Numerical simulation on natural gas hydrates exploitation via multilateral well: Impacts on sand production and geomechanical responses

Abstract

Multilateral wells are regarded as a well type that enhances the efficiency of natural gas hydrates (NGHs) exploitation by promoting pressure propagation and expanding the drainage area, while might causing sand production, stress concentration, subsidence, and other hazards. Understanding sand production and geomechanical responses in multilateral wells is crucial for ensuring safety. As a continuation of our previous research, a coupled thermal–hydraulic-mechanical-chemical (THMC) model was constructed to investigate sand production and geomechanical responses in multilateral wells. The gas productivity, sand production, and potential geomechanical risks were assessed using various well configuration designs. The findings indicate that, compared to vertical wells, a single-branch multilateral well can increase gas production by 413 %. Compared to the right-angle layout of branches, the symmetric configuration of a 180° dual-branch well can reduce the risk of sand production by nearly 25 %. Additionally, sand production issues are most severe during the initial phase of exploitation, while stress concentration and stratum deformation pose long-term geological risks. This study provides critical insights into the potential application of multilateral well technology in NGHs exploitation.