摘要
通过对塔里木盆地库车坳陷南天山山前带克孜勒努尔沟与依奇克里克野外露头沉积相的精细研究,结合山前带大量地震剖面分析与迪那201井、东秋5井等多口钻井测井相和岩心精细描述,将古近系库姆格列木群划分为2个层序。层序2低位域以冲积扇沉积为主,自湖侵体系域始,研究区广泛发育退积与进积型扇三角洲沉积。库姆格列木群层序2湖侵体系域内扇三角洲平原砂体以正韵律沉积为主,砂砾岩占地层厚度的(68.4～87)%;扇三角洲前缘砂体正、反韵律均有分布,砂砾岩占地层的百分比有所降低,为(55.2～77)%。高位体系域内主要发育以反韵律砂体为主的扇三角洲前缘沉积。古近系苏维依组只发育一个层序,其低位体系域的砂体为扇三角洲平原与前缘的分流河道砂体,湖侵体系域内扇三角洲前缘砂体正、反韵律均发育,高位体系域内主要发育扇三角洲前缘沉积,以反韵律砂体为主,正韵律砂体相对较少。对比苏维依组不同体系域内砂体储集性,湖侵域内砂体优于高位域内砂体。扇三角洲沉积体中有利储集砂体首选为湖侵体系域内的扇三角洲前缘水下分流河道和河口坝砂体,次之为低位域扇三角洲前缘(平原)分流河道砂体,最后是高位域内的河口坝及席状砂沉积砂体。特别要指出:低位体系域或者湖侵体系域底部发育的扇三角洲前缘(平原)分流河道砂体(底砂砾岩)被快速湖侵的较厚的暗色泥岩所覆盖,可形成较好储集场所。
By studing sedimentary facies of the field profiles at Kezilenuer and Yiqikelike in foreland of the Tianshan Mountains, analyzing lots of seismic profiles and logging facies, and systematic describing cores from the Wells Dina 201 and Dongqiu 5, two stratigraphic sequences were established in the Paleogene Kumugeliemu Group. At the beginning of transgressive system tract of the sequence 2, backstep and progradational fan-deltas deposited in foreland of the Tianshan Mountains. There were some distributed channels, with a grade of becoming finer upward, and a little bar with a grade becoming coarser upward in transgressive system tract of the sequence 2 of the Kumugeliemu Group. The grain size became finer upward in the sandstone of fan-delta plain deposits. The thickness of grit layers was （68.4 - 87 ） % of the total strata. In the deposits of fan-delta front, both the grades of finer and coarser upward could be observed, with the thickness of grit layers being （55.2 - 77） % of the total strata. In the fan-delta front deposited in highstand system tract, the reverse grade seemed more often,with thickness of grit layers being （35 - 96.4） % of the total strata. Only one sequence occurred in the Suweiyi Formation, and the sandstone of channel sediments distributed in lowstand system tract, with a normal grade. The thickness of grit layers was 67.3% of the total strata. In lowstand system tract, the sandstones of fan-delta front sediments became finer upward, with thickness of grit layers being （90.7 - 96.4） % of the total strata. In fan-delta front and plain deposits, the thickness of grit layers was （58- 66.6） % and （37.1 - 96） % , respectively. A comparative study on reservoirs in different system tracts demonstrated that the reservoirs in TST might be better than that in HST. The best reservoirs should be sandstones of subwater distributed channel and bar of fandelta front in TST. The relatively better one was distributed channel sandstone of fan-delta plain in LST. The sandstone of bar of
出处
《地质科学》
CAS
CSCD
北大核心
2008年第4期758-776,共19页
Chinese Journal of Geology(Scientia Geologica Sinica)
关键词
扇三角洲
体系域
砂体及其对比
古近系
库车坳陷
塔里木盆地
Fan-delta, System tract, Sandbody correlation, Paleogene, The Kuqa Depression, The Tarim Basin
