Geochemistry and origin of Ordovician oils in the Rewapu Block of the Halahatang Oilfield(NW China)

作     者：You-Jun Tang Mei-Jun Li Rong-Hui Fang Bao-Shou Zhang Zhe Yang Da-Xiang He Meng-Ru Li 

作者机构：Key Laboratory of Exploration Technologies for Oil and Gas Resources (Yangtze University) Ministry of EducationCollege of Resources and Environment State Key Laboratory of Petroleum Resources and Prospecting College of Geosciences China University of Petroleum Research Institute of Petroleum Exploration and DevelopmentTarim Oilfield Company PetroChina 

出 版 物：《Petroleum Science》 (石油科学（英文版）)

年 卷 期：2019年第16卷第1期

页      面：1-13页

核心收录：

学科分类：0820[工学-石油与天然气工程] 08[工学] 

基　　金：funded by the National Natural Science Foundation of China(Grant No.41272158) the Foundation of the State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing(PRP/open-1710) 

主　　题：Biodegradation Water washing Oil charging process Ordovician Tarim Basin 

摘      要：The oils in the Rewapu Block of the Halahatang Oilfield in the Tarim Basin(northwestern China) were geochemically analyzed by gas chromatography–mass spectrometry to investigate their origin and possible secondary alteration. The physical properties and chemical compositions of these Ordovician oils vary greatly, ranging from light to extremely heavy oils. All these oils belong to one single population and were derived from same source kitchen/bed. The differences in their chemical compositions and physical properties mainly result from secondary alteration of oils that were charged during the early phase of trap formation. The thickness of Upper Ordovician and Silurian caprocks of oil reservoirs in the Rewapu Block is higher than that in the north part of the Halahatang region, and therefore, significant biodegradation process is prevented. Compared to heavy oils in the north part, the Rewapu oils are dominated by light oils with no 25-norhopanes and no GC–MS ‘‘hump (UCM: unresolved complex mixture) on the chromatographic baselines. The heavy oils in Wells RP7 and RP101 C were primarily influenced by water washing since apparent reduction of alkylated dibenzothiophenes was observed. The local geological background favored the water washing alteration. The reservoir geochemical study has practical application in hydrocarbon exploration and predicts the nature of oils in this oilfield.