基于地层元素测井的混积岩岩性识别模型及应用——以莱州湾凹陷KL油田沙三下亚段为例

Lithology Identification Model of Mixed Rock Based on Formation Element Logging and its Application——Taking of Lower 3rd Member of Shahejie Formation of KL Oilfield in Laizhouwan Sag as an Example

莱州湾凹陷KL油田沙三下亚段主要发育辫状河三角洲相、滨浅湖相以及扇三角洲相,沉积环境复杂。岩石类型主要为陆源碎屑岩以及陆源碎屑质-碳酸盐混积岩和碳酸盐质-陆源碎屑混积岩两种类型的混积岩,岩性类型多样,不同岩性测井响应特征复杂,因此岩性识别困难。本次研究主要结合研究区岩心观察、井壁取心、铸体薄片、扫描电镜等资料对研究区不同岩性进行了细致的分类识别,在研究区壁心、薄片岩性观察的基础上,结合元素测井对研究区各井岩性进行校正。根据不同岩性测井参数概率密度分布特征绘制了置信度为90%的二维测井参数图,优选出具有代表性测井参数。并利用决策树方法建立了研究区混积岩岩性识别模型,形成了一套莱州湾凹陷KL油田沙三下亚段混积岩岩性测井识别方法,为后期储层评价及寻找优质储层起到重要作用。

The lower 3 rd member of Shahejie Formation of KL Oilfield in Laizhouwan sag as mainly develops braided river delta facies,coastal shallow lake facies and fan delta facies,and the sedimentary environment is complex.The rock types are mainly terrigenous clastic rocks and terrigenous clastic-carbonate mixed rocks and carbonate-terrestrial clastic mixed rocks.The lithology types are diverse and different lithology logs are used.The response characteristics are complex,so lithology identification is difficult.In this study,the lithology of the study area was classified and identified based on the core observation,core wall coring,cast thin section and scanning electron microscope.Based on the observation of the wall and lithology of the study area,Combined with elemental logging,the lithology of each well in the study area was corrected.According to the probability density distribution characteristics of different lithologic logging parameters,a two-dimensional logging parameter map with a confidence level of 90%was drawn,and representative logging parameters were selected.Based on the decision tree method,the lithology identification model of the mixed rock in the study area was established,and a lithology logging identification method for the mixed rock in the lower member of the Shahe Formation in the KL oilfield of the Laizhouwan Sag was formed,which was used for later reservoir evaluation and search for high quality reservoirs.Play an important role.