基于蒙特卡罗方法的密度测井薄层影响分析

The Effect of Density Logging on Thin Layer Based on Monte Carlo Method

薄层是影响密度测井的重要因素，利用蒙特卡罗方法对密度测井进行数值模拟，获取密度测井对薄层的响应资料，用于研究薄层对密度测井的影响，确定密度测井记录点及计数率曲线变化规律。研究表明，对于低密度薄层，随着薄层纵向位置的移动，计数率先增大后减少，曲线形态对称，极大值点为记录点；对于高密度薄层，随着薄层纵向位置的移动，计数率先减少后增大，曲线形态近似对称，极小值点为记录点。同时针对密度测井最小纵向分辨率进行了讨论。

Thin layer was an important factor influencing the density logging. Monte Carlo method was ap- plied to simulate the density logging and get the data of density logging response of thin layer, by which the influence of thin layer on the density logging was studied to determine the density log- ging record point and the change rules of the counting rate curve. The research indicates that the counting rate of low density thin layer increases initially and then decreases with the longitudinal movement of the thin layer. The shape of the curve is approximately symmetrical and the maxi- mum point is a recorded point, while for the high density thin layer, the counting rate decreases first and then increases with vertical movement of the thin layer, the shape of the curve is also ap- proximately symmetrical and the minimum point is the recorded point. Meanwhile, the minimum vertical resolution of density logging is discussed in this paper.