琼东南盆地松南—宝岛凹陷三亚组“源—汇”体系与主控因素分析

Analysis of“source-sink”systems and major controlling factors of Sanya Formation in the Songnan-Baodao Sag of Qiongdongnan Basin

琼东南盆地松南—宝岛凹陷主体位于琼东南盆地深水区东部,是已被钻探证实的富烃凹陷。中新统三亚组是深水区重要的勘探目的层,储集体规模和粒度是制约松南—宝岛凹陷三亚组油气成藏的关键因素。应用最新的三维地震和已钻井资料,结合区域地质背景,系统分析松南—宝岛凹陷三亚组“源—汇”体系及主控因素,预测有利砂体平面展布。研究表明,松南—宝岛凹陷三亚组沉积期,发育海南隆起和松南低凸起2个“源—汇”体系:中新世构造活跃的海南隆起主控北部“源—汇”体系,供源能力强,凹陷北部发育陆架坡折,发育“陆架三角洲和陆坡沟谷+深水扇”沉积体系;松南—宝岛凹陷以斜坡向松南低凸起过渡,不发育陆架坡折,南部“源—汇”体系具有“近源、沟谷汇聚阶槽控制下的多期深水扇”特征。搬运距离、构造活动和底流改造等因素主控三亚组储集体的发育,优选凹陷南缘为三亚组最有利的储集体发育区;优选松南区和宝岛区东部海底扇为三亚组有利储集体发育区。

The main part of Songnan-Baodao Sag is located in eastern part of deep-water area,Qiongdongnan Basin,which has been proved by drilling to be a hydrocarbon rich sag.Miocene Sanya Formation is an important exploration target in the areas,and the scale and particle size of reservoir are the key factor to the hydrocarbon accumulation of Sanya Formation in Songnan-Baodao Sag.Based on 3D seismic and drilled data,combined with regional geological background analysis,the source to sink system and main controlling factors of the Sanya Formation in the area are systematically analyzed to predict the favorable reservoirs distribution.Research has shown that during the period of Sanya Formation in the area,two source-sink systems were developed:the northern system with strong sediment supply capacity,whose provenance is Hainan Uplift,with strong uplifting in the Miocene;the northern part of the sag developed a continental shelf slope break with"shelf delta+slope canyon+fan"sedimentary system.The sag transitions from a slope to Songnan Low Uplift,with no development of continental shelf slope breaks.The southern system controlled by Songnan Low Uplift is a multi-stage fan model controlled by short transport distance and converging channels.The factors such as transportation distance,tectonic activity,and bottom-current transformation control the development of the reservoirs in Sanya Formation.The southern edge of the sag is selected as the most favorable reservoir development area;the favorable reservoir development areas are the Songnan area and the eastern part of Baodao area.