基于岩石物理模板的孔隙度非敏感流体因子构建方法及应用

流体因子是一种指示储层含流体特征的常用工具,在储层流体识别中发挥着重要作用.现有的大多数流体因子除了反映孔隙流体性质以外还与孔隙度密切相关,对同一储层的高孔和低孔区域具有不同的流体敏感性,可能造成非均质储层的流体识别假象.本文提出一种消除孔隙度影响的流体因子,并将其应用于非均质储层流体识别.首先根据研究区地质特征选择并校准岩石物理模型,以此为基础优选横波阻抗I_S和饱和岩石体积模量与剪切模量之比K_sat/μ_sat构建能够分离岩石骨架和孔隙流体性质的I_S-K_sat/μ_sat岩石物理模板;而后通过对数域多项式拟合和归一化的方式构建孔隙度非敏感流体因子PINF(Porosity-Insensitive Normalized Fluid Factor).最后将本文提出的流体因子应用于苏里格气田非均质储层流体识别,实际测井和地震资料测试结果表明该流体因子的预测结果与测井解释结果相符,在同一储层段的高孔和低孔区域均显现出较好的应用效果,适用于非均质储层流体识别.

Construction and application of porosity-insensitive normalized fluid factor based on rock physics template

Fluid factor is an indicator for reservoir fluid,which plays an important role in reservoir fluid identification.Most widely used fluid factors both related to pore fluids and porosity.They show different fluid sensitivities to the regions with high porosity and low porosity in a same heterogeneous reservoir,which may lead to incorrect fluid identification results.In this paper,an attribute,the Porosity-Insensitive Normalized Fluid Factor(PINF),is proposed and applied to fluid identification in heterogeneous reservoirs.Firstly,we choose S-wave impedance IS and the ratio of bulk modulus and shear modulus Ksat/μsat as porosity and fluid sensitive parameters respectively.Then,we construct a new IS-Ksat/μsat Rock Physics Template based on a calibrated site-specific rock physics model to separate the properties of rock skeleton and pore fluid.Finally,the PINF is obtained by correcting the normal fluid factor related to porosity with fitting curves.We applied the proposed fluid factor to fluid identification of heterogeneous reservoir in Sulige gas field located in the Ordos Basin,central China.The results obtained from the well logging and seismic inverted data are both consistent with the well logging interpreted results,which demonstrate the effectiveness of PINF in fluid identification of heterogeneous reservoir.