一种新型底流与浊流交互作用形成的储集砂体——以北礁凹陷为例  

A new reservoir sand body resulted from interaction between turbidity flows and bottom currents:a case from Beijiao Sag of Qiongdongnan Basin

作　　者：李俞锋 蒲仁海[3] 唐明[4] 袁超 吴仕玖 LI Yufeng;PU Renhai;TANG Ming;YUAN Chao;WU Shijiu(School of Environment and Resource,Southwest University of Science and Technology,Mianyang 621010,Sichuan,China;Key Laboratory of Marine Mineral Resources,Ministry of Land and Resources,Guangzhou 510075,China;State Key Laboratory of Continental Dynamics,Northwest University,Xi’an 710069,China;Research Institute of Zhanjiang Branch,CNOOC Ltd,Zhanjiang 524057,Guangdong,China)

机构地区：[1]西南科技大学环境与资源学院,四川绵阳621010 [2]自然资源部海底矿产资源重点实验室,广州510075 [3]大陆动力学国家重点实验室.西北大学,西安710069 [4]中海石油(中国)有限公司湛江分公司研究院,广东湛江524057

出　　处：《岩性油气藏》2018年第6期55-66,共12页Lithologic Reservoirs

基　　金：国家自然科学基金重大项目"中国非常规油气组成特征;分类与典型地质模型建立"(编号:41390451);自然资源部海底矿产资源重点实验室公开基金"琼东南盆地北礁凹陷构造断层特征;成因及地质意义"(编号:KLMMR-2018-B-07)联合资助

摘　　要：目前地质学家对垂直于大陆斜坡发育的浊积水道研究已较为成熟,而对平行于大陆斜坡水道的研究还处于起步阶段。在深水环境中,底流与浊流交互作用较为普遍,但研究少且程度较低,与这种交互作用相关的平行斜坡水道亟待深入研究。通过二维地震资料对北礁凹陷的古地貌进行研究,再利用三维地震资料的时间域构造、均方根振幅等,结合三维区的地震剖面和该区沉积环境及海平面升降、古气候等因素对平行斜坡强振幅水道进行综合研究。结果表明:北礁凹陷中中新世具有狭窄通道古地形特征,东北部发育一条近平行斜坡水道,且主要分布在该狭窄通道的右侧,该水道呈指状或锥状展布。沿水道方向有前积现象,且水道头部也有前积现象,而中部、尾部均以平行充填为主,该水道下方不发育大型断层。该平行斜坡水道是垂直于斜坡的浊流与沿斜坡的底流在狭窄通道处交互作用的沉积结果,该水道是一种新型的岩性储集砂体,具有潜在的高孔、高渗特征,该水道形成时的古气候和狭窄通道的古地形是其主控因素,并提出了这种新型储集砂体的沉积模式,丰富了我国深水砂体的类型。该水道具有重要的古海洋、古气候意义,可能在深水环境下的狭窄通道处广泛分布,是南海深水油气勘探的潜在接替新区,应引起石油地质工作者的重视。Nowadays,geologists have mainly focused on channels originated from turbidite flows and perpendic ular to continental margin slope,of which the field is now mature.In the deep-water environment,there is pervasive phenomenon for interaction between bottom currents and turbidity flows,of which the study is less.The interaction,resulting in parallel-slope channels,needs to be further researched urgently.Parallel-slope channels,however,are in the initial stage of research.The paleogeomorphology of Beijiao Sag was studied by using 2 D seismic data.Then the time-domain structure and root-mean-square amplitude of 3 D seismic data were used to comprehensively study the high-amplitude parallel-slope channels combined with the seismic profiles of 3 D region,sedimentary environment,sea level change and paleoclimate.The results show that Beijiao Sag was narrow-pathway shaped paleotopography in the Mid-Miocene.A parallel-slope channel with high amplitude was mainly distributed on the right side of narrow pathway in the northeastern Beijiao Sag,exhibiting multi-finger shaped or coneshaped.There was a progradation seismic reflection along the channel,and there were similar progradation seismic reflections and parallel-filling seismic reflections at the head and middle-tail of the channel in the crossing profile of channels,respectively.There was no tectonic fault beneath the parallel-slope in underlying strata.The parallelslope channel is a sedimentary result of interaction between turbidity flows and bottom currents associated with intermediate water,in the process of which fined grained debris such as mud was carried away by bottom currents and coarse-grained debris such as sand was deposited and filled within the channels.The channel is a new type of lithologic reservoir sandbody characterized by high porosity and high permeability.Finally,the main controlling factors consisting of paleoclimate and special paleotopography were analyzed and their sedimentary model was proposed.The channel has important paleoceanic and paleocl

关 键 词：平行斜坡水道 底流与浊流交互作用 狭窄通道 新型储集砂体 北礁凹陷 

分 类 号：TE121.3[石油与天然气工程—油气勘探]