【摘要】 杭州湾地区第四系覆盖区蕴藏着丰富的浅层生物气资源,气藏最大特点是埋藏浅、分布广、丰度低、规模小。文中对埋深大于60m的浅层气藏进行了浅层二维高分辨率地震AVO分析,AVO分析的实质就是分析地震反射系数随入射角的变化。为了提高AVO分析的勘探效果,针对工区的地理、地震地质条件,在野外采集和资料处理中采用了以下措施:①采用改变观测系统的办法以减少跳炮现象。②资料处理中采取了初至折射波静校正和地表一致性剩余静校正;进行了细致的速度分析和真振幅恢复(TAR)处理;针对地层较平缓的特点,采用差分偏移。③在常规处理的基础上,进一步采取真振幅、地表一致性和去噪等处理手段。通过对工区7条新测线的角道集剖面进行细致的对比解释,并结合AVO属性剖面进行综合解释,发现了多处AVO异常,其与非地震物化探资料(如静电α法、遥感资料解释、微生物勘探资料)所反映的含气情况一致,证明文中所提方法是检测第四系浅层生物气的有效手段。更多还原

【Abstract】 The Quaternary overburden in Hangzhou Bay area is rich in shallow biogas resource that is characteristics of shallow berried depth,broad distribution,low abundance and small scale.The 2D high-resolution seismic AVO analysis for shallow gas reservoirs where the buried depth is greater than 60m was carried out in the paper.The nature of AVO analysis is to analyze the variation of seismic reflectivity with incident angles.In order to improve the exploration effects of AVO analysis and in view of geographic,seismic-geologic conditions of work area,the following measures were adopted in field acquisition and data processing: using geometry-changed system to reduce the not shot phenomenon; ②in data processing,using first break refraction static corrections,surface-consistent residual static corrections,fine velocity analysis and true amplitude restoration,using finite difference migration for the purpose of flat horizons; ③based on ordinary processing,further using such tools as true amplitude,surface consistence and denoise processings.The fine correlation and interpretation were carried out for angle-gather sections of 7 new acquired lines in work area and many AVO anomalies were discovered in combining with integrative interpretation of AVO attributes sections.The interpreted results were consistent with gas-bearing situation reflected by non-seismic geophysical and geochemical data such as static αmethod,remote-sensing data interpretation and microbial exploration data,which showed the method presented in the paper is effective tool for detection of Quaternary shallow biogas.更多还原