海上稀疏井区高精度地层格架约束下的地震沉积学刻画——以东海盆地西湖凹陷中央背斜带X区块古近系花港组为例  

Seismic sedimentological characterization of an offshore area with sparse well control under the constraint of a high-resolution stratigraphic framework:A case study of the Paleogene Huagang Formation in block X of the central anticlinal zone in the Xihu

作　　者：董鑫旭 周兴海[2] 李昆[2] 蒲仁海[1] 王爱国[1] 关蕴文 张鹏[1] DONG Xinxu;ZHOU Xinghai;LI Kun;PU Renhai;WANG Aiguo;GUAN Yunwen;ZHANG Peng(State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi’an,Shaanxi 710069,China;Shanghai Offshore Petroleum Company,SINOPEC,Shanghai 200120,China)

机构地区：[1]西北大学地质学系/大陆动力学国家重点实验室,陕西西安710069 [2]中国石化上海海洋油气分公司,上海200120

出　　处：《石油与天然气地质》2024年第1期293-308,共16页Oil & Gas Geology

基　　金：国家自然科学基金项目(41390451)。

摘　　要：海上工区面积辽阔,单井资料匮乏,花港组内部横向上的沉积微相界定存在争议、纵向上的沉积演化规律不明。为充分挖掘现有井、震资料的地质解释潜力,选取东海盆地西湖凹陷中央背斜带X区块古近系花港组为研究对象,提出了井-震小波变换建立高精度等时地层格架、井点沉积相标志定相类型、分频RGB属性刻画沉积相展布以及古地貌恢复辅助沉积相演化规律分析的地震沉积学解释技术。研究结果表明:(1)测井-地震小波变换结果有较好的一致性,可将研究区花港组分为花港组上段(花上段)3个(H1—H3)和花下段5个(H4—H8)四级旋回,并在此基础上建立高精度等时地层格架。(2)根据岩心相、测井相和地震相相互印证,确认研究区花港组沉积期为辫状河三角洲沉积环境。分频振幅属性验证不同厚度砂岩层在15,30和45 Hz单频体的振幅响应明显,采用分频RGB属性融合可在平面凸显不同沉积体的边界。(3)研究区H1和H2旋回整体为三角洲前缘沉积,H3—H6旋回为浅水背景下的三角洲平原-前缘沉积,H7和H8旋回为辫状河三角洲平原沉积,砂层组沉积相垂向演化受控于物源供给、相对湖平面高低和古地貌形态。在井-震时频分析建立等时地层格架基础上,通过相关性分析优选属性进行RGB融合能够凸显不同厚度砂岩的展布,减少了人为主观因素的影响,提升了沉积体边界的识别能力,可为其他井网稀疏地带沉积相刻画提供借鉴。Exploration in vast offshore survey areas faces the challenge of limited single-well data.To reveal the lateral sedimentary microfacies variations still in controversy and vertical sedimentary evolution pattern of the Huagang Formation,we focus on the Huagang Formation in block X of the central anticlinal zone in the Xihu Sag based on a comprehensive analysis of available logs and seismic data.Using the seismic sedimentological interpretation technology,which allows for analyzing the evolutionary pattern of sedimentary facies with the assistance of paleogeomorphic reconstruction,we establish a high-resolution isochronous stratigraphic framework through the wavelet transform of logs and seismic data.Furthermore,we calibrate the seismic facies types based on single-well sedimentary facies and delineate the distribution of sedimentary facies using frequency-division spectral decomposition red,green,and blue(RGB) attributes.Key findings are as follows:(1) The wavelet transform results from logs and seismic data,demonstrating high consistency,allow for the division of the Huagang Formation of the study area into eight fourth-order cycles:three in the upper member(H1—H3) and five in the lower member(H4—H8).Consequently,a high-resolution isochronous stratigraphic framework is formed;(2) A comprehensive analysis of core facies,logging facies,and seismic facies suggests that the Huagang Formation in the study area had a sedimentary environment of braided deltas.Frequency-division seismic amplitude attributes reveal that sandstone layers of varying thicknesses exhibit the most significant seismic amplitude responses in single-frequency volumes of 15 Hz,30 Hz,and 45 Hz.Therefore,the frequency-division RGB blends can be used to effectively delineate the boundaries of different sedimentary bodies in a planar view;(3) In the study area,the H1 and H2 cycles generally consist of deltafront sediments,the H3 to H6 cycles feature a combination of delta-plain and delta-front sediments in a shallow-water setting,and the H7 and H8

关 键 词：沉积演化 地层格架 地震沉积学 花港组 古近系 西湖凹陷 东海盆地 

分 类 号：TE121.3[石油与天然气工程—油气勘探]