松辽盆地徐家围子断陷沙河子组沉积相类型及演化模式

Sedimentary Facies Types and Evolution Models of the Shahezi Formation in the Xujiaweizi Fault Depression,Songliao Basin

【目的】徐家围子断陷沙河子组致密砂砾岩储层具有非常大的天然气勘探潜力,有望成为大庆油田深层火山岩气藏勘探的重点接替领域。【方法】综合运用岩心、录井、测井及地震等资料,对徐家围子断陷沙河子组沉积相展布及沉积演化模式开展了研究。【结果与结论】徐家围子断陷沙河子组发育辫状河三角洲、扇三角洲、具供给水道的远岸浊积扇、近岸水下扇、扇三角洲前端滑塌浊积扇以及浅湖—半深湖、深湖相等沉积相。安达凹陷、徐东凹陷以及肇州凹陷东侧的缓坡带接受来自肇东—朝阳沟基底古隆起的碎屑物质而发育辫状河三角洲沉积,局部发育由远源供给水道形成的湖底浊积扇沉积体;安达凹陷、徐东凹陷、徐西凹陷以及肇州凹陷西侧等徐西陡坡带接受来自中央隆起带粗碎屑物而发育扇三角洲沉积体系,以近源短流为基本特征,局部发育近岸水下扇沉积,且由于湖盆边缘发育的扇三角洲沉积体不稳定,在扇三角洲沉积体前方形成滑塌浊积扇沉积。

[Objective]The tight glutenite reservoir of the Shahezi Formation in the Xujiazi Fault Depression has great potential for natural gas exploration and is expected to become the key replacement field of deep volcanic gas reservoir exploration in Daqing oilfield.[Methods]The distribution of sedimentary facies and evolution models of the Shahezi Formation in the Xujiaweizi Fault Depression were studied using comprehensive core,logging,and seismic data.[Results and Conclusions]The results show that there are braided river delta,fan delta,far shore turbidite fan with supply channel,near shore subaqueous fan,slump turbidite fan in front of fan delta,shallow lakesemi-deep lake,and deep lake deposits in the Shahezi Formation of the Xujiaweizi Fault Depression.The gentle slope belt on the east side of the Anda,Xudong,and Zhaozhou Depressions received the detritus from the Zhaodong-Chaoyanggou basement paleo-uplift and developed braided river delta deposits;locally developed lacustrine turbidite fan deposits were formed by distant source supply channels.The western steep slope belts such as the Anda-Xudong,Xuxi,and Zhaozhou Depressions received coarse debris from the Central fault uplift area and developed a fan delta depositional system,which was characterized by near source and short flow.Nearshore subaqueous fan depositions were locally developed,and due to the instability of fan delta depositional bodies developed on the edge of lake ba⁃sin,slump turbidite fan depositions were formed in front of fan delta depositional bodies.