在层序地层学原理和方法的指导下,综合利用地震、测井、钻井及岩心等资料,结合盆地构造演化特征,建立了梨树断陷断陷层(晚侏罗世火石岭组及早侏罗世沙河子组、营城组和登娄库组)层序地层格架。将梨树断陷断陷层划分为1个一级层序(TSq1)、3个二级层序(I—Ⅲ)、7个三级层序(sQ1—sQ7),并在层序格架内进行沉积相划分和沉积体系研究,明确研究区主要发育冲积扇、扇三角洲、辫状河三角洲、近岸水下扇和湖泊等沉积体系。冲积扇沉积体系主要分布在早期SQ2层序中;扇三角洲沉积体系主要分布在SQ3和SQ4层序中;SQ5,SQ6和SQ7层序则以辫状河三角洲沉积为主;近岸水下扇沉积体系主要发育在SQ4、SQ5和SQ6各层序的陡坡带。沉积体系在平面与纵向上的演化受古构造与古地貌的双重控制,提出梨树断陷SQ4和SQ5层序沉积砂体为较有利的勘探区域。。
Based on seismic data, logging, drilling data, cores and characteristic of structure evolution, sequence framework of faulted layer in the Lishu rift is established. The faulted layer of the Lishu rift includes the Late Jurassic-Early Cretaceous strata of Huoshiling, Yingcheng, Shahezi and Denglouku formations, and is subdivided into three second-order sequences (I-Ⅲ) and seven third-order sequences (SQ1-SQ7). Furthermore, sedimentary facies and sedimentary system are studied within the sequence frameworks. The results show that it mainly developed alluvial fan, fan delta, braided fiver deha, nearshore subaqueous fan, and lacustrine sedimentary system. Alluvial fan system mainly developed in the SQ2 sequence. Fan delta system mainly developed in the SQ3 and SQ4 sequences. Braided fiver delta system was found in the SQS, SQ6 and SQ7 sequences. Nearshore suhaqueous fan system mainly developed in the steep-slope zone of the SQ4, SQ5 and SQ6 sequences. The lateral and vertical evolutions of sedimentary systems were controlled by palaeostructure and palaeogeomorphology. The sand bodies of the SQ4 and SQ5 sequences are more favorable exploration area in the Lishu rift.