利用铝钒含量识别碎屑岩有利储层的新技术及其应用--以莺琼盆地DX、BX区为例

Identification of favorable reservoir by using the element contents of Al and V in clastic rocks:taking DX and BX blocks of Yinggehai Basin and Qiongdongnan Basin as examples

对南海西部4个盆地的跟踪研究发现:碎屑岩中铝钒含量越低,储层性质越好。在碎屑岩发育区,铝钒含量普遍具有正相关性,且不受放射性的影响,故可通过寻找低铝低钒含量区来识别泥质含量较低的有利储层。基于铝钒含量交会图,结合录井岩性可界定出有利储层带、过渡带、欠储层带,并定量标定出各带的下限值或上限值。通过铝钒含量平面分布图,可“由点推面”识别有利储层带、过渡带、欠储层带的分布区。应用该项技术识别储层时,首先需结合钙含量把含灰质的致密储层甄别出来。该技术推广应用于莺琼盆地DX、BX等区块,钻前预测的有利储层分布区,与实钻结果基本一致。这项技术是对利用沉积相解释碎屑岩有利储层和泥质岩盖层这一方法的较好补充,也是对受放射性影响的高伽马砂岩进行测井解释的有力手段,尤其是提供了一种新型实用的地球物理手段,即把铝钒含量随深度变化曲线和各储层带的下限值或上限值应用于分频反演,可以识别有利储层和泥质岩盖层或隔夹层。

In the four basins of the western South China Sea,there is a general relationship between reservoir quality and the contents of Al and V in clastic rock,that is the lower the contents of Al and V,the better of the reservoir quality.Further study shows that the contents of Al and V is not affected by radioactivity,and there is a positive correlation between them.Thus we can identify favorable reservoirs with lower mud content through looking for areas of the lower contents of Al and V.Based on the content crossplot of Al and V and logging lithology,the favorable reservoir zone,transition zone and undeveloped reservoir zone can be defined,and the lower or upper limit values of each zone can be demarcated quantitatively.The distribution areas of favorable reservoir zone,transitional zone and undeveloped reservoir zone can be identified by the plane distribution of the contents of Al and V.When using this technology to identify the favorable reservoir,the first step is to identify the dense reservoir by using the content of calcium element.This technology is widely used in DX,BX and other blocks of Yinggehai Basin and Qiongdongnan Basin.The favorable reservoir distribution area predicted before drilling is basically consistent with the actual drilling results.This technology is a good supplement to the method of using sedimentary facies to interpret favorable clastic reservoir and argillaceous rock cap,and also a powerful means of logging interpretation for high gamma sandstone affected by radioactivity.The technology also offer a new practical geophysical means to predict favorable reservoir and shale cover or interlayer,which applies the content curve of Al and V changing with depth and the lower or upper limit value of each reservoir zone to perform frequency division seismic inversion.