鄂尔多斯盆地中东部二叠系山西组深层煤岩地球化学特征及成煤环境  

Geochemical characteristics and coal-forming environments of deep coal rocks of Permian Shanxi Formation in central and eastern Ordos Basin

作　　者：范立勇[1,2] 史云鹤 董国栋[1,2] 张君莹 潘博[1,2] 王彦卿 FAN Liyong;SHI Yunhe;DONG Guodong;ZHANG Junying;PAN Bo;WANG Yanqing(Exploration and Development Research Institute,PetroChina Changqing Oilfield Company,Xi′an,Shaanxi 710018,China;National Engineering Laboratory of Low-permeability Oil&Gas Exploration and Development,Xi'an,Shaanxi 710018,China)

机构地区：[1]中国石油长庆油田公司勘探开发研究院,陕西省西安市710021 [2]低渗透油气田勘探开发国家工程实验室

出　　处：《天然气工业》2024年第10期113-125,共13页Natural Gas Industry

基　　金：中国石油天然气股份有限公司科技项目“中国(中石油矿权内)深地煤岩气资源分类评价”(编号:2023ZZ18YJ01)。

摘　　要：鄂尔多斯盆地蕴含丰富的煤岩气资源,展现出了巨大的煤岩气勘探开发潜力,煤岩的地球化学特征及其指示的沉积条件、古气候信息可以为煤岩气的形成及有利区优选提供重要依据。为了探究鄂尔多斯盆地中东部二叠系山西组5号煤岩地球化学特征及煤岩发育控制因素,在钻井岩心观察、采样的基础上对5号煤岩进行了煤工业组分及全硫含量、镜质体随机反射率(R_(o))和主微量的测试分析,并揭示了煤岩的成煤环境。研究结果表明:①5号煤岩类型以光亮煤、半亮煤为主,灰分含量为6.04%~29.00%,平均为17.23%,挥发分含量为12.21%~35.05%,平均为21.61%,水分含量为0.49%~0.78%,平均为0.63%,全硫含量为0.10%~1.49%,平均为0.53%,Ro为1.75%~1.84%,平均为1.79%;②主元素化合物以SiO_(2)和Al_(2)O_(3)为主,微量元素以Sr、Ba,稀土元素以Ce为主,含量整体较高,稀土元素以轻稀土元素富集为主,上地壳分配模式曲线具有Eu负异常特征,表明5号煤岩聚煤过程中未受到深部热液影响;③结合m_(Sr)/m_(Ba)、GI^(*)、m^(Sr)/m^(Cu)及分布特征分析,表明5号煤岩主要形成于三角洲前缘低位沼泽相和三角洲平原潮湿森林沼泽相,整体以咸水、温湿的还原环境水体为主,且沉积水体北部偏酸性,南部偏碱性,5号煤岩的聚煤过程整体受到海侵作用控制。结论认为,研究成果深化了鄂尔多斯盆地中东部山西组5号煤岩地球化学特征及煤岩发育控制因素的认识,为深层煤岩气的勘探开发提供理论依据。The Ordos Basin is rich in coal-rock gas resources,showing great potential in the exploration and development of coal-rock gas.The geochemical characteristics of coal rocks and their indications in sedimentary conditions and paleoclimate information can provide an important basis for the formation and favorable area selection of coal-rock gas.In order to explore the geochemical characteristics of No.5 coal rock and the controlling factors of coal rock development in the Permian Shanxi Formation of central and eastern Ordos Basin,this paper tests and analyzes the coal industrial components,total sulfur content,vitrinite random reflectance(Ro),and major and trace elements of No.5 coal rock by observing and sampling drilling cores,and then reveals the coal-forming environments of coal rocks.The following results are obtained.First,the types of No.5 coal rock are mainly bright coal and semi-bright coal,with the ash content ranging from 6.04%to 29.00%,averaging 17.23%,the volatile content ranging from 12.21%to 35.05%,averaging 21.61%,the moisture content ranging from 0.49%to 0.78%,averaging 0.63%,the total sulfur content ranging from 0.10%to 1.49%,averaging 0.53%,and the Ro ranging from 1.75%to 1.84%,averaging 1.79%.Second,the main element compounds are mainly SiO_(2)and Al_(2)O_(3),the trace elements are mainly Sr and Ba,and the rare earth element is dominated by Ce,with an overall higher content.The enriched rare earth elements are mainly light rare earth elements.The supracrustal distribution pattern curve exhibits the characteristics of Eu negative anomaly,indicating that No.5 coal rock is not affected by deep hydrothermal fluid in the process of coal accumulation.Third,based on m_(Sr)/m_(Ba),GI^(*),m^(Sr)/m^(Cu)and distribution characteristics analysis,it is suggested that No.5 coal rock is mainly formed in the low swamp facies of delta front and the humid forest swamp facies of delta plain.On the whole,saline water,and water body in a warm and humid reducing environment are dominant,and the sedimentary water bod

关 键 词：鄂尔多斯盆地 二叠系山西组 5号煤岩 地球化学 成煤环境 地质意义 

分 类 号：TE121.3[石油与天然气工程—油气勘探]