四川盆地二三叠系礁滩相储层沉积演化特征

Sedimentary Evolution of Permian and Tertiary Bioreef-shoal Facies Reservoirs in Sichuan Basin

四川盆地中西部二叠系—三叠系礁滩相储层具有广阔的勘探前景。通过大量钻井及地震层序划分对比,分析礁滩相储层赋存规律及层序发育特征,采用"优势相"编图方法,探讨礁滩相储层沉积演化规律。研究表明,四川盆地二、三叠礁滩相储层主要形成于海西晚期—印支早期构造旋回,为一个巨层序序列,处于裂陷盆地阶段;沉积演化经历盆地由西高东低转变为西低东高的格局,发生明显的翘倾;沉积体系经历了开阔台地—蒸发台地的转变。

Exploration practice illustrates that there is a huge prospect of Permian and Tertiary bioreef-shoal facies reservoirs in central and west Sichuan Basin.In this study,both drilling-and seismic-sequence are first classified and correlated;and then,the reservoirs’occurrence regularity and sequence-developed characteristics are analyzed;at last,the sedimentary-evolution law is discussed by means of a mapping method called dominant facies.Results demonstrate that:(1)the Permian and Tertiary bioreef-shoal facies reservoirs mainly formed in a structural cycle from late Hercynian to early Indochina,which is either a huge sequence succession or in a rifting basin stage;(2)the sedimentary evolution experienced a basinal framework from west-high-east-low to west-low-east-high,and an obvious tilting can be found;and(3) the sedimentary system also experienced a change from open platform to evaporate platform.