川东北元坝地区长兴组—飞仙关组台地边缘层序地层及其对储层的控制

Sequence strata of the platform edge in the Changxing and Feixianguan formations in the Yuanba area,northeastern Sichuan Basin and their control on reservoirs

在野外露头、钻井岩心观察与测井、地震资料解释的基础上,开展了四川盆地东北部元坝地区长兴组—飞仙关组层序地层研究,将长兴组—飞仙关组划分为4个Ⅲ级层序,分别为SQ1、SQ2、SQ3及SQ4。对层序与储层的综合研究表明:储层分布明显受Ⅲ级层序体系域及沉积相控制,储层主要分布于SQ1、SQ2及SQ3的高位体系域中,为台地边缘浅滩相及台地边缘礁滩相沉积;长兴组储层岩性以生屑白云岩及生屑灰岩为主,储层物性好;飞仙关组储层岩性以亮晶鲕粒灰岩为主,储层物性一般。

Based on the observation of outcrops and cores as well as on the interpretation of well-log and seismic data,the present paper studied sequence strata of the Changxing and Feixianguan formations in the Yuanba area,and recognized sequence boundaries and system tract boundaries.The Changxing and Feixianguan formations could be divided into four third-order sequences,namely SQ1,SQ2,SQ3 and SQ4.The comprehensive study on the reservoirs and sequences indicated that ① the distribution of reservoirs was clearly controlled by the system tract of the third-order sequence and sedimentary facies;② reservoirs were mainly distributed in high stand system tracts of the SQ1,SQ2 and SQ3 sequences,which were composed of shallow-shoal facies and reef-shoal facies of the platform edge;③ reservoirs in the Changxing Formation were lithologically dominated by bioclastic dolomites and bioclastic limestones with good physical property,while reservoirs in the Feixianguan Formation were mainly composed of oosparites with medium physical property.