EnKF在油藏描述及开发优化中的应用研究与进展

Review on Reservoir Description and Optimization Problemswith Ensemble Kalman Filter

油藏精细描述模型和方法在油田开发调整方案设计计算中起主导作用,油藏精细描述成果是油藏开发设计中的基础。油田开发调整方案优化研究已有50多年历史,但截止本世纪初,优化方法都是基于控制理论的算法和基于敏感系数的算法,计算效率低,收敛性差,缺乏可操作性。最近几年来国际上许多学者将集合卡尔曼滤波(EnKF)方法引入到油藏工程领域,在油藏精细描述方面以及开发优化方面的取得了重要进展。本文对该理论的优势以及存在的问题做了评述。指出了在解决强非均质性、大规模油藏计算效率及多相流非线性等方面的突破,提供开发指标不确定性评价方法的可能性,该理论最终将形成与油藏数值模拟软件相结合的油藏开发优化算法,大大提高优化模型和方法的可靠性和实用性。论文指出了有待解决的问题及下一步研究方向。

In order to design modification program known properties of a reservoir. The research how to of field development, it is critical to characterize unoptimize reservoir adjustment plan has more than 50 years history. Efficient applications have, however, required either an adjoint or a gradient simulator method to compute the gradient of the objective function or a sensitivity coefficient matrix for the minimization. Both computations are expensive when the number of model parameters or the number of observation data is large. Recently, EnKF was introduced to petroleum engineering by many international scholars and has significant headway especially in reservoir characterization and Optimization Problems. the advantages and existing problem of ensemble Kalman Filter method is described briefly in this paper. This theory has been successfully applied to overcome strong heterogeneity, large number of variable and multiphase non--linearity in petroleum reservoir engineering and its applications look promising. The EnKF has been taken into use with simulation models for optimize method and provides optimize model with high efficiency and reliability. The possible developing direction in the near future and the problems implicit in EnKF are summarized as well.