鄂尔多斯盆地合水地区长2油层低阻成因及识别  

Genesis and Identification of Low Resistivity of Chang 2 Oil Layer in Heshui Area,Ordos Basin

作　　者：潘祎文 左晓欢 张世涛[1] 张耀华 PAN Yiwen;ZUO Xiaohuan;ZHANG Shitao;ZHANG Yaohua(Kunming University of Science and Technology,School of Land and Resources Engineering,Kunming,Yunnan 650031,China;Kunming University of Science and Technology,School of Public Safety and Emergency Management,Kunming,Yunnan 650031,China;Department of Geology,Northwest University,Xi’an,Shaanxi 710069,China)

机构地区：[1]昆明理工大学国土资源工程学院,昆明650031 [2]昆明理工大学公共安全与应急管理学院,昆明650031 [3]西北大学地质学系,西安710069

出　　处：《新疆石油地质》2020年第3期253-260,共8页Xinjiang Petroleum Geology

摘　　要：为明确鄂尔多斯盆地合水地区延长组长2油层低阻成因,利用扫描电镜、铸体薄片、压汞实验、图像粒度、图像孔隙和水质等分析资料进行研究。结果表明,合水地区油层低阻成因主要为地层水矿化度高、孔隙结构复杂及束缚水含量较高。由于大气降水带入了上覆地层风化剥蚀形成的离子,导致地层水矿化度增高;大气降水携带CO2进入储集层,与长石发生反应,生成高岭石,高岭石矿物的不饱和电性吸附阳离子,使阳离子交换量变大,导致其附加导电性增强;蒙皂石析出层间水从介质中吸取K+,Al3+等金属离子,致使晶体结构重排,发生类质同象替代,导致储集层电阻率降低。针对研究区油层特征,提出了利用电阻率与厚度交会图识别低阻油层,确定各因素在低阻油层中的上、下限值,建立了长2低阻油层识别图版,其识别结果与试油结果符合率在80%以上。In order to determine the genesis of low resistivity of Chang 2 oil layer in Heshui area of Ordos basin,the paper analyzes the data of scanning electron microscope,casting thin section,mercury injection experiment,grain size,porosity and water quality.The results show that the low resistivity of the oil layer is attributed to high salinity of formation water,complex pore structure and high content of irreducible water.The high salinity of formation water is mainly caused by atmospheric precipitation which brings the ions from weathering and denuda⁃tion of the overlying strata into the formation;CO2 carried by atmospheric precipitation reacts with feldspar in the formation and then kaolin⁃ite forms.The kaolinite with unsaturated electrical properties can adsorb cation and the cation exchange quantity increases,causing the en⁃hancement of kaolinite additional conductivity.The metal ions such as K+and Al3+in medium are absorbed by smectite,which results in the rearrangement of the crystal and the substitution of isomorphism,leading to the low resistivity of the reservoir.In view of the characteristics of the oil layer in the study area,the paper proposes that a crossplot of resistivity and thickness can be used to identify low⁃resistivity oil lay⁃ers,and to determine the upper and lower limits of each factor in the low⁃resistance oil layer,and establishes a chart to identify low⁃resis⁃tance oil layers for Chang 2 member with the coincidence rate between the identification result and the oil test result being more than 80%.

关 键 词：鄂尔多斯盆地 合水地区 延长组 低阻油层 测井响应特征 孔隙结构 矿化度 

分 类 号：TE122.111[石油与天然气工程—油气勘探]