应用陆坡形态-迁移轨迹组合法寻找大型富砂深水扇

在海外选区研究阶段，盆地勘探程度极低，资料贫乏，导致常规深水沉积分析工作很难开展。而陆坡形态与陆坡迁移轨迹富含丰富的地质信息，可借助二者的组合对深水沉积进行宏观分析。以二维地震资料为基础，应用陆坡形态-迁移轨迹组合法寻找大型富砂深水扇的有利发育区。A盆地发育上升型、平直型、下降型三种陆坡迁移轨迹类型，其中平直-下降型迁移轨迹对应的陆坡进积距离更大，更有利于发育大型深水扇沉积；同时A盆地发育上凸型、下凹型、直线型和坡坪型四种陆坡类型，上凸型与下凹型陆坡的坡度更缓，宽度更大，更有利于重力流的砂泥分异，从而形成富砂深水扇沉积。将同一时期的大型、富砂深水扇的有利分布区相叠合，重叠区域即为该时期大型富砂深水扇的有利发育区，主要位于盆地东部拐角带与盆地西部。同时应用组合法还可建立盆地漂移期的沉积演化模式，分析漂移期沉积演化历史。

Application from Combination of Slope Geometries and Shelf-Edge Trajectories to Find Large-Scale,Sand-Rich Deepwater Fan

In overseas selection stage,extremely low exploration degree and poor data of basin lead to work hard to carry out regular deepwater sedimentary analysis.Slope geometries and shelf-edge trajectories have abundant geological information. In this paper,on the basis of 2D seismic data,apply combination of slope geometries and shelf-edge traj-ectories to look for favorable distribution of large-scale,sand-rich deepwater fan.A basin develops three types of shelf-edge trajectories,including increasing shelf-edge trajectories,flat shelf-edge trajectories,decreasing shelf-edge trajec-tories. Progradational distance of linear-decreasing shelf-edge trajectories corresponding slope is longer, more benefi-cial to develop of large-scale deepwater fan deposits. At the same time, A basin develops four types of slope, inclu-ding up convex slope, down concave slope, linear slope, and ramp-flat slope. Up convex slope and down concave slope have smaller slope angle and bigger slope width,more beneficial to sand mud differentiation and thus form deep-water fan deposits with better physical property of reservoir. Overlap favorable distribution of deepwater fan with large-scale and good physical property of reservoir during the same period. Overlapping area is the favorable distribution of large-scale,sand-rich deepwater fan,mainly located in the eastern corner and western area in the basin. Also,apply-ing combination method of slope geometries and shelf-edge trajectories can establish sedimentary evolution model of basin during drifting period and analyze history of sedimentary evolution.