准噶尔盆地春光探区古近系浅水辫状河三角洲沉积特征

Sedimentary Characteristics of Paleogene Shallow Braided River Delta in Chunguang Prospect Area,Junggar Basin

春光探区位于准噶尔盆地西北缘,近年来古近系勘探取得了重大突破,展示出良好的勘探潜力。但古近系地层剥蚀严重,井控程度低,沉积体系及沉积特征认识不清,为此,综合利用岩心、测井、地震、分析测试资料,对古沉积环境进行定量恢复,明确沉积特征及沉积演化过程,建立沉积模式。研究表明:准噶尔盆地春光探区古近系地形平缓,水体浅,属干热气候,具备浅水三角洲发育的条件;沉积粒度相对较粗,发育浅水辫状河三角洲前缘沉积,进一步划分为水下分流河道、滩坝、远砂坝,局部发育河口坝;砂体叠置样式多样,纵向上多期迁移叠置砂体为有利油气运移通道,顶部滨浅湖泥岩为有利遮挡条件,易形成岩性、断层-岩性油气藏,具有良好勘探前景。该研究对春光探区的精细勘探开发具有一定指导意义。

Chunguang Prospect Area is located in the northwestern margin of Junggar Basin,with major breakthroughs made in Paleogene exploration in recent years,demonstrating great exploration potential.However,the Paleogene strata are severely denuded,with low well control intensity and unclear sedimentary system and sedimentary characteristics.To this end,core,logging,seismic,analytical and test data were integrated to quantitatively recover the Paleosedimentary environment,clarify the sedimentary characteristics and sedimentary evolution process,and establish the sedimentary model.As found in the study,the Paleogene strata in Chunguang Prospect Area,Junggar Basin were gentle in topography,with shallow water bodies and a dry-hot climate,conducive to the development of shallow water deltas;the sediment grain size was relatively coarse,and deposits were developed in front of shallow braided river delta,further divided into submerged distributary channels,beach dams and distant sand dams,and locally developed estuary dams;the sand bodies were stacked in various forms,the multi-phase migrating stacked sand bodies were favorable oil and gas migration channels in the longitudinal direction,and shallow lacustrine mudstone at the top was favorable for blocking,which was prone to the formation of lithological and fault-lithological reservoirs,expressing profitable exploration prospect.The study provides guidance for the fine exploration and development of Chunguang Prospect Area.