川中地区下寒武统龙王庙组混合沉积特征研究

发布时间：2018-01-24 15:54

本文关键词： 四川盆地龙王庙组混合沉积物源油气影响　出处：《成都理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：四川盆地是我国西南部重要的含油气盆地,天然气资源非常丰富,寒武系龙王庙组作为重要的储集层位,前人研究较少,近期研究成果表明,龙王庙组发育陆源碎屑与碳酸盐的混合沉积。陆源碎屑与碳酸盐的混合沉积因其特殊的机理及重要的理论和实际意义,为学者们广为关注。然而,针对四川盆地的混合沉积研究较少,对盆地深层的研究更少。本文结合区域地质资料、钻井资料、野外剖面资料等,对川中地区下寒武统龙王庙组混合沉积特征、物源、沉积模式及其对油气地质条件的影响等进行探讨。川中地区龙王庙组沉积期,盆地呈西浅东深的构造格局,沉积环境属于海相台地沉积,形成以碳酸盐组分为主的混合沉积。通过该区多口钻井资料显示,混积岩主要为含粉砂残余砂屑白云岩、含粉砂残余鲕粒白云岩、含粉砂粉晶白云岩,少见粉砂质白云岩,混积层系为碳酸盐岩-混积岩层系与混积岩层系。混合沉积中的陆源碎屑成分为陆源石英,粒级为粉砂级,分选好、磨圆差,主要以5种形式赋存于碳酸盐岩中。混合沉积类型为渐变式混合沉积及复合式混合沉积Ⅱ两种类型;陆源石英含量纵向上受海平面变化控制,混合沉积伴随海侵-海退旋回发育,海侵期混合沉积发育强度及厚度明显高于海退期;在三种沉积微相中,混合沉积发育强度由大到小依次为滩间洼地微相、混积颗粒滩微相、颗粒滩微相。平面上受古地貌控制,高石梯地区混合沉积发育强度及厚度均大于磨溪地区。通过对川中及川北地区龙王庙组混合沉积特征的研究发现:①川北地区龙王庙组混合沉积的陆源石英颗粒粒径及含量大于川中地区;②川北地区龙王庙组混合沉积强度大于川中地区;③川北地区龙王庙组混合沉积样式多于川中地区,说明川中地区龙王庙期环境变化缓慢,与纯碳酸盐沉积环境无差异,而川北地区则有环境突变的现象。川中地区龙王庙组发育三期风暴沉积作用,发育典型的风暴沉积构造,如冲刷-充填构造、风暴砾屑层、风暴层理构造等,对川中地区龙王庙组风暴砾屑厚度统计后发现,风暴岩的展布方向为北东-南西向,说明川中地区龙王庙期古海水的流动方向为北东-南西向。结合川北与川中龙王庙组混合沉积特征、川中地区龙王庙组风暴沉积特点、古海水流动方向及风暴的运动特点的研究,推测混合沉积物源来自川北地区。基于此,笔者认为川中地区龙王庙期沉积环境为台内潮坪沉积,主要以潮间-潮下为主,并建立混积潮坪沉积模式,认为构造运动、海平面变化、古地貌、物源、风暴作用、气候因素对混合沉积具有明显的控制作用,几种因素互相影响,共同作用,形成了川中地区龙王庙组混合沉积特征。综合该区及前人研究,认为混合沉积必须发育裂缝才能形成良好储层,川中地区龙王庙组沉积早期受混合沉积影响,颗粒滩沉积不发育,中后期混合沉积影响减弱,沉积环境过渡为“清水”环境,颗粒滩沉积厚层发育,为储层的形成提供良好的物质基础。推测川东北通南巴地区龙王庙组储层质量不佳。
[Abstract]:Sichuan basin is an important oil-bearing basin in southwestern China, natural gas resources are very rich, the Cambrian Longwangmiao formation in strata as an important reservoir, fewer previous studies, recent research results show that the Dragon King Temple group developed mixed sedimentation of terrigenous clastic and carbonate sedimentary debris and Lu Yuansui. Mixed carbonate because of its special mechanism and an important theoretical and practical significance, for scholars wide attention. However, the less mixed sedimentation of Sichuan basin, the deep basin research. In this paper, combined with regional geological data, drilling data, outcrop, the Sichuan region of Lower Cambrian Longwangmiao formation mixed sedimentary characteristics and provenance. Study on sedimentary model and petroleum geological conditions and so on. During the deposition of Longwangmiao formation in Sichuan Basin, tectonic pattern is shallow in the west east, the sedimentary environment belongs to Taiwan sea deposited to form The carbonate component mixed sediments. Through this area drilling wells data show that hunji rock is mainly silt residual dolarenite, silty residual oolitic dolomite and silty dolomite, rare silty dolomite, hunji sequence for carbonate rock strata and hunji mixed sedimentary strata. Terrigenous clastic composition in mixed sediments are terrigenous quartz particles for silt, good sorting, grinding, mainly in 5 forms in carbonate rocks. Mixed sedimentary type is a gradual mixed sedimentary and composite mixed deposits of two types of terrigenous quartz content vertically; controlled by sea-level change, mixed with sedimentary transgression regression cycles of development, transgression of mixed depositional intensity and thickness was significantly higher than that in the regression period; three kinds of sedimentary micro facies, intensity from high to low is flat depressions between microfacies mixed sedimentary development, hunji shoal Micro facies, grain beach microfacies. The plane by palaeogeomorphology, Gaoshiti area strength and thickness of the mixed sedimentary development than Moxi area. By studying the Sichuan and Sichuan Longwangmiao formation mixed sedimentary characteristics that mixed sedimentary Longwangmiao formation in northern Sichuan the Lu Yuanshi particle size and content more than Sichuan area; the Sichuan Longwangmiao formation mixed sedimentary strength is greater than the Sichuan area; the Sichuan Longwangmiao formation in Sichuan style more than the mixed sediments, indicating the Dragon King Temple in Sichuan environment changes slowly, with no difference between the pure carbonate sedimentary environment, and has the mutation of Sichuan Sichuan. In Longwangmiao formation developed three stages of storm deposition, the development of storm sedimentary structures typical, such as scouring filling structures, storm gravel layer, storm bedding structure, statistics of Sichuan Longwangmiao formation storm gravel thickness After that, the direction of storm rock is NE-SW, which indicates that the flow direction of ancient seawater Longwangmiao period in Sichuan is NE-SW. Combined with Sichuan and Sichuan in Longwangmiao formation mixed sedimentary features of Sichuan Longwangmiao formation characteristics of storm deposits, study the movement characteristics of ancient water flow direction and the storm, that mixed sediment source from Sichuan. Based on this, the author thinks that the sedimentary environment of Longwangmiao period in Sichuan Taiwan in the tidal flat deposits mainly in the intertidal - subtidal mainly, and the establishment of mixed tidal flat sedimentary model, it is considered that the tectonic movement, sea level change, ancient landform, provenance the storm, effect of climate factors has obvious control effect on mixed sediments, several factors influence each other, together, formed in Sichuan Longwangmiao formation mixed sedimentary characteristics. A comprehensive study of the region and the previous, think mixed deposits must develop cracks to form A good reservoir, Sichuan Longwangmiao formation sedimentary early mixed sediments, sedimentary particles are not developed, weakened in the late mixed deposition effect, the sedimentary environment of transition to "clean" environment, shoal deposition of thick layer development, provide good material foundation for the formation of the reservoir. That northeast Sichuan through the Dragon King Temple of the reservoir Nanba area of poor quality.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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