鄂尔多斯盆地白豹地区长6油层组湖底滑塌浊积扇沉积特征及其研究意义

鄂尔多斯盆地上三叠统延长组第6段在白豹地区是最重要的勘探目的层之一,其沉积相类型及其对砂体展布和油气储层的控制等开发地质问题倍受重视.作者在岩心描述和测井分析基础上,结合铸体薄片、扫描电镜、重矿物、微量元素和孔渗分析等大量测试资料,对该地区长6油层组沉积相类型及特征进行深入研究,首次提出白豹地区长6油层组属于湖底滑塌浊积扇沉积体系,岩性以成分和结构成熟度均偏低的微-细粒长石砂岩为主,具粒序层理、液化包卷层理、滑动截切和变形构造、小型同生断层、槽模、沟模和重荷模等浊积沉积相标志.在浊积扇岩相组合、沉积序列及平面演化特征分析的基础上,结合区域地质背景,探讨了浊积扇的成因机制,建立了相应的沉积模式,分析了浊积扇在油气开发工程中的意义.

Discovery and significance of sublacustrine slump turbidite fans in Chang 6 oil-bearing formation of Baibao region in Ordos Basin, China

Chang 6 of the Upper Triassic is one of the most important exploration target zones in the Baibao region,Ordos Basin.The research on its sedimentary facies types and its control over the sandstone distribution and reservoir and other exploitation geology questions is paid more attention.On basis of the analysis for cores and well-logging,the authors have thoroughly studied the sedimentary facies types and characters of Chang 6 oil-bearing formation of the Baibao region with casting thin sections,SEM,trace elements and porosity and permeability analysis and a great deal of indoor testing data.The authors propose that the sedimentary facies type of Chang 6 oil-bearing formation of the Baibao region is a sublacustrine slump turbidite fan for the first time, and lithology is lower componential and textural maturities microfine feldspar sandstone primarily,with graded bedding,fluidified convolute bedding,slipping-cut and deformational structures,minitype syngenetic faults,flute cast,groove cast,load cast and other turbidite sedimentary facies signatures.Based on the analyses of turbidite fan lithofacies assciations,deposition sequence and plane evolution characteristics foundation,with regional geology background,the authors discuss the genetic mechanism of the sublacustrine slump turbidite fan,set up relevant sedimentary models,and analyze its significance in developing the oil reservoir in Chang 6 finally.