准中地区三工河组三角洲砂体成因地质模型

Geologic Model for Delta Sand Genesis of Sangonghe Formation in Central Junggar Basin

综合分析了准噶尔盆地中部地区下侏罗统三工河组辫状河三角洲与曲流河三角洲砂体的成因机理及差异性,认为辫状河三角洲较曲流河三角洲水动力条件、搬运能力及侵蚀能力均较强,砂体连通性及颗粒分选性较好,从而建立曲流河三角洲"孤立砂体"、辫状河三角洲"砂夹泥"和"泛连通块砂"等3种砂体成因地质模型,并分别对应岩性圈闭、构造-岩性圈闭或低幅构造圈闭等3种圈闭(组合)类型采取不同的勘探方式。最终明确在研究区早期油气充注、后期构造掀斜调整的背景下,三工河组二段上亚段的"孤立砂体"模型所对应的岩性圈闭是目前准中1区块油气勘探的主要目标。

The comparative analysis of sand genetic mechanism and difference between the meandering river delta and braided river delta is conducted.It is suggested that the hydrodynamic condition,transport capacity and erosion ability of the braided river delta are more powerful and better sand interconnectivity than the meandering river delta,by which three sand genetic geologic models（isolated sand for meandering one,sand-intercalated mud and panto-communicated sandbody for braided one） are developed,and the corresponding three traps（lithologic trap,structural-lithologic trap and low-amplitude structural trap） and their composite types are studied by using different exploration approaches.It is concluded that under the background of early oil-gas charging,late tectonic tilting reconstruction in Junggar basin,the lithologic trap corresponding to the isolated sand model of the upper sub-member of second member of Sangonghe formation could be the main target for petroleum exploration in Block-1 of central Junggar basin.