| 吐哈盆地WM油田辫状河三角洲前缘砂体分析 |
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| 引用本文： | 周丽清,吴胜和,熊琦华,马晓芬,郭燕华,林双运.吐哈盆地WM油田辫状河三角洲前缘砂体分析[J].沉积学报,2000,18(2):248-252. |
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| 作者姓名： | 周丽清 吴胜和 熊琦华 马晓芬 郭燕华 林双运 |
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| 作者单位： | 1 石油勘探开发科学研究院海外研究中心 北京 100083; |
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| 摘 要： | 湖盆可容空间较小时,辫状河三角洲相对发育,水下分支河道横向迁移频繁,易形成席状分布的砂体 (水下分支河道复合体 )。可容空间增大时,辫状河三角洲相对不发育,水下分支河道延伸不远,河道砂体较孤立,河口坝相对比较发育。文中根据水流和波浪强弱提出九种水下分支河道与河口坝的关系图,基本上总结了吐哈盆地WM油田三间房组河口坝的形态;并对水下分支河道复合体的形成机制提出了独特的推理。
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| 关 键 词： | 辫状河三角洲 水下分支河道 河口坝 沉积模式 吐哈盆地 |
| 收稿时间： | 1998-09-04 |
Analysis of Sandbodies in the Braided Delta Front,WM Oilfield, Turpan-Hami Basin |
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| ZHOU Li-qing,WU Sheng-he,XIONG Qi-hua,MA Xiao-fen,GUO Ya n-hua,LIN Shuang-yun.Analysis of Sandbodies in the Braided Delta Front,WM Oilfield, Turpan-Hami Basin[J].Acta Sedimentologica Sinica,2000,18(2):248-252. |
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| Authors: | ZHOU Li-qing WU Sheng-he XIONG Qi-hua MA Xiao-fen GUO Ya n-hua LIN Shuang-yun |
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| Institution: | 1 Overseas Research Center of CNPC,Beijing 100083;2 The University of Petroleum,Changpin,Beijing 102200 |
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| Abstract: | The braided delta front is developed in WM oilfield, Turpan-Hami Basin, which is composed of the underwater distributary channels, mouth bars, distal sands, sh eet-like sands, and interchannel muds microfacies. The deposition features of t he braided deltas are low sedimentary maturation and abundant current structures caused by the traction current. The underwater distributary channels have an er osion surface in the channel bottom, and are fining upward from conglomerates in the base to fine-sandstones in the top of the channels. They are 2.5m in rhythm, and 4～10 m in complicate rhythms, and are 200～400 meters in width. The para llel bedding are well developed in the sandstones. While the mouth bars are cour sing upward from siltstones to sandstones, and are large than 4 m in thickness. The sheet-like sands are mainly sandstones, fine to medium grained, well sorted and rounded, and are mostly coursing upward. They are 3-4m in thickness. The rivers in the braided delta are strong, so that the distributary channels s till erode downwards after entering lake,and forms underwater distributary cha nnels as a result of water flow in the bottom of the lake, The underwater distri butary channels can frequently migrate laterally so as to form sheet-like sandb odies (complicated sandbodies of the distributary channels). Some uneroded inter channel muds are scatterd in the inner of complicated sandbodies of the distrib utay channels, and will be flowing barriers. The volumes of the mouth bars depend directly on the amounts of sediments carrie d by underwater distributary channels,while the shapes are partly influenced by the waves of the lake. The mouth bars may be ellipsoid parallel to underwater d istributary channels (i.e. perpendicular to the shore of lake),but may become fa n-like and even ellipsoid parallel to the shore of the lake by the modification of the waves. The nine kinds of relationship between the underwater distributary channels and the mouth bars are proposed according to the strength of the curr ents in the distributary channels and the strength of the waves in the lake. It has concluded the shapes of the mouth bars in the Sanjianfang Formation, WM Oilf ield, Turpan-Hami Basin. The underwater distributary channels of next stage may flow by the franks of the former mouth bars and develop forward; as a result,th e mouth bars are presented along with the franks of the underwater distributary channels. The underwater distributary channels of next stage, however, may flow on the top of the former mouth bars and erode them. They may cut part of the mou th bar deposits and may form composed sand bodies of the mouth bar (upper) and u nderwater distributary channel (lower) if erosion is weak. They way cut all the mouth bar as the latter is never presented if the erosion is strong and the form er mouth bar is too thin. A kind of thin-beded, fine-grained, lenticular sand bodies, which is called dis tal sands microfacies in the paper, is deposited in inter bars, shallow lakes in the weak wave region by the reworking of deposits of the mouth bars and underwa ter distributary channels by the weak waves or other currents in the lake. Howev e r, in the region of strong waves, the sediments of the underwater distributary c hannels and the mouth bars are by strong waves and migrated laterally to form co ntinuos, large scaled sheet-like sands. When the accomodation space of the lake basin is smaller, the braided deltas are well developed, and inter channel mud deposits are eroded by the underwater dis tributary channels in braided deltas, so as to form sheet-like sandbodies (compl icated sandbodies of the distributary channels). When the accomodation space of the lake basin is larger, the braided deltas are less developed, and the underwa ter distributary channels can not stretch too far away and channels sandbodies a re much more isolated, while the mouth bars are relatively more developed. |
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| Keywords: | braided deltas underwater distributary channels river mouth bars depositional models Turpan-Hami Basin |
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