合肥盆地安参1井粘土矿物XRD及成岩程度分析

文章对合肥盆地安参1井内15个泥岩样粘土矿物进行了X射线衍射分析,从获得的伊利石结晶度和伊/蒙混层比测试结果,揭示了该深井所钻遇地层的成岩程度和热演化程度.在井深1 000 m以上段地层处于成岩阶段,所经历的温度小于200℃.在井深1 000～4180 m段地层已进入埋藏变质阶段,所经历的温度介于200～300℃;而在井深4 180 m以下段已进入浅变带(即绿片岩相开始阶段),指示温度略大于300℃.文章还对该井伊利石结晶度纵向变化曲线进行了讨论,认为井深370.75 m处样品结晶度高于下伏地层的原因是受燕山运动古城幕的影响所致,该现象反映出盆地形成时处于活动的构造背景.

X-ray diffraction study of clay minerals in Well Ancan 1 of Hefei Basin and analysis of the diagenesis degree

The quantitative study is conduted on the XRD data of clay minerals in 15 mudstone samples from the Well Ancan 1 in Hefei Basin,and the testing results of illite crystallinity and illite/smectite interlaying reveal the stratigraphical diagenesis degree and thermal evolution degree of the strata met by the deep well drilling.The stratum abcIve 1 000 m in depth was in the diagenesis stage,and the temperature that it had experienced was below 200℃.The strata from 1 000 m to 4 180 m in depth Was at a burial metamorphic stage and the temperature that it had undergone Was between 200～300℃.Whereas below 4 180 m in depth,the strata had entered the epizone,which is the beginning stage of greenschist fades,thus indicating that the temperature was slightly higher than 300℃.The longitudinal change curve of illite crystallinity was discussed in the paper.It is considered that it was because the influence of the Gucheng episode of the Yanshanian movement that the sample crystallinity in 370.75 m was higher than the underlain strata,which revealed that the basin growth was in an active tectonic setting.