地层元素测井仪器结构参数的蒙特卡罗数值模拟

Monte Carlo Numerical Simulation of Structure Parameters in Formation Elements Logging Tool

建立地层元素测井的蒙特卡罗方法数值模拟模型,分别对仪器的屏蔽体、硼套、源距等仪器参数对测井响应的影响进行数值模拟研究。单一屏蔽体材料中钨镍铁屏蔽率最高,组合材料中钨镍铁+硼砂和钨镍铁+聚乙烯的屏蔽率比相同厚度钨镍铁的屏蔽率略高一些,钨镍铁+聚乙烯的效果更明显。实际仪器模型中11cm厚的钨镍铁屏蔽率大于0.9;硼套为10B与氟橡胶混合材料时其10B含量达到10%以上,达到降低仪器内部元素影响的效果;仪器外壳材料均可以采用沉淀不锈钢或铜,其对地层元素的解谱几乎没有影响。这些模拟结果可以为优化仪器结构参数提供参考。

The Monte Carlo simulation model of formation elements logging tool is established. With the model the effects of tool parameters including the shield, boron coating and source spacing are studied on logging responses. In the single shield materials, the shielding effect of Tungsten（W）, Nickel（Ni） and Iron（Fe） is the best. In the combined shield materials, the shielding effect of W-Ni-Fe＋Boron（B） and W-Ni-Fe＋polyethylene is better then that of W-Ni- Fe with the same thickness; the shielding effect of W-Ni-Fe＋polyethylene is much better. In practical tool model, the shielding effect of 11 cm thick of W-Ni-Fe material is above 0.9; if the Boron coating is the mixed material of ^10B and fluoro-elastomer, its ^10B content is more than 10%, which may reduce the tool＇s internal elements influencing effect. The tool shells may use settling stainless steel or Copper （Cu）, because they don＇t have any influence on spectrum deconvolution of formation elements. The above results may be used as a reference for optimizing the tool structure design.