深海水合物生产井筒水合物二次形成规律研究OA

To prevent secondary hydrate formation and enhance wellbore flow,the mathematical model to investigate the tem-perature and pressure in the development of the argillaceous natural gas hydrate.With the moderate sand control technique,this model predicted the temperature and pressure profiles along the well considering the sand particle size effect and the Joule-Thompson effect on heat transfer within the hydrate production wellbore.According to the moderate sand control principle,the paper also analyzed how the size of produced formation sand and the wellbore size could affect the secondary formation of natural gas hydrates in the wellbore.The effect is quantitatively described in the sensitivity analysis.Considering the develop-ment environment of NGH,several key factors were selected in the sensitivity analysis including produced formation sand size,wellbore diameter and thickness,production rate,thermal conductivity,and NGH formation depth.The analysis recommended the produced formation sand as less than 30 μm and the wellbore thickness as 0.389 m to reduce the risk of NGH secondary formation.The risk secondary NGH formation for shallow reservoir depth was higher than that for deep reservoir.The calcu-lation verified that the installation of local heating electrode could effectively reduce the secondary formation risk of hydrate near the mud line.The research results of this paper provide theoretical support for fine sand control and well structure design of deep sea hydrate reservoir production.