和什托洛盖盆地侏罗系辫状河三角洲沉积模式研究

辫状河三角洲砂体是有利的油气储集砂体，深入分析其沉积特征及沉积序列对油气勘探具有重要的指导意义。 以和什托洛盖盆地侏罗系三工河组辫状河三角洲露头实测为基础，通过对各微相沉积特征和岩相类型进行分析，建立了该区辫状河三角洲的沉积序列和沉积模式。结果表明：研究区发育进积型辫状河三角洲，自下而上可划分出前辫状河三角洲、辫状河三角洲前缘和辫状河三角洲平原 3 个亚相，并可进一步细分为远砂坝、河口坝、水下分流河道、分流河道及沼泽等微相；在辫状河三角洲沉积中可识别出 8 种岩相类型，分别为粒序层理砾岩相、滞留砾岩相、不明显平行层理砾岩相、平行层理砂岩相、块状砂岩相、水平层理粉砂岩相、水平层理泥岩相和水平层理炭质泥岩相；三工河组沉积时期沉积物堆积速率大于盆地沉降速率，辫状河三角洲扇体向盆地方向不断推进并叠置在远端之上，自下而上呈现出反旋回的沉积特征。

Sedimentary model of braided river delta of the Jurassic in Heshituoluogai Basin

The braided river delta sand body is favorable oil and gas reservoir sand body, and the study of its sedimentary characteristics and sedimentary sequence has important guiding significance for the oil and gas exploration. Based on the field measurement of the braided river delta outcrop of Jurassic Sangonghe Formation in Heshituoluogai Basin, by analyzing the sedimentary characteristics of various microfacies and the types of lithofacies, this paper established sedimentary sequence and sedimentary model of the braided river delta. The results show that progradational braided river delta developed, prodelta, delta front and delta plain of the braided river delta successively developed upwards, which can be subdivided into distal bar, mouth bar, underwater distributary channel, distributary channel and swamp microfacies. Eight types of lithofacies can be identified in the braided river delta, including graded bedding conglomerate facies, lag conglomerate facies, less obvious parallel bedding conglomerate facies, parallel bedding sandstone facies, massive sandstone facies, horizontal bedding siltstone facies, horizontal bedding mudstone facies and horizontal bedding carbonaceous mudstone facies. During the sedimentary period of Sangonghe Formation, the sediment accumulation rate is greater than the basin subsidence rate, and braided river delta fan advanced towards the basin direction and superimposed on the distal side, showing coarsening upwards sedimentary characteristics.