用层序地层学构建辫状河三角洲岩性油藏地质模型

Construction of geologic model for lithologic oil reservoirs in braided river delta with sequence stratigraphy

近期在冀中坳陷饶阳凹陷留西地区下第三系沙三段新发现的岩性油藏是较典型的辫状河三角洲砂岩岩性油藏。应用层序地层学原理 ,对该地区层序地层进行了划分 ,建立了地震等时格架。综合分析各项资料结果表明 :留西地区下第三系沙三段为一个三级层序 ,发育低位、湖侵和高位 3个完整的体系域。通过大量的岩心观察、岩电组合特征分析和识别 ,将辫状河三角洲前缘亚相划分出分流水道、分流河口坝和楔状砂等沉积微相。用Jason等多种地震反演方法识别出辫状河三角洲的平面形态和空间展布 ,预测出辫状河三角洲的前缘亚相的储集性能 ,指出了有利的储集相带。对留西地区辫状河三角洲砂体形成的沉积环境、构造背景、砂体类型等岩性油藏的成藏条件进行了系统剖析 ,构建了该区岩性油藏的成藏地质模型 。

The lithologic oil reservoir of Paleogene Es3 recently discovered in Luixi area of Raoyang sag is typical sediment of braided river delta. The data from the lithologic oil reservoirs of this area were analyzed. The sequence stratification of Paleogene in Luixi area was compartmentalized, and the homology stratum era was found from seismic data. The data analysis shows that the Paleogene Es3 is a three-class sequence and three system tracts of subsisting lowstand, lakegressive and high systems tract are developed in Liuxi area. Sedimentary tiny facies of the braided river delta in Luxi area, such as embranchment aquatic sand and estuary dam sand, were identified by observing rock core and analyzing the lithologic compages and logging curves. The plane occurrence and space shape of braided river delta were determined using computer software of Jason seismic inversion. The reservoir rock of the braided river delta in Luixi area was predicted, and the advantaged sections for forming lithologic oil reservoirs were suggested. The conditions for forming lithologic oil reservoirs including sediment environment, sandstone body types of stratigraphy of braided river delta and structure characteristics were investigated. The geologic model for the lithologic oil reservoirs in Luixi area of Raoyang sag was established. The research method for identifying sandstone bodies of lithologic oil reservoirs from seismic data and the effectiveness of exploration in Luixi area of Raoyang sag were described.