沉积过路现象的地震识别特征及控制因素探讨  

Discussion on seismic identification characteristics and controlling factors of sediment bypass

作　　者：尚文亮 徐少华 蔡默仑 高红灿 李小刚[1,2] 陈岑 蔡长娥[1,2] 秦磊 SHANGWenliang;XU Shaohua;CAI Molun;GAO Hongcan;LI Xiaogang;CHEN Cen;CAI Change;QIN Lei(Chongqing Key Laboratory of Complex Oil&Gas Exploration and Development,Chongqing 401331,China;School of Petroleum Engineering,Chongqing University of Science&Technology,Chongqing 401331,China;Geological Exploration&Development Research Institute,CNPC Chuanqing Drilling Engineering Company Limited,Chengdu 610051,China)

机构地区：[1]复杂油气田勘探开发重庆市重点实验室,重庆401331 [2]重庆科技学院石油与天然气工程学院,重庆401331 [3]中国石油集团川庆钻探工程有限公司地质勘探开发研究院,成都610051

出　　处：《岩性油气藏》2020年第6期85-96,共12页Lithologic Reservoirs

基　　金：国家自然科学基金项目“陆架边缘三角洲体系供源速率的侧向差异对地层叠加样式的控制:以珠江口盆地SQ13.8为例”(编号:41902114);重庆市自然科学基金面上项目“三角洲体系物源供给差异对层序构成样式的控制”(编号:cstc2019jcyj-msxmX-0719);重庆科技学院大学生科技创新训练计划项目“基于地震正演模拟的低位体系域识别技术与应用”(编号:2019008)联合资助。

摘　　要：目前对沉积过路现象的研究大多停留在对陆架或陆坡内的无沉积现象作简单的说明,而对于沉积过路的主控因素尚不明确。通过收集国内外沉积过路的实例,并对不同案例进行对比分析,明确沉积过路在地震上的识别标志,并探明沉积过路的主控因素。结果表明:①沉积过路代表着沉积间断,在地震上表现为顶底地层的地震反射同相轴合并。②沉积过路多发生在非均衡陆坡之上,非均衡陆坡内的不同可容纳空间(池状可容纳空间、愈合陆坡可容纳空间及陆坡可容纳空间)充填阶段为沉积过路提供了潜在过路区。③沉积物粒度、浓度、流体流量及地形坡度决定沉积物能否过路。其中,沉积物粒度与流体流量是影响浊流过路的主要因素,沉积物浓度是影响碎屑流过路的主要因素。④坡度对沉积过路的控制作用体现在相邻地层的相对坡度比和绝对坡度差等2个方面。相对坡度比是沉积过路作用启动的重要条件。绝对坡度差决定沉积过路的距离,绝对坡度差越小,沉积过路的距离越短;绝对坡度差越大,沉积过路的距离越长。该研究结果有助于加深对沉积物运输过程的理解与认识,对今后沉积过路现象的研究也具有借鉴意义。At present,most of researches on sediment bypass are focused on explaining the non-deposition that occur in continental shelves or slopes,but the main controlling factors of sediment bypass are still not clear.By collecting domestic and foreign cases of sediment bypass and making comparative analysis on different cases,the identification signs of sediment bypass on seismic profiles and the main controlling factors of sediment bypass have been ascertained.The result shows:(1)Sediment bypass represents depositional break,and appears as the merging of seismic events of the top and bottom formation in seismic profile.(2)Sediment bypass mostly occurs on above-graded slope,and the filling stages of different accommodation spaces(ponded-basin accommodation space,healed-slope accommodation space and slope accommodation space)in above-graded slope provide potential areas for sediment bypass.(3)Sediment grain size,concentration,fluid flow,and slope determine whether the sediment can pass by.Among them,sediment grain size and fluid flow are the main factors that affect the turbidity currents bypass.Sediment concentration is the main factor that affects the debris flow.(4)The controlling effect of slope on sediment bypass is reflected in two aspects:absolute gradient difference and relative slope ratio of adjacent formation.Relative slope ratio is an important condition for the start of sediment bypass.The absolute slope difference determines the distance of sediment bypass.The smaller the absolute gradient difference is,the shorter the bypass distance is;the larger the absolute gradient difference is,the longer the bypass distance is.This research is helpful to deepen the understanding and knowledge about the sediment transport process,and also has reference for future research of sediment bypass.

关 键 词：沉积过路 非均衡陆坡 可容纳空间 相对坡度比 

分 类 号：P512.2[天文地球—地质学]