Multi-rate time stepping schemes for hydro-geomechanical model for subsurface methane hydrate reservoirs

TL;DR

This paper introduces two multirate time stepping schemes for hydro-geomechanical models of methane hydrate reservoirs, improving computational efficiency while balancing accuracy and robustness.

Contribution

It presents novel extrapolation-based semi-implicit and compound-fast multirate schemes tailored for multi-time-scale hydrate reservoir simulations.

Findings

Semi-implicit method achieves higher speed-up but depends on time scale separation.

Compound-fast method is more robust and less sensitive to time scale ratios.

Performance varies with the relative time scales of model components.

Abstract

We present an extrapolation-based semi-implicit multirate time stepping (MRT) scheme and a compound-fast MRT scheme for a naturally partitioned, multi-time-scale hydro-geomechanical hydrate reservoir model. We evaluate the performance of the two MRT methods compared to an iteratively coupled solution scheme and discuss their advantages and disadvantages. The performance of the two MRT methods is evaluated in terms of speed-up and accuracy by comparison to an iteratively coupled solution scheme. We observe that the extrapolation-based semi-implicit method gives a higher speed-up but is strongly dependent on the relative time scales of the latent (slow) and active (fast) components. On the other hand, the compound-fast method is more robust and less sensitive to the relative time scales, but gives lower speed up as compared to the semi-implicit method, especially when the relative time scales of the active and latent components are comparable.