基于空间响应分布函数的水平井补偿密度测井快速正演模拟

水平井中补偿密度测井的正演模拟主要采用蒙特卡罗方法，计算时间较长，难以满足生产实时评价的需求。提出种补偿密度测井快速正演模拟的新方法，引入空间响应分布函数表征伽马场分布及地层不同体积元对探测器计数贡献。采用蒙特卡罗程序建立快速正演模拟所需数据库，利用空间响应分布函数计算不同地层区域对探测器计数贡献，实现补偿密度测井的快速正演模拟。数值模拟结果表明，新方法的计算精度与蒙特卡罗方法致，但计算速度提高十万倍以上，能够满足水平井井眼轨迹与地层关系确定中快速正演的需求。
Monte Carlo method is commonly used in forward simulations of compensated density logging in horizontal wells, but is computationally time-consuming and cannot meet the needs for real-time production evaluation. In this paper, a fast forward simulation method of compensated density logging is developed, and a spatial response distribution function is introduced to describe the contribution of gamma ray field distribution and different formation volume elements to the detector counts. Monte Carlo simulation is then employed to establish the database of fast forward simulation in advance. The spatial response distribution function is used to calculate the contribution of different formation regions to the detector counts, and the fast forward simulation of density logging is realized. The numerical simulation results show that the new method can provide results with the same accuracy as regular Monte Carlo simulation method, but the computation speed is increased by over two orders of magnitude, which can meet the needs for determining the relation between well trajectory and drilled formation in the horizontal well