苏南区块声波测井计算孔隙度方法改进

Sonic logging porosity calculation method improvement in south Sulige block

苏南区块属于低孔、低渗、低压、低丰度的致密岩性气藏,储层非均质性强,孔隙结构复杂。孔隙度由于受岩性和孔隙结构的影响,骨架值不确定,很难用定值来表示,声波测井用传统的威里公式计算孔隙度方法难以准确求得地层真实孔隙度。根据声波测井原理以及岩石响应特征,并结合本区和邻区岩心分析数据,首先利用声波时差和岩心分析孔隙度回归公式计算孔隙度,然后根据泥质含量的不同,在岩心回归公式的基础上对泥质较重的层段进行了泥质校正,消除了由于泥质含量的影响导致的孔隙度计算误差。实际应用表明,利用该方法计算的孔隙度与岩心分析结果吻合较好,可以更真实地反映地层的储层特征和生产能力。

South Sulige block is a lithologic gas reservoir with low porosity and permeability,low pressure and low abundance,of which the heterogeneity is very high and pore structure is complex.Due to the influence of lithology and pore structure,the skeleton value is uncertain and it is hard to give a fixed value.It is difficult to obtain the true porosity of formation accurately by using the traditional method of calculating porosity by Wiley formula in sonic logging.In this paper,according to the principle of sonic logging and rock response characteristics,combined with core analysis data of this area and adjacent areas,using the acoustic time and core analysis porosity regression formula to calculate porosity first,and then,according to different shale content, the corresponding shale correction is carried out for the heavy shale content intervals on the basis of core regression formula, which eliminates the porosity calculation error caused by the influence of shale content. Practical application shows that the porosity calculated by this method is in good agreement with the results of core analysis, and can reflect the reservoir characteristics and production capacity of the formation more truly.