧口凹陷古近系超深气藏烃类检测方法  

Hydrocarbon detection methods for the Paleogene ultra-deep gas reservoirs in the Qikou Sag

作　　者：洪忠[1] 张猛刚[1] 刘化清[1] 苏明军[1] 袁淑琴[2] 

机构地区：[1]中国石油勘探开发研究院西北分院,甘肃兰州730020 [2]中国石油大港油田公司勘探开发研究院,天津300280

出　　处：《石油与天然气地质》2013年第6期847-854,共8页Oil & Gas Geology

基　　金：中国石油天然气股份有限公司"歧口富油气凹陷大油气田勘探及综合配套技术研究"项目(2008-030504)

摘　　要：近几年来,歧口凹陷古近系超深层天然气勘探呈可喜态势。然而,目前还没有针对该地区超深层天然气藏的地震响应总结和与之相匹配的天然气检测技术研究,制约了超深层天然气勘探的进程。为满足扩大勘探的要求,根据超深气藏在频率域所表现的"低频共振,高频衰减"的典型响应特点,对比研究不同的频谱分解方法。同时,根据研究区超深层天然气储层发育特点,应用瞬时子波吸收技术及振幅频率比属性等方法来预测含气层段和边界。结果表明:频谱分解方法是检测含气异常的基础,通过选择时间大小约2倍于地震记录子波两波谷间平均距离的Hanning时间窗函数,进行短时傅氏变换。该方法适用于检测含气储层低频异常,并可获得较高的时频分辨率。烃类检测方法应用结果与新近部署探井的超深层气藏分布吻合,证明了该套方法预测厚含气储层的有效性,为歧口凹陷深层天然气的扩大勘探提供了有力的技术保障。In recent years, exploration of the Paleogene ultra-deep gas reservoirs in the Qikou Sag has been fruitful. Yet no researches have been performed on the seismic response features of these gas reservoirs and relevant gas detection tech- niques, impeading exploration to some degree. In an attempt to solve these problems, a comparative study on various spec- tral decomposition methods was performed according to the typical frequency domain responses of the ultra-deep gas re- servoirs,i, e. high-frequency attenuation and low-frequency resonation. In addition, according to the features of the ultra- deep gas reservoirs, instantaneous wavelet absorption and amplitude to frequency ratio attribute were employed to detect gas-bearing intervals and their boundaries. The result shows that the spectral decomposition method is the basis of abnor- mal gas-bearing reservoir detection. The Short Time Fourier Transformation through Hanning time function with a time window length being two times of average distance between two through of seismic wavelets is suitable for detecting low- frequency abnormaly of gas reservoir with high resolution both in time and frequency domains. The results of gas detection with these techniques match the drilling results of the new exploratory wells, verifying the effectiveness of these methods in ultra-deep gas reservoir detection in the Qikou Sag.

关 键 词：窗函数 频谱分解 烃类检测 超深层气藏 歧口凹陷 

分 类 号：TE135[石油与天然气工程—油气勘探]