利用层序地层学方法预测川东北大安寨段介屑滩分布
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摘要
川东北地区侏罗系自流井组大安寨段介屑灰岩储层是川东北地区一个重要的油气产层,储层主要是“高能”介屑滩。目前有两种方法预测这类介屑滩,即地震预测方法和层序地层学预测法。文章利用层序地层学法预测了“高能”介屑滩,首先利用钻井统计分析结合介屑滩的沉积模式预测到高能介序屑滩主要分布在浅湖相靠近深湖相的斜坡上沿;其次根据钻井统计结果,制作大安寨段黑色页岩/地层厚度平面图来代替地层厚度图,这样作能避免不均匀沉积对地层厚度的影响,利黑色页岩/地层厚度变化能反应沉积相变化的这种规律,将黑色页岩/地层厚度平面图转换成为大安寨段地层的沉积相图;最后综合沉积古地理图和高能介屑滩的分布规律,制作出高能介屑滩的平面分布图。从最新的钻井结果证明,文章所预测的结果准确性较高。
The Da’anzhai bio-fragmental limestone of Ziliujing Formation, Jurassic, is an important oil/gas payzone in Northeast Sichuan, and the reservoir is mainly the “high-energy” bio-fragmental beach. There are two methods for predicting the beach at present there, i.e.seismic method and sequence stratigraphic method, and the later was applied by the auther. First, through the statistical analysis of drilling data and in consideration of the sedimentary pattern, it was predicted that the “high-energy” bio-fragmental beach was distributed in the shallow lacustrine facies near to the upper edge of the slope of deep lacustrine facies; second, according to the statistical result of drilling data, the horizontal plan of black shale-to-layer thickness ratios of Da’anzhai member was made up instead of its isopoch map, by which the influence of nonuniform sedimetation on layer thickness can be eliminated, and the horizontal plan was transformed into sedimentary facies map of Da’anzhai member because the change in sedimentary facies can be reflected by that in the ratios; and third, the distribution map of “high-energy” bio-fragmental beaches was achieved at last in consideration of the genetic relation between the palaeogeographic environments of sedimentation and the “high-energy” bio-fragmental beaches. In light of the latest drilling results, it was proved that the achievement predicted by the author has an high accuracy.
The Da’anzhai bio-fragmental limestone of Ziliujing Formation, Jurassic, is an important oil/gas payzone in Northeast Sichuan, and the reservoir is mainly the “high-energy” bio-fragmental beach. There are two methods for predicting the beach at present there, i.e.seismic method and sequence stratigraphic method, and the later was applied by the auther. First, through the statistical analysis of drilling data and in consideration of the sedimentary pattern, it was predicted that the “high-energy” bio-fragmental beach was distributed in the shallow lacustrine facies near to the upper edge of the slope of deep lacustrine facies; second, according to the statistical result of drilling data, the horizontal plan of black shale-to-layer thickness ratios of Da’anzhai member was made up instead of its isopoch map, by which the influence of nonuniform sedimetation on layer thickness can be eliminated, and the horizontal plan was transformed into sedimentary facies map of Da’anzhai member because the change in sedimentary facies can be reflected by that in the ratios; and third, the distribution map of “high-energy” bio-fragmental beaches was achieved at last in consideration of the genetic relation between the palaeogeographic environments of sedimentation and the “high-energy” bio-fragmental beaches. In light of the latest drilling results, it was proved that the achievement predicted by the author has an high accuracy.
引文
1 许红梅.薄层灰岩的油气富集区预测方法初探.石油地球物理勘探;2002;(2)
2 胡宗全.四川盆地下侏罗统大安寨组层序分析.天然气工业,2000;(5)
3 刘宝王君等.岩相古地理基础和工作方法.北京:地质出版社,1985
4 蔡希源等.陆相盆地高精度层序地层学.北京:地质出版社,2003
5 刘震.储层地震地层学.北京:地质出版社,1997
2 胡宗全.四川盆地下侏罗统大安寨组层序分析.天然气工业,2000;(5)
3 刘宝王君等.岩相古地理基础和工作方法.北京:地质出版社,1985
4 蔡希源等.陆相盆地高精度层序地层学.北京:地质出版社,2003
5 刘震.储层地震地层学.北京:地质出版社,1997
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