基于微电阻率成像测井图像的琼东南盆地松涛隆起新近系沉积相研究

Study of Neogene sedimentary facies in Songtao uplift of Qiongdongnan Basin based on micro resistivity imaging logging images

沉积相分析是恢复古地理环境、进行油气储层、烃源岩和盖层预测,为油气资源勘探开发服务的常用手段之一。基于微电阻率成像测井图像的精细解译,结合岩心、录井、常规测井与相关实验等资料,在岩心刻度微电阻率成像测井图像的基础上,以沉积学理论方法为指导,对琼东南盆地松涛隆起新近系的岩性、岩石序列组合和沉积构造等进行了识别,并以此为相标志进行了沉积相分析,建立了研究区新近系的沉积相模式。研究结果表明:(1)从琼东南盆地新近系高清微电阻率成像测井图像上共识别出泥岩、粉砂岩、细砂岩、中砂岩、粗砂岩等共5类岩性,岩性较为复杂,整体粒度较细,粒径跨度很大,垂向上岩性呈现明显的旋回性。(2)根据琼东南盆地松涛隆起新近系高清微电阻率成像测井图像中不同形态线条的组合方式,结合倾角矢量模式,共识别出5类层理类型(水平层理、波状层理、板状交错层理、槽状交错层理和块状层理),此外还识别出了钙质结核和生物扰动构造。(3)琼东南盆地松涛隆起新近系沉积环境总体为滨-浅海相、半深海和深海相沉积,局部层段发育浊流沉积;沉积演化规律表现为在渐新世晚期陵水组沉积时期全区发生海进,接受了滨海三角洲为主的各类沉积作用;到中新世早期的三亚组和梅山组沉积时期,沉积环境逐步由滨岸沉积环境过渡到浅海和半深海沉积;至黄流组和莺歌海组沉积期海水进一步加深,出现了半深海和深海沉积;而到莺歌海组沉积末期,发生了缓慢的海退,逐步变为半深海沉积。

Sedimentary facies analysis is one of the commonly used methods to reconstruct the paleogeographic environment,predict oil and gas reservoirs,hydrocarbon source rocks,and cap rocks,and serving the exploration and development of oil and gas resources.In this paper,on basis of the detailed interpretation of micro resistivity imaging logging images,combined with data from rock cores,logging,conventional logging,and related experiments,and guided by sedimentary theory methods,the lithology,rock sequence combination,and sedimentary structure of the Neogene in the Songtao uplift of Qiongdongnan Basin were identified,and sedimentary facies analysis was conducted using this as a facies marker,a sedimentary facies model for the Neogene in the study area was established.The results show that:①Five types of lithologies,including mudstone,siltstone,fine sandstone,medium sandstone and coarse sandstone,were identified from the high-definition micro resistivity imaging logging images of the Neogene in Qiongdongnan Basin.The lithology is relatively complex,with a fine overall grain size and a large particle size span.The vertical lithology exhibits obvious cyclicity.②Based on the combination of different morphological lines in the high-definition micro resistivity imaging logging images of the Neogene in Songtao uplift of Qiongdongnan Basin,five types of bedding(horizontal bedding,wavy bedding,tabular cross bedding,trough cross bedding and massive bedding)were identified in combination with the dip log model,and calcareous nodules and bioturbation structures were also identified.③The Neogene sedimentary environment in Songtao uplift of Qiongdongnan Basin is generally characterized by coastal-shallow sea,semi deep sea,and deep sea sediments,with local intervals developing turbidite deposits.The sedimentary evolution law shows that during the late Oligocene Lingshui Formation sedimentation period,the entire area underwent marine transgression and underwent various sedimentary processes mainly dominated by coastal deltas.During the early Miocene sedimentary period of Sanya and Meishan Formations,the sedimentary environment gradually transitioned from coastal sedimentary environment to shallow sea and semi deep sea sedimentary environment.During the sedimentation period of Huangliu Formation and Yinggehai Formation,the seawater further deepened and semi deep sea and deep sea sediments appeared.At the end of the sedimentation period of the Yinggehai Formation,a slow regression occurred,gradually transforming into semi deep sea sedimentation.