| 花岗质基岩风化壳结构特征及油气地质意义:以柴达木盆地东坪地区基岩风化壳为例 |
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| 引用本文： | 黄建红,谭先锋,程承吉,李泽民,马丽娟,张海丽,吴颜雄.花岗质基岩风化壳结构特征及油气地质意义:以柴达木盆地东坪地区基岩风化壳为例[J].地球科学,2016,41(12):2041-2060. |
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| 作者姓名： | 黄建红 谭先锋 程承吉 李泽民 马丽娟 张海丽 吴颜雄 |
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| 作者单位： | 1.中国石油青海油田公司勘探开发研究院，甘肃敦煌 736202 |
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| 基金项目： | 国家自然科学基金项目41202043中国石油科技创新基金项目2014D-5006-0108国家科技重大专项项目2011E-0302国土资源部页岩气资源勘查重点实验室开放基金项目BSYS2014-01 |
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| 摘 要： | 近年来，不少学者开始关注基岩油藏，但有关基岩风化壳的研究尚未有报道.以柴达木盆地东坪地区基岩风化壳为研究对象，结合东坪地区的地质资料、测井资料及地球化学资料，对花岗质基岩风化壳的结构特征及其与油气储集的关系进行了系统的研究.结果表明:(1) 建立了以Al2O3、CaO、Na2O、K2O为主要判别依据的花岗质基岩风化指数，准确的识别出古土壤层、残积层、半风化层、未风化层；(2) 根据成像测井响应特征及常规测井曲线可以很好地识别古风化壳特征；(3) 东坪地区基岩风化壳的主要储集空间有基岩溶蚀孔洞、基质矿物溶孔和基岩裂缝，共3种，为致密储层，风化壳由风化基面向上，孔隙逐渐发育，至半风化岩石中部的孔隙度较大，且以大孔隙为主，由半风化岩石到风化粘土层，孔隙的规模变小，逐渐以微孔隙为主，纵向上，孔隙度与风化程度、构造缝发育情况、埋藏深度及其和应力释放中心的距离具有相关性.风化壳的存在大大的改善了储层物性，扩展了含气面积，增加了含气层系，对花岗质基岩地层油气藏和深层油气勘探具有重要的理论价值和科学意义.
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| 关 键 词： | 基岩风化壳 风化壳结构 风化指数 油气地质 |
| 收稿时间： | 2016-03-13 |
Structural Features of Weathering Crust of Granitic Basement Rock and Its Petroleum Geological Significance: A Case Study of Basement Weathering Crust of Dongping Area in Qaidam Basin |
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| Abstract: | In recent years, many scholars have begun to pay attention to the basement reservoir, but there is no report about the study of weathering crust of basement. In this paper, structural characteristics of bedrock weathering crust and its relationship with oil and gas accumulate are systematically studied in Dongping area in the Qaidam Basin, combining with the geological data, logging and geochemical data. It is found that establishment of granitic bedrock weathering indexes based on Al2O3, CaO, Na2O, and K2O can ensure accurate identification of the ancient soil layer, elurium, semi-weathered layer, and unweathered layer. According to the imaging logging response characteristics and logging curves can well identify paleocrust characteristics, there are three types of tight reservoir space in weathering crusts of Dongping area: rock erosion holes, matrix mineral dissolved pores, and cracks in bedrock. Weathering crust on the base up gradually develops porosity, large semi-weathered rock porosity to the middle, and large pores mainly from semi-weathered rock to weathering exclusion soil, the pore size becomes smaller, and gradually to micro pore-based. In the longitudinal direction, porosity and degree of weathering and tectonic development, the burial depth and distance from the stress relief center have some relevance. The presence of weathering crust, greatly improves the reservoir properties, extends the bearing area, increases the gas-bearing system, which has important theoretical values and scientific significance to the granitic bedrock stratigraphic reservoirs and deep oil and gas exploration. |
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