Implementation of a Numerically Stable Algorithm for Capillary Hysteresis in Gas Hydrate Deposits

Area of Science:

• Geosciences
• Petroleum Engineering
• Computational Fluid Dynamics

Background:

• Gas hydrate deposits are significant energy resources.
• Accurate simulation of multiphase flow in these deposits is crucial for production.
• Capillary hysteresis effects complicate fluid flow modeling.

Purpose of the Study:

• To develop a numerically stable algorithm for intrinsic capillary hysteresis in gas hydrate simulations.
• To improve the fidelity of multiphase flow simulations in gas hydrate systems undergoing cyclic processes.

Main Methods:

• Developed a new algorithm based on elastoplastic return mapping for capillary hysteresis.
• Extended a stable two-phase immiscible flow algorithm.
• Implemented the algorithm in a gas hydrate flow simulator.
• Incorporated dynamic computation of reversible and irreversible gas saturation components.

Main Results:

• The developed algorithm demonstrates numerical stability and robustness for cyclic drainage and imbibition processes.
• Numerical tests, including a field-scale case, validate the algorithm's performance.
• The code successfully simulates multiphase flow in gas hydrate systems.

Conclusions:

• The new algorithm provides a stable and robust method for simulating capillary hysteresis in gas hydrate systems.
• This advancement is critical for accurate forward simulation of gas production via cyclic depressurization.
• The developed code enhances the reliability of predicting gas recovery from marine gas hydrate deposits.