| 致密砂岩储层骨架砂体构型特征——以鄂尔多斯盆地合水地区延长组长6段砂体为例 |
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| 引用本文： | 曹江骏,杨友运,陈朝兵,卜广平,王茜,杨一茗.致密砂岩储层骨架砂体构型特征——以鄂尔多斯盆地合水地区延长组长6段砂体为例[J].沉积学报,2019,37(6):1105-1116. |
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| 作者姓名： | 曹江骏 杨友运 陈朝兵 卜广平 王茜 杨一茗 |
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| 作者单位： | 西安石油大学地球科学与工程学院,西安 710065;西北大学地质学系,西安 710069;西安石油大学地球科学与工程学院,西安 710065;中国石油天然气股份有限公司长庆油田分公司第六采油厂,西安 710200 |
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| 基金项目： | 国家科技重大专项（2016ZX05050006）；国家自然科学基金项目（41802140） |
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| 摘 要： | 合水地区长6油层组深水重力流沉积厚层砂体发育，但砂体较为致密，石油多赋存于其中某一段，连片性差。为更好预测优势砂体分布，基于野外剖面、测井解释成果、铸体薄片、高压压汞、物性等资料，结合前人对湖盆演化、物源等相关问题的研究成果，根据不同成因、单砂体在空间上的叠置关系，将长6段骨架砂体组合类型划分为连续叠加型、间隔叠加型、侧向尖灭型、砂泥互层型四类。并在此基础上，定量表征了长6段四类复合砂体的结构特征，确定了优势砂体组合类型，探讨了优势砂体的分布规律。结果表明:1）连续叠加型砂体以砂质碎屑流为主，单砂体平均厚度为8.20 m，以砂体内夹层为主，砂体连通性好，多发育在湖底扇内扇；间隔叠加型砂体以砂质碎屑流为主，浊流次之，单砂体平均厚度为4.10 m，隔夹层均有发育，砂体连通性由隔夹层厚度决定，多发育在湖底扇内扇、中扇；侧向尖灭型砂体以浊流为主，滑塌岩次之，单砂体平均厚度为1.10 m，以砂体间隔层为主，砂体不连通或连而不通，多发育在湖底扇中扇、外扇；砂泥互层型砂体以浊流为主，单砂体平均厚度为0.38 m，以砂体间隔层为主，砂体不连通，多发育在湖底扇外扇。2）从连续叠加型到砂泥互层型，砂体发育规模减小，非均质性增强，物性变差，含油性降低。最终，确定了研究区连续叠加型与间隔叠加型为优势砂体的组合类型。在平面上，大规模优势砂体以片状、条带状在研究区东北部沿东北-西南向展布，而在西南部基本不发育。
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| 关 键 词： | 鄂尔多斯盆地 合水地区 长6油层组 砂体组合类型 优势砂体 |
| 收稿时间： | 2019-01-09 |
Analysis of Configuration Characteristics for Skeleton Sand Body with Tight Sandstone Reservoir: A case study of Triassic Chang 6 members in Heshui area,Ordos Basin,NW China |
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| Institution: | 1.School of Earth Sciences and Engineering, Xi'an Shiyou University, Xi'an 710065, China;2.Department of Geology, Northwest University, Xi'an 710069, China;3.The 6th Oil Production Plant, Changqing Oilfield Company, PetroChina, Xi'an 710200, China |
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| Abstract: | Deepwater gravity-flow thick sedimentary sand bodies in the Chang 6 oil-bearing formation are developed in Heshui area,but sand particles are relatively compact,and oil accumulates only in a certain areas with poor continuity. To predict the location of high-quality sand bodies,and considering their different genesis and spatial superposition,the skeleton sand bodies were divided into four types:continuous superposition type;interval superposition type;lateral thinning-out type;and sand/mud interbedded type. This was done based on information gained from field sections,log interpretations,casting thin sections,high-pressure mercury injection testing,physical properties and so on,and taking into account previous research results on lake basin evolution,provenance and other related issues. On this basis,structural characteristics of four compound sand bodies in the Chang 6 oil-bearing formation were quantitatively characterized. Combinations of high-quality sand body types were determined and their distribution is discussed. The results show the following. (1) A sand body of the continuous superposition type is mainly composed of sandy clastic flows of average thickness 8.20 m. Most sand bodies of this type developed in the inner fan of a sublacustrine fan. They have good connectivity and are mainly intercalated. A sand body of the interval superposition type is mainly composed of sandy clastic flows,followed by turbidity flow;the average thickness of single sand body is 4.10 m. Most sand bodies of this type developed in the inner and middle fan of sublacustrine fan. They have barriers and are intercalated;connectivity is determined by the thickness of barrier and intercalation. A sand body of the lateral thinning-out type is mainly composed of sandy turbidity flow,followed by slump rock,and the average thickness of single sand body is 1.10 m. Most sand bodies of this type developed in the middle and outer fan of sublacustrine fan. They are either disconnected(or connected but obstructed),and mainly develop barriers. A sand body of the interbedded sand and mud type is mainly composed of turbidity flow,and have an average thickness of 0.38 m. Most sand bodies of this type are developed in the outer fan of sublacustrine fan. They have no connectivity and mainly develop barriers. (2) From the continuous superposition type to sand/mud interbedded type,the sand bodies become smaller with increased heterogeneity,and their physical properties become poorer,and the oil content lessens. Finally,combination types of high-quality sand body are continuous superposition type and interval superposition type. Planar distribution of high-quality sand bodies occur in the NE of the study area in the NE-SW direction and in plan they flakeshaped or in strips. The SW of the study area is basically undeveloped. |
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