分流河道是很多大型油气田的重要储集体,但目前对分流河道内部砂体的系统研究仍较少,在一定程度上制约了油气的开发效果.采用野外实地考察、浅钻孔、探坑、探槽等方法,对赣江三角洲分流河道内发育的砂体类型、沉积特征、砂体规模进行了系统研究.分流河道内发育水道、边滩、汊口滩、并口滩4种砂体,其中汊口滩发育在分流河道的分汊口处,并口滩发育在分流河道的合并处；不同砂体的堆积方式不同,水道为垂向加积,边滩为侧向加积,汊口滩为逆流加积,并口滩为顺流加积.对不同砂体的规模进行测量,建立了分流河道内砂体定量参数地质资料库.上三角洲平原分流河道内边滩、汊口滩的规模普遍大于下三角洲平原,上三角洲平原的边滩长度集中在500~2000 m 之间,边滩宽度集中在100~400 m 之间,下三角洲平原边滩长度一般为300~900 m,宽度一般为50~200 m.并口滩的规模较小,长度一般为20~100 m,宽度一般为20~60 m,且仅在下三角洲平原发育.本次研究对油气田开发中预测砂体和寻找新的潜力目标区具有重要的借鉴作用.%Distributary channel is important reservoir of many large oil-gas fields.Oil and gas development is restricted because few research has paid attention to the sand body in distributary channel in the past. Based on field investigation, shallow borehole, exploration pit and exploration trench,the study on sand body types,sedimentary characteristics and quantitative parameters of sand bodies in distributary channel was carried out in Ganjiang delta.There are four kinds of sand bodies in distributary channel,i.e.waterway,point bar,branch mouth bar and confluence mouth bar.Branch mouth bar develops in the branch site of distributary channel, and confluence mouth bar develops in the confluence site of distributary channel.Stacking manners of the four kinds of sand bodies are different, including waterway with vertical accretion,point bar with lateral accretion,branch mouth bar with countercurrent accretion and confluence mouth bar with downstream accretion.The quantitative parameters of sand bodies in distributary channel were studied.The point bar and branch mouth bar in upper delta plain are bigger than that in lower delta plain.The point bars in upper delta plain are 500-2 000 m long and 100-400 m wide,while the point bars in lower delta plain are 300-900 m long and 50-200 m wide. Confluence mouth bars are small in size with the length of 20-100 m and the width of 20-60 m, and only develop in lower delta plain.The study has great implication for guiding the sand body prediction and searching for new potential area in oil and gas development.
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