| 致密储层石油充注成藏过程分析:以准噶尔盆地吉木萨尔凹陷二叠系芦草沟组为例 |
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| 引用本文： | 郑民,李建忠,王文广,李鹏,杨海波,吴晓智,于京都.致密储层石油充注成藏过程分析:以准噶尔盆地吉木萨尔凹陷二叠系芦草沟组为例[J].地球科学,2018,43(10):3719-3732. |
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| 作者姓名： | 郑民 李建忠 王文广 李鹏 杨海波 吴晓智 于京都 |
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| 作者单位： | 1.中国石油勘探开发研究院, 北京 100083 |
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| 基金项目： | 国家科技重大专项2016ZX05046-001国家科技重大专项2017ZX05008-006 |
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| 摘 要： | 作为油气地质领域研究的热点和难点，单一研究手段很难理清致密油充注成藏机理和运聚成藏过程.以准噶尔盆地吉木萨尔凹陷二叠系芦草沟组致密油层为例，通过充注物理模拟实验与成岩-成储-成藏过程分析相结合，分析研究致密油运聚成藏过程.芦草沟组烃源岩自晚三叠世（对应的地层中Ro=0.5%）开始进入生油窗，在中侏罗世（对应的地层中Ro=0.7%）进入大量生烃阶段，至今仍处于生油阶段.烃类包裹体研究表明，吉木萨尔凹陷主要有两期成藏，一期在侏罗纪，包裹体均一温度在50~70 ℃；第二期是在白垩纪-古近纪，包裹体均一温度在120 ℃左右.吉木萨尔凹陷芦草沟组致密储层成岩阶段可划分为三个阶段:①早成岩A期:晚二叠世早期（260 Ma）及之前；②早成岩B期:晚二叠世早期至晚三叠世时期（距今260~220 Ma）；③中成岩A期:晚三叠世至今（220~0 Ma）.根据成岩演化阶段与生烃成藏过程分析，结合致密储层充注模拟实验结论，认为芦草沟组致密油成岩-成储-成藏过程可分为3个阶段:（1）早期储层中-高孔渗条件下低熟油气的充注阶段（晚三叠世之前）；（2）边致密边成藏及改变岩石表面为油润湿性阶段（晚三叠世至早白垩世末期）；（3）芦草沟组致密层中成熟油的持续充注阶段（早白垩世末期至今）.吉木萨尔凹陷芦草沟组致密油资源潜力大，上甜点体（B段）致密油地质资源量约为4.45×108 t，下甜点体（E段）致密油地质资源量约为7.95×108 t.
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| 关 键 词： | 致密油 准噶尔盆地芦草沟组 运聚成藏 成藏机理 成岩阶段 源储组合类型 石油地质 |
| 收稿时间： | 2018-04-20 |
Analysis of Oil Charging and Accumulation Processes in Tight Reservoir Beds: A Case Study of Lucaogu Formation in Jimsar Sag of Junggar Basin,NW China |
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| Abstract: | As a hot and difficult research topic in the field of oil and gas geology, it is hard to clarify the tight oil charging and accumulating mechanism, migration and accumulation processes by a single approach. Taking the tight oil layers in the Lucaogu Formation in the Jimsar Sag of the Junggar Basin as an example, oil migration and accumulation processes in tight reservoir beds have been examined by combining physical modeling experiments of oil charging with the analysis of the process of diagenesis-reservoir formation-hydrocarbon generation and accumulation in this study. Has entered oil-generating window since Late Triassic period (corresponding to Ro=0.5%), and has entered massive hydrocarbon generation stage since Middle Jurassic period (corresponding to Ro=0.7%), the source rock in the Lucaogu Formation is still at the oil generation stage now. Many studies on hydrocarbon inclusions show that the Jimsar Sag has experienced two stages of hydrocarbon accumulation:the first stage was in Jurassic period (with inclusion homogenization temperature at 50~70℃, and the second stage was in Cretaceous-Paleogene period (with inclusion homogenization temperature at about 120℃). The diagenetic stages of tight reservoir beds in the Lucaogu Formation in the Jimsar Sag can be classified into three periods:①Period A in early diagenesis:early period of Late Permian (260 Ma) and before; ② Period B in early diagenesis:from early period of Late Permian to Late Triassic (260-220 Ma); ③Period A in middle diagenesis:from Late Triassic to present (220~0 Ma). According to analysis of diagenetic evolution stages and hydrocarbon accumulation process, and the conclusions from the physical modeling of oil charging in tight reservoir beds, the process of diagenesis-reservoir formation-hydrocarbon accumulation of tight oil in the Lucaogu Formation can be divided into the following three periods:(1) low-maturity oil and gas charging period under medium-high porosity and permeability condition in early reservoir beds (before Late Triassic); (2) the period that simultaneous tightness and accumulation occurs, and rock surface wettability changing to oilwet (from Late Triassic to the end of Early Cretaceous); (3) continuous charging period of mature oil in tight reservoir beds in the Lucaogu Formation (the end of Early Cretaceous to present). The Lucaogu Formation in the Jimsar Sag has large tight oil resource reserves potentials. The geological resources reserves of tight oil in upper sweet spot volume (Section B) are about 4.45×108 t, and in lower sweet spot volume (Section E) are about 7.95×108 t. |
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