| 北部湾盆地乌石凹陷东部流沙港组物源分析 |
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| 引用本文： | 袁晓蔷,姚光庆,姜平,陆江.北部湾盆地乌石凹陷东部流沙港组物源分析[J].地球科学,2017,42(11):2040-2054. |
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| 作者姓名： | 袁晓蔷 姚光庆 姜平 陆江 |
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| 作者单位： | 1.中国地质大学构造与油气资源教育部重点实验室, 湖北武汉 430074 |
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| 基金项目： | 国家"十三五"油气重大专项2016ZX05024-006 |
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| 摘 要： | 乌石凹陷是北部湾盆地继涠西南凹陷之后又一极具潜力的产能接替区，探讨其物源供给对掌握砂体展布规律及源-汇体系研究具有重要意义.基于地震资料、新钻井资料、岩心、测试分析等，试图从地震反射特征、岩矿特征、重矿物组合特征、水动力特征等方面探讨乌石凹陷无露头、无源-汇组分对比条件下沉积源区分布特征.研究表明:（1）乌石凹陷东洼流沙港组不同构造部位岩石组分存在明显差异，可以分为两种类型，其中源自企西隆起的北部WS17-2和中部WS16-1井区长石含量相对高，结构成熟度中等-差，以长石岩屑砂岩为主，源自流沙凸起的南部WS22-7和WS22-9井区岩屑含量高，结构成熟度差-中等，以岩屑砂岩为主；（2）北部和中部井区电气石、赤褐铁矿含量高、石榴子石含量低，南部井区赤褐铁矿、石榴石、锆石含量高，电气石含量低，反映该区域受到不同性质母岩碎屑影响；（3）水动力特征方面，北部井区与南部井区具有相似的最大碎屑粒径（-2~-1Φ）和最大悬浮粒径（2~3Φ），跳跃组分低含量呈低斜度，显示近源杂乱沉积特征；中部WS16-1井区最大碎屑粒径0~1Φ，最大悬浮粒径3.6~4.0Φ，跳跃组分呈高含量高斜度，显示较好分选的远离物源沉积特征；（4）研究区砂岩分选磨圆差，塑性岩屑颗粒与基质含量较高，体现了小型凹陷的沉积充填特征.乌石凹陷流沙港组物源是小型裂陷盆地近源快速供给的典型代表，储层抗机械压实强度低，储层物性主要受机械压实与粘土含量的影响.
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| 关 键 词： | 物源分析 源-汇体系 北部湾盆地 流沙港组 沉积 石油地质 |
| 收稿时间： | 2017-05-13 |
Provenance Analysis for Liushagang Formation of Wushi Depression,Beibuwan Basin,the South China Sea |
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| Abstract: | The Eocene Liushagang Formation, the main hydrocarbon-bearing stratum in Wushi depression, is a promising replacement area in Beibuwan basin. Provenance analysis of the sandbody is significant for better understanding of its distribution and "Source-to-Sink system", which facilitates in turn the oil-gas exploration and development in this area. However, the study in this area, especially on the provenance is very limited. In this study, the provenance of sediments in Eocene Liushagang Formation is analyzed by integrating with the seismic, lithological and electric properties, core, components of the sandstones, assemblage styles of the heavy mineral, and probability cumulative grain size curves. Results show as follows:(1) There are two provenances, one from north and the other from south, in the study area. Northern sourced well WS17-2 and WS16-1 area is mainly feldspathic litharenite with high feldspar contents. However southern sourced well WS22-7-2 and WS22-9 area is mainly litharenite with high lithic contents. (2) The well WS17-2 and WS16-1 area exhibits high tourmaline, hematite contents and low garnet contents, while the well WS22-7-2 and WS22-9 area exhibits high hematite, garnet, zircon contents and low tourmaline contents. (3) A large number of probability cumulative grain size curves indicate that northern sourced well WS17-2 area and southern sourced well WS22-7-2 and WS22-9 area share equivalent largest particle diameter (-2 to -1Φ) as well as suspended particulate diameter (2-3Φ). However both measures in well WS16-1 area are 0-1Φ and 3.6-4.0Φ, with smaller scales implying characteristics of long distance transport. (4) The debris in study area shows poor sort and round, rich plastic debris and matrix, implying typical characteristics of sedimentary filling in small sag. It is concluded that the provenance of Liushagang Formation in Wushi depression is a typical example of small rift basin, with reservoir parameters mainly involved with compaction and matrix contents. |
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