【作者】 张海峰；

【导师】 田世澄；

【作者基本信息】 中国地质大学（北京） ， 矿产普查与勘探， 2005， 博士

【摘要】 准噶尔盆地腹部主要目的层侏罗系形成于地形平缓的大型坳陷盆地中心地带,油气藏不仅仅受构造的控制,岩性在油气成藏过程中起到相当重要的作用,所形成的非构造圈闭包括上倾尖灭圈闭、三角洲分支河道砂岩岩性圈闭以及地层超覆圈闭等。论文通过对侏罗系这种平缓地形中形成的层序地层格架内沉积体系类型、储层特征、油气藏成藏条件及特征等方面的研究,探讨层序对地层油气藏的控制作用,进而指导研究区有利勘探区带的选择和评价。鉴于腹部地区面积大,钻井少,地震测网密度稀,论文中充分利用周边和凸起的钻/测井资料,以区域钻井、地震资料为基础,运用层序地层学理论与分析技术,建立了准噶尔盆地腹部侏罗系三级层序地层格架。研究认为,研究区侏罗系6 个三级层序均形成于平缓斜坡背景之中,但根据古地形、气候等古地理因素特征的不同,可以归结为三种古地理沉积背景:潮湿气候具平缓坡折平缓斜坡背景(Sq1,Sq2,Sq4)、潮湿气候平缓斜坡背景(Sq3)、干旱气候具平缓坡折平缓斜坡背景(Sq5,Sq6),相应地出现不同的层序特征。通过岩心微相、测井相、地震相、物源等沉积学方面的研究,发现在三种不同的古地理背景中,从盆地边缘至盆地中心分别形成不同的沉积体系组合:曲流河(泛滥平原)—三角洲平原(滨岸湖沼)—滨浅湖沉积体系组合;辫状河—辨状河三角洲平原、前缘—浅湖—半深湖沉积体系组合;三角洲平原—滨浅湖(前缘)—浅湖沉积体系组合。在地层格架内,本文利用微观实验手段,对钻井岩心资料比较丰富的地区(如中部Ⅰ区块庄1 井区、中部Ⅳ区块董1 井)开展了储集层微观特征分析,探讨控制储层发育及储集性能的地质因素,把控制本区砂岩储集性能的因素归结为沉积微相类型、低地温场、早期浅埋后期快速掩埋的埋藏环境以及埋藏过程中的成岩作用。通过对油源条件、盖层条件、储盖组合、油气运移等油气藏基本条件方面的研究,建立起了本区油气藏成藏模式,并认为控制研究区侏罗系油气藏形成的因素有三个:一是圈闭的落实;二是该圈闭是否位于油气输导路径上;三是储层质量。综合以上各方面的研究成果认为,层序地层格架内,在不同的沉积时期、不同的古地理位置形成了不同特征的沉积体系,进而控制着地层圈闭的形成、储层宏观分布和特征、控制了油气封隔层和运移通道,并最终控制大量隐蔽油气藏的分布。有利区带的选择原则与控制油气藏形成的三个因素密切相关,即有利区带需要具备较好的储层发育条件、具有形成有利圈闭的地质条件、并且所形成的有利圈闭应该位于油气输导路径中。据此,本文圈定出中部各区块层序地层格架内各层序的有利勘探区带。更多还原

【Abstract】 Junggar basin has good oil and gas potential, however, the source rocks are deeply buried, with poorly developed positive elements. During the deposition of the Jurassic system, the major exploration-target interval, the basin was wide, shallow, and smooth, with multiple cycles of alternately deposited sand stone and clay. The sand stone intervals were scattered in the vertical direction extending horizontally in limited distance. Exploration results from a few wells show that, oil and gas in the center of the basin are controlled not only by the geological structures but also by the lithology. The non-structural traps discovered in the basin include upwarding check out trap, lithologic trap and stratigraphic overlap trap. Through the systematic study of the depositonal systems, reservoir characteristics, and the formation of oil and gas traps in the gently dipped Jurrasic intervals in the basin, this paper discusses the control of the stratigraphic sequences on the oil and gas resource gathering, and provides guidance to the selection and evaluation of the favorable exploration targets. The central part of Junggar basin has huge unexplored area, with few drilling wells and highly scattered seismic exploration. Based on the wells and seismic data constructed,the sequence stratigraphic theory and techniques are used to build the sequence stratigraphic frame of Jurassic in the center of the basin, which consists of 2 2nd and 7 3rd sequences. During the construction of the frame, the author fully used the well logs of peripheral area and salient of the basin as aid and reference. The research results show that all the 6 3rd sequences of Jurassic were formed in the gently dipped slope. However, due to the difference in dead forms and palaeoclimate,their deposition environments can be divided into three palaeogeographic groups:gentle dipped slope with a gentle break in a humid climate(Sq1,Sq2,Sq4); gentle dipped slope in a humid climate (Sq3); gentle dipped slope with a gentle break in an arid climate (Sq5,Sq6)). Accordingly, each group has different stratigraphic characteristics. Through the study of cores, logs, seismic crosses and provenances,this research has discovered that in the three different palaeogeographic groups,different deposition systems were formed from the verge to the center of the basin: meander river-delta plain-shallow lake; braided river-delta plain with braided rivers and delta front-shallow lake-deep lake;delta plain-shallow lake. In the sequence frame,micro-experimental techniques are used to do a detailed characteristic analysis of the reservoirs in the area where cores are available, for example, Zhuang1 in the 1st region and Dong1 in the 4th region.,and to discuss the geological factors that control the reservoir development and reservoir quality. It shows that the factors controlling the quality of the reservoir sandstone include sedimentary facies, the surrounding environment under low geothermal gradient and diagenesis. Through the study of source rocks, cap rocks, the combination of reservoir sandstone and cap rocks, migration, etc., the authors has constructed models for the formation of the oil and gas traps in the studied area. It is believed that three factors control the formation of Jurrasic oil and gas traps in the studied area: the existence of traps, the location of the traps in the oil and gas transfer path, and the reservoir quality. In summary, results from this research show that the sequence frame,in which different deposition systems are formed in the different deposition time and different palaeogeographic position, controls the formation of stratigraphic traps, the distribution and characteristics of the reservoirs、confining layers and migration passages,and, hence, controls the distribution of many obscure oil and gas reservoirs. The favorite areas are selected for all the 6 sequences in the studied area..The selection of favorite exploration target area is closely related to the three factors that controls the oil and gas reservoirs,i.e., the favorite area should have high quality reservoir rocks, there are available traps, and the traps exists in the migration passages.更多还原