摘要
元坝气田的长兴组天然气主要为原油裂解气。研究古原油的运移方向与聚集特征,对于分析从古油藏到现今气藏的演化过程以及揭示现今气-水界面的分布特征,从而指导元坝气田及邻区的天然气勘探与开发具有重要意义。本文利用流体包裹体确定了古原油的充注时间,恢复了原油充注期的储层顶面构造形态,并以此为基础模拟了古原油的运移路径;然后利用储层沥青的烷基二苯并噻吩类分子标志物示踪了古原油的运移方向;最后分析了古原油的聚集特征与油气藏的演化过程。结果表明:(1)长兴组储层发育较多的沥青包裹体,与之伴生的盐水包裹体的均一温度为110~130℃,结合地层埋藏史和温度演化史确定的古原油充注的时间为晚三叠世到早侏罗世;(2)古原油充注期的长兴组顶面形态继承了长兴组沉积期的顶面形态,台地边缘的礁滩处于相对高部位,而礁后滩处于相对低部位;(3)数值模拟显示古原油从台地边缘斜坡向台地边缘的礁滩圈闭侧向运移,储层沥青的烷基二苯并噻吩比值也沿着运移方向逐渐降低,表明古原油具有侧向运移特点;(4)位于相对高部位的台地边缘礁滩圈闭的古原油充满度高,而位于相对低部位的礁后滩圈闭的古原油充满度低。综合来看,元坝气田的古原油具有近源充注、在相对高部位的台地边缘礁滩圈闭聚集的特征;对经历高热演化的古油藏而言,烷基二苯并噻吩类化合物在古原油的运移方向示踪方面具有一定潜力。
The natural gas in the Permian Changxing Formation(P2ch)in the Yuanba gas field is mainly derived from oil cracking.Study on the migration direction and accumulation characteristics of paleo-oil can provide valuable insights into the reservoir evolution and fluid contact distribution in the P2ch reservoirs to guide natural gas prospecting and exploration in the region.In this paper,the paleo-oil charging period was first determined using fluid inclusions data,and the reservoir cap structure during oil charging was restored.Based on the reservoir cap structure the oil migration pathway was simulated,and the oil migration direction was traced using alkyl dibenzothiophene markers from solid reservoir bitumen.Finally,the paleo-oil accumulation characteristics and oil/gas reservoir evolution in the P2ch reservoirs were analyzed.The main findings were(1)bitumen inclusions were widespread,and the associated brine inclusions had a homogenization temperature of 110-130℃.Combined with the burial history and thermal evolution data,the estimated paleo-oil charging period spaned from the Late Triassic to Early Jurassic.(2)The reservoir cap structure during reservoir deposition was retained during paleo-oil charging.(3)Paleo-oil migrated laterally from the platform margin slope to the reef-shoal traps,while the alkyl dibenzothiophene ratio for solid reservoir bitumen also gradually decreased along the migration direction consistent with lateral oil migration.(4)The degree of paleo-oil filling was higher in reef-shoal traps in the platform margin compared to lower positions.On the whole,the paleo-oil in the Yuanba gas field was characterized by near-source charging and oil accumulation in reef-shoal traps in the elevated platform margin.For paleo-reservoirs that had undergone high temperature thermal evolution,alkyl dibenzothiophenes may be used to trace the paleo-oil migration direction.
作者
李平平
魏广鲁
徐祖新
李毕松
彭雨晴
邹华耀
LI Pingping;WEI Guanglu;XU Zuxin;LI Bisong;PENG Yuqing;ZOU Huayao(National Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing 102249,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Carbonate Research Center,China University of Petroleum(Beijing),Beijing 102249,China;Exploration Company,Chengdu 610041,SINOPEC,China)
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2023年第6期277-288,共12页
Earth Science Frontiers
基金
国家自然科学基金联合基金项目“海相深层油气富集机理与关键工程技术基础研究(U19B6003)”。
关键词
烷基二苯并噻吩
固体沥青
古原油运移方向
长兴组
元坝气田
四川盆地
alkyl dibenzothiophene
solid bitumen
migration direction of paleo-oil
Changxing Formation
Yuanba gas field
Sichuan Basin
