构造控制的油气晚期快速成藏:松辽盆地大庆长垣流体包裹体和自生伊利石证据  

Tectonically Controlled Rapid Hydrocarbon Accumulation in the Big Daqing Anticline of Songliao Basin: Evidence from Fluid Inclusions and Illite Dating

作　　者：向才富[1,2] 冯子辉[3] 王富东[1,2] 张顺[3] 彭鹏[1,2] 梁晓东[3] 

机构地区：[1]中国石油大学油气资源与探测国家重点实验室,北京102249 [2]中国石油大学地球科学学院盆地与油藏研究中心,北京102249 [3]大庆油田勘探开发研究院,黑龙江大庆163458

出　　处：《地质学报》2012年第11期1799-1808,共10页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号40872097;41272161);国家重大专项项目(编号2011ZX05006-005;2011ZX05006-006)联合资助成果

摘　　要：松辽盆地大庆长垣存在两期流体活动,第一期流体活动代表了受成岩作用控制的储层流体活动,只存在小规模的油气运移,可以根据流体包裹体均一温度结合埋藏史分析限定其流体活动年龄在白垩纪末期—古近纪初期;第二期代表了受构造控制的流体活动,并与油气大规模运聚密切相关,流体包裹体均一温度超过了取样点地层所经历的最大埋藏温度,不能通过埋藏史确定其形成时间,显示了幕式流体活动的特点。在系统自生伊利石钾氩测年的基础上,进一步限定第一期流体活动在白垩纪末期之前,代表了储层埋藏成岩期的流体活动,而第二期流体活动是伴随着燕山期强烈构造反转的流体活动,与油气充注作用伴生。大庆长垣的自生伊利石年龄随深度的演化关系表现出两种模式,即正斜率模式和负斜率模式。其中正斜率模式下部储层油气充注时间晚,而上部储层油气充注时间早,主要分布在大庆长垣的核部;负斜率模式与正斜率模式相反,主要分布在大庆长垣的翼部,两者的分界线大致沿大庆长垣的-900m高程展布。油气成藏年龄模式阐明了大庆长垣的油气成藏过程是典型的背斜型油气充注过程,在大庆长垣的周缘(海拔<-900m)是油气在浮力的控制下向输导层顶面的运移过程,表现为下部储层油气成藏时间早,上部储层油气成藏时间晚;而大庆长垣的主体(海拔>-900m)是背斜油气的充注过程和油气的脊运移阶段,上部储层油气成藏时间早,下部储层油气成藏时间晚。测年数据表明大庆长垣-900m高程的油气在晚白垩世—古近纪初期(59～69Ma)的10Ma中已经充注完成,在此范围内发现的油气储量约为7×109t,可见油气充注是高效的幕式注入,而不是传统所认为的稳态成藏。由于第二期流体活动与燕山期主幕构造活动密切相关,因此文章认为大庆长垣的油气高效快速充注主要受控于构造作�There were two episodes during which fluids migrated in the Big Daqing Anticline （BDA）, Songliao basin. The first-episode inclusions represent the fluid migrating in reservoir, which was controlled by diagenetic process, only in small scale. Timing of fluid activities was limited within late Cretaceous and early Paleogene using homogenization temperature of fluid inclusions and burial history. The second episode represents fluid activity dominated by the tectonic movement and closely related to large-scale migration of fluid. Because the homogenization temperature exceeded the maximum burial temperature of the sequences where sampling took place, the burial history can not be used to determine forming age, and this shows the feature of fluid episodic activities. Small-scale hydrocarbon migration during the first episode is indicated by a low content of hydrocarbon fluid inclusions （GOI ~ 5~）, while large-scale hydrocarbon migration in the second episode is indicated by a high content of hydrocarbon inclusions （GOI ~15%） and a strong fluorescence of yellow-white or brown-yellow. A systematic authigenic illite dating deciphers a rapid hydrocarbon charging process during the tectonic folding. The hydrocarbon accumulation process in the BDA is a typical anticlinal hydrocarbon charging indicated by the negative age-depth distribution model which applies in the flank of BDA with an elevation %--900 m, and the positive age- depth distribution model which is suitable in the centre with a height 〉--900 m. The age distribution model indicates that all the strata under the main seal level had undergone hydrocarbon charging in a relatively short period of 59 ~ 69 Ma, with reserves ~ 7 X 109 t, which is an efficient but instant hydrocarbon charging process rather than a steady one. Due to the fact that the fluid activity in the second episode was closely related to Yanshanian tectonic activities, this study suggests that the rapid effective charge of gas and oil in the BDA was mainly subject to tectonics, ie. ep

关 键 词：流体包裹体 自生伊利石K—Ar测年 幕式成藏 大庆长垣 松辽盆地 

分 类 号：P618.13[天文地球—矿床学]