逆断层型构造坡折带对沉积相和储层控制作用——以玛湖凹陷西缘八道湾组厚层砂砾岩为例  

Influence of Reverse Fault Structural Slope Break Zones on Sedimentary Facies and Reservoir Development:Example of thick sandy conglomerate of the Badaowan Formation at western margin of Mahu Sag

作　　者：王辉[1] 王智强[1] 罗淦 周伟军 WANG Hui;WANG ZhiQiang;LUO Gan;ZHOU WeiJun(No.2 Oil Production Plant,PetroChina Xinjiang Oilfield Company,Karamay,Xinjiang 834000,China)

机构地区：[1]中国石油新疆油田分公司采油二厂,新疆克拉玛依834000

出　　处：《沉积学报》2022年第6期1513-1524,共12页Acta Sedimentologica Sinica

基　　金：国家科技重大专项(2017E-0401)。

摘　　要：玛湖凹陷西缘坡折带控制着古地貌、沉积相类型和展布、油气藏分布等,但目前缺少该坡折带形成机理、演化的研究,制约了该区油气勘探进程。在岩心、测井和地震资料分析的基础上,认为该区八道湾组为湿润型冲积扇相和辫状河三角洲相。八道湾组下段为冲积扇和辫状河三角洲平原亚相组合,地震剖面中可见清晰的扇体前积结构;上段为辫状河三角洲平原和前缘的组合,以辫状河三角洲前缘为主。八道湾组沉积过程受坡折带控制,坡折带的形成与逆冲推覆体派生逆断层有关。分析表明:多条逆断层形成的坡折带阻碍沉积物向盆地搬运,而单断层形成的坡折带在风化侵蚀作用下消失殆尽,利于沉积物的搬运。坡折带靠近物源的一侧为构造高部位,常发育冲积扇和辫状河三角洲平原;坡折带之下为构造低部位,常发育辫状河三角洲前缘,体现了坡折带对沉积相的控制作用。坡折带对储层物性也具有一定的控制作用,物性较好的储层分布在坡折带东南侧,且易于形成上倾尖灭的油气藏,坡折带东侧是油气勘探的重点。The slope break zone at the western margin of the Mahu Sag controls the paleogeomorphology,sedimenta⁃ry facies type and distribution,oil and gas reservoir distribution,etc.,but to date there is a lack of research on the formation mechanism and evolution of the slope break zone.This restricts the process of oil and gas exploration in this area.Based on the analysis of core logging and seismic data,it is considered that the Badaowan Formation in this area comprises wet alluvial fan facies and braided river delta facies.The lower member of the formation is composed of al⁃luvial fan and braided river delta plain subfacies,and a fan progradation structure is clearly seen in the seismic sec⁃tion.The upper member is a combination of braided river delta plains and fronts,mainly fronts.The sedimentation process in the Badaowan Formation was controlled by the slope break zone,which is related to the thrust fault derived from the thrust nappe.The analysis shows that the slope break zone formed by multiple reverse faults hindered the transport of sediments to the basin;the slope break zone formed by single faults has vanished completely due to weathering and erosion,and thus does not hinder the transport of sediments.The side of the slope break zone closest to the provenance is the highest part of the structure,and alluvial fans and braided river delta plains were often devel⁃oped;the lowest part of the structure is below the slope break zone,and braided river delta fronts were often devel⁃oped.The slope break zone thus influences the sedimentary facies,and also plays a role in controlling the physical properties of the reservoir.The reservoirs with the best physical properties are distributed towards the southeast side of the slope break zone,and readily form upward pinchout oil and gas reservoirs.The lower part of the slope break zone is therefore the focus of oil and gas exploration.

关 键 词：准噶尔盆地西缘 八道湾组 湿润型冲积扇 坡折带 储层 

分 类 号：P618.13[天文地球—矿床学]