| 鄂尔多斯盆地姬塬油区铁边城区块长8储层成岩致密化及其与油气成藏关系 |
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| 引用本文： | 康昱,陈刚,张卫刚,黄军平,夏晓雨,霍建伟.鄂尔多斯盆地姬塬油区铁边城区块长8储层成岩致密化及其与油气成藏关系[J].地质科技通报,2021,40(2):64-75. |
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| 作者姓名： | 康昱 陈刚 张卫刚 黄军平 夏晓雨 霍建伟 |
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| 基金项目： | 国家自然科学重点基金项目41630312国家基础科学人才培养创新基金项目XDCX2018-08 |
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| 摘 要： | 通过铸体薄片、扫描电镜、阴极发光、X衍射、高压压汞和流体包裹体等多种测试分析，系统研究了鄂尔多斯盆地姬塬油区东南部铁边城区块延长组长8油层组致密砂岩储层的岩石物性、成岩作用和致密化过程及其与油气充注成藏的时序关系。结果表明，研究区长8储层岩石类型以细粒岩屑长石砂岩为主，成分成熟度和结构成熟度低，储集性能较差，平均孔隙度为7.34%、平均渗透率为0.11×10-3 μm2，属于较为典型的(特)低孔-超低渗致密储层，成岩作用类型以压实、胶结和溶蚀作用为主，成岩演化阶段主体已进入中成岩A期；储层成岩-致密化过程先后经历了早成岩A-B期压实+胶结减孔、中成岩A1期溶蚀增孔+胶结减孔、中成岩A2期胶结减孔3个主要阶段。早白垩世末(100 Ma)最大埋深之前的压实和胶结作用是储层致密化的根本原因，造成孔隙度分别降低了21.14%和14.0%，溶蚀增加的孔隙度仅为1.76%；早白垩世中期2个主要幕次(123 Ma和105 Ma)的大规模烃类充注-成藏事件开始发生时，储层孔隙度已在晚期胶结作用影响下降至7.82%，成为典型的(特)低孔-超低渗致密砂岩储层，因而具有“先致密、后成藏”的特征。
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| 关 键 词： | 鄂尔多斯盆地 铁边城区块 长8油层组 成岩作用 致密化 油气成藏 |
| 收稿时间： | 2020-06-08 |
Diagenetic densification of Chang 8 sandstone reservoirs and its relationship with hydrocarbon accumulation in Tiebiancheng area,Jiyuan Oilfield,Ordos Basin |
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| Abstract: | Based on multiple testing data from the casting slice, cathodoluminescence, scanning electron microscopy, X-ray diffraction, HPMI, reservoir physical property, and fluid inclusion thermometry, systematic research was conducted to investigate the petrologic features, reservoir properties, diagenetic porosity evolution, and temporal relations between the densification and oil charging process of the Chang 8 sandstone reservoirs of the Upper Triassic Yanchang Formation in Tiebiancheng area of Jiyuan Oilfield, Ordos Basin. The results show that the Chang 8 reservoirs in the study area are mainly composed of fine-grained lithic feldspar sandstones with low maturity of composition and texture, featuring unconventional tight reservoirs with an average porosity of 7.34% and permeability of 0.112×10-3μm2, which generally reach the middle diagenetic stage A. The diagenetic porosity evolution of the Chang 8 reservoirs mainly experienced three stages: porosity reduction by compaction and cementation in early diagenetic stage A-B, porosity increase by dissolution and reduction by cementation in middle diagenetic stage A1, and porosity reduction to densification by cementation in middle diagenetic stage A2 to B1. Until the end of the Early Cretaceous, all the occurred compaction and cementation made the reservoir porosity decrements approach 21.14% and 14%, respectively, while the porosity increment by dissolution was only about 1.76%. At the beginning of two episodic large-scale oil charging events that occurred at 125 and 105 Ma during the middle to late period of the Early Cretaceous, the porosity of the Chang 8 sandstone reservoirs decreased to 7.82% under the influence of late cementation. It became a typical ultra-low porosity and ultra-low permeability tight sandstone reservoir, thus most likely indicating that the densification of the Chang 8 reservoirs occurred earlier than the hydrocarbon accumulation in this study. |
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