Subsurface flow and geomechanics are often modeled with sequential approaches. This can be computationally beneficial compared with fully coupled schemes, while it requires usually compromises in numerical accuracy, at least when the sequential scheme is non-iterative. We discuss the influence of the choice of scheme on the numerical accuracy and the expected computational effort based on a comparison of a fully coupled scheme, a scheme employing a one-way coupling, and an iterative scheme using a fixed-stress split for two subsurface injection scenarios. All these schemes were implemented in the numerical simulator DuMu^x. This study identifies conditions of problem settings where differences due to the choice of the model approach are as important as differences in geologic features. It is shown that in particular transient and multiphase flow, effects can be causing significant deviations between non-iterative and iterative sequential schemes, which might be in the same order of magnitude as geologic uncertainty. An iterated fixed-stress split has the same numerical accuracy as a fully coupled scheme but only for a certain number of iterations which might use up the computational advantage of solving two smaller systems of equations rather than a big monolithical one.

中文翻译：

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完全耦合和顺序方法对水力和地质力学过程建模的准确性

地下流动和地质力学通常采用顺序方法进行建模。与完全耦合方案相比，这可能在计算上是有益的，而通常至少在顺序方案为非迭代方案时，通常需要在数值精度上做出折衷。我们将基于全耦合方案，采用单向耦合的方案以及使用固定应力分裂的两个地下迭代方案的比较，讨论方案选择对数值精度和预期计算量的影响。注入方案。所有这些方案都在数值模拟器DuMu ^x中实现。这项研究确定了问题设置的条件，其中因模型方法的选择而引起的差异与地质特征方面的差异一样重要。结果表明，在特定的瞬态和多相流中，影响可能会导致非迭代和迭代序列方案之间的显着偏差，该偏差可能与地质不确定性处于相同的数量级。迭代的固定应力拆分具有与完全耦合方案相同的数值精度，但仅用于一定数量的迭代，这可能会消耗解决两个较小的方程组而不是一个大的整体方程组的计算优势。