摘要
泥质潮坪中,高自然伽马特征多指示浅水沉积环境,导致利用自然伽马测井划分层序界面的传统方法在浅水台地中并不完全适用。为此,以渤海海域渤中21-22地区奥陶系马家沟组为例,提出一种基于自然伽马能谱测井的层序划分新方法,并探讨了层序对储层的控制作用。结果表明:①渤中21-22地区奥陶系马家沟组高自然伽马可划分为风化作用、储层铀富集以及泥质沉积三大成因类型;②自然伽马能谱测井中,Th/K可以有效区分不同成因的高自然伽马,是开展层序界面划分的有效参数;③基于Th/K曲线,将渤中21-22地区奥陶系马家沟组划分为5个三级层序,其中BZ21-2-A井层序完整,而BZ22-1-B井缺少SQ5层序;(4)层序划分结果与储层对应关系表明,裂缝型储层主要分布在风化壳100 m以内,受层序界面控制作用不明显,而溶蚀孔隙型储层主要集中在SQ1—SQ2层序的顶、底面附近,受层序界面控制作用明显。该认识对台地相碳酸盐岩层序界面划分具有借鉴意义。
The traditional sequence division method based on natural gamma ray is not applicable in shallow platform,due to that the high gamma ray in mud flat corresponds to shallow water sedimentary environment.Taking Ordovician Majiagou Formation in Bozhong 21-22 structure of Bohai Sea as an example,a new sequence division method based on natural gamma-ray spectral logging was proposed,and the control of sequence on reservoir was discussed.The result shows that:①Weathering,uranium enrichment of reservoir and normal sedimentary shale can cause high gamma of Ordovician Majiagou Formation in Bozhong 21-22 structure.②In natural gammaray spectrum logging,Th/K can effectively distinguish high gamma with different genesis,which is an effective parameter for sequence division.②There are five third-order sequences developed in Ordovician Majiagou Formation in Bozhong 21-22 structure.The sequence in well BZ21-2-A is complete,while SQ5 is lacked in well BZ22-1-B.The corresponding relationship between sequences and reservoir shows that the fractured reservoirs are mainly distributed within 100 m of weathering crust and are not obviously controlled by the sequence boundary.While dissolved pore reservoirs are mainly concentrated near the top and bottom of SQ1-SQ2 sequence and are obviously controlled by the sequence boundary.The research results can be used for reference in the sequence division of carbonate rocks in platform facies.
作者
叶涛
王清斌
代黎明
陈容涛
崔普媛
YE Tao;WANG Qingbin;DAI Liming;CHEN Rongtao;CUI Puyuan(Tianjin Branch of CNOOC,Tianjin 300459,China)
出处
《岩性油气藏》
CSCD
北大核心
2021年第3期95-103,共9页
Lithologic Reservoirs
基金
国家油气重大专项“渤海海域勘探新领域及关键技术研究”(编号:2016ZX05024-003)资助。
关键词
层序划分
自然伽马能谱
储层展布
台地相碳酸盐岩
奥陶系
渤中凹陷
sequence division
natural gamma-ray spectrum
reservoir distribution
carbonate rocks of platform facies
Ordovician
Bozhong Sag
