松辽盆地北部中央古隆起带基底风化壳综合解释及储层地震预测

Comprehensive interpretation and reservoir prediction with seismic data for basement weathering crust of central paleo-uplift zone in northern Songliao Basin

松辽盆地北部中央古隆起带从三叠纪到早白垩世末期,经历了长达1.5亿年风化剥蚀,钻井揭示基底风化壳普遍发育,厚度为90~300m,是深层重要的勘探领域。该区基底发育变质岩和花岗岩两大类共16种岩性,岩石种类复杂多样,储层类型以孔隙—裂缝型为主,孔隙度(0.33%~2.43%)较低,岩性及储层预测难度大。为此,应用钻井资料结合地震数据,明确基底风化壳特征,将风化壳划分为两层结构;基于岩性地震反射特征分析,应用多属性模式判别岩性识别技术,预测不同岩性分布特征。综合测井解释和岩石物理分析成果,明确不同岩性风化壳储层具有低波阻抗特征,应用GeoEast解释系统的确定性高分辨率Z反演技术,预测风化壳储层分布,初步形成了基底复杂岩性风化壳储层地震预测技术。

From the Triassic to the end of the early Cretaceous,the central paleo-uplift zone in the northern Songliao Basin experienced weathering and denudation for up to 150 million years.The drilling reveals that the basement weathering crust is generally developed,with a thickness of 90~300mand is an important deep exploration field.There are 16 kinds of lithology of metamorphic rock and granite in the basement,with complex and diverse types of rocks.The reservoir types are mainly the pore-fracture type with low porosity of 0.33%~2.43%,so lithology and reservoirs are difficult to predict.This paper employs drilling and seismic data to identify the characteristics of the basement weathering crust,and then the weathering crust is divided into two layers.After the analysis of lithological seismic reflection characteristics0,the paper applies the lithological identification technique based on multi-attribute pattern discrimination to predict the distribution characteristics of different lithology.According to the results of comprehensive logging interpretation and rock physical analysis,the weathering crust reservoirs of different lithology feature low wave impedance.The deterministic high-resolution Z-inversion technique of the GeoEast system is applied to predict the distribution of weathering crust reservoirs.Finally,the prediction technique of complex basement lithology of weathering crust reservoirs based on seismic data is preliminarily formed.