三种混合泥质砂岩有效介质通用电阻率模型比较

复杂泥质砂岩油气层的识别与评价一直是测井解释领域亟待解决的难点和热点问题,因此,针对复杂泥质砂岩油气层的特点,有必要研究能够描述这类储层导电规律的新导电理论。针对用于复杂泥质砂岩油气层解释的3种混合泥质砂岩有效介质电阻率模型,从理论和实验角度,进行了全面系统的比较。通过对3种有效介质通用电阻率模型建模理论基础的分析,可知混合泥质砂岩有效介质非对称模型基于HB方程和并联导电理论,对称模型基于对称导电理论和并联导电理论,而孔隙结合模型基于混合介质电导率积分方程;对称电阻率模型可用于多连续项存在的地层,而非对称电阻率模型和孔隙结合电阻率模型只允许水为连续项。对骨架不导电的纯砂岩进行模型化简,可知非对称电阻率模型和孔隙结合电阻率模型可以简化成阿尔奇公式,而对称电阻率模型能化简成类似阿尔奇公式。通过1组混合泥质砂岩人造岩样和2组分散泥质砂岩岩样以及1组骨架导电人造岩样的实验数据,验证3种有效介质通用电阻率模型均适用于混合泥质砂岩地层解释,且精度相近。

Comparison of Three Generalized Effective Medium Resistivity Models in Laminated and Dispersed Shaly Sands

Evaluation on complex hydrocarbon-bearing shaly sand reservoirs is a difficult problem in logging technology.Since conductance mechanism in complex hydrocarbon-bearing reservoirs is different from that in common hydrocarbon-bearing reservoirs,a new conducting theory should be proposed to describe the conducting mechanism for complex hydrocarbon-bearing reservoirs.The theoretical and expe-rimental comparison of three effective medium resistivity models in laminated and dispersed shaly sands is addressed in detail.Theoretical analysis shows that asymmetrical effective medium resistivity model comes from HB equation and parallel conductance theory,and symmetrical effective medium resistivity model is established from symmetrical theory of resistivity interpretation and parallel conductance theory,while effective medium pore combination resistivity model is derived from conductivity integration equation of mixed medium.Also symmetrical effective medium resistivity model can be applied to the multi-continuous formation with more than two continuous components;asymmetrical resistivity model and pore combination resistivity model can be used only in the formation of a continuous component of water.The asymmetrical effective medium resistivity model and effective medium pore combination resistivity model can be simplified to Archie equation,and symmetrical effective medium resistivity model can be simplified to an equation similar to Archie equation in clean sand with non-conducting matrix grains.One set data from synthetic core sample of dispersed and laminated shaly sands,two set data of the rock sample of dispersed shaly sands,and one set data of artificial sample with conducting matrix grains show that the three models can be applied to dispersed and laminated shaly sands,and their application accuracy is about the same.