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三角洲砂体是已开发油气田中最重要的储集类型之一 ,对该类砂体的形成过程开展物理模型研究以预测储集砂体的分布特征及演变规律具有重要的实际意义。文中以鄂尔多斯盆地三叠系延长统长 6三角洲砂体为模拟原型 ,对三角洲前缘水下分流河道及河口坝形成过程进行了较深入研究。指出长 6三角洲储层主要是在基准面下降过程中 ,由水下分流河道的频繁分汊、交汇、叠合、迁移形成的。由于受到不同期水下分流河道的切割 ,河口坝保持时间较短而欠发育。实验结果与油田地质研究 ( 14口井资料 )对比表明 ,砂体组成及粒度参数的符合率达73% ,砂层厚度分布的符合率达 62 %～ 81% ,沉积微相展布的符合率达 58%。实验过程显示 ,水下分流河道的变迁与湖平面的下降速率及活动底板的运动强度密切相关
Delta sand body is one of the most important reservoir types in developed oil and gas fields. It is of great practical significance to carry out physical model studies on the formation process of such sand bodies in order to predict the distribution and evolution of reservoir sand bodies. In this paper, the Triassic Yanchang Chang 6 delta sand body in the Ordos Basin is used as a prototype to study the formation process of the delta front distributary channel and estuary dam. It is pointed out that the Chang 6 delta reservoir is mainly formed by the frequent subdivision, convergence, superimposition and migration of underwater distributary channel during the lowering of datum. Owing to the cutting of underwater distributary channel at different stages, the estuary dam is short and underdeveloped. The comparison between the experimental results and oilfield geology (14 wells) shows that the coincidence rate of sand body composition and grain size parameters is 73%, the coincidence rate of sand thickness distribution is 62% -81%, and the coincidence rate of sedimentary microfacies distribution Up to 58%. The experimental process shows that the change of underwater distributary channel is closely related to the descending speed of lake plane and the intensity of moving floor