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成岩圈闭是重要的油气圈闭类型之一,其成因类型较多,在准噶尔盆地玛湖凹陷三叠系百口泉组中发育的受沉积相和成岩相共同控制而形成的砂砾岩成岩圈闭是其中一种重要的成因类型。玛湖凹陷百口泉组发育扇三角洲沉积体系,在顺物源方向上,有机酸溶解扇三角洲前缘砂砾岩中的长石而形成次生溶解孔隙储层,其上倾方向上压实作用和胶结作用使扇三角洲平原砂砾岩致密化而形成圈闭遮挡层;在垂直物源方向上,次生溶解孔隙储层分布在由通源断裂和古鼻状构造构成的有机酸优势运移通道上,通道两侧前缘相砂砾岩较致密,其与水下分流河道间泥岩、其他物源体系的扇三角洲平原砂砾岩致密层构成圈闭侧向遮挡带;圈闭底板由百口泉组底部不整合面风化黏土层或平原相砂砾岩致密层或湖泛泥岩构成,圈闭顶板由湖泛泥岩构成。百口泉组砂砾岩成岩圈闭主要分布在由通源断裂和古鼻状构造构成的流体优势运移通道上,具有成藏优势,同时圈闭在横向上集群、纵向上叠置分布,具备了形成规模油气聚集的圈闭条件,是玛湖凹陷规模油气勘探的主要对象。百口泉组砂砾岩成岩圈闭的发现对中国东部裂谷盆地和中西部前陆盆地冲断褶皱带一侧陡坡冲积扇、扇三角洲的圈闭勘探具有借鉴意义。
Diagenetic traps are one of the most important oil and gas trap types and are characterized by many types of conglomerate diagenetic lithosphere formed by sedimentary facies and diagenetic facies developed in the Triassic Baikouquan Formation in the Mahu Sag, Junggar Basin Closing is one of the important types of causes. The Baikouquan Formation in the Mahu Depression develops fan delta depositional systems. In the direction of the provenances, organic acids dissolve feldspars in the fan delta front glutenite to form secondary dissolved porosity reservoirs that are compacted in the updip direction In the direction of vertical provenance, the secondary dissolved pores reservoirs are distributed in the predominant migration channel of organic acids formed by Tongyuan fault and ancient nose-shaped structure On the upper edge of the channel, both sides of the facies are relatively dense sand conglomerate, with the shale between the underwater distributary channel mudstone, other provenance system of fan delta plain gravel dense layer constitutes trapping lateral shielding zone; Bottom unconformity weathered clay layer or plain facies glutenite or lake pan mudstone, and the trap roof is composed of the lake pan-mudstone. The diagenetic traps of glutenite conglomerate in the Baikouquan Formation are mainly distributed over the fluid migration channels formed by Tongyuan fault and ancient nose structures, which have the advantages of hydrocarbon accumulation. At the same time, the traps are horizontally clustered and vertically distributed, The formation of large-scale accumulation of oil and gas trap conditions, is the major oil and gas exploration Mahu depression main object. The discovery of the conglomerate diagenetic traps in the Baikouquan Formation can be of reference for the trapping of alluvial fans and fan delta steep sides of the thrust fold belt in the eastern rift valley in the eastern China and the mid-western foreland basin.