基于电成像浮动刻度孔隙度谱的碳酸盐岩储层分类评价

Evaluation of Carbonate Reservoir Based on Electrical Imaging Floating Scale Porosity Spectrum

伊拉克X油田Mishrif组为厚层礁滩相碳酸盐岩,受沉积、成岩及构造作用多重影响,储层孔隙结构复杂,非均质性强,导致储层纵向物性差异大,但已有常规测井与核磁共振测井资料显示研究区储层孔隙度差异不大。因此,仅根据以上资料难以构建储层分类方法以表征储层孔隙结构之间的差异性和孔隙度与渗透率之间的关系。首先根据电成像测井资料,构建电成像绝对与浮动刻度孔隙度谱并提取特征参数,划分5类孔隙结构。然后依据常规测井数据以及取心井物性资料,利用电成像孔隙度谱划分的孔隙结构类型刻度常规测井数据,划分5类储层。最后构建不同类型储层的孔隙度—渗透率模型,且这两种物性参数相关性较好。结合岩心、铸体薄片、多级离心核磁共振实验数据特征,研究发现不同类型的储层孔隙结构、孔隙度和渗透率特征差异明显,充分体现了碳酸盐岩油藏受成岩作用影响导致储层非均质性强的特征。该方法对于储层精确分类与提高储层物性评价精度具有重要的意义。

The Mishrif formation in the X oilfield of Iraq is a thick layer of reef beach carbonate rock,which is influenced by multiple factors such as sedimentation,diagenesis,and tectonic processes.The pore structure of the reservoir is complex and highly heterogeneous,resulting in significant differences in vertical physical properties of the reservoir.However,conventional logging data and nuclear magnetic resonance logging data have shown that there is little difference in reservoir porosity in the study area.Therefore,it is difficult to construct a reservoir classification method based solely on the above data to characterize the differences between reservoir pore structures and the relationship between porosity and permeability.Firstly,the absolute and floating scale porosity spectra are constructed based on the electrical imaging logging data,and the characteristic parameters are extracted to divide the pore structure into five types.Then,based on conventional logging data and core well physical property data,the pore structure types divided by electrical imaging porosity spectrum are used to scale the conventional logging data into five reservoir types.Finally,porosity and permeability models are constructed for different reservoir types,and the correlation between these two physical parameters is good.Combined with the characteristics of core,cast thin section,and multistage centrifugal nuclear magnetic resonance experimental data,it's found that the pore structure,porosity and permeability characteristics of different reservoir types are significantly different,which fully reflected the characteristics of carbonate reservoir with strong heterogeneity caused by diagenesis.This reservoir evaluation method is of great significance for accurate classification of reservoirs and improving the accuracy of reservoir physical property evaluation.