新生界火山岩是泰国Phetchabun盆地Wichian Buri次盆的主要含油气岩系, 但因火山岩喷发环境复杂, 喷发期次频繁, 造成火山岩岩性复杂, 识别难度较大, 岩相展布不清, 这些因素严重制约着油气的进一步勘探和开发.通过岩心、岩石薄片、测井及地震等资料分析, 总结了研究区火山岩的岩性特征, 并提出相应的识别方法, 同时对火山岩的发育期次和岩相展布进行了研究.结果表明:①研究区火山岩类型丰富, 从基性岩至酸性岩、熔岩至火山角砾岩都有发育, 以偏碱性玄武岩为主;②自然伽马、密度及光电吸收界面指数测井对火山岩成分变化最为敏感, 成像测井可以提供火成岩的结构和构造信息, 两者结合可准确地识别火山岩岩性;③结合测井和地震响应特征, 研究区新生界火山岩为3期喷发的产物, 可识别出火山通道相、溢流相、爆发相和火山沉积相等岩相类型, 并预测其分布规律.研究成果为研究区火山岩的岩性识别提供了有效手段, 并明确了岩相展布特征, 可为研究区的油气勘探和开发提供一定的依据.%The Cenozoic volcanic rocks are the main hydrocarbon-bearing layers in Wichian Buri Sub-basin of Phetchabun Basin in Thailand. However, the difficulties of lithology identification and uncertainty of lithofacies distribution have seriously restricted further exploration and development of hydrocarbon, due to various rock types related to the complex eruption environments and frequent eruption stages. In this paper, based on the data of cores, rock slice, logging and seismic, the characteristics of volcanic rocks in the study area were studied, and a set of methods for identifying volcanic rocks was established. Meanwhile, the volcanic eruption periods and lithofacies distribution were predicted. The research results show that: (1) weakly alkalic basalts are the main type in the multi-type volcanic rocks, ranging from basic to acid volcanic rocks and lava to pyroclastic in the study area; (2) GR, DEN and Pe well loggings are sensitive to the variation of volcanic rock composition, and FMI can provide information of textures and structures of volcanic rocks, so the combination of the two methods can effectively identify lithology of volcanic rocks; (3) Cenozoic volcanic rocks are the results of three-stage volcanic eruption, and several volcanic lithofacies, such as volcanic vent facies, effusive facies, explosive facies and volcanogenic sedimentary facies, and their distribution was identified and predicted. The conclusions in this paper can provide an effective method for lithology identification of Cenozoic volcanic rocks in study area, and make clear of its lithofacies distribution, which have a certain significance for further exploration and development of hydrocarbon in this area.
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