Multiphase flow and geomechanical behavior induced by gas production from silty-clay hydrate reservoirs through different horizontal well scenarios

• Published in: Computers and geotechnics Vol. 173; p. 106555
• Main Authors: Cao, Xinxin, Sun, Jiaxin, Qin, Fanfan, Gu, Yuhang, You, Zhigang, Ning, Fulong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2024
• Subjects: Geomechanical behavior; Horizontal well; Multiphase flow; Production prediction; Geomechanical behavior; Production prediction; Multiphase flow; Horizontal well
• ISSN: 0266-352X; 1873-7633
• DOI: 10.1016/j.compgeo.2024.106555

Accurately predicting the coupled response behaviors during production is essential for the exploitation of gas hydrate. However, the multiphase flow and geomechanical analysis for gas production through horizontal wells in fine-grained sediments are few reported. In this study, a coupled thermal–hydraulic-mechanical (THM) model is carried out to assess the production response behaviors under different schemes. The simulation results indicate that the cumulative gas production for dual horizontal wells by depressurization assisted with hot water injection (Winj) is about 4.0 times and 2.46 times as much as that of single horizontal one and dual horizontal wells without Winj during the short-term production, respectively. However, the corresponding multiples in gas production become 2.63 and 1.40 times for the long-term production. The seafloor uplift for these three production scenarios is similar and approximately 0.06 m within 30 days. However, the ultimate seabed subsidence are 1.15 m, 1.56 m and 2.59 m, respectively. The Z-displacement undergoes approximately linear reduction with depth, while the X-displacement exhibits a gradient distribution except in the near-wellbore area. By contrast, dual horizontal wells under the hybrid production condition have the highest gas productivity and the minimal instability risk. Furthermore, the modified Fetkovich formula can effectively perform the inflow dynamic analysis of horizontal well systems by depressurization. These findings provide a reference for determining production strategies involving horizontal wells in silty clay reservoirs.