阿克库勒地区三叠系湖底扇沉积及其主控因素

摘要

综合应用地震、测井、岩心、粒度分析等资料,对塔里木盆地阿克库勒地区中、上三叠统湖底扇沉积特征及其主控因素进行分析.结果表明:研究区发育富砂型、富砾型两类湖底扇,二者在发育背景、沉积特征、控制因素及含油性等方面存在明显差异;富砂型湖底扇发育于研究区南部辫状河三角洲前方,物源为远源搬运,供给充足,规模大,分选中等,主要受古地貌控制,发育相对稳定;富砾型湖底扇仅在研究区北部轮台断裂附近发育,属近源搬运,规模小,粒度粗,分选极差,主要受断裂控制,具有阵发性特点;物源条件、古地貌以及触发机制的差异性控制了不同湖底扇的沉积特征;在富砂型湖底扇中发现了大量的油气藏,相对富砾型湖底扇更具有较大的油气勘探潜力.%Based on seismic , well logs, core and grain size analysis data. the sedimentary characteristics and controlling factors of the middle and upper Triassic sublacustrine fans of Akekule area in Tarim Basin were researched . The results indicate that two kinds of fans , named sand-rich sublacustrine fan and conglomerate-rich sublacustrine fan , are developed in the study area. Significant differences were found between these two types of fans in the aspects of development settings, sedimentary characteristics , main controlling factors and oiliness. The sand-rich sublacustrine fan is located in front of the braided river delto and mainly develops in the southern part of the research area. The fan, far from the source. develops stably with moderate sorting and wide distribution. It is mainly controlled by palaeogeomorphy. On the contrary , the conglomerate-rich sublacustrine fan, whose paroxysmal development is largely influenced by faulting, develops in the northern part of the research area, near the Luntai fault. As a result. this fan is small in scale. close to the source area. and coarse-grained with poor sorting. The source, the palaeogeomorphy and the trigger mechanism together determine the characteristic difference of suhlacustrine fan sediment. Since a great number of reservoirs were discovered within the sand-rich sublacustrine fans. it can be concluded thatsand-rich sublacustrine fan has better prospect for petroleum exploration compared with conglomerate-rich fan.