准噶尔盆地A区上侏罗统齐古组物源体系和沉积特征

Source system and sedimentary characteristics of Upper Jurassic Qigu Formation in area A of Junggar Basin

准噶尔盆地腹部上侏罗统齐古组是近年来油气勘探的热点地区。近期,包括A303在内的多口钻井获得了高产油气流,展示了较大的油气资源潜力,但有利砂体分布规律不清制约了A区油气富集高产因素的进一步研究。以A区齐古组为研究对象,以岩心、测井、重矿物等资料为基础,结合近期的野外地质调查对研究区齐古组物源体系和沉积特征展开研究,结果表明:1)A区齐古组主要来源于准噶尔盆地西北缘的扎伊尔山;2)区内主要发育辫状河三角洲前缘亚相,其中分支水道、分流砂坝微相储层物性、含油性最好,是有利的勘探相带;3)区内主要发育东西两支浅水三角洲扇体,纵向上不同期扇体横向迁移变化,控制形成4套砂组叠合连片。研究成果深化了该区浅水河控三角洲沉积特征认识,为下一步优选区带提供依据,也可为类似区块提供借鉴。

In recent years,the Upper Jurassic Qigu Formation in the abdomen of Junggar Basin has been a hot area for oil and gas exploration.Recently,many wells,including A303,have obtained high oil and gas flow production,showing great potential for oil and gas resources.Still,the unclear distribution pattern of favorable sand bodies restricts the further study of the factors of oil and gas enrichment and high production in area A.Taking the Qigu Formation in Area A as the research object,the material source system and sedimentary characteristics of the Qigu Formation in the study area are studied based on core,logging,heavy minerals,etc.,and combined with the recent field geological surveys.The results show that:1)The Qigu Formation in Area A mainly originated from the Zaire Mountain in the northwest margin of the Junggar Basin;2)The braided river delta front subfacies is mainly developed in the area,in which the reservoir physical properties and oil-bearing properties of the microfacies of branching channels,and distributary sand bars are the best,and it is a favorable exploration phase belt;3)Two shallow water delta fan bodies in the east and west are mainly developed in the area,and the transverse migration changes of the different periodical fans in the longitudinal direction control the formation of four sets of superimposed-contiguous sand sets.This research results deepen the understanding of the sedimentary characteristics of the shallow river-controlled delta in this area,which can provide a basis for the next step of selecting the preferred zones and also provide a reference for similar blocks.