Study Of Well Test Design And Interpretation Method In Deep Water Gas Reservoir With High Temperature And High Pressure

Deep water gas reservoir with high temperature and high pressure usually has a strong stress sensibility and a trend to produce hydrate in well testing,causing difficulty for well test design and well test interpretation.As an important method to evaluate gas reservoir,well test plays a significant role in understanding reservoir characteristics and analysis gas reservoir production performance.Thus,it is necessary to establish a suitable well test model for deep water gas reservoir with high temperature and high pressure.The paper reviewed the methods for calculating z-factor of gas,which include HallYarbough method,Dranchuk-Purvis-Robinson method,Dranchuk-Abu-Kassem method?BrillBeggs method and LXF-RMP method.Based on the review and error analysis,the paper selected suitable methods to calculate z-factor for natural gas in gas reservoir with high temperature and high pressure.Then the paper discussed the method to determine well test time and the principle to design well test working system.And considering the strong trend to produce hydrate in well testing,the paper established a wellbore temperature distribution calculation model considering seawater temperature distribution and Joule-Thomson effect to predict risk of hydrate formation.And the paper established the well test models for vertical well in infinite gas reservoir or composite gas reservoir and horizontal well in infinite gas reservoir.All the models are solved by both perturbation method and numerical method.And the well test curves for pressure drawdown test and pressure buildup test are drawn.The basic characteristics of the well test curves and parameter sensitivity are analyzed.And the differences between pressure drawdown well test curves and pressure buildup well test curves are also analyzed.Based on the above research results,the deep water gas reservoir with high temperature and high pressure well test interpretation software is designed.The software is vertified by well test data coming from a deep water gas reservoir.And the well test interpretation result also suggested that a better interpretation result would be obtained after taking stress sensibility into consideration.