靖邊—鄂托克前旗地區(qū)油氣成藏模式
(1. 中南大學(xué) 有色金屬成礦預(yù)測教育部重點實驗室，長沙 410083；
2. 中南大學(xué) 地球科學(xué)與信息物理學(xué)院，長沙 410083；3. 中石油長慶油田公司 采油四廠，銀川 750006)
摘 要: 以陜北斜坡靖邊—鄂托克前旗地區(qū)下侏羅統(tǒng)延安組延9油藏為例，運用印模法恢復(fù)了前侏羅紀(jì)古地貌形態(tài)。研究表明：研究區(qū)古地貌主要為高地、斜坡、河谷和河間丘4種古地貌單元。在此基礎(chǔ)上分析了富縣組+延10段沉積相帶展布以及前侏羅紀(jì)古地貌對延9油藏的控制作用，認(rèn)為古地貌景觀基本控制了富縣組及延安組下部的沉積相帶展布。古河谷的下切作用不僅使延9段與延長組油源層的接觸距離縮短，而且為油氣運移提供了良好的通道，如遇到有利的儲集體與背斜和鼻隆等構(gòu)造，即可有機配置和富集成藏。存在兩種成藏模式，即河間丘 區(qū)−分流河道組合式和斜坡區(qū)−分流河道組合式。指出前侏羅紀(jì)古地貌斜坡區(qū)與河間丘區(qū)是下一步延9段油藏勘探的有利地區(qū)。
關(guān)鍵字: 古地貌；前侏羅紀(jì)；控制因素；成藏模式；延安組；鄂爾多斯盆地
Ordos Basin from angle of pre-Jurassic palaeogeomorphology
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
Changsha 410083, China;
2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China;
3. The Fourth Oil Extraction Factory, Changqing Oilfield Company, Yinchuan 750006, China）
Abstract:Taking the number 9 oil reservoir of Yan’an Formation of Low Jurassic in Jingbian—Etuokeqianqi area of Ordos Basin as an example, the palaeogeomorphic form of the pre-Jurassic was reconstructed by the mold method. The pre-Jurassic palaeogeomorphic framework is divided into upland, slope, river valley and mound. On that basis, the sedimentary facies belts distribution of the Fuxian Formation and the member 9 of the Lower Yan’an Formation and the pre-Jurassic palaeogeomorphic form control on the number 9 oil reservoirs were studied. The palaeogeomoyphic form had a certain control on the sedimentary facies belts distribution of the Fuxian Formation and the Lower Yan’an Formation of Lower Jurassic. The incision of the palaeo-valley not only decreases the distance between the Lower Yan’an Formation and the hydrocarbon source intervals, but also provides hydrocarbon migration pathways. If there exist profitable reservoirs combining with anticline and nose-up lifting structures, they can entrap hydrocarbons and form hydrocarbon reservoir. Two palaeogeomorphic reservoir models, i.e., slope-distributary channels combination model and mound-distributary channels combination model, are generalized, and the pre-Jurassic palaeogeomorphic slope and mound are the profitable areas for the exploration the member 9 of the Lower Yan’an Formation.
Key words: palaeogeomorphology; pre-Jurassic; control factor; accumulation model; Yan’an Formation; Ordos Basin
