喇萨杏油田储层非均质性表征新参数——地层系数变异程度

A New Characterization Parameter of Reservoir Heterogeneity in La-sa-xing Oilfield—Formation factor variation degree

目前储层非均质性的表征主要考虑渗透率这一个因素,衍生出的非均质参数有时会受到平均值、最大值的影响使非均质表征的准确程度降低,为此结合喇萨杏油田20口取芯井资料,基于洛伦兹曲线,引入储层有效厚度,提出储层非均质性表征的新参数一地层系数变异程度,以细分小层为单位,将各小层的地层系数由高到低排序,绘制地层系数贡献率和层数累计百分数的关系曲线,计算的基尼系数即为地层系数变异程度,该参数与级差、突进系数和变异系数相比更加全面的反映了储层的非均质程度,并与储层动用程度成反比.经过实例分析可得,地层系数变异程度对储层动用程度的影响更加显著,该参数与动用程度关系曲线的相关系数为0.855,高于其他非均质参数,当只考虑薄差储层时,相关系数可达0.9866,所以新参数可应用于评价储层的宏观非均质程度,尤其是薄差储层.

Reservoir heterogeneity characterization usually based on the factor permeability at present,the derived parameters may be affected by average value or maximum value,which can decrease the accuracy,in this paper we collected data of 20 coring wells,according to lorenz curve and introduced effective thickness to put forward the new parameter—formation factor variation degree which can characterize the reservoir heterogeneity.The formation factor of every layer was calculated then sorted,the curve of formation factor contribution rate and layers cumulative percentage was drawn,the Gini coefficient was formation factor variation degree,the formation factor variation degree can reflect the heterogeneous degree of reservoir more comprehensively than permeability ratio,permeability max-mean ratio and permeability variation coefficient and was inversely proportional to producing degree.The instance analysis showed that the influence of formation factor variation degree on producing degree was larger,the curve correlation coefficient of formation factor variation degree and producing degree was0.855,which was higher than other heterogeneous parameters,especially for the poor and thin reservoir,the correlation coefficient reached to 0.9866,so the formation factor variation degree can evaluate the macro heterogeneity of reservoir especially for the poor and thin reservoir.