Multiphase Flow Behavior of Layered Methane Hydrate Reservoir Induced by Gas Production

Abstract

Gas hydrates are expected to be a potential energy resource with extensive distribution in the permafrost and in deep ocean sediments. The marine gas hydrate drilling explorations at the Eastern Nankai Trough of Japan revealed the variable distribution of hydrate deposits. Gas hydrate reservoirs are composed of alternating beds of sand and clay, with various conditions of permeability, porosity, and hydrate saturation. This study looks into the multiphase flow behaviors of layered methane hydrate reservoirs induced by gas production. Firstly, a history matching model by incorporating the available geological data at the test site of the Eastern Nankai Trough, which considers the layered heterogeneous structure of hydrate saturation, permeability, and porosity simultaneously, was constructed to investigate the production characteristics from layered hydrate reservoirs. Based on the validated model, the effects of the placement of production interval on production performance were investigated. The modeling results indicate that the dissociation zone is strongly affected by the vertical reservoir's heterogeneous structure and shows a unique dissociation front. The beneficial production interval scheme should consider the reservoir conditions with high permeability and high hydrate saturation. Consequently, the identification of the favorable hydrate deposits is significantly important to realize commercial production in the future.

Numerical Investigation on Gas Production Performance in Methane Hydrate of Multilateral Well under Depressurization in Krishna-Godavari Basin

“…Furthermore, the method used to decompose the solid hydrate was depressurization. And the depressurization processes both in this simulation lasted for 6 days [36]. The wellbore pressure of the production well was decreased from 25.22 MPa to 19.0 MPa.…”

“…The simulation domain was discretized into 22 × 18 × 34 grids (13464 cells) in X, Y, and Z directions. According to Yuan et al, the principal processes occur around the production well within a limited distance during the exploitation [36]. Therefore, the interval of each grid in MHCZ is 1.0 m along the z-coordinate.…”

Effect of Perforation Interval Design on Gas Production from the Validated Hydrate-Bearing Deposits with Layered Heterogeneity by Depressurization

“…For different NGH sites, numerical simulation was used to evaluate the production potential of hydrate reservoirs and to conduct sensitivity analysis. Based on the geological data in the Eastern Nankai Trough, Konno et al [29], Yuan et al [30], and Sun et al [31] investigated the long-term production performance through depressurization from the hydrate-bearing sediments. All of their results showed excessive simulated water production.…”

The effect of heterogeneities in hydrate saturation on gas production from natural systems

“…Kim et al, 2018;Yan et al, 2018;Yu et al, 2018;Zheng et al, 2018), or as a sequence of layers with constant hydrate saturation (e.g. Chen et al, 2018a;Feng et al, 2019;Yuan et al, 2017). Natural systems rarely display this level of homogeneity, as small compositional variations or structural irregularities will alter how hydrate is distributed (Behseresht and Bryant, 2012).…”