摘要
【目的】明确古地貌、古物源及古沉积环境对沉积相的控制作用,充分认识沉积相平面展布特征,进而优选有利相带及开展储层评价。【方法】以台北凹陷中西部三叠系克拉玛依组为例,采用印模法恢复古地貌,通过重矿物组合法和微量元素分别进行古物源、古沉积环境分析,并结合岩石相、单井相及剖面相标志、砂砾岩厚度、砂地比,确定台北凹陷中西部三叠系克拉玛依组沉积相平面展布特征,最终依据模糊数学评判法对储层进行多因素综合分类评价。【结果与结论】克拉玛依组沉积时期台北凹陷中西部整体古地形较缓,古水流相对较缓,水动力相对较弱,发育广覆式辫状河三角洲沉积,克拉玛依组为辫状河三角洲前缘沉积,沿盆地边缘呈席状分布。沉积物源主要来自南部古凸起,沉积环境为半湿润、厌氧还原的盐湖环境。辫状河三角洲凸起前缘是克拉玛依组优质储层有利沉积相带,生运聚条件良好,是有利的油气勘探区带。
[Objective]This study aimed to clarify the controlling effect of paleogeomorphology,paleo-provenance,and paleosedimentary environment on sedimentary facies,fully understand the plane distribution characteristics of sedimentary facies,and optimize the next exploration field[.Methods]Taking the Triassic Karamay Formation in the midwestern Taibei Sag as an example,the petrological characteristics of the Triassic Karamay Formation reservoir were studied by field outcrop,core observation,particle size analysis,and rock thin section identification.The paleogeomorphology and tectonic evolution characteristics were restored by impression method.The paleogeomorphology analysis was conducted by heavy mineral combination method,and the paleosedimentary environment was analyzed by trace elements.Under the constraint of sequence stratigraphic framework,comprehensive utilization of field outcrops,drilling cores,logging and mud logging,and a variety of analysis and testing data were applied to summarize the rock facies marks,logging facies marks,and other characteristics and determine the sedimentary facies type.Based on the study of sedimentary facies types,the research idea of'point-line-surface-body'was adopted,and the sedimentary facies distribution law of the Triassic Karamay Formation was studied using single well core sedimentology analysis,sandstone thickness contour map,sandstone percentage contour map,and profile facies analysis.Based on the study of sedimentary system distribution and favorable reservoir facies belt,the favorable direction and zone of oil and gas exploration in the Triassic Karamay Formation of the Taibei Sag in the Turpan-Hami Basin are analyzed based on a fuzzy mathematics algorithm combined with the hydrocarbon generation and structural zones.[Results and Conclusions]The reservoir rocks of the Triassic Karamay Formation are mainly glutenite,sandstone,and mudstone,with low compositional maturity,showing characteristics of near-source deposition.The thickness of the residual strata in the sedimentary period of the Triassic Karamay Formation showed a trend of gradual thinning from north to south and from the middle to both sides,indicating that the northern part of the Triassic in the Taibei Sag was the sedimentary center.The overall paleotopography in the central and western parts of the Taibei Sag is relatively slow,the paleocurrent is relatively slow,the hydrodynamic force is relatively weak,and the wide-covered braided river delta deposit is developed.The Karamay Formation is a braided river delta front deposit,which is distributed along the edge of the basin.The sediment source mainly comes from the ancient uplift in the south,and the ZTR(Zircon,Tourmaline,Rutile)index in the north of the basin increases from south to north,indicating that the source migrates from south to north.The sedimentary environment is a semi-humid,anaerobic reduction salt lake environment.Affected by the paleogeomorphology,the sand bodies in the central and western parts of the Taibei Sag are relatively developed,with large thickness and wide distribution.The T_(2-3)k^(1) period was a braided river delta front deposition,which is distributed in a sheet along the edge of the basin.During the T_(2-3)k^(2) period,the braided river delta front deposition was developed and distributed in a sheet along the edge of the basin.Based on the sandstone thickness,sedimentary microfacies parameters(sand ratio),physical parameters(porosity and permeability),etc.,the comprehensive evaluation of the reservoir was conducted using fuzzy evaluation.The braided river delta front is the favorable sedimentary facies zone of the high-quality reservoir of the Karamay Formation.The conditions of migration and accumulation are good,and it is a favorable oil and gas exploration zone.
作者
魏生云
王建国
蔡丽娜
邢佳
胡建
王志男
WEI ShengYun;WANG JianGuo;CAI LiNa;XING Jia;HU Jian;WANG ZhiNan(Department of Geological Engineering,Qinghai University,Xining 810016,China;The Second Geological Exploration Institute,Henan Geological Bureau,Zhengzhou 450000,China)
出处
《沉积学报》
北大核心
2025年第2期555-575,共21页
Acta Sedimentologica Sinica
基金
国家自然科学基金项目(42164007)。
关键词
古地貌
古物源
古沉积环境
沉积相
台北凹陷
克拉玛依组
paleogeomorphology
paleo-provenance
paleosedimentary environment
sedimentary facies
Taibei Sag
Karamay Formation
