泛开江－梁平海槽及勘探有利相带地震预测

Kaijiang-Liangping Pan-trough and seismic prediction of favorable facies belt

四川盆地上二叠统长兴组生物礁的预测工作,在20世纪80～90年代主要以地质研究为主,研究初期常有生物礁目标井打不到生物礁,而非目标井又时而钻遇生物礁的现象。近年来,结合地质、钻测井资料,利用区域大剖面地震相预测技术,建立了一套识别晚二叠世末期台地—海槽沉积相带的方法,首次分别在川北、川中及川东地区地震大剖面发现了台地—海槽地震相形迹。在此基础上,对上述地区生物岩隆(礁、滩)有利相带进行了重点识别,总结了台地边缘生物岩隆的地震相预测方法,并编制了四川盆地晚二叠世末期泛开江—梁平海槽古地貌及沉积相预测图,表明环海槽周缘生物岩隆具有延伸远、勘探潜力大的基本态势。通过川东五百梯、川中LG等区块的钻井表明,所应用的技术是预测二叠系碳酸盐岩礁、滩有利区带及勘探部署的实用技术。

The prediction of bioherm in the Upper Permian Changxing Formation in the Sichuan Basin focused on geologic research in the 1980s and 1990s.It was common in the early stage of the study that wells being targeted at bioherm did not encounter bioherm,while wells that were not targeted at bioherm sometimes encountered bioherm.In recent years,a set of methods for identifying seismic facies of platforms at the end of Late Permian have been developed by using seismic facies prediction techniques of regional large section as well as geologic,drilling and log data.Evidences of platform-trough seismic facies have been identified,for the first time,on Chuanbei(north Sichuan),Chuanzhong(middle Sichuan) and Chuandong(east Sichuan) regional large seismic sections respectively.Based on these jobs,the favorable facies belts on biogenic buildups(reef facies,beach facies) are identified,the seismic facies prediction techniques of biogenic buildups on platform margin are summerized,and the palaeogeomorphology and sedimentary facies of Kaijiang-Liangping Pan-trough at the end of Late Permian in the Sichuan Basin are mapped.The study results show that the biogenic platforms on the periphery of the trough are long in extension and huge in exploration potential.Drilling results in the Wubaiti block of Chuandong(east Sichuan) area and the LG block in the Chuanzhong(middle Sichuan) area indicate that these techniques are suitable for the identification of the favorable targets of reef and beach facies in the Permian carbonates and for exploration planning.