海拉尔盆地乌南凹陷南一段高伽马砂岩成因与识别

Genesis and identification of high gamma sandstone in the first member of Nantun formation of Wunan depression in Hailar Basin

关键词:  海拉尔盆地  乌南凹陷  高(4然伽H砂治  岩石成因  识別方法

Key words:  Hailaer Basin  Wunan depression  high natural gamma sandstone  lithogenesis  recognition method

摘要:

为f提高海拉尔盆地乌南凹陷高伽马砂岩测井沿性解释的准确性，采用岩心观察、显微镜下描述和测井曲线 分析相结合的方法对高伽马砂畀的成因和识別方法进行探W。对砂畀的补偿屮子值进行分类以排除孔隙度对测并 曲线的影响,再利用深侧向电阳率、微侧向电阻率和补偿密度交会识别高A然伽4砂耑。研究结果表明:影响砂岩 fi然伽马特怔的W素有凝灰质、黏土、油、长石以及钙质;卨S然伽4砂耑搀存高钍或荇高铀含3:的特征;凝灰质导 致针富集，黏士导致铀、钍和钾均富集，油导致铀常集，长石导致钾富集，钙质导致铀含降低;从四陷边缘至凹陷中 央影响砂岩卨fl然伽马W素依次为高凝灰质含M、高长石含i以及高黏土含fl。

Abstract:

In order to improve the accuracy of logging lithology identification of high natural gamma sandstone in Wunan depression in Hailar Basin，in terms of rock core and microscopic sections description and logging analysis, the causes and i-dentifiration of high gamma sandslones were discussed. The classification of the sandstone CNL values can provide a estimating under a certain porosily degree. The high natural gamma sandstones can be identified using deep lateral resistivity (DLL), micro lateral resistivity logging(RMLL) , DEN and AC. The research results show that the factors aiTecting these sandstones with high natural gamma are tuffaceous matter, clay, oil，felcJspar and calcium. High natural gamma sandstones express high content of thorium or uranium from logging data. The tuffareous matter leads to the enrichment of thorium, clay leads to the enrichment of uranium, thorium and potassium, oil leads to the enrichment of uranium，feldspar leads to the enrichment of potassium y and calcareous matter leads to the decrease of uranium content. The affecting factors of sandstone nature gamma ray are high tuffaceous matter, high feldspar and high clay ranging from edge to center of the depression.