C/O与C/H测井响应的数值模拟对比研究

Comparative study on numerically simulated C/O and C/H logging responses

准确地测定地层中含油饱和度是储层岩石物理评价的重要组成部分,C/H测井和C/O测井都是计算低矿化度储层含油饱和度的主要方法。为了对比C/H与C/O两种方法的测井响应效果,采用蒙特卡罗模拟方法,应用球状模型和参考Halliburton公司的C/O测井仪器储层性能检测仪(Reservoir Performance Monitor,RPM)所设置的模型进行数值模拟。计算得到了不同地质参数和孔隙结构下地层原子特征能窗的γ光子计数,分析了C/O和C/H与孔隙度和饱和度的关系以及对饱和度的灵敏度。计算结果表明:在套管井中C/H和C/O与孔隙度和饱和度具有相同的关系,都可以用于井下的饱和度计算。但是C/H受井眼环境影响更大,对饱和度的灵敏度更低,不适用于复杂井眼的饱和度计算。

[Background]The accurate determination of oil saturation is an essential part of reservoir petrophysical evaluation.Both C/H and C/O logging methods are primarily used to determine oil saturation in low-salinity reservoirs.[Purpose]The study aims to compare the logging response effects of the C/H and C/O methods.[Methods]Firstly,a spherical model and the model set by the C/O logging instrument RPM(Halliburton Company)were applied to Monte Carlo simulations,and the window counts of the atoms formed under different geological parameters and pore structures were calculated by MCNP5.Then,the relationship between C/O and C/H with saturation and the sensitivity to saturation were analyzed,and the response effects of C/O and C/H were compared.Finally,the mechanisms underlying the different response effects of C/H under different models were clarified.[Results&Conclusion]The analysis results show that C/H and C/O exhibit the same relationship with porosity and saturation in casing wells,and both can be used to calculate saturation.However,compared to C/O,C/H is more affected by the borehole environment and is less sensitive to saturation;therefore,it is not suitable for saturation calculations in complex boreholes.