基于单井敏感性区域的油藏模拟辅助历史拟合

Reservoir assisted history matching based on sensitivity region of single well

针对当前历史拟合中单井敏感性区域难以确定和反演参数变量维数大的问题,建立了一种快速有效计算单井敏感性区域的方法,并提出了一种模型参数化方法。利用Fast-Marching Method(FMM)求解油藏压力传播过程中的程函方程,计算压力波从井点到达每个网格的飞行时间,依据飞行时间确定油藏三维单井敏感性区域。以单井敏感性区域内网格的模型参数平均值作为参数变量来降低求解维数,并通过近似扰动梯度升级优化算法来提高拟合效率。实例证明,此方法对油藏动态生产指标的拟合取得了较好的效果,整体过程计算代价小,满足工程应用的要求。

In view of the limitations that sensitivity region of single well cannot be accurately estimated and the dimension of inversion model parameter vector in objective function is huge for assisted history matching, this study establishes a novel method to calculate sensitivity- region of single well fast and efficiently, and proposes a simple method for model parameterization. We use the Fast-Marching Method （FMM） to solve the pressure-diffusivity equation of Eikonal equation form and calculate the arrival time from well point to each grid of reservoir model. The sensitivity- region of single well is determined according to the arrival time in 3D space. Based on the sensitivity- region of single well, we take the average of model parameter of the grids in the region as the elements of inversion model parameter vector to reduce its dimension, and use an upgraded perturbation gradient approximation algorithm to improve the computational efficiency. With the proposed method for calculation of sensitivity region of single well and model parameterization, the application case shows a good matching result and low computational cost for historical dynamic production data, and can meet the engineering requirements.